Multiple instances of an incoming call in an integrated system capable of communicating through multiple networks are associated such that the called party is provided a single (merged) notification along with options to select among available call types. The call is established using a selected network and end device registered to the called user. Association of the instances is accomplished by comparing caller identity derived from a variety of information associated with the calling party. Conversation or correlation IDs are used to associate the instances as being for the same call and with other related communications such as a related instant messaging session.

In telecommunication, telephony is the term for the general use of equipment to provide voice communication over distances, specifically by connecting telephones to each other. Telephones originally were connected directly together in pairs. Each user had separate telephones wired to the various places they might wish to reach. With the invention of the telephone exchange, each telephone could be connected to other local ones and eventually far away phones.
In modern systems, equipment at the exchange connects a telephone line to another in the same wire center, or to a trunk at a distant exchange when the user of a telephone wants to make a telephone call. The exchanges together form the Public Switched Telephone Network ("PSTN"). Digital telephony is the use of digital technology in the provision of telephone services and systems. Almost all telephone calls are provided this way, but sometimes the term is restricted to cases in which the last mile is digital or where the conversion between digital and analog signals takes place inside the telephone.
IP Telephony is a modern form of telephony which uses the TCP/IP protocol popularized by the internet to transmit digitized voice data. Computer Telephony Integration ("CTI") enables computers to know about and control phone functions such as making and receiving voice, fax, and data calls with telephone directory services and caller identification. The integration of telephone software and computer systems is a major development in the evolution of the automated office. With the proliferation of various types of telephony systems, it is not uncommon to have two or more independent systems exist side-by-side in a location.
Users of two or more independent systems may experience cross ringing where a single incoming call is directed to multiple end devices (or even client applications). For example, a call from an external network such as a PSTN may be directed to a user's desktop device and mobile device on a Voice Over IP (VOIP) network. Similarly, calls from a mobile network (e.g. a cellular network) may also be connected to the user through the mobile network directly or through a combination of the mobile network with the VOIP network.

Merging call notifications in cross ringing systems


In a 2D photonic crystal waveguide comprising a 2D photonic crystal structure based on a slab (11) formed of a material having a higher refractive index than air, in which a material (16) having a lower refractive index than the slab material is periodically arrayed to provide a refractive index distribution, a photonic crystal waveguide is created by forming a line defect (12), which functions as a waveguide, in the periodic array of photonic crystal, and at least one point defect (14) is disposed adjacent the photonic crystal waveguide to act as a disorder in the periodic array of photonic crystal. The point defect functions as a light or electromagnetic radiation outlet/inlet port for trapping light or electromagnetic radiation of a selected wavelength among light or electromagnetic radiation propagating through the waveguide and radiating it, or trapping light or electromagnetic radiation of a selected wavelength from the exterior and introducing it into the waveguide.

This invention relates to a photonic crystal for use as a ultrasmall optical circuit device, and more particularly, to a two-dimensional photonic crystal having a two-dimensional periodic distribution of refractive index. It further relates to a waveguide having a light or electromagnetic radiation outlet/inlet port created by introducing a line defect and a point defect in such photonic crystal, and a wavelength demultiplexer.
With the recent advance of wavelength multiplexing communication systems, wavelength demultiplexers, multiplexers and filters become more important.
The optical branching/inserting device for wavelength multiplexing communication systems, also known as optical add/drop multiplexing device, has a function of taking a signal of a certain channel out of multiplexed signals or add the same to an empty channel. General constructions include array waveguide diffraction grating and fiber grating types. The array waveguide diffraction grating is a kind of diffraction grating having an array of a plurality of optical waveguides of different length in which the difference in length between waveguides creates a wavelength-dependent slope of wavefront so that upon input of wavelength-multiplexed light, the light is demultiplexed in terms of wavelength into different waveguides to produce outputs (see Journal of IEICE, pp. 746-749, 1999, for example). In the fiber grating type, only signals of a specific wavelength are taken out of the drop port or introduced from the add port by Bragg reflection at the fiber grating.
In the prior art wavelength multiplexers/demultiplexers of the array waveguide diffraction grating type, however, the radius of curvature must be kept significantly large in order to reduce a bend loss, resulting in a very large device size.
Many proposals were then made based on the concept of forming an ultrasmall optical multiplexer/demultiplexer using photonic crystal. These proposals are described in, for example, Applied Physics Letters, vol. 75, pp. 3739-3741, 1999 (Reference 1) and Physical Review Letters, vol. 80, pp. 960-963, 1998 (Reference 2).
The photonic crystal is a crystal having a periodic distribution of refractive index therein, which enables to establish novel optical characteristics using an artificial periodic structure.
One of the important features of the photonic crystal is the presence of a photonic bandgap. In photonic crystal having a three-dimensional periodicity (referred to as a 3D photonic crystal, hereinafter), a full bandgap that prohibits propagation of light in all directions can be formed. This enables local confinement of light, control of spontaneous emission light, and formation of a waveguide by the introduction of a line defect, indicating a possibility to realize an ultrasmall optical circuit.
Reference 1 suggests that an ultrasmall light demultiplexer can be formed by branching a waveguide formed by introducing a line defect into a 3D photonic crystal, but does not illustrate any specific structure.
Active studies have been made on a photonic crystal having a two-dimensional periodic structure (referred to as a 2D photonic crystal, hereinafter), because its fabrication is relatively easy. Reference 2 describes the analytic results of a demultiplexer using a branched waveguide.
A refractive index periodicity structure of 2D photonic crystal is formed by arranging cylindrical holes in a high refractive index material in a square or triangular lattice pattern. Alternatively, it is formed by arranging cylinders of a high refractive index material in a low refractive index material in a square lattice pattern. Photonic bandgaps are formed from these periodicity structures whereby the propagation of in-plane light is controlled. By introducing a line defect into this periodic structure, a waveguide can be created. See, for example, Physical Review Letters, vol. 77, pp. 3787-3790, 1996, and Reference 2.
Reference 2 relates to the array of cylinders of a high refractive index material in a square lattice pattern. It is noted that although the propagation of light in the in-plane direction can be controlled by a bandgap as previously described, the propagation of light in upward and downward directions cannot be controlled by the periodic structure. Analysis is thus made on a straight waveguide and a 90xc2x0 bend branch configuration and branch configuration on the assumption that the height is infinite.
However, since it is impossible for an actual device to have an infinite height, light must be confined within a finite height.
On the other hand, where cylindrical holes are formed in a high refractive index material, a waveguide can be created by forming the high refractive index material as a slab, and providing low refractive index layers above and below the slab so as to confine light by total reflection.
However, no research has been made on multiplexers and demultiplexers of such a structure. Also, no research has been made on the 90xc2x0 bend branch configuration and branch configuration of guiding light propagating in the in-plane direction to the orthogonal direction or guiding light from the orthogonal direction to the in-plane direction.
Optical multiplexers and demultiplexers using a super-prism based on self-organized 3D crystal have also been studied. See, for example, Applied Physics Letters, vol. 74, pp. 1212-1214, 1999 and 0 plus E, December 1999, pp. 1560-1565. They are not combined with waveguides, and only the function of an independent device is investigated.
If a photonic crystal waveguide is able to deliver a light output with wavelength selectivity in a certain wavelength region or receive a light input with wavelength selectivity, it becomes possible to realize an optical circuit having a light demultiplexing/multiplexing function of much smaller size than conventional devices. Also, if light or electromagnetic radiation in a 2D photonic crystal waveguide can be guided to the orthogonal direction, a steric light or electromagnetic radiation circuit can be obtained.
An object of the invention is to provide a construction capable of guiding or receiving light or electromagnetic radiation propagating through a 2D photonic crystal waveguide in a direction orthogonal to the plane thereof, the construction being effective for forming a light or electromagnetic radiation waveguide or a light or electromagnetic radiation multiplexer/demultiplexer.
The above and other objects are attained by the invention which is defined below.
(1) A two-dimensional photonic crystal waveguide comprising
a two-dimensional photonic crystal structure based on a slab formed of a material having a higher refractive index than air, in which a material having a lower refractive index than the slab material is periodically arrayed to provide a refractive index distribution,
a photonic crystal waveguide created by forming a line defect in the periodic array of photonic crystal, the line defect functioning as a waveguide, and
at least one point defect disposed adjacent the photonic crystal waveguide to act as a disorder in the periodic array of photonic crystal,
wherein the point defect functions as a light or electromagnetic radiation outlet/inlet port for trapping light or electromagnetic radiation of a selected wavelength among light or electromagnetic radiation propagating through the waveguide and radiating it, or trapping light or electromagnetic radiation of a selected wavelength from without the waveguide and introducing it into the waveguide.
(2) The two-dimensional photonic crystal waveguide of (1) wherein the light or electromagnetic radiation outlet/inlet port is to radiate or introduce the light or electromagnetic radiation propagating in a direction orthogonal to the slab surface.
(3) The two-dimensional photonic crystal waveguide of (1) or (2) wherein the wavelength of light or electromagnetic radiation radiated or introduced by the point defect differs depending on the shape of the point defect.
(4) The two-dimensional photonic crystal waveguide of any one of (1) to (3) wherein the array of the lower refractive index material is formed by filling cylindrical holes in the slab with the lower refractive index material.
(5) The two-dimensional photonic crystal waveguide of any one of (1) to (4) wherein the array of the lower refractive index material is a triangular lattice array.
(6) The two-dimensional photonic crystal waveguide of any one of (1) to (5) wherein the point defect is configured so as to be asymmetric on opposite sides with respect to the slab surface.
(7) The two-dimensional photonic crystal waveguide of any one of (1) to (6) wherein the slab material has a refractive index of at least 2.0.
(8) The two-dimensional photonic crystal waveguide of (7) wherein the slab material is an inorganic material containing at least one element selected from the group consisting of In, Ga, Al, Sb, As, Ge, Si, P, N, and O or an organic material.
(9) The two-dimensional photonic crystal waveguide of any one of (1) to (8) wherein the lower refractive index material is air.
(10) A photonic crystal wavelength demultiplexer comprising the two-dimensional photonic crystal waveguide of any one of (1) to (9).
(11) The photonic crystal wavelength demultiplexer of (10) wherein there are included a plurality of point defects and wavelength of light or electromagnetic radiation radiated or trapped by each point defect differs.
(12) The photonic crystal wavelength demultiplexer of (10) or (11), further comprising an optical fiber disposed in proximity to the point defect.
(13) The photonic crystal wavelength demultiplexer of (10) or (11), further comprising a semiconductor device having a photoelectric conversion function disposed in proximity to the point defect.
In the 2D photonic crystal waveguide of the invention comprising a 2D photonic crystal structure based on a slab formed of a material having a higher refractive index than air, in which a material having a lower refractive index than the slab material is periodically arrayed to provide a refractive index distribution, a photonic crystal waveguide is created by forming a line defect, which functions as a waveguide, in the periodic array of photonic crystal, and at least one point defect is disposed adjacent the photonic crystal waveguide to act as a disorder in the periodic array of photonic crystal. The point defect functions as a light or electromagnetic radiation outlet/inlet port for trapping light or electromagnetic radiation of a selected wavelength among light or electromagnetic radiation propagating through the waveguide and radiating it, or trapping light or electromagnetic radiation of a selected wavelength from the exterior and introducing it into the waveguide.
The waveguide and the point defect according to the invention can transport, receive and deliver not only light, but also electromagnetic radiation having a character approximate to light.
Where a point defect is formed in proximity to the waveguide formed by the line defect, introduction and removal of light or electromagnetic radiation into and out of the point defect becomes possible so that a light or electromagnetic radiation inlet/outlet port is available. The point defect becomes a disordered site in the 2D photonic crystal structure based on a slab formed of a material having a higher refractive index than air, in which a material having a lower refractive index than the slab material is periodically arrayed to provide a refractive index distribution.

