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US 6377558 B1 Abstract A transmitter is provided for simultaneously transmitting a plurality of signals in a plurality of directive beams to corresponding destination stations, each destination station located in a separate fan within a service area. The transmitter includes a plurality of beamformers, each beamformer receiving one of the signals to be transmitted to an associated fan, each of the beamformers having a plurality of outputs for each different signal to be transmitted. A plurality of Butler matrices each receive one of the plurality of outputs from the plurality of beamformers for each different signal to be transmitted, each Butler matrix having a plurality of outputs in phased relationship to one another, wherein each of the signals to be transmitted is simultaneously provided across the outputs of each Butler matrix in a phased relationship. An antenna is provided with an aperture within which a two-dimensional array of antenna elements are disposed, wherein equal fractions of adjacent antenna elements are connected to the outputs of each Butler matrix, and wherein each of the plurality of signals are simultaneously transmitted by the entire two-dimensional array of antenna elements. Each of the plurality of beamformers receives steering control signals for steering the direction of each beam within its respective fan.
Claims(39) 1. A transmitter for simultaneously transmitting n different signals in l directive beams, said transmitter comprising:
n beamformers receiving n different signals with each beamformer receiving a signal to be transmitted, each of said beamformers having m outputs for each signal to be transmitted, and wherein said n beamformers have an m�n output array;
m passive couplers each operatively connected to said n beamformers, wherein each passive coupler has n inputs for receiving said n different signals to be transmitted simultaneously from said n beamformers, each passive coupler having p outputs in phased relationship to one another; and
an antenna with an aperture within which a two-dimensional m�p array of radiating elements are disposed, said radiating elements connected to the outputs of the passive couplers and transmitting said n different signals simultaneously in l directive beams,
wherein each of said n beamformers receives steering control signals for determining the direction of transmission for each of said directive beams.
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14. A transmitter for simultaneously transmitting 2n different signals in 2l directive beams, said transmitter comprising:
n beamformers receiving 2n different signals with each beamformer receiving two signals with first and second polarizations, respectively, each of said beamformers having m output pairs, for the first and second polarizations, where said n beamformers have a 2m�n output array;
m passive coupler pairs each operatively connected to said n beamformers, wherein each passive coupler pair comprises a first passive coupler having n inputs for receiving n different signals of the first polarization, and a second passive coupler having n inputs for receiving n different signals of the second polarization, permitting all of said 2n different signals to be transmitted simultaneously, each of the first and second passive couplers having p outputs in phased relationship to one another defining 2p outputs for each passive coupler pair; and
an antenna with an aperture within which a two-dimensional m�p array of dual-polarization radiating elements are connected to the outputs of the passive coupler pairs, with each element having a connection for the first polarization and a connection for the second polarization,
wherein each of said n beamformers receives first and second steering control signals, for the first and second polarizations, respectively, for determining a direction of transmission for said directive beams.
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27. A transmitter for simultaneously transmitting n different signals in a plurality of directive beams to corresponding destination stations, each destination station located in a separate sub-region within a service area, said transmitter comprising:
n beamformers receiving n different signals with each beamformer receiving a signal to be transmitted to an associated sub-region, each of said beamformers having m outputs for each different signal to be transmitted;
m passive couplers are operatively connected to said m outputs for receiving said n different signals to be transmitted simultaneously from said n beamformers, each passive coupler having r outputs in phased relationship to one another; and
an antenna with an aperture within which a two-dimensional q�p array of radiating elements are disposed, with a fraction of adjacent radiating elements connected to the r outputs of each passive coupler,
wherein n is less than or equal to the number of radiating elements coupled by each passive coupler,
wherein each of said n beamformers receives steering control signals for steering the direction of each beam within its respective one of said sub-regions.
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34. A transmitter for simultaneously transmitting a plurality of signals in a plurality of directive beams to corresponding destination stations, each destination station located in a separate fan within a service area, said transmitter comprising:
a plurality of beamformers, each beamformer receiving one of the signals to be transmitted to an associated fan, each of the beamformers having a plurality of outputs for each different signal to be transmitted;
a plurality of Butler matrices each receiving one of the plurality of outputs from the plurality of beamformers for each different signal to be transmitted, each Butler matrix having a plurality of outputs in phased relationship to one another, wherein each of the signals to be transmitted is simultaneously provided across the outputs of each Butler matrix in a phased relationship;
an antenna with an aperture within which a two-dimensional array of antenna elements are disposed, wherein equal fractions of adjacent antenna elements are connected to the outputs of each Butler matrix, wherein each of the plurality of signals are simultaneously transmitted by the entire two-dimensional array of antenna elements,
wherein each of the plurality of beamformers receives steering control signals for steering the direction of each beam within its respective fan.
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36. A method for providing simultaneous communication to a plurality of stationary user terminals located at known locations within a plurality of fan beams, said method comprising the steps of:
defining a plurality of fan beams along a first axis, with each of the plurality of fans having a length along a second axis substantially perpendicular to the first axis;
providing a plurality of groups of directional transmitting beams, each of the groups of directional transmitting beams associated with a respective fan beam;
providing a plurality of communication signals each intended for a stationary user terminal;
determining which of the groups of directional transmitting beams to use for transmitting each of the plurality of communication signals to each respective destined preselected fixed user terminal;
multiplexing the plurality of communication signals on respective groups of directional transmitting beams associated with the respective destined stationary user terminal; and
transmitting the plurality of communication signals to each respective destined stationary user terminal via the signal multiplexed directional transmitting beam groups.
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38. A communications system for providing communication to a plurality of fixed user terminals located at a known locations within a grid of geographical cells, said communications satellite comprising:
an orbiting satellite in a non-geostationary orbit defining a ground track;
a satellite-borne, multi-beam transmitter simultaneously creating a plurality of directional transmitting beams, each of said transmitting beams having a different angular displacement to the right or left of the satellite's ground track and being electronically steerable in a plane approximately parallel to the satellite's ground track via electronic steering signals; and
a satellite-borne, multi-beam receiver receiving signals from said user terminals including a destination location identifier signal of a terminal for which each signal is destined, said receiver translating the destination location identifier signals to determine which of said directional transmitting beams to use for transmitting each of said signals to its respectively indicated destination terminal.
