A nail polish remover device adapted for removing fingernail polish from all the fingers and thumb on a hand comprising a cylindrical receptacle defining a chamber with a liner casing mounted within the chamber. A finger support member defining a plurality of concave recesses to receive the fingers of a user is secured to the liner casing and a plurality of bristle members extend from a side support of the liner casing toward the concave recesses. A thumb support member defining two concave recesses is secured to the liner casing and a plurality of bristle members are mounted to the liner casing and project toward the thumb recesses.

1. Field of Invention
The present invention relates to devices for removing fingernail polish and in particular relates to a molded container having an insertible one piece molded bristle liner suitable for removing fingernail polish from the thumb and fingers of either hand.
2. Description of the Prior Art
The prior art contains many references directed to nail polish removal receptacles which support or suspend an insert structure to aid in the removal of hardened nail polish from fingernails after a finger has been immersed in nail polish remover contained within the receptacle. U.S. Pat. Nos. 4,474,195; 4,440,181; and 4,282,891 disclose nail polish remover devices in which a receptacle is provided with a sponge or sponge-like absorbent member insert. The sponge member insert is formed with an aperture forming a finger hole into which the finger is placed. The absorbent sponge absorbs nail polish remover and upon insertion of the finger into the sponge aperture, the polished fingernail comes into contact with the sponge and nail polish remover solution to remove the polish from the nail. The solution and polish fragments are wiped from the inserted fingernail by the sponge as the fingernail is removed from the receptacle jar. A multilayer foam surgical scrub sponge similar to those shown in the patents noted above is disclosed by U.S. Pat. No. 4,866,806. In this reference a removable serrated insert is accommodated in the center of the sponge to enable insertion of the fingers to cleanse and disinfect the cuticle areas.
U.S. Pat. No. 4,480,351 discloses a surgical scrub brush provided with two sets of brushes in each side of the molded container body. The brush bristles are formed with a configuration of smaller bristles disposed in a longitudinal channel or gap between taller bristle groups whose tips are laterally exposed to facilitate nail cleaning. The individual bristle members have a triangular cross-section.
Another surgical scrub brush is shown in U.S. Pat. No. 3,966,335. This patent features four bristle-lined troughs for simultaneous scrubbing of the four fingers. Rows of relatively short stiff bristles are used for cleaning the finger tips, nails, and under the nails.
U.S. Pat. No. 4,397,324 discloses a nail polish receptacle which is provided with a brush member disposed in the receptacle by wire legs which support the brush element in the approximate determines of a circular finger opening. Similarly, U.S. Pat. No. 4,321,936 discloses a nail polish remover receptacle containing a plurality of downwardly spaced apart free floating legs with an inwardly curved end portion. The legs have bristles or brush like elements secured thereto which extend inward. When a person inserts a finger into the device, the finger will contact the bristles and push the legs outward in such a manner that the nail polish remover liquid on the bristles will remove the nail polish from the fingernails. U.S. Pat. No. 3,316,922 discloses a nail polish remover device in which a circular brush with a circular open center is mounted on a group of abutments extending inwardly from an insert surface. The brush member is positioned on the abutments and the brush stem is moved against the abutments to snap into an inclined position. In U.S. Pat. No. 2,771,621 a reciprocating spring braced member carries a brush head with bristles extending into a recess into which a finger is placed to remove the nail polish.
U.S. Pat. No. 4,397,324 discloses a combination golf ball and club head cleaner that is mounted to the fender of a golf cart or post. The device includes a watertight housing having a first brush-lined chamber for cleaning a golf ball and a second brush-lined parallelepiped chamber for cleaning a golf club. A ball holder mounted for reciprocation along its vertical axis in the ball cleaning chamber retains a golf ball allowing it to rotate when scrubbed. Brushes lining the first chamber scrub the ball as the holder is reciprocated.
An apparatus for cleaning and sanitizing combs through mechanical bristles and disinfectant fluids is disclosed in U.S. Pat. No. 5,454,131. The apparatus includes a container having a rectangular base with enlarged rectangular front and rear walls and smaller rectangular side walls. The container further includes a lid having a lower open end which is removably positioned on the upper edges of the walls. A plurality of pointed semi-rigid bristles are secured to the interior surfaces of the front and rear walls of the container.
U.S. Pat. Nos. 5,048,547 and 4,819,672 issued to the present inventor disclose a cylindrical housing holding a one piece brush assembly which has inwardly projecting integral triangular shaped bristles configured to receive a finger and remove the fingernail polish.
One patent of interest which is directed toward cleaning the thumb and fingers of a hand is U.S. Pat. No. 4,476,883. This patent discloses an U-shaped container assembly for applying a predetermined liquid or solution to the fingernails of a person. A sponge material is disposed in the interior of a housing and is provided with a plurality of recesses dimensioned and configured to receive the fingertip and the fingernail of the user in a predetermined array facilitating placement of all the fingers and thumbs in the various recesses. A liquid or solution is applied to the interior of the housing and the sponge material and the housing is filled to a level sufficient to form small pools in the bottom of each of the finger recesses.
Another thumb and finger cleaner, U.S. Pat. No. 5,065,778 discloses a fingernail polish removing container with a base, and a lid, and a fingernail scrubbing structure mounted within the container in spaced relation to the container base bottom wall and to the lid top wall. In some of the disclosed embodiments the finger nail scrubbing structure is supported within the container base, and includes five finger bore openings, four of which are of substantially equal diameter on a circle with the fifth bore opening, a thumb tip receiving opening, being of greater diameter than the other four finger openings and displaced closer to the center of the fingernail scrubbing structure to receive simultaneously the fingernails of the fingers and thumb of one hand. The finger bore openings are provided with sponge like inner walls to remove nail polish from the nails, and the nail polish removing liquid is sloshed between the bottom and the upper chambers to saturate the finger bore opening wall surfaces.
Another finger nail cleaning patent which uses a mechanical pump assembly, U.S. Pat. No. 4,020,856, pulsates jets of liquid to the ends of the fingers of a user's hand while the hand is positioned on a grooved hand rest.
It can thus be seen that the aforenoted patents do not teach or disclose the present invention which utilizes a molded container having a removable one piece integrally molded bristle liner which provides a simple means of removing nail polish from the thumb nail and fingernails of each hand in a clean environment relatively free of bacteria and virus. Many of the above cited patents use sponge or sponge-like product to apply nail polish remover to the fingernails. There are health reservations about the use of sponge product in beauty salons because of the occurrence of bacterial collection and growth in the sponge.

Thumb and finger nail polish remover device


A power adapting device has a connecting seat, at least two conductive strips, and an adapter. The connecting seat has a mounting portion with two slots. The at least two conductive strips are mounted in the connecting seat. Each of the at least two conductive strips has a positioning sheet, a conductive sheet obliquely protruding upward from the positioning sheet, an arced sheet protruding down from the positioning sheet, and an engaging sheet protruding down from the arced sheet. The engaging sheet has a semispherical contact. The adapter is electrically connected to the conductive sheets of the at least two conductive strips. With different power adapting devices of different standards using in cooperation with a charger, the charger can comply with different electrical socket standards via the power adapting devices.

1. Field of the Invention
The present invention relates to a power adapting device, especially to a power adapting device for a charger, such that the charger can comply with different electrical socket standards.
2. Description of the Prior Art(s)
In recent years, usage of consumer electronic products, such as smart phones, tablet computers, portable listening devices, and the like, has been greatly increased. Since the electronic product is continuously used for a long time in everyday life and consumes much electric power, a user of the electronic product would carry a charger along with him so as to recharge the electronic product whenever needed. The charger has multiple power input pins and multiple power output pins. The power input pins are inserted in an electrical socket. The power output pins are electrically connected to the electronic product. Thus, the electronic product is charged through the charger. However, the electrical sockets differ by countries, and so do the power input pins of the charger. For example, a charger with American standard power input pins is unable to be fitted in a European standard socket or a United Kingdom (UK) standard socket. Therefore, whenever a business traveler goes on the trip abroad and wants to charge the electronic products carried with him, the business traveler has to prepare a charger that has power input pins fitting in the specific socket of the country, and preparing different chargers for different country is troublesome.
To overcome the shortcomings, the present invention provides a power adapter to mitigate or obviate the aforementioned problems.


An implantable defibrillation arrangement comprising a defibrillation device having a sensing component and a defibrillation component, and an electrode lead comprising a lead body, a plug, a sensing electrode for sensing cardiac action potentials with a first electrode supply lead, and a defibrillation electrode for transmitting shock pulses to cardiac tissue with a second electrode supply lead, wherein a switching unit is provided to switch the sensing electrode to the potential of the defibrillation electrode in response to the output of a defibrillation shock by the defibrillation component.

1. Field of the Invention
At least one embodiment of the invention relates to an implantable defibrillation arrangement.
2. Description of the Related Art
Implantable defibrillators or cardioverters (ICD) have been known and used in clinical applications for a long time, and have been the subject of sustained technical development for decades. This applies to an even greater extent for implantable cardiac pacemakers and the associated electrode leads. Combination cardiac stimulation and defibrillation arrangements, including the electrode leads (ICD electrodes) developed especially therefore, have also become established as a special class of devices on the device market and in clinical applications. Such combination devices are referred to as cardiac pacemakers for cardiac resynchronization therapy with defibrillator, or CRT-D devices.
FIG. 1 shows a schematic depiction of such an arrangement 100 including electrodes implanted in the heart H of a patient. Accordingly, a cardiac stimulation and defibrillation device 110 is connected to the heart H via an electrode lead 120 which comprises three lead branches or electrode supply leads 130, 140 and 150. Each lead branch comprises sensing or stimulation electrodes (which are not depicted individually) on or near the distal end thereof, and lead branch 150 also comprises an elongated defibrillation electrode 160. In the arrangement shown, lead branch 130 is placed in the right atrium, lead branch 140 is placed in the left atrium of the heart H, and lead branch 150 on which defibrillation electrode 160 is installed is placed in the right ventricle (RV).
When a shock is administered, only the shock coil of the RV electrode is switched to a high-voltage potential, while the bipolar sensing and stimulation system remains at the output potential. The supply leads inside electrode lead 120 must therefore be designed with insulating clearances that are resistant to high voltage.
In all of the ICD electrodes known to date, insulating clearances for high voltages must be maintained within the electrode lead, which limits a further reduction of the electrode diameter and prevents the integration of a shock coil onto a CS electrode.