Two-dimensional photonic crystal, and multiplexer/demultiplexer using the same

Kansai Technology Licensing Organization Co., Ltd.


A motherboard assembly includes a motherboard with a memory slot, an adapter board, and a serial advanced technology attachment dual-in-line memory module (SATA DIMM) with a circuit board and a connector. An edge connector is set on a bottom edge of the circuit board. The adapter board includes a SATA interface, a hard disk drive (HDD) signal multiplier, a power interface, and an expansion SATA interface. The edge connector is connected to the memory slot and the connector is connected to the expansion SATA interface, to enable the motherboard communication with SATA DIMM modules, which are connected to the memory slots.

1. Technical Field
The present disclosure relates to a motherboard assembly with a serial advanced technology attachment dual in-line memory module (SATA DIMM).
2. Description of Related Art
Solid state drives (SSD) store data on chips instead of on magnetic or optical discs. One type of SSD has the form factor of a DIMM module and it is called a SATA DIMM module. The SATA DIMM module can be inserted into a memory slot of a motherboard, to receive voltages from the motherboard through the memory slot and receive hard disk drive (HDD) signals through SATA connectors arranged on the SATA DIMM module and connected to a SATA connector of the motherboard. However, these SATA connectors are arranged on the motherboard and occupy precious space. Therefore, there is room for improvement in the art.

Motherboard assembly having serial advanced technology attachment dual in-line memory module

Hong Fu Jin Precision Industry (ShenZhen) Co., Ltd.


An improved method for adaptively cancelling acoustic feedback in hearing aids and other audio amplification devices. Feedback cancellation is limited to a frequency band that encompasses all unstable frequencies. By limiting the bandwidth of the feedback cancellation signal, the distortion due to the adaptive filter is minimized and limited only to the unstable feedback regions. A relatively simple signal processing algorithm is used to produce highly effective results with minimal signal distortion.

1. Field of the Invention
The present invention relates generally to the field of audio amplification, especially for hearing aids. More particularly, the invention provides a method for efficiently cancelling acoustic feedback in the hearing aid.
2. Prior Art
Acoustic feedback in a hearing aid, from the electroacoustic transducer (commonly referred to as the "receiver") back to the microphone, is common and difficult to suppress. Feedback may produce an audible whistle, which is irritating to the hearing aid wearer so that the wearer must often reduce the volume to a lower than desired level, thereby reducing the effectiveness of the hearing aid.
One reason that it is difficult to effectively suppress acoustic feedback in a hearing aid is that the frequency at which feedback occurs varies with changing external conditions. Therefore, for feedback to be effectively cancelled without undesirably degrading the amplified signal, some form of adaptive cancellation is required. Various techniques have been proposed for implementing adaptive feedback cancellation. Such techniques are disclosed, for example, in U.S. Pat. Nos. 5,016,280; 5,091,952 and 5,259,033.
One of the principal design objectives for hearing aids is miniaturization of physical volume. Most wearers prefer a hearing aid that can be worn entirely within the ear. Advances in microelectronics have vastly improved the signal processing capabilities of in-the-ear (ITE) hearing aids. Even so, the provision of effective feedback cancellation remains a practical design challenge. Prior art techniques necessarily require certain trade-offs. As a result of such trade-offs, the hearing aid may exhibit only a small increase in maximum stable gain, slow filter adaptation, distortion, interference and/or lack of adaptation to individual wearers.

Band-limited adaptive feedback canceller for hearing aids


An electronic processing system contains a power supply subsystem and a multi-processor module. Programmable control circuitry manages power consumption in the electronic system by allocating priority among a plurality of competing demands, such as total power consumption, power consumption at any one of the processors, and thermal measurements. Analog sense measurements of incoming power are transmitted to the control circuits, which are protected from noise through use of an isolation barrier established by a linear isolation amplifier.

1. Field of the Invention
The invention pertains to the field of power management for electronic processing systems. More specifically, power usage is controlled on the basis of sensed feedback signals, such as voltage, current and temperature.
2. Discussion of the Related Art
Electronic systems designers are challenged by stringent and ever-changing requirements of new-generation processors. U.S. Pat. No. 6,414,469 issued to Zhou et al. describes these challenges as being a progressive drop in operating voltage from 5V to 3.3V towards an eventual range of from 1.1V to 0.8V. At the same time, current draws are increasing from about 13A to a range between 30A and 70A per processor. The tolerance for operational voltage is shrinking, e.g., from ±5% to ±1% of design voltage, while the processors are operating at ever higher frequencies and consuming more power. All of these factors combine to require more aggressive power management features than have previously been installed in electronic systems. The '469 patent addresses the problem of DC-DC converter noise by connecting voltage regulator modules in parallel such that, when a processor becomes active, the resultant transient response time of the converter is improved by transient ripples from the respective converters canceling one another. The '469 patent does not disclose a robust power management capability.
In general, robust power management features have not been incorporated into power converters or power supplies. U.S. Pat. No. 6,420,858 issued to Kitagawa et al. describes a DC-to-DC converter having a power saving mode. The '858 patent describes a variety of converters including converters with sense circuitry to monitor the voltage output. Sense signal feedback is used to control the voltage output of the converter at a level equal to a design power output. The use of sense circuitry that does not require a sense resistance may reduce power consumption in some designs. These features may save power, but they do not manage or control the delivery of power to a processor.
U.S. Pat. No. 4,276,591 issued to Quick describes a DC power supply that rectifies AC input power to produce a desired DC voltage. The DC power output is compared to a control signal to regulate the DC voltage through use of saturable reactors in the AC input lines. Thus, the system is capable of providing a constant output power at variable DC voltage and load current. While the power supply is useful in cathode sputtering systems and the like, the inability to control power output renders the power supply poorly suited for use in power management systems that require a varying power output.
Processor power management systems may include a programmable brownout detector, for example, as described in U.S. Pat. No. 6,304,823 issued to Smit et al. The brownout detector is designed to sense an under-voltage condition below a minimum operating threshold for the processor. The minimum operating threshold may be supplied as a programmable value. The '823 patent, however, does not describe a power management system in which the brownout control may conflict with other power management objectives.

System and method for managing power consumption for a plurality of processors based on a supply voltage to each processor, temperature, total power consumption and individual processor power consumption

Hewlett-Packard Development Company, L.P.


Antiglaucoma compositions containing 3-aryl-carbonyl-1-aminoalkyl-1H-indoles, as the active component thereof, and a method of use thereof in the treatment of glaucoma.

(a) Field of the Invention
This invention relates to 2-R.sub.2 -3-arylcarbonyl-1-aminoalkyl-1H-indole-containing antiglaucoma compositions and method of use thereof.
(b) Information Disclosure Statement
Deschamps et al. U.S. Pat. No. 3,946,029 discloses compounds having the formula: ##STR1## where A is alkylene; R.sub.2 is one to four carbon alkyl, phenyl or phenyl substituted by fluorine, chlorine, bromine, methoxy or cyclohexyl; R.sub.3 is a 2-, 3- or 4-pyridyl group; and R.sub.4 and R.sub.5 are either the same or different 1-5 carbon alkyl or R.sub.4 and R.sub.5 are joined together to form, with the nitrogen atom, a piperidino, pyrrolidino or morpholino group. The compounds are said to possess fibrinolytic and anti-inflammatory activities.
Essentially the same disclosure is found in Inion et al., Eur. J. of Med. Chem., 10 (3), 276-285 (1975). Specifically disclosed in both these references is the species, 2-isopropyl-3-(3-pyridylcarbonyl)-1-[2-(4-morpholinyl)ethyl]-indole.
Herbst U.S. Pat. No. 3,489,770 generically discloses compounds having the formula: ##STR2## where R.sub.1 is "diloweralkylamino, pyrrolidinyl, piperidino and morpholino and R.sub.2 is selected from the group consisting of cyclo(lower)alkanoyl and adamantanylcarbonyl". Although not within the ambit of the above-defined genus, the Herbst patent also discloses a variety of species where R.sub.2 is an arylcarbonyl group. The compounds are said to possess anti-inflammatory, hypotensive, hypoglycemic and CNS activities.
Tambute, Acad. Sci. Comp. Rend., Ser. C, 278 (20), 1239-1242 (1974) discloses compounds of the formula: ##STR3## where n is 2 or 3. No utility for the compounds is given.
Bell U.S. Pat. No. 4,581,354 discloses 3-arylcarbonyl- and 3-cycloalkylcarbonyl-1-aminoalkyl-1H-indoles which are useful as analgesic, antirheumatic and anti-inflammatory agents.