39. The communications system of
Description The present invention is directed toward an active phased array transmitter for transmitting multiple signals and, more particularly, toward an active phased array transmitter for simultaneous transmission of multiple signals with a minimum of intermodulation distortion between signals. Transmitters having active phased array antennas, i.e., phased array transmitters, are commonly used in the transmission of signals. Active phased array transmitters can be configured to transmit signals in highly directive beams by using multiple antenna elements each connected to an elementary transmitter power amplifier. The signals are fed through each power amplifier and are relatively phased to achieve constructive addition of radiation in the desired direction. When only a single signal is to be transmitted in a single beam, class-C single frequency power amplifiers may be efficiently utilized. The transmitted spectrum can then be determined from the phase modulation characteristics of the information modulated on the signal. Phased array transmitters may also be configured to transmit multiple signals in multiple directed beams. In this case, combinations of the multiple signals to be transmitted are formed by a beamforming network using a set of beamforming coefficients. The signal combinations are fed to elementary transmit power amplifiers, with each power amplifier associated with a respective antenna element or subgroup of antenna elements. In this case, the power amplifiers must be linear, multiple signal power amplifiers, also known as Multiple Carrier Power Amplifiers or MCPA's. However, a problem with this prior art configuration is that imperfect MCPA linearity causes non-linear distortion or intermodulation between the signals generating unwanted signals. These unwanted signals may lie outside the allocated frequency band, potentially interfering with other services. Even when each signal alone, and thus their linear combinations formed by a beamformer, are band limited, the non-linearly amplified combinations will exhibit out-of-band spectral components due to the non-linear distortion. Improvements to such prior art active phased array transmitters for transmitting multiple signals in multiple beams while reducing intermodulation and improving efficiency are described in U.S. Pat. Nos. 5,548,813; 5,555,257; 5,568,088; 5,574,967; 5,594,941; 5,619,210; 5,619,503; and 5,638,024, all of which are herein incorporated by reference. The afore-listed patents are principally directed toward improving the efficiency of use of a phased array antenna and/or improving the intermodulation and efficiency performance of MCPA's used in phased array antennas. While the afore-listed patents are not principally directed toward reducing intermodulation radiation in unauthorized frequency bands, they may provide guidance. While a single-signal phased array for transmitting a signal in a highly directive beam may of course be provided in multiple copies in order to transmit multiple signals, the total aperture area of the plurality of single-signal antenna arrays is inefficiently used since only a fraction of the antenna elements are used to radiate each signal. For instance, if two single-signal phased array antennas were used, each would use one-half of the total antenna elements; if four single-signal phased array antennas were used, each would use only one-fourth of the total antenna elements; etc. There is thus a need for a transmitter having an active phased array antenna which employs all antenna elements to radiate each directive beam in order to obtain the full directed gain of which the total antenna aperture area is capable, while avoiding excessive inter-modulation. Further, there is a need for a transmitter having an active phased array antenna useful in a situation where no MCPA of reasonable efficiency at the current state of the art can meet the stringent limits imposed on out-of-band intermodulation radiation, thus necessitating the use of single-carrier amplifiers while still allowing multiple signals to be radiated by the antenna element array. The present invention is directed toward overcoming one or more of the above-mentioned problems. An active phased array transmitter is provided by disposing antenna elements on a plane or curved surface along first and second dimensions angled relative to one another forming an active phased array antenna. Antenna elements in the same row lying along the first dimension are coupled by a row-associated Butler matrix to provide a number of drive ports to which transmit power amplifiers may be connected, with successive drive ports of the Butler matrix corresponding to successive, adjacent beam directions in the plane of the first dimension in which a signal fed to the port will be radiated. Each row of antenna elements is thus capable of radiating a number of fan-shaped beams, with the fan's wide dimension being in a plane perpendicular to the row of antenna elements, while its narrow dimension is in the plane of the antenna element row. A first set of transmit power amplifiers is connected to corresponding drive ports of Butler matrices in different rows, a corresponding drive port being one which radiates the signal supplied to it in a fan beam in the same plane as the fan beam from a corresponding drive port of another row. The set of power amplifiers is thus arranged along the second dimension, i.e., the opposite dimension to that of the Butler matrix connections, and may thus be referred to as a column of amplifiers. Other sets of amplifiers may be connected to other columns of corresponding drive ports. Each column of amplifiers is connected to a corresponding beamformer having an input for a signal to be radiated, a set of outputs connected to the inputs of its respective amplifier column and a phase control input to control the relative phasing of the outputs such that the fan beams radiated by different rows add constructively in only a limited angular portion within the wide dimension of the fan, thus reducing the fan beams to a spot beam which has a narrow bandwidth in both dimensions. The direction of the spot beam may be steered in the second dimension, i.e., perpendicular to the antenna element rows, by means of the phase control input, while the spot beam direction along the first dimension may be selected by routing the signal to be radiated, via a router, to an appropriate beamformer. Through use of such a transmitter, all of the elements of the phased array antenna are used to form each radiated beam, while the antenna array simultaneously radiates n different signals in different beam directions using amplifiers that only amplify a single signal at a time. In one implementation, the above-described active phased array transmitter is borne on an orbiting satellite for communicating information to and/or between multiple user terminals located at different positions on the earth. Information to be transmitted to a given user terminal modulates a signal that is routed to the appropriate beamformer and amplifier column that is able to form a beam anywhere in a fan passing through that user terminal. The control input to the beamformer is used to select the direction within that fan corresponding to the user terminal's exact location. Simultaneously, other columns of power amplifiers may be used to transmit to other user terminals that are located anywhere within different fans. Thus, simultaneous transmission to multiple user terminals is permitted so long as they lie in different fans. A scheduler or router groups and selects signals or information packets for simultaneous transmission such that two transmissions are never needed in the same fan at the same time. Multiple user terminals lying in the same fan are selected to be served with information at sequential times, i.e., using time-sharing or Time Division Multiple Access. The grouping may be performed with the aid of a location-related address contained with the header of data packets intended for each user terminal. When the satellite is in a non-geostationary orbit, such as a low earth orbit, it moves rapidly relative to the earth such that the transmitted signal beams sweep across the earth at several kilometers per second. Thus, the selection of beamformer columns, via the router, and the beamformer control signals must be altered as a function of time in order to ensure that data packets transmitted to the same stationary user terminal at different times are correctly directed to the same location on the earth. This is facilitated by arranging the direction of electronic beam steering, effected with the aid of the beamformer control signals, to be along or parallel to the satellite's ground track, while the direction of selective beam steering, by selection of the appropriate beamformer column via the router, to be in a direction at right angles to the satellite's ground track. The beamformers may then be continuously controlled by means of a timer to compensate for orbital velocity such that, to a first order approximation, spot beams continue to be directed to fixed terrestrial locations. Due to geometrical distortions, correcting for satellite movement by routing the signal to a different beamformer to serve a particular terrestrial location is still needed, but less often than if the direction of selective beam steering was in the less favorable direction of the orbital velocity or ground track. In another implementation, each antenna element is a dual-polarization element having two inputs and capable of radiating signals at different polarizations simultaneously, for example, horizontal and vertical or left and right hand circular polarization. One set of Butler matrices connects rows of elements using their inputs for the first polarization, and another set of Butler matrices connects rows of elements using their inputs for the second polarization. Corresponding ports of Butler matrices for the same polarization are connected to a respective column of power amplifiers and associated beamformers. In this manner, the same array of antenna elements may be used to create 2n simultaneous directive transmissions where n is the number of columns of power amplifiers provided for each polarization, while each amplifier need only amplify a single signal. The waveform of such signals may be chosen to be of constant envelope with the information modulating only the signal phase, such that efficient classC amplifiers may be used and operated at saturation without causing signal distortion. A feature of the transmitter is the simultaneous transmission of multiple signals while employing single-signal amplifiers to reduce unwanted out-of-band radiation due to intermodulation distortion. Another feature of the transmitter is improved efficiency of transmission using multiple, directive beams to transmit information to user terminals at different locations on the earth. Other aspects, objects and advantages can be obtained from a study of the application, the drawings, and the appended claims. FIG. 1 depicts a prior art transmitter including a single-signal active phased array antenna; FIG. 2 depicts a prior art transmitter including a multiple-signal active phased array antenna; FIG. 3 depicts a prior art