Implantable defibrillation arrangement and electrode lead


A circuit arrangement for generating a high DC voltage utilizes a voltage multiplier cascade which requires two alternating, non-overlapping pulse trains which are generated by a pulse generator. For given applications, for example, contactless chip cards, the supply voltage is derived from an ac voltage induced into a coil and rectified by means of a bridge rectifier. This gives rise to a voltage drop. When the pulse generator operates utilizing the supply voltage, the amplitude of the output pulses is lower, i.e. a further voltage drop occurs. Therefore, in order to overcome this limitation, the pulse generator does not derive the pulses for feeding the cascade from the rectified operating voltage, but directly from the ac voltage. This results in a higher amplitude and a better efficiency. Another feature includes the blocking of the pulse generator so that it does not represent a load to the ac voltage.

This invention relates to a circuit arrangement for generating a supply voltage in the form of a dc voltage which is high relative to a reference voltage. The circuit comprises a chain of diode arrangements which are connected in series with one end of said clain delivering the high dc voltage, the junctions of the diode arrangements each being connected to a respective capacitor. The other terminals of the capaciters are connected alternately to another one of two pulse outputs of a pulse generator, non-overlapping pulses being generated at the pulse outputs.
A circuit arrangement of this kind is known from the publication "IEEE Journal of Solid-State Circuits", Vol. SC-11, No. 3, June 1976, pp. 374 to 378. The high voltage thus generated serves to power given circuit elements or circuit sections, for example, the so-called EEPROMs in a digital circuit arrangement. In the known circuit arrangement the pulse generator comprises an oscillator which controls the two pulse outputs of the pulse generator via two series-connected inverters. Overlapping of the pulses at the two pulse outputs is prevented by appropriate proportioning and the amplitude of the pulses generated at these outputs is inherently lower than the supply voltage.
Digital circuit arrangements are often powered by way of a comparatively high-ohmic ac voltage, via a bridge rectifier. An example of such an arrangement is the so-called contactless chip card where an integrated semiconductor circuit is inserted in a data carrier resembling a credit card, the data exchange and the powering of the circuit being realised via a single coil by way of an ac voltage of high frequency induced therein. This gives rise to some problems which necessitate special steps. Due to the construction and the operation of such a chip card in conjunction with an appropriate reading device and a coil contained therein, the coupling between the two coils is not very tight, so that the rectified supply voltage derived from the ac voltage may be loaded only to a small extent. Furthermore, the limited size of the coil makes the generation of comparatively high supply voltages difficult or almost impossible. Moreover, the value of the ac voltage and hence that of the dc voltage derived therefrom is not very constant and must be stabilized by way of special steps. The derived dc voltage, moreover, is lower than the amplitude of the ac voltage by an amount corresponding to the forward voltages of the bridge rectifier. Thus, when the described circuit arrangement is to be used in such a device, a comparatively large number of stages will be required in order to reach the necessary level of the high dc voltage in a reliable manner.

Circuit arrangement for generating a high DC voltage


User's interests can be explicitly determined via keywords that the user specifies, and/or are implicitly constructed from user browsing and reading activity. User interests may be expressed as an interest profile. Conceptual keywords related to user interests are selected by combining spreading activation and word co-occurrence, by latent semantic analysis, or other methods.

Reading is a unique and essential human activity that furthers our collective knowledge and history. Reading is impacted by the complexity of the information environment in which it occurs. The over-abundance of information affects the material selected for reading, as well as the depth in which it is studied.
One of the major advantages of electronic text is that it is much easier to search for keywords within electronic text than ordinary text on paper. Arguably, the onset of web search engines that enable massive search over a large amount of electronic text is the most revolutionary information access development since the invention of the paper book.
The amount of available time and resources to understand written text is shrinking in people's ever-busying lives. These changes in their environment have directly affected the way people interact with written text. Increasingly, reading is occurring online in web logs ("blogs") and on the Internet, and less so on paper. Moreover, readers tend to skim quickly for relevant information nuggets instead of analyzing a piece of text for deep meaning.
Readers are increasingly skimming instead of reading in depth. Skimming also occurs in re-reading activities, where the goal is to recall specific facts surrounding a topic. Bookmarks and highlighters were invented precisely to help achieve this goal. These fundamental shifts in reading patterns have motivated researchers to examine possibilities for enhancing modern-day reading activities. For all these skimming activities, readers need effective ways to direct their attention toward the most relevant passages within text.
Unfortunately, there are current deficiencies in reading/browsing interfaces. For example, current search technology typically allows only exact keyword matches. Once the search is performed, a list of search results is displayed to the users, and they are then allowed to select from this list. Since only exact keyword matches are given, users searching for the keyword "tennis" will only find articles that explicitly mention "tennis." Articles that are highly relevant to tennis but do not contain many mentions of "tennis" will be ranked low or may be missed completely.
There is a large body of work in text processing and information retrieval, much of it based upon latent semantic analysis (LSA) and similar techniques, including search-related summarization. Key sentences can be identified in a document to use as a summary of that document.
One related technique is conceptual search, also known as associative search, i.e., finding documents that refer to concepts described by a given set of terms. Typically, conceptual searches are performed by first applying keyword expansion techniques from information retrieval systems to find related conceptual keywords, and then using these conceptual keywords to perform a search. Related conceptual keywords will also be included in the results of this search process.
The results lists generated by search engines do not highlight relevant passages, but they do highlight exact keyword matches. It is desirable to develop a method and system to direct user attention to sentences or portions of the document that are most relevant to the concepts described by the user's keywords, whether or not these sections explicitly include the user-specified keywords.
In traditional text search systems such as Google, search terms occurring in the retrieved documents are highlighted to give the user feedback. However, conceptually similar keywords are not highlighted, which could be computed by techniques such as LSA. LSA is the basis of a variety of document analysis and search techniques. One aspect of using LSA for text-based searches is that it can locate a document that may be highly relevant to the specified search terms and yet may not actually contain those terms. In other words, LSA can be used to model semantic similarity between documents and passages. It is desirable to develop a system capable of highlighting the most relevant search results regardless of whether and with what frequency the search terms themselves are contained in the results.
Another potential model for modeling semantic similarity between words and documents is the cognitive model called spreading activation, which models human memory retrieval. Spreading activation has been studied extensively for the purpose of both information retrieval and modeling human semantic memory. Spreading activation has also been shown to intelligently model user behavior in browsing a web site. Spreading activation has been shown in cognitive psychology research to simulate how humans retrieve memory chunks in the brain. Spreading activation can be used to simulate and predict the degree of similarity between two pieces of memory chunks.
Word co-occurrence models the relatedness of concepts and the semantic network of a body of text. Word co-occurrence has been used in statistical language processing, and is constructed by understanding how often conceptual keywords occur near each other in the text.

Method for automatically performing conceptual highlighting in electronic text

Abstract: One embodiment automatically highlights sentences and other information that contain conceptual keywords related to user interests. Highlights can be activated when the user directly performs a keyword search or index search, or the invention can generate information reflecting user interests, apply it to the text, and generate and display highlights. One embodiment includes an algorithm for computing a conceptual keyword vector through an iterative spreading activation process also employing word co-occurrence. A conceptual index of the text may be created and then combined with conceptual highlighting.


The disclosed, embodiments relate to a high-voltage supply (11, 13, 23) for an X-ray device. The X-ray device comprises an X-ray tube (15) and a high voltage generator(1), for generation of the high voltage necessary for operating the X-ray tube (15). The high voltage supply (11, 13, 23) comprises electrically-conducting lines (11, 13), for the connection of the high voltage generator to the X-ray tube (15). Each of the lines (11, 13) comprises one end which may be connected to the high voltage generator (1) and a further end which may be connected to the X-ray tube (15). At least one end of at least one of the lines (11, 13) may be connected to an electrical terminal resistor (39) which may be arranged between the line (11, 13) and the high voltage generator (1), or between the line (11, 13) and the X-ray tube (15).

X-ray tubes are typically constructed as high-vacuum tubes. Because of the high vacuum, sparkovers, and the resultant short circuit, between the cathode and the anode of the X-ray tube when the X-ray voltage, which is in the kilovolt range, is applied are fundamentally prevented. Slight quantities of residual gases, which contaminate the high vacuum, however, are unavoidable. This is true particularly because over the course of operation of the X-ray tube, gaseous ingredients of material emerge in the interior of the tube. The residual gases can be ionized by the X-ray voltage. The ionization may cause a sparkover and thus the short circuit inside the X-ray tube.
The courses over time of the short-circuit currents and the resultant events for charge compensation in the lines of the high-voltage supply sometimes have very steep flanks, since they proceed very quickly. The resultant interference spectrum therefore extends into the upper megahertz range and is extremely broadbanded. Moreover, the short-circuit currents and charge compensation currents cause vibrations associated with over-voltages, and these vibrations fade only very slowly.
Because of such interference signals and over-voltages in the high-voltage circuit of the X-ray device, problems in the function of the electronics and the computer system can occur. Often, component failures also occur, above all in the high-voltage circuit of the high voltage generator. Besides the downtimes in operation and expensive damage to the X-ray device, these problems also cause an increased radiation exposure to patients to be examined, who because of system failures must be examined repeatedly.