A masking unit for bowling lanes equipped with automatic pinsetters, comprising a vertically moving masking panel and a series of stepped panels in front of the moving panel and extending from the top thereof to the ceiling of the bowling establishment. Stanchions at each end of a panel hold wheeled carriages which engage tracks on the back of the moving panel so that the panel may be vertically raised and lowered. Chain driven control means assures that one end of the panel does not get ahead of the other when the panel is being moved, and spring biasing means aid in raising the panel.

In bowling establishments it is common practice to hide the automatic pinsetters from the view of the bowler with a vertical panel having an artistic design thereon, the lower edge of which is positioned approximately two feet above bowling lane. Such panels are commonly referred to as masking units, a name which generally applies not only to the masking panel itself but also to the structure which supports the panel.
The masking panels are typically positioned close to the front edge of the pin deck and therefore close to the front of the pinsetter. So positioned, they block access to equipment containing microprocessors and other electronic controls which are now frequently mounted to the front of the pinsetters. Therefore, some means of moving the panel to provide access to the front of the pinsetter installation is highly desirable. In the past, an attempt to provide such access was to mount the panel so that it could be rotated to a horizontal position by lifting the front of the panel, as disclosed in U.S. Pat. No. 4,339,129 assigned to Brunswick Corporation. However, this structure did not provide clear access to the front of the pinsetter. The present invention is directed to overcoming this and other problems associated with masking units of past designs.

Brunswick Bowling & Billiards Corporation


A roller bearing unit for a planetary gear is made such that the rollers between the thrust washers are restrained from interference with the thrust washers upon an inclining of the planetary gear either by making the distance between the axially inner faces of washers sufficiently large, or by preventing axial movement of the guide ring between the rollers, so that the axially outer ends are prevented from rubbing hard against the axially inner faces of the washers during running.

1. Field of the Invention
The present invention relates to a roller bearing unit for planetary gear used in an automatic transmission unit for vehicle to rotatably support the planetary gear on a support shaft in the transmission unit.
2. Description of the Prior Art
A typical planetary gear unit of a vehicle automatic transmission is arranged as shown in FIG. 7. In this arrangement, the planetary gear unit is rotatably provided with respect to a support shaft 1. The planetary gear unit comprises a sun gear 2, a planetary gear 6 which is rotatably supported on the support shaft 1 and a support member 3 which is mounted so as to be freely rotatable about an axis of rotation of the sun gear 2 of the planetary gear unit. The support shaft 1 is fixedly attached at its one end (the left end in FIG. 7) to the support member 3, and formed with a cylindrically convex inner race 4 on a central outer peripheral surface thereof.
The planetary gear unit further has a retaining collar 5 which is securely attached to the outer peripheral surface at the other end of the support shaft 1 (right end in the figure).
The planetary gear 6 is provided with gear teeth 7 on an outer peripheral surface thereof, and a cylindrically concave outer raceway 8 formed on an inner peripheral surface thereof. The planetary gear 6 is maintained on the support shaft 1 so as to be freely rotatable about the central outer peripheral surface of the support shaft 1 between the retaining collar 5 and the support member 3.
A double row of first and second free floating rollers 9 are provided without retainer between the inner raceway 4 and the outer raceway 8. A guide ring 10 for guiding the axially inner ends of the rollers 9 (the ends of the rollers 9 of the respective rows facing each other) is provided between the rows of rollers 9. The outer peripheral face of the guide ring 10 is provided adjacent to the outer raceway 8, so that the guide ring 10 rotates with the planetary gear 6.
At least one thrust washer 11 (two washers in the drawings) is provided at the axially inner end faces of the retaining collar 5 and the support member 3 (the faces facing each other), respectively, so that the axially outer ends of the plurality of rollers 9 are faced to the thrust washers 11.
With the above construction, the planetary gear 0 is supported so as to rotate freely with respect to the support shaft 1, and meshes with the sun gear 2 and with a ring gear 12 which is maintained concentric with the axis of the sun gear 2. The gears 2, 6 and 12 are selectively rotated or immobilized with respect to each other, a speed change, or reverse rotation of the output with respect to the input may be achieved in the planetary gear unit.
With the above mentioned planetary gear unit, the distance L between the support member 3 and the retaining collar 5, or between the pairs of thrust washers 11 when the thrust washers 11 are provided,--this is the case for all examples of the present specification, is made a little larger than the sum of the length l(el).sub.1 of the first rollers 9 in one (first row) of the rows of rollers, plus the length l(el).sub.2 of the second rollers 9 in the other row (second row) of rollers (in general l(el).sub.1 =l(el).sub.2), plus the axial length a of the guide ring 10. That is, L>l(el).sub.1 +l(el).sub.2 +a. Consequently, under normal conditions, the axially outer ends of the respective rollers 9 do not rub hard against the thrust washers 11. However, if the guide ring 10, which rotates in accordance with operation of the planetary gear unit, becomes inclined, there is the possibility of the axially outer ends of the rollers 9 rubbing hard against the thrust washers 11.
More specifically, as shown in FIG. 8, during rotation of the planetary gear unit for transmission, the planetary gear 6 may become inclined as a result of axial components of force T1, T2 produced as a result of meshing between the planetary gear 6 and the sun gear 2 and ring gear 12. Consequently the end portions 9a (adjacent the thrust washers 11) of the first and second rollers 9 are driven by the outer raceway 8. As a result, the axes of the rollers 9 are skewed relative to the axis of the support shaft 1 giving rise to a force in an axial direction of the respective rollers 9. As shown by the arrow A in FIG. 8, this force at one point on the inner peripheral surface of the outer raceway 8 pushes on the first rollers 9 of one (first row) of the rows of rollers in an axially inward direction A, while at an opposite point on the inner peripheral surface of the outer raceway 8 (180 degrees around the periphery) the similar force pushes on the second rollers 9 of the other row (second row) of rollers in an axially inward direction indicated by the arrow B of the same figure.
Consequently, due to the inward pushing forces on the double row of rollers 9 at opposite positions 180 degrees around the periphery, like couple of forces, the guide ring 10 disposed between the rows of rollers 9 becomes inclined, so that the apparent axial length of the guide ring 10 is increased to b (b>a).
As a result, the outer ends of the respective rollers 9 rub hard against the thrust washers 11 so that as well as producing an increase in drive (transmission) losses, there is the possibility of failure due to excessive friction and seizure under harsh conditions such as with insufficient lubrication.


A communication device, which is to be mounted on a vehicle, includes: identifying means that identifies a location of the communication device; communication means that successively transmits location information that indicates the location of the communication device that is identified by the identifying means; and setting means that sets a transmission interval at which the location information is to be transmitted in accordance with the location of the communication device that is identified by the identifying means.

In ITS (Intelligent Transport Systems), road-vehicle-vehicle communication is studied in which information is exchanged between a road-side device and a vehicle or between vehicles by using an ad-hoc wireless network.
On the other hand, research into inter-vehicle communication that uses a mobile communication network [for example, 3G, LTE (Long Term Evolution)] has also been undertaken recently.
In order for a center to provide a mobile terminal, such as a cellular terminal (for example, a smart phone) or a dedicated onboard device and so on, with telematics services or road-vehicle-vehicle collaborative services (hereinafter referred to as "information notification services" collectively) which use location information of a vehicle transmitted via a mobile communication network, a location management server in the center needs to collect location information transmitted from mobile terminals via base stations.
However, transmitting location information at high frequency from a mobile terminal that is mounted on a vehicle, leads to an increase in traffic and to over use of the network bandwidth. Therefore, an improvement in the efficiency of the communication of the location information is required.
Patent Documents 1 and 2 describe an onboard communication device that dynamically changes a transmission interval of location information as necessary in order to improve the efficiency of the communication of the location information. The onboard communication device, which is described in Patent Document 1, shortens the transmission interval when a dangerous vehicle approaches. The onboard communication device, which is described in Patent Document 2, changes the transmission interval in accordance with the speed of the approaching vehicle.

Communication device, transmission interval control device, method for transmitting location information, method for controlling transmission interval of location information, and recording medium


A filter medium for filtering matter from a fluid and the manufacture thereof are provided. In one exemplary embodiment, a method may be performed by a filter medium for filtering particulate matter from a fluid. Further, the filter medium may include a nonwoven sliver formed into a predetermined shape and composed of first synthetic staple fibers having a first denier, second synthetic staple fibers having a second denier, and third synthetic staple fibers having a third denier.