transmitter including a dual-polarization active phased array antenna for radiating one signal per polarization; FIG. 4 depicts multiple copies of the prior art transmitter of FIG. 1 for multiple signal transmission; FIG. 5 depicts one embodiment of an active phased array transmitter according to the present invention; FIG. 6 illustrates the preferred orientation of the active phased array transmitter on an orbiting satellite; FIG. 7 depicts another embodiment of an active phased array transmitter; FIG. 8 depicts yet another embodiment of an active phased array transmitter; FIG. 9 illustrates voltage splitting in a 4�4 port, two-dimensional Butler matrix; FIGS. 10A-10D illustrate allowed and disallowed spot patterns for simultaneous illumination with the active phased array transmitter; FIG. 11 illustrates reuse classes of spots for simultaneous illumination with the active phased array transmitter; FIG. 12 illustrates still another embodiment of an active phased array transmitter; and FIG. 13 depicts a block diagram of a satellite directional transponder incorporating the active phased array transmitter. FIG. 1 illustrates a prior art transmitter, identified generally as 10, for transmitting a single signal. The transmitter 10 includes a beamformer 12, a plurality of power amplifiers 14 and an antenna element array 16. The beamformer 12 has a single input for a single signal 18 to be transmitted, and a beam steering control signal input 20 for determining directions of transmission. The beamformer 12 receives the input signal 18 and generates a number of output signals 22 for driving the power amplifiers 14, with each output signal 22 having a phase relative to the other output signals 22 determined by the beam steering control input signal 20. Each power amplifier 14 is connected to a respective one of antenna elements 24 in the antenna element array 16. Each of the antenna elements 24 can alternatively be a sub-array of several elements 24 connected in a predetermined manner. By altering the relative phasing of the output drive signals 22, via the beamformer control signal 20, the direction in which the desired signal radiation is reinforced may be varied, thereby varying the direction of the maximum antenna radiation. In the prior art transmitter 10 shown in FIG. 1, only a single signal 18 at a time is amplified by amplifiers 14, such that no intermodulation between signals at different frequencies arises. The single signal 18 transmitted may be deliberately chosen to be a constant amplitude signal modulated only in phase with information, such that amplifiers 14 do not need to be of a linear type, but rather may be an efficient class-C type. While not shown in FIG. 1, the radiated spectrum is then conventionally determined by filtering the phase modulation used to impress the information on the transmitted signal, and is not distorted or degraded by the amplifiers 14. FIG. 2 illustrates a prior art phased array transmitter, indicated generally as 30, for transmitting multiple signals. The transmitter 30 includes a beamforming matrix 32, a plurality of multi-signal power amplifiers 34, and the antenna element array 16 as previously described with respect to FIG. 1. Beamforming matrix 32 has multiple inputs for multiple signals 36 to be transmitted. The beamforming matrix 32 generates output signals 38 which are linear combinations of the input signals 36 using a matrix of weighted beam steering coefficients 39 that determines the direction in which maximum radiation will occur independently for each signal 36. The output linear combinations 38 are amplified by multi-signal power amplifiers 34, which are connected to corresponding elements 24 of the antenna element array 16. The multi-signal power amplifiers 34 must be of a linear type that faithfully reproduce both a varying amplitude and a varying phase, since a linear combination of signals has a widely varying amplitude even when each signal alone is of constant amplitude. Departures from ideal linearity in the power amplifiers 34 cause inter-modulation distortion between the different output signals 38, producing unwanted distortion products. The unwanted distortion products, known as third order inter-modulation, are at frequencies such as 2f1−f2 or f1+f2−f3, where f1, f2 and f3 are the individual signal center frequencies. If the center frequencies are all identical, then intermodulation occurs on top of the desired signal and on either side. Intermodulation that lies only on top of other desired signals is known as �in-band intermodulation� and one is free to determine the level of acceptable in-band intermodulation. On the other hand, when f1 lies near one edge of an authorized frequency band and f2 lies near the other edge, intermodulation at 2f1−f2 and 2f2−f1 will lie outside the authorized band, and must be suppressed sufficiently to avoid interference with users of the adjacent frequency bands, known as �out-of-band intermodulation�. One is not free to determine the acceptable level of out-of-band intermodulation without reference to other potential users. Various regulatory bodies such as the FCC in the USA will usually determine the limits for out-of-band intermodulation based on the envisaged use for the adjacent frequency bands. In some cases, it may be very difficult to meet the regulatory requirements utilizing the prior art transmitter 30 shown in FIG. 2 without excessive loss of efficiency in the power amplifiers 34. A conventional technique for meeting more onerous intermodulation suppression requirements while transmitting more than one signal at a time is through the use of dual-polarization. FIG. 3 illustrates such a dual-polarization transmitter, indicated generally as 40. The concept of dual-polarization is to transmit a first signal using one polarization, for example Right Hand Circular Polarization (RHC) using a first set of power amplifiers driven by a first beamformer for directing a first radiated signal beam, and to transmit a second signal using a second polarization, for example a Left Hand Circular Polarization (LHC) with the aid of a second beamformer and second set of power amplifiers. It should be noted that vertical and horizontal polarization may also be implemented. The dual-polarization transmitter 40 shown in FIG. 3 includes a dualpolarization beamformer 42, a plurality of power amplifier pairs 44, and a dual-polarization antenna element array 46. The dual beamformer 42 includes inputs for two inputs signals 48 a,48 b to be radiated simultaneously, and first and second steering control inputs receiving beam steering control signals 50 a,50 b for the first and second polarizations, respectively. The dual beamformer 42 receives input signals 48 a,48 b and generates output drive signals 52 a,52 b driving amplifier pairs 44 a,44 b, with each amplifier 44 a or 44 b of each pair receiving only a single signal to be radiated with a given polarization. Antenna elements 54 within the dual-polarization antenna element array 46 may be dual-polarized elements such that the same antenna array 46 may be used to transmit both polarizations simultaneously. It should be realized, however, that the above-described prior art transmitter 40 is limited to simultaneously forming only two beams, as there are only two independent (orthogonal) polarizations available. FIG. 4 depicts a prior art transmitter, indicated generally as 60, utilizing multiple single polarization prior art transmitters (as shown in FIG. 1) to transmit more than two signals in different directions at the same time. The transmitter 60 includes four beamformers 62 a,62 b,62 c,62 d which are used to independently steer each of four different input signals 64 a,64 b,64 c,64 d via beam steering control signals 66 a,66 b,66 c,66 d input to the respective beamformers. The output drive signals 68 a,68 b,68 c,68 d produced by the beamformers 62 a,62 b,62 c,62 d drive corresponding sub-arrays (a-d) including single-signal amplifiers and antenna elements in a manner as previously described with respect to FIG. 1. These four sub-arrays (a-d) are each a sub-section of the whole array aperture 74, and thus each beam is formed using only one-fourth of the total antenna aperture area 74, resulting in inefficient use of the available aperture 74. If each beam had used the whole aperture 74, the beam directivity would have been 6 dB more, that is a beam of four times the peak power, allowing the power amplifiers to be of one-fourth the power level. This saving in power is extremely important in orbiting satellites as all power must be collected by large solar cell arrays. Furthermore, heat dissipation in the vacuum of space is problematic. Although the prior art transmitter 60 of FIG. 4 was described utilizing single polarization sub-arrays (a-d), dual-polarization arrays, as described with respect to FIG. 3, may be implemented to essentially double the number of signals transmitted by the transmitter 60. FIG. 5 depicts a transmitter, indicated generally as 80, for transmitting multiple independently steerable beams using the whole antenna array aperture. The transmitter 80 includes an antenna aperture array 82, columns 84 a-84 n of power amplifiers 85, beamformers 86 a-86 n, and a signal router 88. The antenna aperture array 82 includes antenna elements 90 grouped in rows, with each row connected to a respective passive coupler or Butler matrix, and more specifically, matrix 91 for row one, matrix 92 for row two, matrix 93 for row three, matrix 94 for row four, and matrix 95 for row five. The Butler matrices 91-95 each have a number of inputs, usually but not necessarily equal to the number of outputs connected to the antenna elements 90. Each of the Butler matrix inputs are indicated with the corresponding Butler matrix reference number followed by a-n, while each of the Butler matrix outputs are indicated with the corresponding Butler matrix reference number followed by a′-n′. Each input signal to each Butler matrix is split between the outputs in a manner different from, and orthogonal to, the manner in which signals at the other inputs are split. For instance, input signal 91 a is split across outputs 91 a′-91 n′ in a first manner; input 91 b is split across outputs 91 a′-91 n′ in a second manner; etc. In the simplest form of a two-input, two-output Butler matrix, a signal presented to the first input may be split in two, in-phase, half-power copies at the outputs, while the signal presented at the second input is split out-of-phase. A four-input, four-output Butler matrix splits the signals presented at respective inputs in the phase-sequences:
The signals to successive inputs split with a phase incremented successively through multiples of an incremental phase; in the above example the phase increments are a multiple of 90�. The incremental phase shift being 0� for Input 1, 90� for Input 2, 180� for Input 3, and 270� for Input 4. Referring again to FIG. 5, the Butler matrices 91-95 are eight-input, eight-output Butler matrices which accordingly use phase increments which are a multiple of 45�. More specifically, the Butler matrices 91-95 split the signals presented at respective inputs in the following phase-sequences:
While an eight-input, eight-output Butler matrix is shown in FIG. 5, it should be understood that Butler matrices of any order can be utilized without departing from the spirit and scope of the present invention. Butler matrices can be produced by suitable stripline or waveguide structures. Waveguide Butler matrices may be constructed economically by injection molding of plastic, which is subsequently metallized to form the conducting waveguide cavities. Each signal input to Butler matrix inputs 91 a-91 n, 92 a-92 n, etc., is transmitted by the associated row of elements 90 connected to its outputs 91 a′-91 n′, 92 a′92 n′, etc. with a fan-shaped radiation beam 1-n as shown in FIG. 6. Different Butler matrix inputs produce fan beams at different angles as illustrated by fan 1, fan 2, . . . fan n of FIG. 6, which will be described in greater detail below. Referring back to FIG. 5, a first column 84 a of amplifiers 85 is connected to the first inputs 91 a-95 a of each Butler matrix 91-95, that is to the inputs which produce the same fan angle from every row. When all the amplifiers 85 are excited with a signal in the appropriate relative phasing, radiation from all the rows 1-5 will add constructively in only one direction within fan 1 (see FIG. 6), thus creating a spot beam. The location of the spot beam within fan 1 (see FIG. 6) may be controlled by varying the beam steering control signal 98 a input to beamformer 86 a. Similarly, there are columns 86 b-86 n of amplifiers 85, with associated beamformers 86 b-86 n, connected to the other Butler matrix inputs namely, inputs b, c . . . n, which are not fully shown in FIG. 5 to preserve clarity. More specifically, the number of amplifier columns 84 a-84 n and beamformers 86 a-86 n depends on the number of inputs to the Butler matrices 91-95. Each beamformer 86 a-86 n controls the direction of the spot beam within a different fan, thereby giving n independently steerable beams. Each beam is formed using all of the elements 90 of the antenna aperture array 82, while each power amplifier column 84 a-84 n amplifies only a single signal at a time, thus avoiding intermodulation. It should be noted that the transmitter 80 can be configured without the plurality of amplifier columns 84 a-84 n, but with n power amplifiers (not shown), with each power amplifier amplifying a different signal 99 a-99 n input to respective beamformers 86 a-86 n. In this case, however, beamformers 86 a-86 n will have to operate on high power, amplified signal which is not preferred. In operation, the signal router 88 receives the various signals 1-n which are to be transmitted simultaneously. To direct radiation of a signal to a given spot, the signal router 88 first determines the fan in which the spot lies, and routes that signal 99 a-99 n to the beamformer 86 a-86 n for that fan. The selected beamformer 86 a-86 n is electronically steered, via steering control signals 98 a-98n, to effect radiation in the desired spot direction within the fan for that signal 99 a-99 n. The signal router 88 may thus direct radiation of one signal in each fan at a time. Beamformers 86 a-86 n provide for continuous variation of the spot direction within the associated fan, while the router 88 allows selection of a fan. Thus, the transmitter 80 of FIG. 5 provides continuous beam steering in one plane with switched beam steering in the other plane. FIG. 6 illustrates the preferred orientation of the plane of continuous, electronic steering versus the plane of switched, discrete-step steering when the transmitter 80 is used on a low earth orbiting satellite 100. The long dimension of the fans 1-n, shown by arrow 102, along which continuous steering is effected via the beamformers 86 a-86 n is preferably oriented along the ground track of the satellite 100; that is, in the direction of the orbital motion or velocity of the satellite 100. As shown in FIG. 6, different fans occupy different positions to the right and left of the ground track, with coverage by the two extreme fans 1 and n illustrated in FIG. 6. The switched, discrete-step steering between fans occurs in the plane or dimension generally depicted by arrow 104 and is effected by the router 88. A spot beam directed toward a particular user terminal, as shown in the coverage region of fan 1, may then be maintained by controlling the appropriate beam-former 86 a to move the beam progressively backwards in the opposite direction to the satellite's 100 motion, thus compensating for satellite movement. Due to geometrical distortions, namely that the extremes of the fan beams are further away from the ground track than the center of the fans, it may eventually become necessary for the router 88 to switch the fan used to serve a particular user terminal. However, this switching is at a much reduced rate than if the fans had been oriented to cover regions elongated across the ground track. In cases where the number of antenna array elements 90 in a row is large, for example greater than about 16, a Butler matrix to couple all elements in a row having sixteen inputs and sixteen outputs may become excessively large as a waveguide structure or else excessively lossy. When such a full-sized Butler matrix is used for the Butler matrices 91-95 in FIG. 5, e.g., a 16�16 Butler matrix, the number of fan-shaped sub-regions produced is sixteen and the number of beamformers 86 a-86 n and columns 84 a-84 n of independent amplifiers 85 which can be connected is also sixteen, providing the ability to radiate sixteen different signals, one per fan, using only single signal amplifiers. However, as shown in FIG. 7, the transmitter can be usefully configured to generate fewer than the maximum number of simultaneous beams. FIG. 7 depicts a transmitter 110 wherein the row of Butler matrices 91-95 of FIG. 5 have been split into smaller Butler matrices. More specifically, the 8�8 Butler matrix 91 in FIG. 5 has been replaced with two 4�4 Butler matrices 112 a,112 a′ in FIG. 7; the 8�8 Butler matrix 92 in FIG. 5 has been replaced by two 4�4 Butler matrices 114 a,114 a′ in FIG. 7; etc. Similarly, in a transmitter utilizing a full size 16�16 Butler matrix, four 4�4 Butler matrices can be replaced therefore. Corresponding input ports of each Butler matrix 112 a,112 a′-120 a,120 a′ are driven by matrices 122 a-122 n of amplifiers 85, with each matrix having a column of amplifiers 85 for each of the undersized Butler matrices 112 a,112 a′-120 a,120 a′. For clarity purposes, only beamformer 86 a and amplifier matrix 122 a are shown in FIG. 7. Thus, in the transmitter 110 shown in FIG. 7, there are four amplifier matrices 122 a-122 n, each having two columns. In the case of sixteen row elements coupled by four, 4�4 Butler matrices, there would be four amplifier matrices, each having four columns of amplifiers, making a matrix of 4�M amplifiers, where M is the number of rows, i.e., antenna elements 90 in a column. All amplifiers 85 of same matrix connect to corresponding inputs of all Butler matrices, i.e., to inputs number 1. Other, independent amplifier matrices may be connected to the other Butler matrix inputs number 2, 3, etc. Thus, when using 4�4 Butler matrices, four independent amplifier matrices 122 a-122 n may be used, allowing four independent beams to be generated using single-signal amplifiers. The use of sub-sized Butler matrices effectively produces fewer, broader fans. Beamformers 86 a-86 n, steering control signals 98 a-98 n and signal router 88 function as previously described with respect to FIG. 5, albeit there need now be only half as many beamformers 86 a-86 n and steering control signals 98 a-98 n. The beamformers 86 a-86 n of FIG. 7 produce signals controlled in relative phasing down each column to produce beams steered along the fan region's largest dimension as before (see arrow 102 in FIG. 6), but now also controls the relative phasing between the different columns of amplifiers within the same amplifier matrix 122 a-122 n, so as to produce fine beam steering across the fan's narrow dimension in the direction of arrow 104 in FIG. 6. Thus, in operation, the signal router 88 receives signals 1-n to be transmitted and determines the coarse fan-shaped region in which the user to which the signal is to be transmitted lies. The router 88 selects the beamformer 86 a-86 n and associated power amplifier matrix 122 a-122 n that are configured to transmit within that particular region. The beamformer 86 a-86 n is controlled, via steering control signals 98 a-98 n, to fine-steer the beam both along and across the selected region to place the peak beam directivity as close as possible to the user's location. In FIGS. 5 and 7, the Butler matrices are connected only to elements in the same row. The Butler matrices function as partial beamformers, forming the directivity only in one plane in FIG. 5, and forming only part of the total directivity in one plane in FIG. 7. The beamformers 86 a-86 n complete the formation of the required directivity by forming all of the directivity in the column plane (FIG. 5), and in the case of FIG. 7 completing the formation of the directivity in the row plane. A further embodiment of the transmitter is shown in FIG. 8. Transmitter 130 depicted in FIG. 8 includes two-dimensional Butler matrices 132 a-132 d which connect both row and column elements 90 of the antenna aperture array 82. FIG. 8 depicts four 2�2 two-dimensional Butler matrices 132 a-132 d, however, other sized matrices can be utilized without departing from the spirit and scope of the present invention. The two-dimensional Butler matrices form part of the directivity in both the row and column planes. Each input 1,2,3,4 to the Butler matrices 132 a-132 d include a separate power amplifier array 134 a-134 d including a separate single-signal power amplifier 85 for each Butler matrix 132 a-132 d. Similar to FIGS. 5 and 7, there are separate beam-formers 86 a-86 d with accompanying steering control signals 98 a-98 d for each of the four inputs of the Butler matrices 132 a-132 d. For clanty purposes, only beamformer 86 a and associated amplifier matrix 134 a are depicted in FIG. 8. Thus, in FIG. 8 there are four beamformers 86 a-86 d, four steering controls signals 98 a-98 d, and four power amplifier arrays 134 a-134 d. Accordingly, the transmitter 130 in FIG. 8 is capable of transmitting four separate signals 99 a-99 d simultaneously. The two-dimensional Butler matrices 132 a-132 d effectively perform an analog Discrete Fourier Transform (DFT) using the Fast Fourier Transform (FFT) structure. Two-dimensional FFT structures are simpler than one-dimensional FFT structures of the same number of input and output signals, and thus the configuration of the two-dimensional Butler matrices 132 a-132 d of FIG. 8 can be advantageous. For example, a four input, four output two-dimensional Butler matrix can be made using only 180� hybrid junctions or �Magic Tee's� in waveguide terminology. Alternatively, as shown in FIG. 9, 90� couplers, such as branch line couplers, can be used. In FIG. 9, four signal voltages a,b,c,d are input on the left and are split in different combinations to form the four outputs at the right. A scaling of two at the input and root-2 after the first two couplers 140,142 reflects conservation of energy. The four outputs from couplers 144,146 drive a square sub-array of four elements 90 in the whole array 82 of FIG. 8, such that the