A system and method for communications link status analysis is disclosed. In embodiments, the system includes a radio systems interface (RSI) for listening to communications assets of a ground-based or mobile host platform. Radio data on communications traffic and their originating platforms is stored and analyzed to determine the link status of current communications links to other platforms. A link record is updated with the current links and associated platform information. A propagation analyzer forecasts future link statuses for identified current links based on the available platform data and forwards the propagation forecasts to operators of the host platform.

Nuclear events, natural disasters, or other manmade catastrophic events may result in widespread disruption of radio frequency (RF) communications infrastructure. In such contested environments (e.g., Nuclear Command, Control, and Communications (NC3) environments or cyber contested environments), assessment of communications systems, their components, and their performance is essential to establishing and maintaining enduring, survivable, and path-diverse airborne communications networks.

Unified communications link status analyzer apparatus for agile control in contested environments


The invention relates to a nozzle head and to a fluid injection valve, in particular to a motor vehicle injection valve. A nozzle head for atomizing a fluid for a fluid injection valve with a valve body, through which flow can pass, may include a longitudinal axis and a nozzle perforated disk having a front surface and an opposite inner surface. The nozzle perforated disk may comprise at least one nozzle hole channel completely penetrating the nozzle perforated disk in the direction of the longitudinal axis and including includes an entry surface at a first channel end and an outlet surface at a second channel end wherein the entry surface is formed on the inner surface of the nozzle perforated disk. A nozzle hole projection of the nozzle hole channel has a channel wall with a wall height (h) extending away from the inner surface and is configured over a circumference of the nozzle hole projection so that the second channel end corresponds to a channel wall end of the channel wall configured so as to face away from the front surface.

Fuel injection valves may include a nozzle head for atomizing a fluid. Fuel injection valves of this type are customarily used for atomizing fuel in a combustion chamber of an internal combustion engine. In particular, if the fuel is "directly injected" into the combustion chamber of an internal combustion engine designed as a spark-ignition engine, the fuel may be very finely atomized, inter alia with the aid of the nozzle head. In order to produce as complete a combustion as possible in a spark-ignition engine, a fine mixture of air present in the combustion chamber and the injected fuel is required.
With the aid of the direct injection, the fuel in spark-ignition engines of internal combustion engines may be directly injected into the combustion chamber, thus affording the advantage of reduced fuel consumption in comparison to an earlier method of introducing fuel, the "manifold injection". Furthermore, control of an exhaust gas after treatment system of the internal combustion engine may be considerably improved with the aid of direct injection.
A further advantage of direct injection is an improvement in elasticity of the internal combustion engine in respect of the response behavior thereof during dynamic operation. The fuel enters the combustion chamber substantially more rapidly than in the case of the manifold injection, in which the fuel enters the combustion chamber together with the combustion air flowing in via a gas inlet valve. However, it is problematic that the required homogeneous mixture has to be prepared within a short period of time in order to obtain the direct injection advantages mentioned. Since the fuel is introduced rapidly in the combustion chamber, only little time is available for the fuel to evaporate and to mix with the combustion air.
The fuel injection valve and the spray preparation thereof are therefore particularly important in particular for the direct injection. The fuel should be introduced into the cylinder with the aid of particularly fine atomization. A droplet size of the fuel should be designed to be as small as possible so that rapid preparation can be achieved providing a homogeneous mixture within a very short period of time.
The fuel also should not pass onto cylinder walls of the combustion chamber since this creates the possibility of "oil dilution". Since the oil dilution causes a change in a lubricant composition, it can cause severe damage to the internal combustion engine because the diluted lubricating oil has an inadequate viscosity behavior. A piston head and/or gas inlet valves should not be wetted by the fuel since the fuel can only inadequately evaporate from there.
Deposition of the fuel on the fuel injection valve is a further problem. After a few operating hours of the internal combustion engine, the fuel injection valve has a firm and soot-like deposition layer. Fuel of subsequent injection cycles may accumulate in said deposition layer. In later combustion cycles, said fuel may escape in the form of fuel vapor and lead to undesirable, soot-developing combustion. This leads to a disadvantageously large and possibly impermissible number of soot particles in the exhaust gas of the internal combustion engine.
A reduction in soot particles is intended by providing nozzle holes into the nozzle head with the aid of a laser method. This may provide the advantage over a customary electrode method by providing sharp-edged nozzle holes. A further possibility for reducing the deposition layer is an increase in a fuel pressure upstream of the nozzle head so the fuel exits the nozzle head at a magnitude that deposits are avoided and therefore a deposition layer is not built up. However, this is highly costly since an increase in the fuel pressure can be realized only with a higher consumption of energy. Furthermore, all of the components exposed to the fuel pressure have to have a higher strength which is adapted to the higher fuel pressure and which can be realized firstly with more expensive materials and/or with an increase in a corresponding component wall.


A device is provided for firmly attaching a plurality of coaxial cable terminus to a plurality of standard connection jacks in such a way that each connection point is effectively shielded from tampering by individuals and is effectively sealed from degrading elements in the atmosphere. The device is a locking shroud which defines a plurality of locking shroud chambers, each adapted to attach to a respective connection jack so as to surround the connection of a cable terminus to the jack. The use of the locking shroud of the invention makes it difficult to de-attach and/or re-attach the cable terminus to the jack without special tooling. The use of the locking shroud further makes it difficult to break off the locking shroud by twisting the shroud, such as with a pair of pliers. The device can be used to make coaxial cable connections secure from tampering and atmospheric degradation. It is simple and inexpensive to install and maintain. Furthermore, the system can be retrofitted into existing coaxial cable equipment, using standard coaxial cable connection jacks.

Coaxial cable is in widespread use for distributing wide band radio frequency information, such as television and radio signals. The cable television/radio industry, which relies almost exclusively on coaxial cable, is one of the most rapidly expanding segments of the United States' economy. It is anticipated that in the very near future the amount and type of information available via coaxial cable networks will be greatly expanded beyond traditional television and radio signals. By the early part of the twenty-first century, coaxial cable networks may be the principal vehicle by which consumers obtain their daily news, access library information, do their shopping, pay their bills, and otherwise interact with much of the outside world. Maintaining and controlling the integrity of the coaxial cable distribution networks which will carry such a large amount and such a wide variety of consumer information and services is a major challenge for the cable network industry.
Coaxial cable typically includes a pair of conductors, a central axial conductor and an outer conductor which is disposed concentrically around the central conductor. A low-loss, high dielectric insulation material, such as plastic foam, is used to separate the two conductors. An outer insulating jacket is often provided over the concentric conductor to provide electrical insulation and physical protection to the cable. The concentric conductor may be a single continuous element or, more commonly, it is a composite of several layered elements of conductive foil, wire braid or similar material.
For ease of initial installation and for flexibility with respect to subsequent modifications, coaxial cable networks comprise lengths of cable connected to one another by some sort of connection equipment. In most coaxial cable networks, such connection equipment takes the form of a male/female connection system wherein the male member is provided by a connection jack and the female member is provided by a threaded or friction-fit coupler dimensioned to attach over the jack. A standard connection jack comprises a cylindrical, externally threaded body having an outside diameter of about 0.375 inches. The outwardly projecting end of the jack is covered by a planar member which has a central aperture. Behind the aperture, within the confines of the body of the jack, is disposed an internal conductor which is shielded from the body. The body is electrically connected to one of the coaxial cable circuits and the inner conductor is connected to the other coaxial cable circuit.
The female member in the typical male/female connection system commonly comprises a jack connection moiety which is adapted to attach to the cable connection jack. The female member also comprises a cable connection moiety which physically attaches to the terminus of a coaxial cable in such a way that the cable connection moiety is in electrical contact with the concentric conductor of the coaxial cable. The cable connection moiety is adapted to allow the terminus of the central conductor to project through the center of the female member without contacting the female member, so that, when the jack moiety is attached to the outside of the conductor jack body, the central conductor terminus protrudes into the connection jack central aperture (without contacting the jack connection moiety of the female member or the conductor jack body) and is placed into electrical contact with the internal conductor of the connection jack.
Coaxial cable networks are traditionally distributed to individual residences using existing telephone company poles and underground conduits. A coaxial cable "trunk" is run through a neighborhood in parallel with telephone and electrical lines, and each residence to be serviced by the cable network is connected into ("tapped into") the trunk line. The interface between the trunk line tap and the cable line running to an individual residence (the "drop line") is traditionally called a "tap block." A tap block traditionally is a small metal box having a flat face plate called a "tap plate." Projecting outwardly from the tap plate are several coaxial cable connection jacks. Each cable service-subscribing residence in the immediate vicinity of the tap block is connected to one of the connection jacks on the tap plate.
Typically, all of the services provided by the cable network company are available at the tap face connection jacks. If a residence chooses not to pay for certain special cable network services (such as the HBO television network and the Pay-Per-View television network), a "signal trap" is interposed between the tap face connection jack and the drop line for that individual residence. A signal trap is a small electrical device having an input connector jack and an output connector jack. The signal trap is electrically configured so as to filter out or scramble the signal of a non-subscribed-to cable service.
From the tap block, a drop line is run to each individual residence and is connected to individual "receivers" (i.e., televisions or radios). Where more than one receiver is used by the residence, the drop line will terminate at a "signal splitter" having one input connection jack and two or more output connection jacks. It is common practice for many coaxial cable networks to charge an additional subscriber fee for the use of signal splitters to connect up additional receiving devices.
The problem with the use of such typical coaxial cable connection equipment is that such equipment is easy to connect, disconnect and reconnect. It is unfortunately easy for a dishonest consumer to be able to surreptitiously tap into a coaxial cable network. It is also far too easy for a dishonest consumer to reconfigure his existing coaxial cable connection system to surreptitiously connect up the cable network to additional receiving devices and to reconfigure his cable net work to eliminate signal traps.
One way that the cable industry has attempted to minimize such tampering is to surround the cable connection points with some sort of shroud which makes it difficult for an individual to get to these connection points. It is usually least expensive to fashion the shroud so that it is threadably attached to the connection jack, either by threads fashioned into the shroud itself or by a nut.
It has been found, however, that such a protecting shroud can be easily broken away from the connection point by twisting the shroud about its longitudinal axis with a pair of pliers or similar pincers-like tool. This is especially a problem where the shroud is constructed of a plastic or light-weight metal material.
Accordingly, there is a need for a coaxial cable connection protection system which provides increased tamper resistance. Specifically, there is a need for a coaxial cable connection protection system which employs a shroud to surround the connection junction wherein the shroud is more resistant to tampering by being twisted about its longitudinal axis.