Filter media is used in a filter for filtering matter such as particulate matter from fluids and includes media for air filters, chemical filters, coolant filters, hydraulic filters, oil filters, water filters, and the like. Further, filter media is used in many consumer and industrial filtration applications such as for drinking water, swimming pools, aquaculture, waste-water recycling, oil separation, and other applications. In one example, a filter media disposed in a cartridge filter filters water input at the top of the cartridge through a fluid inlet. The filter media then filters the water with the filtered water output through a fluid outlet.
A filter medium is fabricated from a diverse range of materials such as sand, glass, asbestos, natural fibers such as wood pulp and the like, and synthetic polymers such as thermoplastics and the like. Thermoplastics are a plastic material that becomes pliable or moldable above a certain temperature and solidifies during cooling. Thermoplastics may be used to form polymeric and non-polymeric thermoplastic fibers.
A filter medium is typically designed to provide a high filtering efficiency to prevent fine particulate matter from passing through while maintaining a low pressure drop across the medium over its useful life. Further, a filter medium is typically designed for an increased useful life while not requiring frequent cleaning or replacement. However, these design requirements tend to be inversely related, requiring design trade-offs. For instance, a medium having a high filtering efficiency tends to accumulate more particulate matter resulting in a high pressure drop. The loft or thickness of a filter medium typically indicates its ability to entrap particulate matter within the medium's interstitial spaces or pores without impeding the flow of a fluid through the medium. This filtration process is commonly known as depth filtration. In contrast, surface filtration accumulates particulate matter on a surface of a medium, building a high pressure drop across the medium.
There have been many attempts to develop a filter medium having high filter efficiency while maintaining a low pressure drop across the medium. One such attempt uses nonwoven material as a two-dimensional filter. For instance, a fluid having particulate matter flows through one side of the nonwoven material of a filter and a filtered fluid flows out of the other side of the nonwoven material. Further, the filtered particulate matter forms a filter cake on the nonwoven material, resulting in reducing the effectiveness of the filter and requiring a higher pumping power to maintain operation over a longer period. In addition, the use of nonwoven material as a filter material typically suffers from fiber migration, since the fibers do not always stay in their initial positions.
In another such attempt, nonwoven material has been constructed using hollow polyester fibers to form staple fibers. These staple fibers are used to form a single sliver, which may be rolled to form the filtered media. However, the staple fibers cause undesirable fiber migration. Also, the use of hollow fibers have less tensile strength and are prone to breaking, leading to increased fiber migration.
In another such attempt, a porous, compressible filter medium is disposed between compression plates to achieve desired filtration results. The compression plates are used to vary the density and denier (linear mass density) of the fibers of the filter medium. In addition to requiring the use of compression plates, this medium also suffers from a reduced capacity to hold particulate matter in the filter bed. Further, this medium is typically limited to an upflow filter systems.
Accordingly, there is a need for improved techniques relating to a filter medium having high filter efficiency while reducing filter migration and maintaining a low pressure drop across the medium and the manufacturing thereof. In addition, other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and claims, taken in conjunction with the accompanying figures and the foregoing technical field and background.

Nonwoven sliver-based filter medium for filtering particulate matter


A voice call method, device and system, the method including establishing, by a first device, a Bluetooth link to a second device, receiving, by the first device, call request information sent by a third device, sending the call request information to a second device through the Bluetooth link, sending, by the first device in response to an answer command from the second device, the answer command to the third device, establishing, by the first device, a call with the third device, sending a downlink audio signal received from the third device to the second device, or sending and uplink audio signal received from the second device to the third device, and converting, by the first device, in response to a sound channel switching command and receiving a downlink audio signal sent by the third device, the downlink audio signal into a sound signal, and playing the sound signal.

With progress of science and technology and improvement of people's living standards, mobile phones have become necessary in people's daily life and work. Calling is the most primitive and basic function of a mobile phone, and can meet a basic communication requirement between people. Currently, if it is inconvenient for a user to hold a mobile phone on a call, the user may switch the call from the mobile phone to a peripheral device (such as a headset or a speaker) connected to the mobile phone, that is, use an earpiece and a microphone of the peripheral device for the call, to free both hands.
In the prior art, an audio signal in a call process is usually transmitted between the mobile phone and the peripheral device through a voice link established by using a Bluetooth technology. Specifically, the mobile phone and the peripheral device establish the voice link by using the Bluetooth technology. After receiving a downlink audio signal from a network device, the mobile phone transmits the downlink audio signal to the peripheral device through the established voice link, so that the peripheral device converts the received downlink audio signal into a sound signal and plays the sound signal through the earpiece. When the user speaks, the microphone of the peripheral device may collect a corresponding sound signal. The peripheral device converts the collected sound signal into an uplink audio signal, and transmits the uplink audio signal to the mobile phone through the established voice link, so that the mobile phone forwards the received uplink audio signal to a peer end of the call through the network device, to implement the call.
At least the following problem exists in the prior art. An amount of data of an audio signal that can be transmitted through the voice link established between the mobile phone and the peripheral device by using the Bluetooth technology is limited, and a call requirement in a scenario in which a relatively large amount of data needs to be transmitted cannot be met.

Voice call method, electronic device, and system


A system for retrieving messages of a supply process in a supply chain and methods for making and using the same. The system may bind a message received from a player of the supply chain with existing related messages, build a binding message set based on bound messages and retrieve the messages based on the binding message set. Messages issued by the player may follow frameworks generated between the player and other players of the supply chain. In accordance to a specific framework, a message between two players may have a common data element and may follow rules proscribed within the framework. Global standards or common data elements is not required, thereby permitting each participant in the supply chain to transmit messages in their preferred format.

Supply chain management, sometimes known as logistics management, comprises the management of the flow of goods and services from raw materials to the point of consumption. Supply chain management includes planning, implementing and controlling the efficient, effective forward and reverse flow and storage of goods, services and related information between the point of origin and the point of consumption in order to meet customer's requirements. This flow of goods, services and related information can be complicated and involve numerous participants who have minimal or no exposure to each other or understanding of the tasks each individual party is performing in the supply chain.
Supply chain logistics is a complex operation. In a general business sense, logistics is the management of the flow of messages between the point of origin and the point of consumption. Manufacturers, customers, shippers, carriers and other players or participants of the supply chain each have requirements and preferences regarding access to information and messages during the supply chain process, thus, it is difficult to implement unified data standard and data model among the plurality of players in the supply chain. For example, a unified keyword for identifying messages of a specific supply process is difficult, if not impossible, to implement, because, among other factors, of the competing interests and attention paid by various participants or players in the supply chain.
A goal of supply chain automation, or logistics automation, is to build a transaction model among players of the supply chain, which meets each player's expectations and can be followed by the players or participants of the supply chain process. Various solutions for supply chain automation are designed to help the supply chain industry in automating the workflow, as well as management of the system. Yet, because of the complexity of the supply chain, currently-available solutions do not satisfy the goal of supply chain automation and visibility.
An issue with many supply chain management systems is visibility afforded to all of the participants or players or at least the players or participants who desire visibility throughout the supply chain. When activity in the supply chain reaches its full potential, it becomes infeasible to model the transaction processes, because there is no intersection data element, such as common data element, between transactions in the supply chain network. It is not realistic to add new common data elements since the supply chain processes often involve many parties around the world, and thus, it is infeasible to build a unified automation model among the players for supporting proper visibility of the supply chain management.
The invisibility of the supply chain results in uncertainty to the customer or other supply chain participant, which is undesirable even when a minimal number of certain deliveries are impacted, because delivery of particular products may be extremely important for the customer's operations and/or for the operation of various other players or participants in the supply chain, such as for scheduling by carriers. For example, a customer may require a particular chemical compound from a manufacturer to operate their business. If the chemical compound does not arrive on time, the customer's business may be shut down until the compound does arrive. Such shut downs are exceptionally expensive and disruptive. In addition, late deliveries to carriers may disrupt the carrier's scheduling and can be expensive for the carrier and customer who absorbs increased fees from the carrier. Alternatively, if the product is food for the customer's vending machine, delays may be tolerable, as failure to refill the vending machine will not result in shut down of the customer's operations. With improved visibility of the shipment of products, good and services, the customer is able to adapt to potential cancellations or accept delays for shipments on low priority goods, services or products.
In currently-available systems, communications following confirmation of the order create were exclusively between a shipper and a manufacturer. That is, once an order was confirmed, the manufacturer handles shipment of the ordered product to the customer, typically through a third party shipper, and the shipper communicates exclusively with the manufacturer. Even if these communications were exchanged through a centralized supply chain management system, it is difficult to tie the message together and the customer had no access to the shipping status or exposure to potential problems with the shipment. The presently known systems, therefore, lack exposure to the shipping status of a product to a customer by tying communication messages together that relate to an order of the product.
In view of the foregoing reasons, it is desirable to have a system and method to maintain visibility of messages in a supply chain management system between the numerous participants to improve product and service visibility and timing.

System and method for supply chain management


Spread spectrum transceivers communicate using code sequences having low cross-correlations and well-peaked autocorrelations. The initial communications involve broadcasting a beacon signal consisting of a beacon packet repeated at regular intervals (the cycle time). The code sequences may be period-(2nxe2x88x921) Small Kasami sequences; the beacon packet is a repeated series of (2n/2+1) period-(2n/2xe2x88x921) progenitor maximal sequences, and behaves like a member of the Kasami family. The acyclic autocorrelation of the beacon packet has regularly-spaced sharp peaks modulated by a pyramidal envelope. The initial communications involve calculating the correlation between the received signal and delayed versions of an internally-generated beacon packet. The length of the initial communications is proportional to the square of the cycle time divided by the width of the acyclic autocorrelation. Synchronization involves locating the peak of the pyramidal envelope, and has a length related to the cycle time times the number of peaks in the acyclic autocorrelation.