signals a,b,c,d are radiated respectively into each of the four quadrants of the coverage area, which, in the case of an orbiting satellite might be described as: (a) to the right of the ground track and behind the sub-satellite point; (b) to the left and behind; (c) to the right and forward of the sub-satellite point; and (d) to the left and forward. Whichever configuration is used, the principle for directing a signal is the same as previously outlined, namely, first determining the coarse region (which are formed by the Butler matrices) in which the user lies, selecting the corresponding power amplifier, array and beamformer, then adjusting the beamformer to fine steer the beam to the user. Within other design constraints such as Butler matrix complexity and loss, preference should be given to forming coarse regions having a greater dimension along the direction of orbital motion (see arrow 102 in FIG. 6) with the narrower dimension at right angles to the satellite motion (see arrow 104 in FIG. 6), thus allowing the electronic beamformers 86 a-86 n to be preprogrammed to compensate for satellite motion. In one application, the radiated signal is a wideband digitally phased modulated signal carrying bursts of high bit rate information using all of an allocated bandwidth within the radio communications spectrum. As many such signals may be radiated simultaneously as there are beamformers, that is n times, so that the entire allocated bandwidth is reused n times. When a given part of the spectrum is reused, the distance between spots in which the same spectrum is used must be sufficient to avoid self-interference, which is also co-channel interference. This is avoided if the frequency channel is reused in a second beam which is well enough away from the main lobe of a first beam. FIGS. 10A-10D show allowed and disallowed patterns of frequency reuse. In FIG. 10A, the shaded spots indicate allowed locations of simultaneous use, as there is always at least a separation of one or more spot beam diameters between the spots in use. FIG. 10B illustrates that it is perfectly acceptable to illuminate spots that have the same coordinates, i.e., d and f, within their respective fans, providing that this does not occur in adjacent fans. On the other hand, FIG. 10C illustrates a disallowed pattern due to having two spots (1 c and 1 f) in the same fan (fan 1) simultaneously. Such a spot beam pattern is not capable when single-signal power amplifiers are used to create each fan. FIG. 10D shows another disallowed pattern in which spots having the same direction (c) within their respective fans occur in adjacent fans (fan 1 and fan 2). Such a separation is insufficient to avoid co-channel interference. Further, even the spot beams that are diagonally adjacent at locations 3 f and 4 e may be too closely spaced to avoid co-channel interference. Accordingly, the signal router 88 must queue signals for transmission to different terminals according to their locations in such a way as to utilize the inventive transmitters capability to transmit n simultaneous beams, but in such a way as to avoid violation of reuse distance criteria. An alternative method to impose reuse distance criteria is illustrated in FIG. 11. In FIG. 11, the vertical columns of circles or spots along fans 1-6 are shown offset between adjacent columns, as is customary when discussing reuse in cellular radio systems. Reuse of a frequency channel may occur in regularly spaced places forming a reuse pattern. Different channels must be used in all other places. FIG. 11 illustrates distributing the use of three frequency channels or three timeslots numbered 1,2,3 in a so-called three-cell pattern across six fans. The separation between cells, or spot beams, such as the shaded cells corresponding to channel 1, is equal to the square root of the cell pattern size (3 in this example for the three frequency channels) multiplied by the cell diameter. Thus, a larger cell pattern increases the separation between co-channel cells, reducing their mutual interferences. In the example of FIG. 11, it is assumed that a reuse pattern size of 3 reduces mutual interference to an acceptable level, and that the same channel may thus be used in all of the shaded spots simultaneously. The inventive transmitter is, however, only capable of illuminating one spot in each vertical column or fan at a time, due to the use of single frequency power amplifiers for each fan beam. The selected spot may, however, be any of the shaded spots in the column at a given first time instant. At a second time instant, anyone of the spots containing a two may be selected in each column, and at a third instant any one of the spots containing a three may be selected in each column. Thus, using this strategy, any one of a first ⅓ of the spots in each column is illuminated in a first timeslot of a repetitive Time Division Multiple Access (TDMA) frame period; any one of a second ⅓ of the spots in each column may be selected during a second timeslot; and any one of a third ⅓ of the spots in each column may be selected in a third timeslot. At any instant, which of the allowed spots in a column, or fan, that is actually selected may depend for example on the backlog of traffic for that particular spot. If no traffic exists for a spot, it is of course not a candidate to be selected. If a data packet destined for a user in a particular spot has been waiting in a queue for a period of time longer than data packets destined for other spots belonging to the same timeslot reuse group, then that spot would be preferentially selected within the column for illumination at the earliest opportunity, i.e., upon the next occurrence of its timeslot. The above-described regular reuse pattern effectively creates three major queues, and each queue receives one out of three timeslots, exactly ⅓ of the transmit capacity, in which to transmit traffic whether needed or not. Within each queue, each column or fan of cells disposes of the capacity of one transmit beam, whether needed or not. Occasionally, this could lead to inefficiency where the transmit capacity available for one column of cells was not used while the traffic demands in another column of cells temporarily exceeded the capacity available for that column. This so-called trunking loss is the penalty one must pay for dividing up transmission into three timeslots of fixed size. Other reuse patterns can be used when such inefficiency is encountered and cannot be tolerated. For example, a larger number of timeslots that are a multiple of the reuse pattern size can be defined, such as twelve timeslots (4�3) in the present example of a three-cell pattern. Each reuse group may be visited up to four timeslots out of twelve in the case of equal traffic demand per group. However, if there is one cell that demands the largest amount of traffic flow, then the reuse group containing that cell may be allocated more than four out of twelve timeslots by reducing the number of timeslots to less than four for another reuse group. This is equivalent to varying the original timeslot sizes away from exactly ⅓ of the frame in discrete steps of {fraction (1/12)} of the frame period to better adapt to the traffic pattern. Another exemplary use pattern is to transmit, during the next fraction of a frame period, to a spot for which a data packet has been queued longest. That spot is located in a particular row in a particular column, and referring to FIG. 11, we may not then transmit simultaneously in either of the adjacent spots in adjacent rows in that column. All other spots in the adjacent rows of that column are however candidates for receiving a signal. Selection among the candidates in the adjacent rows is based on the length of time packets have been waiting for delivery in those spots. Having selected one spot in each of the adjacent rows, this disallows two spots in each of the next-adjacent rows from being served at the same time. All others are, however, possible candidates for selection and are selected once more upon packet delivery backlog. This method continues until one spot in each row of a column has been selected to receive service at the next timeslot. While these packets are being delivered, the scheduler, which may form part of the router 88, determines the spots that shall receive service in the following timeslot. This method is not constrained to a fixed reuse plan, and therefore offers more flexibility in servicing a very unequal traffic demand for different cells. The inventive transmitter may also be constructed using both polarizations to transmit twice as many simultaneous beams from the same antenna aperture. Referring to FIG. 12, such a dual-polarization transmitter, indicated generally as 150, is depicted. The signal router 88 receives the incoming signals 1-2 n and routes respective signal pairs 152 a,152 a′-152 n,152 n′ to corresponding dual beamformers 154 a-152 n. The dual beamformers 154 a-154 n each include first and second steering control inputs receiving beam steering control signals 156 a,156 a′-156 n,156 n′ for the first and second polarizations, respectively. The dual beamformers 154 a-154 n receive input signals 152 a,152 a′-152 n,152 n′ and generate corresponding pairs of output drive signals 158 a,158 a′-158 n,158 n′ to columns 160 a-160 n of amplifier pairs 85 a,85 a′. For clarity purposes, only dual beamformer 154 a and column 160 a of amplifier pairs 85 a,85 a′ is depicted in FIG. 12. While operation of transmitter 150 will be described with respect to dual beamformer 154 a and amplifier column 160 a, it should be understood that the other beamformers 154 b-154 n and associated amplifier columns 160 b-160 n operate in the same manner. The dual beamformer 154 a applies the output drive signal pairs 158 a,158 a′ to corresponding amplifier pairs 85 a,85 a′ in amplifier column 160 a, which in turn supply the signals to a corresponding input of Butler matrix pairs 162 a,162 a′-166 a,166 a′. As in the prior art of FIG. 3, dual-polarization antenna elements 54 are distributed over a two-dimensional antenna aperture 46. Each element 54 has a connection for transmitting an RHC polarized signal and a separate connection for transmitting an LHC polarized signal, however, vertical and horizontal polarizations may also be used. All of the RHC connections for a row of elements 54 are then connected to the outputs of an RHC Butler matrix 162 a, while all the LHC connections for a row of elements 54 are connected to a similar LHC Butler matrix 162 a′. Other Butler matrix pairs are connected to the antenna elements 54 in a similar manner. The transmitter 150 operates in the same manner as previously described with respect to the transmitter 80 of FIG. 5, except that now twice as many signals may be transmitted utilizing both RHC and LHC element connections. Further, similar to FIG. 5, the number of amplifier pair columns 160 a-160 n and dual beamformers 154 a-154 n are equal to the number of Butler matrix input pairs. Assuming sufficient polarization isolation can be achieved to allow the same frequency to be used twice in the same location at the same time with opposite polarizations, then the reuse pattern of FIG. 11 can be used for both polarizations. In this case, each spot may be illuminated with either RHC or