Coaxial cable connection protection system with multiple chambered shroud


Quality of Service (QoS) support is provided by means of a Tiered Contention Multiple Access (TCMA) distributed medium access protocol that schedules transmission of different types of traffic based on their service quality specifications. In one embodiment, a wireless station is supplied with data from a source having a lower QoS priority QoS(A), such as file transfer data. Another wireless station is supplied with data from a source having a higher QoS priority QoS(B), such as voice and video data. Each wireless station can determine the urgency class of its pending packets according to a scheduling algorithm. For example file transfer data is assigned lower urgency class and voice and video data is assigned higher urgency class. There are several urgency classes which indicate the desired ordering. Pending packets in a given urgency class are transmitted before transmitting packets of a lower urgency class.

Wireless Local Area Networks (WLANs)
Wireless local area networks (WLANs) generally operate at peak speeds from 1 to 54 Mbps and have a typical range of 100 meters. Single-cell Wireless LANs, as shown in FIG. 1A, are suitable for small single-floor offices or stores. A station in a wireless LAN can be a personal computer, a bar code scanner, or other mobile or stationary device that uses a wireless network interface card (NIC) to make the connection over the RF link to other stations in the network. The single-cell wireless LAN 100 of FIG. 1A provides connectivity within radio range between wireless stations 102, 104A, 104B, 106, and 108. Access point 108 allows connections via the backbone network 110 to wired network-based resources, such as servers. A single-cell wireless LAN can typically support several users and still keep network access delays at an acceptable level. Multiple-cell wireless LANs provide greater range than does a single-cell, by means of a set of access points and a wired network backbone to interconnect a plurality of single-cell LANs. Multiple-cell wireless LANs can cover larger multiple-floor buildings. A mobile appliance (e.g., laptop computer, SmartPhone, or data collector) with the appropriate integrated chip set or a wireless network interface card (NIC) can roam within the coverage area while maintaining a live connection to the backbone network 11.
Of the multitude of wireless LAN specifications and standards, IEEE 802.11 technology has emerged as a dominant force in the enterprise WLAN market over the past years. The WiFi group, commonly known as the Wireless Ethernet Compatibility Alliance (WECA) has led its development. Supporters include 3Com, Alantro Communications, Apple, Artem, Breezecom, Cabletron, Cisco (Aironet), Compaq, Dell, ELSA, Enterasys, Fujitsu, Intermec, Intel, Intersil, Lucent/Agere, MobileStar, Nokia, Samsung, ShareWave, Symbol, Telxon, WavePort and Zoom.
IEEE 802.11b is the newest 802.11 standard—finalized in September 1999—which is an 11 Mbps high rate DSSS (direct sequence spread spectrum) standard for wireless networks operating in the 2.4 GHz band. 802.11b high-rate products started shipping in late 1999 Task Group E, a MAC enhancements study group recently completed a feasibility study on integrating Quality of Service (QoS) and security into the standard.
Open Air was the first wireless LAN standard, pioneered by the Wireless Interoperability Forum (WLIF), with Proxim as its main proponent. It employs FHSS (frequency hopped spread spectrum) in the 2.4 GHz band. A recent FCC ruling allowed use of 5 MHz channels, up from its previous 1 MHz, in the 2.4 GHz frequency. With wideband frequency hopping (WBFH) data rates of 10 Mbps are possible.
HomeRF was designed specifically for the home networking market. As with Open Air, WBFH permits data transmission speeds to extend to 10 Mbps (up from 2 Mbps), which makes HomeRF more competitive with 802.11 technology. However, although HomeRF has significant backing from Proxim, Compaq, Motorola, and others.
Bluetooth is aimed at the market of low-power, short-range, wireless connections used for remote control, cordless voice telephone communications, and close-proximity synchronization communications for wireless PDAs/hand-held PCs and mobile phones. It has been confused on occasion as a pure-play WLAN standard, which it is not.
IEEE 802.11a is the 5 GHz extension to 802.11b, will provide speeds as high as 54 Mbps at a range less than half of 802.11b. It will prove attractive in high traffic-density service areas, where reduction of the 802.11b power (and hence range) to increase re-use is not adequate. With QoS enhancements similar to those pursued for 802.11b presently, it will appeal especially to users familiar with the 802.11 architecture.
HiperLAN/2 is the European (and global) counterpart to the "American" 802.11a standard first ratified in 1996 (as HiperLAN/1) by the European Telecommunications Standards Institute (ETSI). HiperLAN/2 has QoS features.
The unveiling of 802.11g, the 22 Mbps extension to 802.11b, will give further life to the 2.4 GHz band in the near term, where 802.11b operates. Much like 10/100 Mbps Ethernet wired LANs, the new standard will provide backward compatibility to 802.11b networks.
Wireless LAN specifications and standards include the IEEE 802.11 Wireless LAN Standard and the HIPERLAN Type 1 and Type 2 Standards. The IEEE 802.11 Wireless LAN Standard is published in three parts as IEEE 802.11-1999; IEEE 802.11a-1999; and IEEE 802.11b-1999, which are available from the IEEE, Inc. web site http://grouper.ieee.org/groups/802/11. An overview of the HIPERLAN Type 1 principles of operation is provided in the publication HIPERLAN Type 1 Standard, ETSI ETS 300 652, WA2 Dec. 1997. An overview of the HIPERLAN Type 2 principles of operation is provided in the Broadband Radio Access Networks (BRAN), HIPERLAN Type 2; System Overview, ETSI TR 101 683 VI.I. 1 (2000-02) and a more detailed specification of its network architecture is described in HIPERLAN Type 2, Data Link Control (DLC) Layer; Part 4. Extension for Home Environment, ETSI TS 101 761-4 V1.2.1 (2000-12). A subset of wireless LANs is Wireless Personal Area Networks (PANs), of which the Bluetooth Standard is the best known. The Bluetooth Special Interest Group, Specification of the Bluetooth System, Version 1.1, Feb. 22, 2001, describes the principles of Bluetooth device operation and communication protocols.
Collision Avoidance Techniques
Four general collision avoidance approaches have emerged: [1] Carrier Sense Multiple Access (CSMA) [see F. Tobagi and L. Kleinrock, "Packet Switching in Radio Channels: Part I—Carrier Sense Multiple Access Models and their Throughput Delay Characteristics", IEEE Transactions on Communications, Vol 23, No 12, Pages 1400-1416, 1975], [2] Multiple Access Collision Avoidance (MACA) [see P. Karn, "MACA—A New Channel Access Protocol for Wireless Ad-Hoc Networks", Proceedings of the ARRL/CRRL Amateur Radio Ninth Computer Networking Conference, Pages 134-140, 1990], [3] their combination CSMA/CA, and [4] collision avoidance tree expansion.
CSMA allows access attempts after sensing the channel for activity. Still, simultaneous transmit attempts lead to collisions, thus rendering the protocol unstable at high traffic loads. The protocol also suffers from the hidden terminal problem.
The latter problem was resolved by the MACA protocol, which involves a three-way handshake [P. Karn, supra]. The origin node sends a request to send (RTS) notice of the impending transmission; a response is returned by the destination if the RTS notice is received successfully; and the origin node proceeds with the transmission. This protocol also reduces the average delay as collisions are detected upon transmission of merely a short message, the RTS. With the length of the packet included in the RTS and echoed in the clear to send (CTS) messages, hidden terminals can avoid colliding with the transmitted message. However, this prevents the back-to-back re-transmission in case of unsuccessfully transmitted packets. A five-way handshake MACA protocol provides notification to competing sources of the successful termination of the transmission. [See V. Bharghavan, A. Demers, S. Shenker, and L. Zhang, "MACAW: A media access protocol for wireless LANs", SIGCOMM '94, Pages 212-225, ACM, 1994.]
CSMA and MACA are combined in CSMA/CA, which is MACA with carrier sensing, to give better performance at high loads. A four-way handshake is employed in the basic contention-based access protocol used in the Distributed Coordination Function (DCF) of the IEEE 802.11 Standard for Wireless LANs. [See IEEE Standards Department, D3, "Wireless Medium Access Control and Physical Layer WG," IEEE Draft Standard P802.11 Wireless LAN, January 1996.]
Collisions can be avoided by splitting the contending terminals before transmission is attempted. In the pseudo-Bayesian control method, each terminal determines whether it has permission to transmit using a random number generator and a permission probability "p" that depends on the estimated backlog. [See R. L. Rivest, "Network control by Bayesian Broadcast", IEEE Trans. Inform. Theory, Vol IT 25, pp. 505-515, September 1979.]
To resolve collisions, subsequent transmission attempts are typically staggered randomly in time using the following two approaches: binary tree and binary exponential backoff.
Upon collision, the binary tree method requires the contending nodes to self-partition into two groups with specified probabilities. This process is repeated with each new collision. The order in which contending nodes transmit is determined either by serial or parallel resolution of the tree. [See J. L. Massey, "Collision-resolution algorithms and random-access communications", in Multi-User Communication Systems, G. Longo (ed.), CISM Courses and Lectures No. 265, New York: Springer 1982, pp. 73-137.]
In the binary exponential backoff approach, a backoff counter tracks the number of idle time slots before a node with pending packets attempts to seize the channel. A contending node initializes its backoff counter by drawing a random value, given the backoff window size. Each time slot the channel is found idle, the backoff counter is decreased by 1 and transmission is attempted upon expiration of the backoff counter. The window size is doubled every time a collision occurs, and the backoff countdown starts again. [See A. Tanenbaum, Computer Networks, 3rd ed., Upper Saddle River, N.J., Prentice Hall, 1996.] The Distributed Coordination Function (DCF) of the IEEE 802.11 Standard for Wireless LANs employs a variant of this contention resolution scheme, a truncated binary exponential backoff, starting at a specified window and allowing up to a maximum backoff range below which transmission is attempted. [IEEE Standards Department, D3, supra] Different backoff counters may be maintained by a contending node for traffic to specific destinations. [Bharghavan, supra]
In the IEEE 802.11 Standard, the channel is shared by a centralized access protocol—the Point Coordination Function (PCF)—which provides contention-free transfer based on a polling scheme controlled by the access point (AP) of a basic service set (BSS). [IEEE Standards Department, D3, supra] The centralized access protocol gains control of the channel and maintains control for the entire contention-free period by waiting a shorter time between transmissions than the stations using the Distributed Coordination Function (DCF) access procedure.
IEEE 802.11 Wireless LAN Overview