The present invention is related generally to nonsinusoidal spread spectrum radio communication systems, and more particularly to signal acquisition by nonsinusoidal spread spectrum radio transceivers.
In contrast with traditional sinusoidal-carrier radio communication systems where the transmitted electromagnetic power is concentrated in a narrow frequency band, in spread spectrum communication systems the power is distributed over a relatively large bandwidth. Spread spectrum radio communications are used in place of traditional systems to circumvent communications jamming by interference signals, prevent detection and interception by unwanted receivers so as to provide privacy, provide tolerance to multipath transmissions, send multiple independent signals over a frequency band, and/or provide accurate ranging information.
Nonsinusoidal spread spectrum (NSS) transmissions a(t) relevant to the present invention are of the form
a(t)=xcexa8(t)*d(t),xe2x80x83xe2x80x83(1.1)
where t is time, d(t) is a data function with data values of positive and negative unity where the data values of the data function d(t) have a bit width ts, and xcexa8(t) is a pseudorandom code sequence consisting of a repeated series of a pseudorandom code "PHgr"(t) of length ts, i.e.,
xcexa8(t)="PHgr"(t mod ts),xe2x80x83xe2x80x83(1.2)
where the pseudorandom code "PHgr"(t) has a value of zero for t less than 0 and t greater than ts. The data function d(t) changes value at integer multiples of ts, and one bit of data from d(t) is therefore encoded on each repetition of the pseudorandom code "PHgr"(t).
An exemplary NSS transmission a(t) based on a pseudorandom code "PHgr"(t) having a length of seven bits is shown in FIG. 1A. The first five bits of the data function d(t) are (1, xe2x88x921, 1, 1, xe2x88x921, . . . ) and the pseudorandom code "PHgr"(t) consists of the bits (1, 1, 1, xe2x88x921, 1, xe2x88x921, xe2x88x921). Therefore, as shown in FIG. 1A, the product of the data function d(t) and the pseudorandom code sequence xcexa8(t), which consists of bits (1, 1, 1, xe2x88x921, 1, xe2x88x921, xe2x88x921, 1, 1, 1, xe2x88x921, 1, xe2x88x921, xe2x88x921, . . . ), is the transmission a(t) consisting of bits (1, 1, 1, xe2x88x921, 1, xe2x88x921, xe2x88x921, xe2x88x921, xe2x88x921, xe2x88x921, 1, xe2x88x921, 1, 1, 1, 1, 1, xe2x88x921, 1, xe2x88x921, xe2x88x921, 1, 1, 1, xe2x88x921, 1, xe2x88x921, xe2x88x921, . . . ).
The cross-correlation xcex9(t) between a first function A(t) and a second function B(t) is given by                                           Λ                          A              ,              B                                                      xe2x80x83                                          (            t            )                          =                              ∫                          -              ∞                        ∞                                          A                                      xe2x80x83                                                  (                              τ                -                t                            )                        *            B                                      xe2x80x83                                                  (              τ              )                                                  xe2x80x83                                                                  ⅆ                τ                            .                                                          (        1.3        )
When the first function A is the same as the second function B, the above equation provides the autocorrelation xcex9A(t), i.e.,                                           Λ            A                                          xe2x80x83                                          (            t            )                          =                              ∫                          -              ∞                        ∞                                          A                                      xe2x80x83                                                  (                              τ                -                t                            )                        *            A                                      xe2x80x83                                                  (              τ              )                                                  xe2x80x83                                                                  ⅆ                τ                            .                                                          (        1.4        )
If the first function A(t) and the second function B(t) are both periodic with period T, then the cross-correlation xcex9A,B(t) and the autocorrelation xcex9A also are periodic with period T, i.e.,
xcex9A,B(t)=xcex9A,B(t mod T),xe2x80x83xe2x80x83(1.5)
and
xcex9A(t)=xcex9A(t mod T).xe2x80x83xe2x80x83(1.6)
Therefore, if the first and second functions A(t) and B(t) have period T, the integration used to determine the correlation function may be performed over a time t of length T and then normalized, and the starting time for an integration over a time t of length T is immaterial.
If the functions A(t) and B(t) are actually bit sequences xcex1(i) and xcex2(i) of length N bits, with each bit having a bit length of xcex94t, then
xe2x80x83xcex9A,B(nxcex94t)=xcfx80xcex1xcex2(n)xcex94t,xe2x80x83xe2x80x83(1.7)
where xcexxcex1xcex2 is the discrete cross-correlation given by                                                         λ                              α                ,                β                                                                xe2x80x83                                                  (              n              )                                =                                    ∑                              i                =                1                            N                                                  xe2x80x83                                                  α                                            xe2x80x83                                                          (                                  i                  -                  n                                )                            *              β                                            xe2x80x83                                                          (                i                )                                                    ,                            (        1.8        )
where i and n are integers. Similarly, if the function A(t) is a bit sequence xcex1(i) of length N, with each bit having a bit length of xcex94t, then
xcex9A(nxcex94t)=xcexxcex1(n)xcex94t,xe2x80x83xe2x80x83(1.9)
where xcexxcex1 is the discrete autocorrelation given by                                           λ            α                                          xe2x80x83                                          (            n            )                          =                              ∑                          i              =              1                        N                                          xe2x80x83                                          α                                      xe2x80x83                                                  (                              i                -                n                            )                        *            α                                      xe2x80x83                                                                  (                i                )                            .                                                          (        1.10        )
For example, consider the discrete autocorrelation xcexxcex1 for the five-bit sequence xcex1={1, xe2x88x921, xe2x88x921, 1, xe2x88x921}. For instance, the n=1 value of the discrete autocorrelation xcexxcex1 is calculated by
xcexxcex1(1)=xcex1(0)xcex1(1)+xcex1(1)xcex1(2)+xcex1(2)xcex1(3)+xcex1(3)xcex1(4)+xcex1(4)xcex1(5)=xe2x88x921 xe2x88x921+xe2x88x921xe2x88x921=xe2x88x923.xe2x80x83xe2x80x83(1.11)
As can be shown by similar such calculations, the discrete autocorrelation xcexxcex1 has values of 5, xe2x88x923, 1, 1 and xe2x88x923 for n equals 0, 1, 2, 3 and 4, respectively. As shown in FIG. 2, the continuous autocorrelation xcexxcex94 for the corresponding function xcex94(t) is easily generated from the discrete autocorrelation xcexxcex1 by connecting autocorrelation values at integer multiples of xcex94t by straight lines. It should also be noted that the continuous autocorrelation xcex9A is symmetric about t=0, and, of course, periodic with a period of T=5xcex94t.
A fundamental class of binary sequences which have useful autocorrelation properties is the maximal sequence class. Any maximal sequence may be generated by a linear feedback shift register (LFSR). (It is important to note that the binary bit values of unity and negative unity, which will be used in the present specification when discussing correlations and autocorrelations, may be directly translated to the binary bit values of zero and unity, which will be used in the present specification when discussing the operation of LFSR""s and generating polynomials.) The exemplary LFSR 100 shown in FIG. 3A is a five-stage shift register consisting, from right to left, of five flip-flops 101, 102, 103, 104, and 105. (In the present specification the convention will be that for LFSRs with an output on the right, the rightmost flip-flop will be referred to as the first flip-flop, the second-from-the-right flip-flop will be referred to as the second flip-flop, etc. For instance, the leftmost flip-flop 105 will be referred to as the fifth flip-flop 105.) On each clock pulse, the bit value held in each of the four leftmost flip-flops 102, 103, 104 and 105 of the LFSR 100 is shifted one flip-flop to the right. (A clock and its connections within the LFSR 100 are not shown in FIG. 3A.) Therefore, on a clock pulse the bit value in the fifth flip-flop 105 is shifted into the fourth flip-flop 104, the bit value in the fourth flip-flop 104 is shifted into the third flip-flop 103, etc. The output 111 of the LFSR 100 is produced by the first flip-flop 101. The input value to the fifth flip-flop 105 of the LFSR 100 is provided by a feedback loop 110 which, in the case of this particular LFSR 100, consists of an XOR adder 121 which taps the output 113 of the third flip-flop 103, as well as the output 111 of the first flip-flop 101. (Although the exemplary LFSR 100 of FIG. 3A has only a single XOR adder 121 in the feedback loop 110, it should be understood that, in general, an LFSR may direct taps from the outputs of any of its flip-flops to additional XOR adders in the feedback loop.) The XOR addition, which is typically notated as xe2x80x98⊕xe2x80x99, of two binary value inputs is equal to unity when one, and only one, of the binary value inputs is unity, and is zero otherwise, i.e., 0⊕0=0; 0⊕1=1; 1⊕1=1; and 1⊕1=0. This type of flip-flop configuration, with taps from the outputs of some or all of the flip-flops to XORs in a feedback loop (the output of the first flip-flop is necessarily directed to the feedback loop), which is summed and directed to the leftmost flip-flop, is known as a Fibonacci construction LFSR.
For instance, if xe2x80x98seedxe2x80x99 values of {0, 0, 1, 1, 1} are placed in the flip-flops 105, 104, 103, 102 and 101, respectively, then on the next clock pulse the fourth, third, second and first flip-flops 104, 103, 102 and 101 receive the bit values of 0, 0, 1, 1, respectively. The XOR 121 receives the outputs of the first and third flip-flops 101 and 103, and therefore produces an output of zero which is sent to the fifth flip-flop 105. Therefore, the new state of the LFSR is {0, 0, 0, 1, 1}. Similarly, on the next clock pulse the fourth, third, second and first flip-flops 104, 103, 102 and 101 receive the bit values of 0, 0, 0, 1, respectively. The XOR 121 receives the outputs of the first and third flip-flops 101 and 103, and therefore produces an output of unity which is sent to the fifth flip-flop 105. Therefore, the new state of the LFSR is {1, 0, 0, 0, 1}. As can be seen from Table 1, which provides a list of the first ten states and outputs produced by the seed of {0, 0, 1, 1, 1}, the output values from this seed are (1, 1, 1, 0, 0, 0, 1, 1, 0, 1, . . . ).
Transitions between states of an LFSR may be represented as arrows in a state transition diagram, where the states of the LFSR may be depicted on a linear or a circular axis. A state transition diagram 150 for an n-stage LFSR is shown in FIG. 3D on a circular axis 151 where the state (2nxe2x88x921) is located adjacent to state 0. For a Fibonacci LFSR in state X, there are only two possibilities for the next state. Either (a) a zero can be output from the LFSR and put into the most significant bit, in which case the state becomes └X/2┘, or (b) a one can be output from the LFSR and put into the most significant bit, in which case the state becomes (2nxe2x88x921+└X/2┘), where the partial brackets xe2x80x9c└ ┘xe2x80x9d indicate that the greatest integer less than or equal to the value inside the partial brackets is taken. The transition from state X to state └X/2┘ is represented by an arrow 155 which begins at X and ends approximately halfway between X and 0. The transition from state X to state (2nxe2x88x921+└X/2┘) is represented by an arced arrow 157 which begins at X and ends diametrically opposite state └X/2┘, ie., the end of the arced arrow 157 is located where arrow 155 sums with arrow 156 which spans the diameter of the circular axis 151. Similarly, the transition from state Y, which has a value somewhat greater than 2nxe2x88x921, to state └Y/2┘ is represented by an arrow 165 beginning at Y and ending approximately halfway between Y and 0, and the transition from state Y to state (2nxe2x88x921+└Y/2┘) is represented by an arced arrow 167 which begins at Y and ends diametrically opposite state └Y/2┘.
A mirror image version 110xe2x80x2 of the LFSR 100 of FIG. 3A, is shown in FIG. 3B. Although it may seem trivial that the mirror image LFSR 100xe2x80x2 functions in exactly the same way as the LFSR 100 of FIG. 3A, due to frequent confusions found in the literature it is important to point out that the xe2x80x9cmost significant bitxe2x80x9d is held in the leftmost flip-flop 105 of the LFSR 100 of FIG. 3A, while the xe2x80x9cmost significant bitxe2x80x9d in the mirror-image LFSR 100xe2x80x2 of FIG. 3B is in the rightmost flip-flop 105.