LHC polarization, or both, at the same time. This implies that user terminals in every location are somehow divided into those receiving service via RHC polarization and those receiving service via LHC polarization. Preferably, the polarization can be fixed for each terminal to avoid the extra complexity of being able to receive polarizations. When very high frequencies such as 20-30 GHz are used for communication, polarization corruption can take place due to the presence of non-spherical water droplets in the atmosphere, thus reducing the amount of polarization isolation. In that case, it may be insufficient to rely entirely upon polarization isolation, and instead utilizing partly polarization isolation and partly spacial isolation may be necessary. With reference to FIG. 11, assuming that the shaded spots are being illuminated by RHC polarization during timeslot 1, the intervening spots labelled �2� may be receiving service using LHC polarization. That is, the spots which are illuminated by RHC in timeslot 2 may be illuminated by LHC in timeslot 1. Likewise, the spots which are illuminated by RHC in timeslot 3 may be illuminated by LHC in timeslot 2, and the spots which were illuminated by RHC in timeslot 1 may be eliminated by LHC in timeslot 3. Since the two polarizations are never used in the same place at the same time, this pattern does not rely entirely upon polarization isolation to prevent co-channel interference. Both RHC and LHC polarizations may also be used without the constraint of a regular reuse pattern such as shown in FIG. 11. As previously described, a scheduler (170 in FIG. 13) determines the spot that has the greatest traffic backlog to receive priority treatment during the next available timeslot. This principle can be extended to determining which spot and polarization has the greatest backlog in the case where user terminals are only configured for one polarization at a time and thus must be served with a specific polarization. The scheduler 170 thus determines which of the two polarizations will be used first to serve the chosen spot in the next timeslot. The scheduler 170 then continues as before to determine one spot in each of the other rows, excluding the use of adjacent spots in adjacent rows, that can receive service at the same time using that same polarization. Independently, the scheduler 170 can determine the spot which has the greatest backlog for service using the opposite polarization, excluding the spots already determined to receive service using the first polarization in order to avoid using both polarizations in the same place at the same time. Efficiency may result in determining the spots that shall receive RHC service and the spots that shall simultaneously receive LHC service in an interleaved manner, instead of determining all RHC spots first followed by all LHC spots. First, the spot and polarization having the greatest backlog is determined. Then, the spot having the greatest backlog for service with the opposite polarization is determined, excluding the first spot if it is desired to avoid use of both polarizations in the same spot at the same time. Next, the spot having the next greatest backlog is determined, excluding the already determined spots and spots adjacent to those that use the same polarization, but not excluding adjacent spots that use the opposite polarization, and excluding columns containing an already determined spot needing the same polarization, as only one beam per column per polarization can be created. It should be understood that many other variations of scheduler strategies can be implemented by a person of ordinary skill in the art without departing from the spirit and scope of the present invention, and it is not an objective herein to provide an exhaustive list of all possibilities based on the principle of scheduling traffic based on demand while avoiding use of both polarizations in the same place at the same time. In yet another implementation, the polarization used to serve a particular spot or region on the earth is fixed to be either RHC or LHC. User terminals sold and installed in a particular region would then be equipped to receive only the designated polarization for that region. The entire surface of the earth would be mapped to LHC and RHC regions in an interleaved manner. For example, alternate columns or fans of spots in FIGS. 10A-10D could be designated as LHC and RHC respectively. Then the pattern of service which was disallowed in FIG. 10D would no longer be disallowed, as adjacent spots in different columns would employ opposite polarizations. This allows for a simpler scheduler algorithm since the spot to serve during a particular timeslot can be decided independently for each column of cells without reference to the choice in other columns of cells. The algorithm thus reduces to determining the cell in each column having the greatest traffic backlog. Other regular frequency or timeslot reuse patterns exist, of a size given by integers of the form i2+j2−ij. For example, with i=1, j=2 this expression evaluates to 3, confirming that a regular 3-cell pattern exists. With i=j=2, a regular 4-cell pattern exists. Other regular cell pattern sizes are 7, 9, 12, 13, 16, etc. As is generally known in the art, the size of a cell used in a satellite communication system can advantageously be much smaller than the main-lobe beam diameter produced by the phased array antenna/transmitter. A cell can be defined to lie only around the gain peak of the antenna beam and not down to the −4 dB edge, as was previously customary. However, the spacing of cells using the same channel must be chosen with regard to the antenna's beamwidth and thus its ability to discriminate radiation coming from different angles. By defining small cells that occupy only the beam peak, the co-channel cell spacing can be reduced as user terminals will not now lie at worst case beam edge locations. The co-channel cell spacing can then be reduced to approximately two times the beam radius, where beam radius is measured at the −4.5 dB point relative to beam peak, when a cell occupies the area only out to � the cell radius from beam center. Since a cell is then only � of the area of the beam's −4.5 dB coverage, a 16-cell pattern is required to cover the whole surface area with different cells within the 16-cell cluster not employing the same frequency resource at the same time. Since reuse distance, i.e., the distance between cells using the same frequency resource at the same time, is reduced by this technique, the system capacity defined in traffic per square kilometer is increased. Thus, the use of larger or smaller reuse patterns does not determine system capacity for multi-beam satellite communication systems, but rather the reuse distance. The reuse distance is minimized, thus maximizing system capacity when a reuse pattern size is large and the cell size is small, as is generally known in the art. When, in addition to frequency and time, polarization is introduced at a resource, there is an interest in defining a resource reuse pattern that includes frequency, time and polarization. Since there are only two orthogonal polarizations, the product of the number of frequencies, timeslots and polarizations available will always be even, thus suggesting the use of one of the even-sized reuse patterns such as 4, 12 or 16. For example, a system having two timeslots combined with two polarizations can be employed instead of the 3-timeslot�2-polarization system previously discussed with respect to FIG. 11. Thus, a four-cell reuse pattern could be created by assigning one of the four resources (t1, RHC), (t1, LHC), (t2,RHC), (t2,LHC) to cells in a fixed manner. For example, (t1,RHC) can be alternated with (t2,RHC) up the first column or fan of FIG. 11, thus making the entire column RHC. The second column of cells may be assigned to use (t1,LHC) alternating with (t2,LHC), thus making the second column or fan entirely LHC, and so on alternating the polarization used between successive columns or fans of cells. In this manner, not only is the polarization fixed for a user terminal in a fixed location, but also the � of the frame period in which it shall receive is also fixed, thus reducing its receiving processing and allowing it to transmit in the remaining half period. This may avoid simultaneous transmit and receive, which can be problematic for low cost terminals. With a larger reuse pattern, such as an 8-timeslot�2-polarization (a 16-cell pattern), each receiver only receives a single polarization for ⅛ of the time, further reducing complexity in processing. When a number of beams that a satellite can simultaneously create is limited due to use of single-signal power amplifiers for intermodulation reasons, each beam, when created, should transmit with the maximum data rate possible, that is, the single carrier signal in the beam should be modulated with the highest information rate possible that fits within the total allocated band. Power limitations may prevent the maximum data rate from being used, in which case the frequency band can be divided into a number of lower information rate channels which can be combined with timeslots and polarizations in a joint reuse plan. The inventive multi-beam transmitter allows different beams to transmit different frequencies, and allows transmission of two frequencies even in the same fan using different polarizations. Referring now to FIG. 13, a block diagram of a satellite communications transponder, indicated generally as 172, embodying the inventive multi-beam transmitter is depicted. Signals 174 are received from terrestrial terminals or other satellites (not shown) by a multi-beam receive antenna 176. Unlike the antenna used for transmission, the receive antenna 176 is not restricted to receive single frequency channels at a time because the low level received signals do not challenge the linearity of the receive amplifier components. U.S. Pat. Nos. 5,539,730 and 5,566,168 to applicant, which are herein incorporated by reference, disclose that different access protocols may therefore be in order for the uplink as compared to the downlink. For example, multiple narrow frequency channels combined with few, long timeslots (narrowband TDMA) can be advantageous for the uplink by reducing the user terminal peak transmit power requirement. Wideband TDMA having few or only one frequency channel combined with many, short timeslots is however beneficial for the downlink as it allows efficient class-C amplifiers to be used without causing intermodulation. When different uplink and downlink formats are used, and direct terminal-to-terminal communication via the satellite relay is employed, then the satellite must perform format conversion on board. One simplified method of converting narrowband TDMA to wideband TDMA is described in U.S. patent application Ser. No. 08/581,110, filed Dec. 29, 1995 to applicant, which is herein incorporated by reference. The method of the above-identified application includes sampling narrowband received signals at a rate at least equal to the Nyquist rate, storing the samples temporarily in a buffer during an uplink timeslot, then bursting out the buffer contents at a higher rate during a shorter downlink slot, thereby increasing the downlink