The IEEE 802.11 Wireless LAN Standard defines at least two different physical (PHY) specifications and one common medium access control (MAC) specification. The IEEE 802.11(a) Standard is designed to operate in unlicensed portions of the radio spectrum, usually the 5 GHz Unlicensed-National Information Infrastructure (U-NII) band. It uses orthogonal frequency division multiplexing (OFDM) to deliver up to 54 Mbps data rates. The IEEE 802.11(b) Standard is designed for the 2.4 GHz ISM band and uses direct sequence spread spectrum (DSSS) to deliver up to 11 Mbps data rates.
802.11 Architecture Components
The IEEE 802.11 Wireless LAN Standard describes the following components. The station (STA) is any wireless device with conformant 802.11 interfaces to the wireless medium. A Basic Service Set (BSS) consists of two or more wireless nodes, or STAs, which have recognized each other and have established communications. In the most basic form, stations communicate directly with each other on a peer-to-peer level. When stations can communicate only among themselves, we say we have an Independent Basic Service Set (IBSS). This type of arrangement is commonly referred to as an ad hoc network. It is often formed on a temporary basis. BSSs can communicate with one another and with other networks. The distribution system (DS) integrates different BSS into a network; it may take any form, but it is typically a wired LAN. It provides address mapping. In most instances, the BSS contains an Access Point (AP). The AP is a station. The main function of an AP is to provide access to the distribution system. All communications between stations or between a station and a wired network client go through the AP. The AP is analogous to a base station used in cellular phone networks. AP's are not mobile, and form part of the wired network infrastructure. When an AP is present, stations do not communicate on a peer-to-peer basis. A multiple-cell wireless LAN using the IEEE 802.11 Wireless LAN Standard is an Extended Service Set (ESS) network. An ESS satisfies the needs of large coverage networks of arbitrary size and complexity. FIG. 1A illustrates the components of a WLAN.
Because of the way BSSs are set up in a plug-and-play manner, it is not uncommon for the coverage areas of two distinct BSSs to overlap.
802.11 MAC Functions
The purpose of the MAC protocol is to provide for the delivery of user data; fair access control; and privacy. Each wireless station and access point in an IEEE 802.11 wireless LAN implements the MAC layer service, which provides the capability for wireless stations to exchange MAC frames. The MAC frame transmits management, control, or data between wireless stations and access points. After a station forms the applicable MAC frame, the frame's bits are passed to the Physical Layer for transmission. The same MAC protocol serves all PHY specifications.
In the IEEE 802.11 Standard, the channel is shared through two access mechanisms: DCF and PCF. The distributed coordination function (DCF) is the basic media access control method for 802.11. It is mandatory for all stations. It is based on contention.
The point coordination function (PCF) is an optional extension to DCF. It is a contention-free centralized access protocol, especially useful for periodic time-sensitive services like cordless telephony. It is based on a polling scheme controlled by the access point (AP) of a basic service set. The centralized access protocol gains control of the channel and maintains control for the entire contention-free period by waiting a shorter time between transmissions than the stations using the DCF access procedure.
DCF Access Mechanism
The distributed coordination function (DCF) is the basic access method in 802.11 LANs. The PCF employs the DCF access mechanism to gain control of the channel. DCF uses Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA). This requires each station to listen for other users and if busy postpone transmission by a random delay, known as backoff.
The backoff procedure in DCF relies on the ability of every station to 'hear' all other stations. But this is not always the case. It is possible for a station unable to hear the source of a transmission to interfere with the receipt of that transmission. This is known as the 'hidden node' problem. The RTS/CTS exchange can be used to combat this problem. RTS/CTS is also a mechanism for reserving the channel for point-to-point transmissions; it involves the exchange of messages between the origin and destination.
The source of the transmission sends an RTS frame, which may, or may not, be heard by a hidden node. The RTS frame contains a 'duration' field that specifies the period of time for which the medium is reserved. The NAV of a STA is set by the duration field. The NAV is set by all stations detecting the RTS frame. Nodes other than the destination set the NAV at this value and refrain from accessing the medium until the NVA expires. Upon receipt of the RTS, the destination node responds with a CTS frame. It, too, contains a 'duration' field specifying the remaining period of time for which the medium is reserved. A station within interfering range from the destination, which may not hear the RTS, will detect the CTS and update its NAV accordingly. The NAV provides protection through the ACK. The NAV serves as a 'virtual' carrier sense mechanism. Thus, collision is avoided even though some stations are hidden from others.
The RTS/CTS procedure is invoked optionally. As a channel reservation mechanism, the RTS/CTS exchange is efficient only for longer frames because of the extra overhead involved.
In order to increase the probability of successful transfer across the medium, frames are fragmented into smaller ones. A MAC service data unit (MSDU) is partitioned into a sequence of smaller MAC protocol data units prior to transmission. DCF transmits MSDUs as independent entities, thus providing best-effort connectionless user data transport.
DCF Backoff Procedure
If the channel has been idle for a time period of length DIFS (defined below) when a new frame arrives, the station may transmit immediately. However, if it is busy, each station waits until transmission stops, and then enters into a random backoff procedure. Deferring transmission by a random delay tends to prevent multiple stations from seizing the medium immediately after a preceding transmission completes. A backoff delay is chosen randomly from a range of integers known as the contention window. This delay measures the total idle time for which a transmission is deferred. It is expressed in units of time slots.
The CSMA/CA protocol minimizes the chance of collisions between stations sharing the medium, by waiting a random backoff interval 128A or 128B of FIG. 1C, if the station's sensing mechanism indicates a busy medium when a frame arrives. The period of time immediately following completion of the transmission is when the highest probability of collisions occurs, as all stations with newly arrived frames will attempt to transmit. For example, stations 102, 104B, and 106 may be waiting for the medium to become idle while station 104A is transmitting, and stations 102, 104B, and 106 will attempt to transmit at the same time, once station 104A stops. Once the medium is idle, CSMA/CA protocol causes each station to delay its transmission by a random backoff time. For example, station 104B delays its transmission by a random backoff time 128B, which defers station 104B from transmitting its frame 124B, thereby minimizing the chance it will collide with those from other stations 102 and 106, which have also selected their backoff times randomly.
As shown in FIG. 1D, the CSMA/CA protocol computes the random backoff time 128B of station 104B as the product of a constant, the slot time, times a pseudo-random number RN which has a range of values from zero to a contention window CW. The value of the contention window for the first try to access the network by station 104B is CW1, which yields the first try random backoff time 128B.
Backoff Countdown
An internal timer is set to the selected backoff delay. The timer is reduced by 1 for every time slot the medium remains idle. Backoff countdown is interrupted when the medium becomes busy. The timer setting is retained at the current reduced value for subsequent countdown. Backoff countdown may start or resume following a busy channel period only if the channel has been idle for time interval of length equal to DIFS. If the timer reaches zero, the station may begin transmission. The backoff procedure is illustrated in FIG. 1.
When a collision occurs, retransmission is attempted using binary exponential backoff, which refers to the process of increasing the range from which another backoff delay is drawn randomly. The contention window size is doubled with every transmission retry. This serves as a good mechanism for adapting to congestion because collisions are a result of congestion; with congestion a wider window is desirable. In the example in FIG. 1D, if the first try to access the network by station 104B fails, then the CSMA/CA protocol computes a new CW by doubling the current value of CW as CW2=CW1 times 2. As shown in FIG. 1D, the value of the contention window for the second try to access the network by station 104B is CW2, which yields the second try random backoff time 128B′. Binary exponential backoff provides a means of adapting the window size to the traffic load. Stations are not forced to wait very long before transmitting their frame in low traffic load. On the first or second attempt, a station will make a successful transmission. However, if the traffic load is high, the CSMA/CA protocol delays stations for longer periods to avoid the chance of multiple stations transmitting at the same time. If the second try to access the network by station 104B fails, then the CSMA/CA protocol computes a new CW by doubling again the current value of CW as CW3=CW1 times 4. As shown in FIG. 1D, the value of the contention window for the third try to access the network by station 104B is CW3, which yields the third try random backoff time 128B″. The value of CW increases to relatively high values after successive retransmissions, under high traffic loads. This provides greater transmission spacing between stations waiting to transmit.
Inter-frame Spaces
In addition to contending stations, the channel is accessed also by the PCF, and by other frames without contention. To prioritize transmissions or remove contention, special idle spaces are defined, the IFS (—Inter Frame Space), which are idle spaces required between frames. They are illustrated in FIG. 1B. Each interval defines the duration from the end of the last symbol of the previous frame 113 at time T1, to the beginning of the first symbol of the next frame. They are the following: The Short Interframe Space (SIFS) 115 allows some frames to access the medium without contention, such as an Acknowledgement (ACK) frame, a Clear to Send (CTS) frame, or a subsequent fragment burst of a previous data frame. These frames require expedited access to the channel. At any point in time there is a single frame needing transmission within this group, and if transmitted within a SIFS period, there will be no contention.