A different type of construction for a five-stage shift register 200 is shown in FIG. 3C. As shown in FIG. 3C, the output 201 from the first flip-flop 201, i.e., the rightmost flip-flop 201, is fed via lead 223 to an XOR adder 233 located between the fourth flip-flop 204 and the third flip-flop 203. The XOR adder 233 also receives the output 214a of the fourth flip-flop 204, and the output 214b of the XOR 233 is directed to the third flip-flop 203. This type of construction, where one or more XOR adders are located in the signal path between the series of flip-flops is known as a Galois construction LFSR. (Again we point out, motivated by confusions found in the literature, that a mirror-image version of the Galois LFSR 200 of FIG. 3C functions exactly as the LFSR 200 of FIG. 3C. Furthermore, the most significant bit is held in the leftmost flip-flop 205 of the LFSR 200 of FIG. 3C, and in the mirror-image version the most significant bit would be held in the rightmost flip-flop.)
Galois construction LFSRs have the advantage of being faster than Fibonacci construction, because the computations required for a Fibonacci construction LFSR will generally have to propagate through more levels of logic, and may therefore require a longer clock cycle. It may be shown that any Fibonacci construction LFSR may be mapped to a Galois construction LFSR which can generate the same sequence of output values. This mapping between Fibonacci and Galois constructions is accomplished by reversal of the ordering of the taps/feeds. For instance, the Galois construction LFSR 200 of FIG. 3C is equivalent to the Fibonacci construction LFSR 100 of FIG. 3A, since the Galois construction LFSR 200 is five flip-flops in length and has a feed to an XOR 233 between the fourth flip-flop 204 and the third flip-flop 203, and the Fibonacci construction LFSR 100 is five flip-flops in length and has a feed to an XOR 121 between the third flip-flop 102 and the second flip-flop 103. Therefore, in general, a Fibonacci LFSR of n flip-flops with m taps from the inputs to the t1, t2, . . . , tm flip-flops is equivalent to a Galois LFSR of n flip-flops with m feeds to XOR adders following the (nxe2x88x92t1), (nxe2x88x92t2), . . . , (nxe2x88x92tm) flip-flops.
The equivalence of the LFSRs 100 and 200 of FIGS. 3A and 3C can be verified by noting that both LFSRs 100 and 200 produce the same periodic output. For instance, if flip-flops 205, 204, 203, 202 and 201 of FIG. 3B have the seed values {1, 1, 1, 1, 1}, respectively, then on the first clock pulse the output 201 of the LFSR 210 is unity, and this value of unity is deposited in the fifth flip-flop 205. Similarly, the fourth, second and first flip-flops 204, 202 and 201 receive the values of unity from the fifth, third and second flip-flops 205, 203 and 202, respectively. The XOR 233 receives the value of unity from the fourth flip-flop 204 and the value of unity from the first flip-flop 201, and so the XOR 233 feeds a value of zero to the third flip-flop 203. Therefore, the new state of the flip-flops 201-205 is {1, 1, 0, 1, 1}. By the same process described above it is easily verified that the next set of values in the LFSR 200 is {1, 1, 0, 0, 1}. Table 2 below provides a list of the first ten states of the LFSR 200, showing that both LFSRs 110 and 210 do indeed have the same output values. As can be seen from Table 1, which provides a list of the first ten states and outputs produced by the seed of {0, 0, 1, 1, 1}, the output values from this seed match the series of output values from listed in Table 1 above.
For certain feedback configurations of Galois or Fibonacci LFSRs, which are termed optimal configurations, the states of the flip-flops of an LFSR cycle through all possible combinations, except the zero state, i.e., {0, 0, 0, . . . , 0}. The zero state cannot be included in the sequence of states, because upon the next clock pulse the LFSR remains in the zero state, so all outputs of the LFSR are zero, and the output sequence as well as the sequence of states of the flip-flops have a period of unity. Therefore, for an optimal configuration LFSR of n flip-flops, the output has a period N of 2nxe2x88x921 which consists of 2n/2xe2x88x921 values of zero and 2n/2 values of unity. Such an output is termed a maximal sequence. The LFSRs 100 and 100xe2x80x2 of FIGS. 3A and 3B are examples of optimal configurations.
Just as Fibonacci-configuration LFSRs can be mapped to Galois-configuration LFSRs and vice versa, it may be shown that each LFSR which generates a maximal sequence can be mapped to a Galois field of order 2n. Elements of the Galois field of order 2n are n-tuples of binary digits which can also be represented as polynomials of degree (nxe2x88x921) with all coefficients being either zero or unity. For instance, the element (1, 0, 0, 1, 1) corresponds to the polynomial
1xc2x7x4+0xc2x7x3+0xc2x7x2+1xc2x7x1+1xc2x7x0=x4+x+1.xe2x80x83xe2x80x83(2.1)
Multiplication in the Galois field is defined as a multiplication of the corresponding polynomials (with coefficients obeying modulo 2 arithmetic) from which the remainder is taken modulo an irreducible polynomial, i.e., a polynomial with no polynomial factors, of degree n. (See, for example, chapter 25 of Number Theory in Science and Communication, Second Edition, M. R. Schroeder, Springer-Verlag, Berlin, 1986.) Using this definition of multiplication, the elements of the Galois field are generated by a primitive element xcex6. That is, the elements of the Galois field are
0, xcex61, xcex62, xcex63, . . . xcex6q(n)xe2x88x922, xcex6q(n)xe2x88x921,xe2x80x83xe2x80x83(2.2)
where q(n)=2n. If the irreducible polynomial used to define the multiplication operation is written as
h(x)=h0xn+h1xnxe2x88x921+ . . . +hnxe2x88x921x+hn,xe2x80x83xe2x80x83(2.3)
where h0=hn=1, then it can be shown that the most significant bits of the sequence of fields xcex61, xcex62, xcex63, . . . xcex6q(n)xe2x88x922, xcex6q(n)xe2x88x921 is a maximal sequence (u1, u2. u3, . . . uq(n)xe2x88x921) given by
uj=h1ujxe2x88x921⊕h2 ujxe2x88x922⊕ . . . , ⊕hnxe2x88x921ujxe2x88x92n+1⊕hnujxe2x88x92n.xe2x80x83xe2x80x83(2.4)
By comparing this functional form to the exemplary Fibonacci LFSR 100 of FIG. 3A it can be seen that this is equivalent to the sequence generated by the LFSR 100 when hi=1 if the ith cell from the left has its output fed back to the input 105 of the LFSR 100, and hi=0 if the ith cell from the left does not have its output fed back to the input 105 of the LFSR 100. In the case of the LFSR 100 of FIG. 3A, equation (2.4) becomes
xe2x80x83uj=ujxe2x88x923⊕ujxe2x88x925,xe2x80x83xe2x80x83(2.5)
and the fifth-order polynomial corresponding to equation (2.5) is
h(x)=1xc2x7x5+0xc2x7x4+0xc2x7x3+1xc2x7x2+0xc2x7x1+1=x5+x2+1.xe2x80x83xe2x80x83(2.6)
The polynomial of equation (2.6) may be written as (1, 0, 0, 1, 0 1), or, even more conveniently, in octal notation as (45o). (It should be noted that although the five-bit LFSR 100 corresponds to a fifth-order polynomial, the octal representation of the polynomial consists of six bits. Therefore, in this case, according to the terminology of the present specification, the five-bit LFSR 100 has a six-bit octal representation.) According to an analogous notation, the locations of feeds for the Galois LFSR 200 of FIG. 3C is written as (1, 0, 1, 0, 0, 1), or (51)o, where the subscript xe2x80x98Oxe2x80x99 indicates an octal number. A primitive polynomial is a polynomial of the form of equation (2.3) that generates a maximal sequence.
A list of all maximal sequences generated by two-bit through sixteen-bit shift registers (i.e., three-bit through seventeen-bit octal representations) is provided as a microfiched appendix to the present specification. The polynomials for the maximal sequences provided in octal Galois form are followed by an xe2x80x9cogxe2x80x9d, and the polynomials for the maximal sequences provided in octal Fibonacci form are followed by an xe2x80x9cofxe2x80x9d. For instance, a maximal sequence for a four-bit Galois-configuration shift register can be produced by the (31)o polynomial or the (23)o polynomial. As may be verified by inspection of the primitive polynomials provided in the microfiched appendix to the present specification., the number of configurations which produce maximal sequences for an n-bit shift register is given by
xcfx86(2nxe2x88x921)/nxe2x80x83xe2x80x83(2.7)
where xcfx86(i) is Euler""s totient function which has a value equal to the number of integers which are less than i and have no common divisors with i. For instance, if n=4, then (2nxe2x88x921)=15, and there are eight integers, namely 1, 2, 4, 6, 7, 8, 11, and 13, which have no common divisors with 15. Therefore, as the microfiched appendix confirms, there are only two (Fibonacci or Galois) polynomials which generate maximal sequences for four-bit LFSRs. Pages 53-54 of the present specification provides C-language programming code for generating the set of all maximal sequences for an n-bit shift register.
The sequences generated by LFSRs are cyclic, i.e., if {u1, u2, . . . , uN} is a sequence generated by equation (2.3), then {umod(N, 1+i), umod(N, 2+i), . . . , umod(N, N+i)} is also a sequence generated by equation (2.3) for any integer i. Therefore, the starting point of a sequence is arbitrary. The sequence {umod(N, 1+i), umod(N, 2+i), . . . , umod(N, N+i)} is a phase shift of magnitude i of the sequence {u1, u2, . . . , uN}, and this is written as
{umod(N, 1+i), umod(N, 2+i), . . . , umod(N, N+i)}=Pi{u1, u2, . . . , uN},xe2x80x83xe2x80x83(2.8)
where P is the phase shift operator.
Generally, families of pseudorandom code sequences which have low cross-correlations and sharply peaked autocorrelations are used in NSS communications. Using these types of code sequences, reception of an NSS transmission a(t) is accomplished by circuitry which calculates the correlation between the received signal a(t) and the expected pseudorandom code sequence "PHgr"(t). To receive the transmission a(t), the transmitted pseudorandom code sequence and the time of its arrival must be known or determined by the receiver. When a receiver calculates the correlation between an incoming signal and an internally-generated signal consisting of the same code sequence and beginning at the time of arrival of the incoming signal, the relatively large value of the calculated correlation indicates that a transmission was indeed received. With low cross-correlations, the communications between one pair of transceivers using one pseudorandom sequence will not interfere with the communications of other transceivers in the vicinity which are using other pseudorandom code sequences.
A maximal sequence has the useful property that its autocorrelation is very sharply peaked. For zero phase shift, the discrete autocorrelation of a maximal sequence has a value of 2nxe2x88x921, and for all other (bit length) phase shifts the discrete autocorrelation has a value of xe2x88x921. However, the cross-correlation properties of maximal sequences are poor, i.e., the cross-correlation values are not small. (See xe2x80x9cCrosscorrelation Properties of Pseudorandom and Related Sequences,xe2x80x9d Dilip V. Sarwate and Michael B. Pursley, Proceedings of the IEEE, Vol. 68, No. 5, May 1980, page. 602, column 1.)
Many types of spread spectrum systems have transceivers which transmit continuous signals and also continually receive incoming signals. In contrast, as specified in detail in U.S. Pat. No. 6,002,708 for Spread Spectrum Localizers, which is incorporated herein by reference, according to the present invention the transmissions of the transceivers are episodic, i.e., not continuous. (According to the terminology of the present specification, an xe2x80x9cepisodicxe2x80x9d transmission may be periodic, i.e., it may consist of one or more transmissions within a period, as long as there are intervals of non-transmission between the transmissions.) According to the present invention, the reception of an episodic transmission a(t) consists of a sequence of operations including: (i) a sequence generator produces an internally-generated integration sequence xcex1i(t) which resembles the expected pseudorandom sequence xcex1e(t) of the received signal a(t); (ii) a set of event registers is armed to trigger reception processing circuitry bracketing a finite time interval during which a reception is expected to occur; (iii) during the reception event the received signal a(t) is multiplied by internally-generated integration sequences xcex1i(t) which are delayed by a number of different time offsets; and (iv) the correlations of the delayed internally-generated integration sequences xcex1i(t) and the received signal a(t) are calculated and analyzed. As specified in detail in U.S. Pat. No. 6,002,708, the correlations are calculated using a time-integrating correlator circuit. Although the time-integrating correlator output resembles a time sampling of the correlation xcex9xcex1,a(t) between the internally-generated integration sequence xcex1i(t) and the received signal a(t), it should be noted that the correlation as a function of time is never actually determined by the time-integrating correlator circuit, and therefore it cannot be sampled. The time-integrating correlation circuit only determines values of discrete correlation function xcexxcex1,a(n) at a number of discrete times, which are referred to as the time bins. If the time bins are separated by an interval of ts seconds, the time-integrating correlator circuit has M integrators, and each time bin has a length of tx seconds, then the length of the time window during which the time-integrating correlator can detect a signal during a reception event is [(Mxe2x88x921)*ts+tx].