TDMA bandwidth by a given factor. Access control is provided in the above-identified application by a central ground station that orchestrates the creation of cipher keys in common between the two communicating terminals, which are envisaged to be of telephone type that operate mainly in one-on-one communications. For Internet terminals, however, the terminal with which a given terminal wishes to communicate data to or from is not necessarily fixed for a given session. It is therefore impractical to establish a session key for each possible pairing of terminals. On the other hand, if terminals use different session keys, then decryption and re-encryption of traffic must be performed on board the satellite. This suggests that the satellite transponder 172 will need to be of the demodulate-remodulate type. Consequently, block 178 in FIG. 11 provides multi-channel down conversion, demodulation and error correction decoding for all uplink traffic. The output of block 178 is in the form of binary bits or data symbols that are fed into an access control unit 180. Access control unit 180 may check that a Cyclic Redundancy Check (CRC) code, which is a function of all data bits, has been decoded properly, and reject any traffic packets with uncorrected errors. The CRC code and other fields of the traffic bursts may in fact be enciphered using a session key established for the originating terminal during an initial logon procedure. The logon procedure can involve communication between a central network control computer located on the satellite or on the ground, during which the network can issue a random challenge and receive an authentication response from the terminal to authenticate it as a genuine subscriber, a byproduct of this process being the creation of a temporary session key. A temporary abbreviated terminal identity code may also be issued for the session to reduce overhead in the packet data headers. Conventional authentication processes are described in U.S. Pat. Nos. 5,091,942, 5,282,250, 5,390,245 and 5,559,886, all of which are herein incorporated by reference. Thus, access control block 180 can include verification that the packet was transmitted by a authenticated subscriber who can be billed for the communications service provided. If a packet contains decoding errors or cannot be verified to have been transmitted by an authentic user, it will not be relayed by the satellite and will not consume any capacity resources. A method for verifying authenticity needs to be designed taking into account all known methods of fraud, such as authentication with the unwitting help of a known terminal, eavesdropping on authentic transmissions to determine a valid code, etc. The most secure method to prevent fraud is to encipher data packet headers and payload together using a block cipher such as DES prior to error-correction coding, such that the transmitted signature is not based on just the session key and the terminal ID, which do not change, but also on the data content or payload, which does change. Thus, the only way to cause the satellite to relay a false packet would be to repeat the entire packet, which has no utility to fraudster. Moreover, this could, if necessary, be prevented by including a real time clock identification in each packet to establish a limited window of validity. The same packet transmitted later with an out-of-date clock value would thus be rejected. The real time clock value can, for example, be a frame counter value that counts TDMA frame periods of the system, as is already known to be useful for enciphering from U.S. Pat. Nos. 5,148,485 and 5,060,266 to applicant. At block 182, the destination terminal ID's contained in the packet headers are related to the position or cell in which the destination terminal is located. In principle, this information could already be converted to beam parameters for downlink transmission, however, packets are not necessarily transmitted instantaneously, but are queued in buffer memory 184 for a short time, during which the satellite may have moved. Consequently, the derivation of beam steering parameters by the router occurs at block 186 immediately prior to transmission. As previously discussed, a preferred concept of routing and scheduling for the downlink is to maintain separate queues for data packets destined for each cell. Scheduler 170 receives packets from the queue buffer memory 184 using any of the above-discussed strategies. For example, if a subset of cells is to be visited by the downlink beams during the next timeslot, then the scheduler 170 only considers packets destined for cells within that subset. After selecting the packets for simultaneous transmission, the exact beam steering parameters for each beam are determined by the router at block 186. More specifically, the scheduler 170 includes a backlog tracker 200 determining a waiting time for each data packet, the waiting time indicative of how long each data packet has waited in the buffer memory 184 for transmission. A first selector 202 selects the data packet that has been waiting the longest, as indicated by the backlog tracker 200. A second selector 204 further selects data packets for simultaneous transmission in descending order of waiting time. The second selector 204 skips data packets requiring a transmit direction incompatible with the direction of transmission of a data packet previously selected for transmission at the same time. For example, a transmit direction may be deemed incompatible by the second selector 204 if: 1) it can only be created using a directional transmission beam that will be fully occupied in transmitting an already selected data packet; or 2) it lies too close in direction to the direction of transmission of a data packet already selected for transmission at the same time. A direction too close in direction to another direction may be one in which an angular separation of the directions is less than a minimum value sufficient to avoid mutual interference. Such minimum angular separation may include a first separation when the polarizations of the transmission used in each direction are the same, and a second separation when the polarizations of transmission used in each direction are different. In order for the scheduler 170 to work properly, the scheduler 170 must first determine a subset of directions in which the directed beams can be transmitted in a next transmission. Then, by mapping a destination identifier code stored with each data packet to a corresponding beam direction, the scheduler 170, via first and second selectors 202, 204, selects only data packets whose destinations map to a direction within the subset of directions. The first and second selectors 202,204 order the selected data packets according to how long they have been stored in the buffer memory 184, with the selected data packets which have been stored the longest ordered first. An indication flag may be set in the buffer memory 184 in association with the selected data packets already transmitted, and/or the selected data packets which have been transmitted may be deleted from the buffer memory 184, releasing memory locations in the buffer memory 184 so as to provide storage capacity for new data packets. Block 186 may contain routing information for routing a signal to a particular fan. The routing information may be updated from the ground network control computer at a relatively slow rate, while signals for steering the spot beam within a selected fan may be generated in real time with the aid of an on-board clock and systematic update procedures that compensate for satellite movement. Some interaction between packet selection from buffer memory 184 and determination of the fan in which the destination lies may be required for the scheduler 170 to function correctly, due to the fact that only one beam of each polarization may be created per fan, combined with the fact that fan coverage areas on the ground do not comprise straight lines or columns of cells, but are rather curved due to geometrical distortion. Therefore, it may be logical to perform the determination of which fan each packet will be transmitted to at block 182, which is possible due to the slower speed at which this parameter changes due to satellite movement when the preferred array orientation is employed, i.e., direction of electronic steering along the satellite's ground track with direction of switched fan selection across the ground track. The beam steering parameters for each beam are determined for the packet to be transmitted in the selected fan and communicated to the beamformer dealing with that fan and polarization. The beamformers, power amplifiers, Butler matrices and dual polarization antenna elements of the various embodiments previously described may be included within transmitter block 188 of FIG. 10. Block 190 comprises downlink burst formatting, error correction coding, modulation and upconversion to the allocated down-link frequency band for transmission. Downlink formatting can comprise multiplexing the destination ID's for all packets destined for terminals in the same cell separately from the payloads destined for those terminals, such that user terminals do not have to continually demodulate data at the generally high transmission bit rate and further omit decoding of non-intended messages sent to the terminal. While the invention has been described with particular reference to the drawings, it should be understood that various modifications could be made without departing from the spirit and scope of the present invention. Patent Citations
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text:
Savory Tuna Burgers
- Total Time:
- 20 min
- Prep:
- 10 min
- Cook:
- 10 min
- Yield:
- 4 servings
- Level:
- Easy
- 3 (6-ounce) cans light tuna in water, drained
- 1/3 cup light mayonnaise
- 3 tablespoons seasoned dry bread crumbs
- 2 tablespoons chopped fresh parsley leaves
- 1 teaspoon Dijon mustard
- 1 teaspoon hot sauce
- 1/4 teaspoon salt
- 1/4 teaspoon freshly ground black pepper
- 1 tablespoon olive oil
- 4 hamburger buns or Kaiser rolls
- 1 beefsteak tomato, sliced
- 1/4 cup thinly sliced sweet pickles (such as gherkins)
In a large bowl, combine the tuna, mayonnaise, bread crumbs, parsley, mustard, hot sauce, salt, and pepper. Mix well and shape the mixture into four equal patties, each about 1-inch thick.
If you're stopping here:
Wrap the burgers tightly in plastic wrap and refrigerate up to 3 days or freeze up to 3 months. Thaw completely in the refrigerator or microwave for 3 to 4 minutes on LOW before cooking.
When you're ready to eat:
Heat the oil in a large skillet over medium heat. Unwrap the burgers and cook until golden brown and heated through, 3 to 5 minutes per side. Serve the burgers on buns with sliced tomato and pickles.
Recipe courtesy Robin Miller, 2006
Cooking Tips
More Recipes and Ideas
Tuna Burgers with Pineapple-Mustard Glaze and Green Chile-Pickle Relish
Recipe courtesy of Bobby Flay
Mediterranean Tuna Melts
Recipe courtesy of Food Network Kitchen

subset: commoncrawl


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text:
Today's bloom is Rhododendron (Rhododendron polycladum)
Bloom of the Day for February 20th, 2010:
« Yesterday's Bloom... |
Photo copyright growin. Unauthorized use prohibited.