The PCF inter-frame space, PIFS, is next; it is used by the PCF to access the medium in order to establish a contention-free period. A contention-free period may be started before a DCF transmission can access the channel because PIFS is shorter than DIFS. The Priority Interframe Space 117 of FIG. 1B is used by the PCF to access the medium in order to establish contention-free period 116 starting at T2 and ending at T3. The point coordinator 105 in the access point 108 connected to backbone network 110 in FIG. 1A controls the priority-based Point Coordination Function (PCF) to dictate which stations in cell 100 can gain access to the medium. During the contention-free period 116, station 102 in FIG. 1A, for example, is directed by the access point 108 to transmit its data frame 122. The point coordinator 105 in the access point 108 sends a contention-free poll frame 120 to station 102, granting station 102 permission to transmit a single frame. All stations, such as stations 104A, 104B, and 106, in the cell 100 can only transmit during contention-free period 116 when the point coordinator grants them access to the medium. In this example, stations 104A and 104B, which have data sources 114A and 114B, must wait until the end of the contention-free period 116 at T3. This is signaled by the contention-free end frame 126 sent by the point coordinator in FIG. 1C. The contention-free end frame 126 is sent to identify the end of the contention-free period 116, which occurs when time expires or when the point coordinator has no further frames to transmit and no stations to poll.
DIFS (DCF inter-frame space) is the longest of the three. Transmissions other than ACKs must wait at least one DIFS before commencing. A contention-free session can be started by the PCF before a DCF transmission because DIFS is longer than PIFS. Upon expiration of a DIFS, the backoff timer begins to decrement. The distributed coordination function (DCF) Interframe Space 119 of FIG. 1B is used by stations 104A and 104B, for example, for transmitting data frames 124A and 124B, respectively, during the contention-based period 118. The DIFS spacing permits the PC of neighboring cells to access the channel before a DCF transmission by delaying the transmission of frames 124A and 124B to occur between T3 and T4 An Extended Interframe Space (EIFS) (not shown) goes beyond the time of a DIFS interval as a waiting period when a bad reception occurs. The EIFS interval provides enough time for the receiving station to send an acknowledgment (ACK) frame.
PCF Access Mechanism
The Point Coordination Function (PCF) is an optional extension to DCF. In a single BSS, PCF provides contention-free access to accommodate time bounded, connection-oriented services such as cordless telephony. PCF involves a point coordinator (PC), which operates at the access point of the BSS. It employs contention-free polling. The PC gains control of the medium at regular time intervals through the DCF CSMA/CA protocol using PIFS for access priority over DCF transmissions. The PC also distributes information relevant to the PCF within Beacon Management frames.
The transmissions coordinated under the PCF experience no contention because control of the channel is maintained through the use of IFS spaces shorter than or equal to PIFS. That is, all frame transmissions under the point coordination function may use an IFS that is smaller than DIFS, the IFS used for DCF transmissions. Point-coordinated traffic is also protected this way from contention with DCF transmissions in overlapping BSSs that operate on the same channel. The contention-free period is also protected by setting the network allocation vector (NAV) in stations.
The PC determines which station transmits when. First, the AP delivers broadcast data. Then, the PC polls STAs on the polling list to send their data. In order to use the channel efficiently, piggybacking of different types of frames, like data frames, ACKs and polls, is possible. For example, a PC data frame can be combined with a poll to a station. STA data frames can be combined with an ACK. A PC can combine an ACK to one station with data and a poll to another. One frame is transmitted per poll by a polled STA.
Stations are placed on the polling list when they associate or re-associate with a BSS, at their discretion. A station may opt not to be polled in order to save power.
Multi-BSS Environment
A BSS is an equivalent to a cell in a cellular system; the AP is equivalent to the base station. When multiple WLANs operate in the same physical space, they share the same wireless spectrum. Coordination of wireless spectrum use in multi-BSS systems is thus comparable to RF planning in a cellular system. But unlike in cellular systems, the RF planning problem in WLANs is made more difficult by the location of the APs. They are not placed on a regular hexagonal grid. When WLANs are installed in multi-tenant office buildings and multiple-unit dwellings, owners simply plug in their AP and start up their LAN. No attention is paid to who else is operating a WLAN nearby. The result is overlapping cell coverage.
Overlapping cells will offer new challenges with the proliferation of WLANs. If there are several PCs attempting to establish contention-free periods (CFPs), they must coordinate their access. Special mechanisms are thus needed to enable multiple PCs to coordinate use of the channel under PCF and provide CFPs for their respective BSS. The current standard does not provide adequate coordination for the operation of the PCF in cases where multiple BSSs are operating on the same channel, in overlapping physical space. New protocols are needed. A complete protocol suite for this purpose has not yet been presented. A BSS operates on a single channel, while several channels are available within each of the bands. There are 3 channels in the 2.4 GHz band and 8 in the 5 GHz band. Once a channel has been assigned, channel time can be shared by using a dynamic bandwidth allocation methods.
The similarity of multi-BSS systems with cellular systems can be exploited in channel assignment only when a single service provider manages all WLANs in a given physical space. Then regular re-use RF planning methods, apply. A re-use factor N=8 can be employed, see Benveniste U.S. Pat. No. 5,740,536. However, repeating assignment of the same channel by a tessellation cannot be used with WLANs whose locations are chosen in an ad hoc manner and may involve even co-located BSSs. Non-regular channel assignment would need to be deployed; it assigns channels optimally, while respecting the interference experienced between BSSs when assigned the same channel—see Benveniste U.S. Pat. No. 5,404,574.
Channel assignment must be adaptive. That is, they should be revised occasionally as the spatial distribution of powered stations changes over time; as different stations are powered on or off at different times, or users are entering and leaving the BSSs. A channel selected upon installation of a station may not be suitable at some future time. While channel selections must be revisited occasionally, dynamic (frame by frame) channel assignment is not feasible as the assigned channel provides control, in addition to data transport.
Self-configuration, which involves stations taking signal-strength measurements to determine during a system operation the interference relationships between BSSs can be employed for adaptive channel assignment—see Benveniste U.S. Pat. No. 6,112,092.
Quality Of Service (QoS)
Quality of service (QoS) is a measure of service quality provided to a customer. The primary measures of QoS are message loss, message delay, and network availability. Voice and video applications have the most rigorous delay and loss requirements. Interactive data applications such as Web browsing have less restrained delay and loss requirements, but they are sensitive to errors. Non-real-time applications such as file transfer, Email, and data backup operate acceptably across a wide range of loss rates and delay. Some applications require a minimum amount of capacity to operate at all, for example, voice and video. Many network providers guarantee specific QoS and capacity levels through the use of Service-Level Agreements (SLAs). An SLA is a contract between an enterprise user and a network provider that specifies the capacity to be provided between points in the network that must be delivered with a specified QoS. If the network provider fails to meet the terms of the SLA, then the user may be entitled to a refund. The SLA is typically offered by network providers for private line, frame relay, ATM, or Internet networks employed by enterprises.
The transmission of time-sensitive and data application traffic over a packet network imposes requirements on the delay or delay jitter and the error rates realized; these parameters are referred to generically as the QoS (Quality of Service) parameters. Prioritized packet scheduling, preferential packet dropping, and bandwidth allocation are among the techniques available at the various nodes of the network, including access points, that enable packets from different applications to be treated differently, helping achieve the different quality of service objectives. Such techniques exist in centralized and distributed variations. The concern herein is with distributed mechanisms for multiple access in a variety of networks, such as cellular packet networks or wireless ad hoc networks. For example, when engaged in dynamic packet assignment in a cellular type of network, the base stations contend among themselves for a channel to be used within their respective cells. Although the channel may be used by the mobile station for an up-link transmission, the serving base station is the one contending. [patent application Ser. No. 113,006, M. Benveniste, "Asymmetric Measurement-Based Dynamic Packet Assignment system And Method For Wireless Data Services", filed on Mar. 22, 2001,] In an ad hoc type of network, individual stations contend for the use of a channel.
Management of contention for the shared transmission medium must reflect the goals sought for the performance of the system overall. For instance, one such goal would be the maximization of goodput (the amount of good data transmitted as a fraction of the channel capacity) for the entire system, or of the utilization efficiency of the RF spectrum; another is the minimization of the worst-case delay. As multiple types of traffic with different performance requirements are combined into packet streams that compete for the same transmission medium, a multi-objective optimization is required.
QoS enhancements are necessary in order to facilitate streaming of voice and multimedia traffic together with data. The high error rates experienced in transmitting over a wireless medium can lead to delays and jitter that are unacceptable for such traffic. More delay is added by acknowledgements that become necessary for wireless transmissions, and by the RTS/CTS mechanism if used.
Ideally, one would want a multiple access protocol that is capable of effecting packet transmission scheduling as close to the optimal scheduling as possible but with distributed control. Distributed control implies both limited knowledge of the attributes of the competing packet sources and limited control mechanisms.
To apply any scheduling algorithm in random multiple access, a mechanism must exist that imposes an order in which packets will seize the medium. For distributed control, this ordering must be achieved independently, without any prompting or coordination from a control node. Only if there is a reasonable likelihood that packet transmissions will be ordered according to the scheduling algorithm can one expect that the algorithm's proclaimed objective will be attained.
What is needed is a distributed medium access protocol that schedules transmission of different types of traffic based on their service quality specifications. Depending on these specifications, one such scheduling algorithm would be to assign packets from applications with different service quality specifications different priorities. Higher priority packets would be given preference over lower priority ones in congestion conditions. But in general, it is not desirable to postpone transmission of lower priority packets merely because there are higher priority packets are queued for transmission. The latter would penalize the lower priority traffic classes excessively.