However, before a pair of transceivers can begin communications, both transceivers must first determine that the other transceiver is broadcasting from within a distance where reception is possible. The transmissions and attempted receptions that occur up until either of the transceivers actually receives a signal from the other is termed the contact stage of the acquisition process. Once the two transceivers have determined that there is another transceiver in the vicinity, then the two transceivers enter the synchronization stage of the acquisition process where they must synchronize their transmission/reception schedules and arrange any other protocols required for continued communications. Two transceivers involved in the acquisition process are referred to as the acquiring transceivers. Furthermore, transceivers which are not involved in the acquisition process are referred to as nonacquiring transceivers.
An exemplary group of transceivers 30A, 30B, 30C, 30D, 30E, 30F and 30G in various levels of communication is shown in FIG. 1B. Transceivers 30A, 30B, 30C and 30D have already completed the acquisition stage with each of the other transceivers 30A, 30B, 30C and 30D within that group, and are involved in two-way communications 40AB, 40AC, 40AD, 40BC, 40BD, 40CD with each other. (The bi-directionality of the communications 40AB, 40AC, 40AD, 40BC, 40BD, 40CD is illustrated by the arrows at each end of the line segments.) Transceivers 30D and 30E are involved in a two-way communication 40DE with each other, but transceiver 30E is not in communication with any of the other transceivers 30A, 30B, 30C, 30D, 30F and 30G. If transceiver 30E is to begin communications with the other transceivers 30A, 30B, 30C which transceiver 30D is in communication with, synchronization information regarding the other transceivers 30A, 30B, 30C may be communicated to transceiver 30E via communications with transceiver 30D. Alternatively, synchronization of transceiver 30E with any of the other transceivers 30A, 30B, 30C, 30D, 30F and 30G may be accomplished by an acquisition process where transceiver 30E locates a beacon signal broadcast by the other transceivers 30A, 30B, 30C, 30D, 30F and 30G, or vice versa. Transceivers 30C and 30G are involved in a one-way communication 40CG with each other where transceiver 30G has located the beacon signal of transceiver 30C, but transceiver 30C has not located the beacon signal of transceiver 30G and so transceiver 30C is not yet aware of the existence of transceiver 30G. Transceiver 30G may possibly be involved in more accurately determining the schedule of beacon transmissions from transceiver 30C, or may have already completed that process. Since transceiver 30G has located the beacon signal of transceiver 30C, transceiver 30G has timing information regarding transceiver 30C, and to complete the acquisition process transceiver 30G can broadcast a beacon signal when transceiver 30C will be attempting to receive beacon signals. Transceiver 30F is not in communication with any other transceivers 30A, 30B, 30C, 30D, 30E and 30G in the group. However, transceiver 30F is broadcasting beacon signals and attempting to receive beacon signals. Furthermore, all the transceivers 30A, 30B, 30C, 30D, 30E, 30F and 30G (which will generically be assigned the reference numeral 30) have recurrent periods of time during which they listen for beacon signals to determine if transceivers 30 which they are not currently in contact with have come into communication range. It may be physically impossible, due to the finite transmission power of the transceivers 30, for all transceivers 30 to be in direct contact with each other. However, information may be passed from transceivers 30 to transceiver 30, so that transceivers 30 which are beyond the range of direct communications may communicate indirectly.
Typically, beacon signals within a prearranged family of codes are used for acquisition. However, according to the preferred embodiment of the present invention, a single prearranged beacon sequence is used for acquisition. As an example of a system that does not provide the advantages of the present invention, consider the acquisition process for a transmitter which is broadcasting a beacon signal 300 which consists of beacon packets 310 of length tb seconds once every tc seconds, as is shown in FIG. 4A, where each beacon packet 310 is a maximal sequence. If the maximal sequences 310 each have a bit length of N then, as shown in FIG. 4B, the central peak 350 of the autocorrelation function xcex9xcex1345 for these beacon packets 310 has a magnitude of N and a width of roughly tb/N, and in the regions 360 outside the peak 350 the value of the autocorrelation function xcex9xcex1345 is considerably smaller than the peak value N. (As is shown in FIG. 4B and discussed in more detail below in conjunction with FIGS. 9A-9C, because of the random nature of the bit values in a maximal sequence, the average magnitude of the sidelobes 360 of the autocorrelation function xcex9xcex1345 of the finite-length beacon packet typically reaches a maximum near the midpoint of the sidelobes 360. Roughly, the sidelobes 360 have an average magnitude of ✓N at time t=tb/2. It should be noted that, for large values of N, the magnitudes of the values in the sidelobes is exaggerated relative to the magnitude of the peak in FIG. 4B.)
The reception procedure for an exemplary receiver is depicted in FIG. 4A. (For convenience of depiction only four reception bins are depicted in FIG. 4A. However, receivers will typically use more than four reception bins per reception time window.) The internally-generated code sequences 315a.1, 315a.2 and 315a.3 for the first time bin for three reception events 341, 342 and 343 are depicted on a first reception time axis 321, the internally-generated code sequences 315b.1, 315b.2 and 315b.3 for the second time bin for the three reception events 341, 342 and 343 are depicted on a second reception time axis 322, and so on. In the first reception event 341 beginning at time t0 the receiver generates a first internally-generated code sequence 315a.1 of length tb, i.e., the length of the anticipated beacon packet 310. The received signal, i.e., the signal 300 broadcast by the transmitter, is multiplied with the internally-generated code sequence 315a.1 and integrated over time. In this case since there is no beacon packet 310 arriving at the receiver beginning at time t0, so the result of the multiplication and integration produces a relatively small value, which is only non-zero due to received noise. The receiver will therefore determine that a beacon packet 310 is not arriving at the receiver beginning at that time. Also, during the first reception event 341 the receiver generates a second internally-generated code sequence 315b.1 of length tb beginning at time [t0+(tw/3)]. The received signal 300 is multiplied with the internally-generated code sequence 315b.1 and integrated over time. Again, the receiver will determine that no beacon packet 310 is arriving at the receiver beginning at that time since the value produced by the integration is relatively small. Similarly, during the first reception event 341 the receiver generates a third and fourth internally-generated code sequences 315c.1 and 315d.1 beginning at times [t0+(2tw/3)] and [t0+tw] and performs multiplications and time integrations, and will determine that a beacon packet 310 did not arrive beginning at those times either.
Since the time-integrating correlator can only perform one set of measurements per cycle time tc, the beacon signal is searched for by incrementing the starting time of the time window 315 by tc+tw and performing another reception. In particular, in the second reception event 342 beginning at time t0+tc+tw the receiver generates a first internally-generated code sequence 315a.2 of length tb which is multiplied with the received signal 300 and integrated over time. Since, in this case there is no beacon packet 310 arriving at the receiver beginning at time t0+tc+tw, the result of the multiplication and integration produces a relatively small value, and the receiver determines that a beacon packet 310 is not arriving at the receiver beginning at that time t0+tc+tw. Similarly, during the second reception event 342 the receiver generates a second, third and fourth internally-generated code sequences 315b.2, 315c.2, and 315d.2 of length tb beginning at times [t0+tc+(tw/3)], [t0+tc+(2tw/3)], and [t0+tc,+tw], respectively. The received signal 300 is multiplied with the internally-generated code sequences 315b.2, 315c.2, and 315d.2 and integrated over time and, again, the receiver will determine that no beacon packet 310 is arriving at the receiver beginning at those times since the value produced by the integration is relatively small. The beacon signal is searched for by incrementing the starting time of the time window 315 by an additional tc+tw and performing another reception 343, and so on.
Therefore, on average the contact time, i.e., the time required for the receiver to locate the beacon signal, will take the transceiver xc2xdxc2x7(tc/tw) cycle times to locate a beacon packet 310. If the cycle time tc is approximately one millisecond, and the time windows have a length tw of around 100 nanoseconds, then it will require approximately 10,000 cycles (ie., on the order of ten seconds) for the transceiver to locate a beacon packet 310. The ten seconds required for the initial stage of the acquisition process is a perceptible length of time by human standards, and it would be desirable to provide improved methods of acquisition which would require less time to perform.
Therefore, it is an object of the present invention to provide a system for rapid acquisition by spread spectrum transceivers.
It is another object of the present invention to provide a system for rapid acquisition by spread spectrum transceivers with finite length reception windows.
It is another object of the present invention to provide a system for rapid acquisition by spread spectrum transceivers using an episodic beacon signal.
It is another object of the present invention to provide a system for rapid acquisition by spread spectrum transceivers using a prearranged beacon signal.
It is another object of the present invention to provide a system which can rapidly perform the contact stage of the acquisition process.
It is another object of the present invention to provide a system which can rapidly perform the synchronization stage of the acquisition process.
Another object of the present invention is to provide a transceiver which broadcasts a beacon signal which has low cross-correlations with code sequences used by other transceivers, where these other transceivers are possibly within the network of transceivers which may communicate with the first transceiver.
Another object of the present invention is to provide a beacon packet which has an autocorrelation function with sidelobes which have a significant time span and are of significant size.
Another object of the present invention is to provide a beacon packet which has an autocorrelation function that has sidelobes with a structure that allows sampling thereof to provide an estimate of the location of the peak of the autocorrelation function.
Furthermore, it is an object of the present invention to provide a transceiver which broadcasts a beacon signal which has low cross-correlations with code sequences used by other transceivers, and which has an autocorrelation function with sidelobes which have a significant time span, are of significant size, and have a structure that allows sampling thereof to provide an estimate of the location of the peak of the autocorrelation function.
In addition, other objects, features and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The present invention is directed to a method for two spread spectrum transceivers to perform signal acquisition in the vicinity of a number of additional spread spectrum transceivers which communicate with each other using a class of code sequences which have low cross-correlations and auto-correlations with small off-peak values. A first one of the two spread spectrum transceivers transmits a beacon signal consisting of beacon packets which are transmitted at regularly spaced times separated by a beacon cycle interval. The length of the beacon packets is shorter than the beacon cycle interval so that there is a period of nontransmission between each of the beacon packets. The beacon packets have an acyclic auto-correlation function with sidelobes that are not small relative to a peak value of the acyclic auto-correlation function, and these sidelobes have a structure which allows a sampling of a number of sidelobe values to be used to provide an estimate of a location of the peak of the acyclic auto-correlation.
If the second spread spectrum transceiver fails to receive a beacon packet during a reception window, the second spread spectrum transceiver attempts a reception during a subsequent reception window which begins at a time which is an integer multiple of said beacon cycle interval plus or minus roughly the beacon packet length later than the beginning of the previous reception attempt. Attempted receptions are performed by calculation of correlations between time delayed versions of an internally-generated beacon packet and the received signal.
Once the second transceiver receives a beacon packet during a reception window (ie., the first successful reception window), the second transceiver performs a reception during a reception window which begins at a time which is an integer multiple of the beacon cycle interval plus or minus a fraction of twice the beacon packet length later than the beginning of the first successful reception window.
However, if the second transceiver fails to receive some portion of a beacon packet during that reception window, the second transceiver performs another reception during a reception window which begins at a time which is an integer multiple of the beacon cycle interval minus or plus, respectively, that fraction of twice the beacon packet length later than the beginning of the first successful reception window.
The time (modulo the cycle time) at which the beacon packets are transmitted by the first transceiver is determined by estimating the location of the maximum of the correlation function between the delayed internally-generated beacon packets and the received beacon packets based on the times and values of the successful receptions of beacon packets by the second transceiver.

Rapid signal acquisition by spread spectrum transceivers


A method and apparatus for estimating stereo misalignment using modified affine or perspective model. The method includes dividing a left frame and a right frame into blocks, comparing horizontal and vertical boundary signals in the left frame and the right frame, estimating the horizontal and the vertical motion vector for each block in a reference frame, selecting a reliable motion vectors from a set of motion vectors, dividing the selected block into smaller features, feeding the data to an affine or a perspective transformation model to solve for the model parameters, running the model parameters through a temporal filter, portioning the estimated misalignment parameters between the left frame and right frame, and modifying the left frame and the right frame to save some boundary space.

1. Field of the Invention
Embodiments of the present invention generally relate to a method and apparatus for stereo misalignment estimation, and more specifically, for stereo misalignment estimation using modified affine or perspective model.
2. Description of the Related Art
Cameras in a stereo system are usually slightly misaligned due to manufacturing imperfection, environmental factors, and the like. Currently, solutions use hardware to resolve such misalignment. However, hardware calibration is expensive and usually unavailable.
Therefore, there is a need for a method and/or apparatus for improving the camera systems to estimate stereo misalignment.

Method and apparatus for stereo misalignment estimation using modified affine or perspective model


Methods, systems, and computer program products for systematic browsing of automated conversation exchange program knowledge bases are provided herein. A computer-implemented method includes generating one or more initial questions to be submitted to an automated conversation exchange program; generating one or more natural language variants of the initial questions; submitting the one or more natural language variants of the initial questions to the automated conversation exchange program; identifying one or more valid responses returned by the automated conversation exchange program in response to the submitted natural language variants of the initial questions; deriving one or more items of data from the identified valid responses; storing the derived items of data in an automated conversation exchange program knowledge base; and systematically browsing the automated conversation exchange program knowledge base in connection with one or more application tasks.

With the availability of less expensive smart phones and mobile Internet, the number of users conversing on messenger platforms has increased in recent years. Additionally, many companies are increasingly utilizing chatbots, automated conversation exchange programs, as another way to interact with users, in addition to mobile applications and webpages.
Additionally, hypertext markup language (HTML) webpages organize information in a structured way, for example, to aid web browsing. Web-crawlers make use of this structured form of HTML pages to extract information from webpages for various applications. However, with the increasing utilization of chatbots, knowledge bases of chatbots are not readily available for current web crawlers to process.

Systematic browsing of automated conversation exchange program knowledge bases

International Business Machines Corporation