This patent is subject to a terminal disclaimer.

Tiered contention multiple access (TCMA): a method for priority-based shared channel access


The present invention relates to a method for transmitting data. An optical pulse stream comprising a plurality of return-to-zero optical pulses is prepared by modulating a phase of light output by an optical source to thereby encode data from a data source. The light of the optical pulse stream has a wavelength. The optical pulse stream is transmitted along an optical fiber of an optical network. Optical pulse streams of the invention enhance transmission performance at least in part by reducing noise at the receiver caused by fiber non-linearities.

High capacity fiber-optic transmission systems such as dense wavelength-division-multiplexed (WDM) and/or time-division multiplexed (TDM) systems with many closely spaced wavelength and/or time channels modulating at high data rate (>10 Gb/s) are required to meet the growing demand of Internet traffic bandwidth. For long distance fiber-optic links, accumulated optical noise from a chain of optical amplifiers and transmission impairments such as fiber nonlinearities and dispersion (chromatic and polarization mode) limits the practical transmission capacity-distance product. As the transmission distance improves with lumped and distributed optical amplifiers, accumulated nonlinear phase shift due to fiber Kerr nonlinearities becomes a primary concern for WDM/TDM channels with tight channel spacing. The detrimental nonlinearities include interaction of different channels through cross-phase modulation (XPM) and four-wave mixing (FWM). The maximum achievable transmission distance for a minimum bit-error-rate at the receiver typically balances the need to launch high optical power to reduce accumulated optical amplifier noise in order to achieve the required signal-to-noise ratio at the receiver with the need to constrain the optical power in order to mitigate fiber nonlinearities with a combination of dispersion and optical power management. Careful engineering design of the dispersion-managed transmission link with novel modulation techniques that resist fiber nonlinear impairments is essential.
Conventional modulation formats use amplitude shift keying or on-off keying (OOK) to encode binary information onto an optical beam. The result is an optical pulse pattern wherein the presence or absence of a pulse represents a logic ONE or logic ZERO. Currently, non-return-to-zero (NRZ) OOK is widely used in deployed commercial systems because it is relatively simple and low cost to implement and the technology is mature and compatible with industry standards. The width of an NRZ-OOK pulse is the same as the bit period. Another OOK data format is return-to-zero (RZ) that has a duty cycle less than 0.5 with a pulse width less than the bit period. The RZ data format is typically used in long- and ultralong-haul transmission systems, such as submarine systems.
Various forms of RZ-OOK format such as chirped RZ pulses with bit-synchronous sinusoidal phase modulation are described in U.S. Pat. Nos. 5,946,119 and 6,005,702. In U.S. Pat. No. 5,875,045, a technique is proposed to actively adjust the duty cycle of the RZ signal. U.S. Pat. No. 6,014,479 proposes to launch RZ-OOK pulses sequentially both in time and in wavelength.
The information capacity of DWDM systems can be enhanced by increasing the spectral efficiency. This can be achieved by reducing the channel spacing. This, however, increases the penalties for linear as well as nonlinear crosstalk between channels. The crosstalk can be mitigated using a spectrally efficient modulation format such as carrier-suppressed RZ-OOK format with reduced spectral width compared with conventional RZ-OOK format.
All of the above-mentioned RZ-OOK techniques, however, do not address effectively the critical problem of cross phase modulation impairment in fiber (intensity-dependent refractive index). As the FWM penalties are minimized by use of non-zero dispersion-shifted and standard single-mode fibers, the impact of XPM increases. The XPM effect coupled with chromatic dispersion of the fiber produces undesirable accumulated amplitude noise to the WDM/TDM channels from inter- and intra-channel interactions or crosstalk. One of the major noise components induced by XPM can be traced to the bit patterning effect of OOK format. Inherent to OOK format are missing pulses, which represent logic zeros, and due to the random nature of the data there are isolated pulse patterns and sequential pulse patterns. As different channels collide with each other, all channels may experience random pulse intensity pattern and therefore crosstalk noise induced by XPM.
The spectrum of a typical OOK optical signal contains a strong carrier component with weaker data sidebands. The strong carrier component provides very efficient FWM components with other channels. A carrier-suppressed signal has a reduced FWM effect. Further, the optical phase of the neighboring pulse of an OOK channel is typically the same (in-phase). As the neighboring pulses spread due to dispersion the trailing and leading edges of the neighboring pulses have different frequencies (colors). The neighboring pulse edges disperse and coincide in time and interact with each other, generating unwanted new frequencies through FWM. This intra-channel FWM effect tends to deplete and distort the pulses and generates unwanted noise-like pulses. The undesirable new frequencies contribute to amplitude noise of other channels.
It should be noted that the peak power of an OOK optical signal is equal to two times the average power of the signal divided by its duty cycle. The factor of two comes from the missing pulses of the OOK data sequence: there are on average 50% zeros. Since the nonlinear phase shift from the fiber Kerr nonlinearities increases with the peak power of the pulses the factor of two due to the missing pulses reduces the maximum launch power that could be used to reduce the accumulated optical amplifier noise. What is needed to mitigate the fiber impairments is therefore a method of transmission that is capable of suppressing the intra and inter-channel FWM, XPM, and bit patterning effects.
A phase shift key (PSK) optical signal is generated by sending a continuous-wave (CW) laser to a phase modulator driven by a source of electrical binary data. To demodulate and recover the PSK signal, the optical phase information is converted to amplitude modulation before detection by a photo-diode. For a PSK signal, homodyne or heterodyne detection is employed that requires a local laser oscillator at the receiver. The frequency and phase of the local oscillator needs to lock to the incoming PSK signal as well as matching the polarization states. A simplified approach is to use DPSK with a self-homodyne demodulator such as an apparatus described in U.S. Pat. No. 5,319,438. The self-homodyne detection does not require a local oscillator and therefore does not need for complex frequency, phase, and polarization tracking devices.
A major drawback of CW-modulated PSK and DPSK formats is the conversion of phase to amplitude modulation through fiber dispersion. Because of the continuous phase modulation of the CW optical beam by the electrical binary signal, fast transitions of the binary data produces undesirable phase modulation on the CW beam (frequency chirping) and therefore spectral spreading. As the phase modulated CW beam propagates through dispersive fiber, amplitude modulations at the transitions are generated. The amplitude modulation produces intra- and inter-channel crosstalk noise induced by intensity patterning effect as a result of XPM. Further, modulation instability of the CW-PSK signal in anomalous dispersive fiber can cause severe distortions of the PSK signal under high launching power. Transmission of PSK signal in low or zero dispersion fiber such as dispersion-shifted fiber reduces the phase-to-amplitude conversion impairment. This, however, limits the application of the CW-PSK signals since significant portions of deployed fibers are non-dispersion-shifted fibers. Further, CW-PSK signals can suffer large FWM penalties for DWDM transmission in low dispersion fiber. A recent experiment demonstrated OCDMA using quaternary PSK with RZ pulses. However, short optical pulses are required for coding. Because of the broad spectrum associated with short pulses the transmission distance is limited.

Method and system for mitigating nonlinear transmission impairments in fiber-optic communications systems


Upstream and downstream pump assemblies are mounted in a capsule having a bulkhead between the upstream and downstream pump assemblies, dividing the capsule into upstream and downstream chambers sealed from each other. In a dual operation mode, well fluid flows through the inlet of the capsule into the upstream chamber, where it is pumped to a first pressure level by the upstream pump assembly and discharged into the downstream chamber. The downstream pump assembly then pumps the well fluid to a second pressure level and discharges the well fluid out the outlet of the capsule. The assembly has also an upstream pump assembly only operational mode and a downstream pump assembly only operational mode.

An electrical submersible pump ("ESP") assembly for wells typically comprises a submersible motor that drives a pump, typically a centrifugal pump. The pump assembly is usually suspended on a string of tubing within the well. The power cable to the motor is strapped alongside the tubing. Periodically, the pump assembly has to be retrieved for maintenance or repair, and this step requires pulling the tubing. Pulling the tubing requires a workover rig and is time consuming, particularly for offshore installations.
In some cases a dual tandem pump assembly is used to provide more lift. Normally two pumps are connected together and driven by a single motor. The pumps thus operate in unison with each other. Repair or replacement of either pump requires pulling the tubing and the entire assembly.
Often a pressure and temperature sensor will be mounted to the base of the motor for sensing the pressure and temperature of the dielectric liquid within the motor. The power to the motor fluid sensor and the signals are superimposed on the ESP power cable. Another measuring tool comprises a reservoir sensor, which is an electrical device that senses various characteristics of the producing reservoir of the well on the exterior of the motor. These tools typically send signals up a dedicated communication line extending to the surface.


A passive keyless entry device is constructed by a car mounting device mounted to an automobile, a portable device and transmitter-receivers for monitoring a tire pneumatic pressure. The car mounting device has a low frequency signal transmitting section for transmitting a request signal to the portable device and the transmitter-receivers for monitoring the tire pneumatic pressure, a receiving section for a keyless entry for receiving an answer signal responsive to the request signal from the portable device, a receiving section for monitoring the tire pneumatic pressure for receiving the answer signal responsive to the request signal from the transmitter-receivers for monitoring the tire pneumatic pressure, and a controller for forming the request signal and controlling the operation of a door lock mechanism in response to the answer signal and displaying tire pneumatic pressure information.

1. Field of the Invention
The present invention relates to a passive keyless entry device also having a function for monitoring a tire pneumatic pressure by performing communication in both directions, and particularly, relates to a passive keyless entry device for monitoring the tire pneumatic pressure in which the tire pneumatic pressure can be stably monitored for a long time by performing the bidirectional communication and the entire construction is simplified by commonly using portions commonly usable in the passive keyless entry device and the tire pneumatic pressure monitoring device.
2. Description of the Related Art
There is conventionally a passive keyless entry (passive RKE) device for releasing a door lock and starting an engine by using a portable device from the exterior of an automobile as a device mounted to the automobile. Further, there is a tire pneumatic pressure monitoring device (TPMS) for periodically monitoring the pneumatic pressure of the tire by using a pneumatic pressure sensor mounted to each tire. In these devices, the main function of the passive keyless entry device is to release the door lock and start the engine, and the main function of the tire pneumatic pressure monitoring device is to monitor the pneumatic pressure of the tire. Accordingly, their functions are different from each other. Therefore, these devices are normally respectively mounted to the automobile as separate devices.
Here, FIG. 5 is a block diagram showing one example of the construction of a main portion of the already known passive keyless entry (passive RKE) device.
As shown in FIG. 5, this passive keyless entry device is constructed by a car mounting device 40 mounted to the automobile and a portable device 41 individually carried by a user, etc. In this case, the car mounting device 40 has a tuner section 42, a low frequency signal amplifying section (LF AMP) 43 and a controller 44. The tuner section 42 is connected to a high frequency wave receiving antenna 42(1) and converts a high frequency signal received by the high frequency wave receiving antenna 42(1) into a base band signal and outputs the base band signal. The low frequency signal amplifying section (LF AMP) 43 is connected to four low frequency wave transmitting antenna (down link antennas) 43(1), 43(2), 43(3), 43(4) individually arranged within the door handles of four doors of the automobile, and transmits a low frequency wireless signal in time division through each of the four low frequency wave transmitting antenna 43(1) to 43(4). The controller 44 controls the transmitting operation of the low frequency signal from the low frequency signal amplifying section 43 and also controls the operation of a car mounting control member such as a door lock mechanism 45, etc. in response to the supplied base band signal. The controller 44 is connected to the door lock mechanism 45 arranged in each door of the automobile, and an engine starting section 46 arranged in the vicinity of the engine.
This passive remote keyless entry device is schematically operated as follows.
The car mounting device 40 supplies a request signal in time division at a constant time interval from the low frequency signal amplifying section 43 to the four transmitting antennas 43(1) to 43(4) by the control of the controller 44. The low frequency wireless signal is transmitted from the corresponding transmitting antennas 43(1) to 43(4). At this time, when a user carrying the portable device 41 approaches the automobile and this portable device 41 receives the request signal transmitted from one of the low frequency wave transmitting antenna 43(1) to 43(4), e.g., the low frequency wave transmitting antenna 43(1), the portable device 41 forms an answer signal including an ID proper to this portable device 41 in response to the received request signal, and transmits the formed answer signal as a high frequency wireless signal. At this time, when the high frequency wave receiving antenna 42(1) receives this high frequency wireless signal on the car mounting device 40 side, the tuner section 42 receives and processes this high frequency wireless signal and converts the processed signal into a base band signal including the ID, and supplies the converted base band signal including the ID to the controller 44. When the base band signal including the ID is supplied to the controller 44, the controller 44 judges whether the supplied ID is conformed to one of IDs already registered or not. When the controller 44 judges that the supplied ID is conformed to the already registered ID, the controller 44 releases the operation of a car mounting control member according to the control contents instructed by the supplied base band signal, e.g., the door lock mechanism 45 of a door knob on the driver's seat side of the automobile. Thus, the user (driver) can open the driver's seat side door and can ride in the automobile by performing such control.
After such control is performed, the engine can be also subsequently started by setting the passive keyless entry device. When the passive keyless entry device is set in this way and the user (driver) rides in the automobile, communication using a wireless signal is performed between the car mounting device 40 and the portable device 41 carried by the user (driver). When the controller 44 confirms that the ID transmitted from the portable device 41 is the same ID as the ID of the portable device 41 judged just before by this communication, the controller 44 supplies a starting signal to the engine starting section 46 and makes the engine starting section 46 start the engine.
FIG. 6 is a block diagram showing one example of the construction of a main portion of the already known tire pneumatic pressure monitoring device (TPMS).
As shown in FIG. 6, this tire pneumatic pressure monitoring device is constructed by a TPMS receiver 50 arranged within the automobile, and TPMS transmitters (TPMS TX) 51(1), 51(2), 51(3), 51(4) individually mounted to four tires of the automobile. In this case, the TPMS receiver 50 has four high frequency wave receiving antennas 52(1), 52(2), 52(3), 52(4), a mixer section (MIX) 52, a TPMS tuner section 53, a signal intensity instructing section (RSSI) 54, a controller 55, a display section 56 and an alarm generating section 57. The four high frequency wave receiving antennas 52(1), 52(2), 52(3), 52(4) are arranged so as to correspond to the four TPMS transmitters 51(1), 51(2), 51(3), 51(4), and individually receive high frequency wireless signals transmitted from the corresponding TPMS transmitters 51(1) to 51(4). The mixer section 52 is connected to the four high frequency wave receiving antennas 52(1) to 52(4), and mixes and outputs the high frequency signals received by the four high frequency wave receiving antennas 52(1) to 52(4). The TPMS tuner section 53 receives the mixed high frequency signal and converts the mixed high frequency signal into a detecting signal showing the tire pneumatic pressure and outputs this detecting signal. The signal intensity instructing section 54 shows detecting signal intensity based on the detecting signal outputted from the TPMS tuner section 53. The controller 55 receives the detecting signal outputted from the TPMS tuner section 53 and the detecting signal intensity obtained by the signal intensity instructing section 54, and generates a tire pneumatic pressure measuring signal, an alarm signal showing a tire pneumatic pressure abnormality, etc. The display section 56 displays the tire pneumatic pressure measuring signal. The alarm generating section 57 generates an alarm when the alarm signal is supplied. A pressure sensor for detecting the tire pneumatic pressure is built in each of the TPMS transmitters 51(1), 51(2), 51(3), 51(4) although this pressure sensor is unillustrated.
This tire pneumatic pressure monitoring device (TPMS) is schematically operated as follows.
When a tire pneumatic pressure detecting time point allocated to the self transmitter has come, each of the four TPMS transmitters 51(1), 51(2), 51(3), 51(4) measures the pneumatic pressure of the corresponding tire by the built-in pressure sensor and transmits the measured tire pneumatic pressure measuring signal as a high frequency wireless signal. In this case, for example, the tire pneumatic pressure detecting time point is set to once for 30 minutes to one hour every each of the TPMS transmitters 51(1) to 51(4) at the stopping time (unusing time) of the automobile, and is also set to about once for one to three minutes at the running time (using time) of the automobile. The arriving time of the tire pneumatic pressure detecting time point is different every each of the four TPMS transmitters 51(1), 51(2), 51(3), 51(4), and the tire pneumatic pressure detecting time point comes in a sequential order in accordance with a determined period. When the tire pneumatic pressure detecting time point has come and the high frequency wave receiving antennas 52(1), 52(2), 52(3), 52(4) arranged correspondingly to the four TPMS transmitters 51(1), 51(2), 51(3), 51(4) sequentially receives this high frequency wireless signal on the TPMS receiver 50 side, the mixer section 52 mixes these received high frequency signals and converts these high frequency signals into a serial signal and supplies the converted serial signal to the TPMS tuner section 53. The TPMS tuner section 53 converts the supplied serial signal into a detecting signal showing the tire pneumatic pressure, and supplies the obtained detecting signal to the signal intensity instructing section 54 and the controller 55. The signal intensity instructing section 54 converts the supplied detecting signal into a detecting signal intensity showing its signal intensity, and supplies the converted detecting signal intensity to the controller 55. When the detecting signal and the detecting signal intensity are supplied to the controller 55, the controller 55 judges whether the supplied detecting signal intensity lies within the range of a prescribed intensity or not. When the controller 55 judges that this detecting signal intensity lies within the range of the prescribed intensity, the controller 55 makes the display section display the tire pneumatic pressure value shown by the detecting signal. In contrast to this, when the controller 55 judges that this detecting signal intensity does not lie within the range of the prescribed intensity, the controller 55 makes the display section display the tire pneumatic pressure value shown by the detecting signal and operates the alarm generating section 57 so as to inform the user (driver), etc. that the tire pneumatic pressure value has become abnormal. In this case, the alarm generated from the alarm generating section 57 may be set to ring a buzzer and turn on or off an alarm display lamp.
The above already known passive keyless entry device and the tire pneumatic pressure monitoring device were respectively recognized as devices for achieving separate independent functions. Therefore, when these devices are mounted to the automobile, these devices are mounted to suitable portions within the automobile every device.
Various car mounting devices are generally arranged within the automobile in addition to these devices. Therefore, a utilization space able to mount these devices is limited, and there is a case in which it is difficult to mount these devices to suitable portions within the automobile every each of these devices. Further, when these devices can be mounted to the automobile but are arranged in proximity to each other, these devices mutually utilize wireless signals so that the situation that their wireless signals interfere with each other and no exact control can be performed, is caused in a certain case.

Passive keyless entry device for monitoring tire pneumatic pressure by bidirectional communication