Information: Type of plant: Shrubs Bloom color: Medium Blue Bloom time of year: Mid Spring Sun requirements: Sun to Partial Shade Cold hardiness: Zone 7b to Zone 9b Height: 18-24 in. (45-60 cm), 24-36 in. (60-90 cm) Spacing: 24-36 in. (60-90 cm) View much more information about this plant at PlantFiles. 2 members have or want this plant for trade. | Talk about this bloom There have been 3 comments posted about this bloom. pixie62560 wrote: growin wrote: onewish1 wrote: |


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In This Section
Journal Forum
Audibility of a CD-Standard A/DA/A Loop Inserted into High-Resolution Audio Playback - September 2007
13 comments
Sound Board: Food for Thought, Aesthetics in Orchestra Recording - April 2015
2 comments
Reflecting on Reflections - June 2014
4 comments
AES E-Library
Providing an Immersive Gaming Experience Using Wireless Low-Latency Coded Audio Streaming
Modern gaming environments contain numerous peripheral devices that enhance the gaming experience by streaming audio in real time to and from the principal gaming platform. Such peripherals include hi-fi equipment, surround speaker systems, specialist gaming headsets and specialist game controllers. Gamers are increasingly demanding the convenience of wireless communications between these devices, without compromising audio quality or significantly adding a sense of delay or lack of synchronisation to the gameplay. This paper discusses how Bluetooth communications technology, coupled with appropriate audio coding and processing techniques, may be configured and deployed to satisfy these stringent demands. Furthermore, the additional advantages of Bluetooth integration throughout the gaming ecosystem are described.
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WestPoint reaches out with scholarships
June 5, 2002
-- Home Textiles Today,West Point, GA — Thanks to home textiles giant WestPoint Stevens, 22 high school seniors' college educations will carry less of a financial burden.
The major mill announced that its WestPoint Stevens Foundation awarded 22 students from communities where the company has manufacturing operations with four-year college scholarships.
Each scholarship provides $1,000 per year for four years to the college of the student's choice as long as the students meets scholarship program criteria. There are no restrictions on the student's choice of study.
Although the children of WestPoint Stevens employees are given first consideration for the scholarships, it may be awarded to any child who is eligible.


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GridDataFormats 0.2.3
Reading and writing of data on regular grids in Python
Latest Version: 0.2.4
The gridDataFormats package provides classes to unify reading and writing n-dimensional datasets. One can read grid data from files, make them available as a Grid object, and allows one to write out the data again.
The Grid class
A Grid consists of a rectangular, regular, N-dimensional array of data. It contains
- The position of the array cell edges.
- The array data itself.
This is equivalent to knowing
- The origin of the coordinate system (i.e. which data cell corresponds to (0,0,…,0)
- The spacing of the grid in each dimension.
- The data on a grid.
Grid objects have some convenient properties:
- The data is represented as a numpy.array and thus shares all the advantages coming with this sophisticated and powerful library.
- They can be manipulated arithmetically, e.g. one can simply add or subtract two of them and get another one, or multiply by a constant. Note that all operations are defined point-wise (see the NumPy documentation for details) and that only grids defined on the same cell edges can be combined.
- A Grid object can also be created from within python code e.g. from the output of the numpy.histogramdd function.
- The representation of the data is abstracted from the format that the files are saved in. This makes it straightforward to add additional readers for new formats.
- The data can be written out again in formats that are understood by other programs such as VMD or PyMOL.
Supported file formats
The package can be easily extended. The OpenDX format is widely understood by many molecular viewers and is sufficient for many applications that were encountered so far. Hence, at the moment only a small number of file formats is directly supported.
format | extension | read | write | remarks |
OpenDX | dx | x | x | subset of OpenDX implemented |
gOpenMol | plt | x | ||
pickle | pickle | x | x | standard Python pickle of the Grid class |
In most cases, only one class is important, the gridData.Grid, so we just load this right away:
from gridData import Grid
Loading data
From a OpenDX file:
g = Grid("density.dx")
From a gOpenMol PLT file:
g = Grid("density.plt")
From the output of numpy.histogramdd:
import numpy r = numpy.random.randn(100,3) H, edges = numpy.histogramdd(r, bins = (5, 8, 4)) g = Grid(H, edges=edges)
For other ways to load data, see the docs for gridData.Grid
Subtracting two densities
Assuming one has two densities that were generated on the same grid positions, stored in files A.dx and B.dx, one first reads the data into two Grid objects:
A = Grid('A.dx') B = Grid('B.dx')
Subtract A from B:
and write out as a dx file:
The resulting file C.dx can be visualized with any OpenDX-capable viewer, or later read-in again.
Load data:
A = Grid('A.dx')
Interpolate with a cubic spline to twice the sample density:
A2 = A.resample_factor(2)
Downsample to half of the bins in each dimension:
Ahalf = A.resample_factor(0.5)
Resample to the grid of another density, B:
B = Grid('B.dx') A_on_B = A.resample(B.edges)
or even simpler
A_on_B = A.resample(B)
The cubic spline generates region with values that did not occur in the original data; in particular if the original data's lowest value was 0 then the spline interpolation will probably produce some values <0 near regions where the density changed abruptly.
File | Type | Py Version | Uploaded on | Size | |
GridDataFormats-0.2.3-py2.7.egg (md5) | Python Egg | 2.7 | 2014-02-09 | 51KB | |
GridDataFormats-0.2.3.tar.gz (md5) | Source | 2014-02-09 | 41KB | ||
- Downloads (All Versions):
- 30 downloads in the last day
- 231 downloads in the last week
- 764 downloads in the last month
- Author: Oliver Beckstein
- Home Page: https://github.com/orbeckst/GridDataFormats
- Bug Tracker: https://github.com/MDAnalysis/GridDataFormats/issues
- Download URL: https://github.com/orbeckst/GridDataFormats/downloads
- Keywords: science array density
- License: GPLv3
- Categories
- Package Index Owner: Oliver.Beckstein
- DOAP record: GridDataFormats-0.2.3.xml


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Definition from Wiktionary, the free dictionary
Alternative forms[edit]
- (idiomatic) Avoidance or inadequate performance of a task or duty; the action of copping out.
- His disappearance on the day of the audition was just a cop-out.
- (idiomatic) An excuse made in order to avoid performing a task or duty; a reason offered when someone cops out.
- It was a cop-out to say he couldn't sign the petition because he sprained his wrist.
- (idiomatic) A person who cops out.
- He's always a cop-out when there's hard work to be done.
Avoidance or inadequate performance of a task or duty
An excuse made in order to avoid performing a task or duty.
A person who cops out.
- "cop-out" in Dictionary.com Unabridged, v1.0.1, Lexico Publishing Group, 2006.
- "cop-out" in Microsoft's Encarta World English Dictionary, North American Edition (2007)
- "cop-out" in Merriam-Webster Online Dictionary, Merriam-Webster Online
- "cop-out" in the Wordsmyth Dictionary-Thesaurus (Wordsmyth, 2002)
- "cop-out" in Cambridge Advanced Learner's Dictionary (Cambridge University Press, 2007)


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Bulgaria: Situation of homosexuals; protection available to victims of harassment or violence; organizations offering assistance or support to sexual minorities (March 2005 - August 2006)
Publisher | Canada: Immigration and Refugee Board of Canada |
Author | Research Directorate, Immigration and Refugee Board of Canada, Ottawa |
Publication Date | 22 August 2006 |
Citation / Document Symbol | BGR101645.E |
Reference | 7 |
Cite as | Canada: Immigration and Refugee Board of Canada, Bulgaria: Situation of homosexuals; protection available to victims of harassment or violence; organizations offering assistance or support to sexual minorities (March 2005 - August 2006), 22 August 2006, BGR101645.E, available at: http://www.refworld.org/docid/45f146fd2f.html [accessed 27 April 2015] |
Disclaimer | This is not a UNHCR publication. UNHCR is not responsible for, nor does it necessarily endorse, its content. Any views expressed are solely those of the author or publisher and do not necessarily reflect those of UNHCR, the United Nations or its Member States. |
In 5 August 2006 correspondence with the Research Directorate, the Public Relations and International Affairs Officer for the Bulgarian Gay Organization (BGO) Gemini noted that despite some progress, lesbian, gay, bisexual and transgender Bulgarians continue to experience discrimination. Although BGO Gemini has been promoting the rights of sexual minorities for 14 years, they claim that discrimination persists and there remains a pervasive belief in Bulgarian society that minority sexual orientations constitute a disorder that can be "treated and cured" (BGO Gemini 5 Aug. 2005).
A series of polls conducted in Bulgaria between 1996 and 2004 by an unnamed source found that 20 per cent of respondents felt that homosexual media publications were acceptable, while 38 per cent of respondents were against them (BTA 9 Mar. 2005). The polls also indicated that women were 25 per cent more likely to be tolerant of gay publications than men (ibid.).
The Executive Director of the Queer Bulgaria Foundation indicated that sexual minorities were visible in all areas of society except sports (1 Aug. 2006). However, the Executive Director described Bulgaria's gay business sector as still in its infancy (Queer Bulgaria Foundation 1 Aug. 2006). According to an undated article by the British Broadcasting Corporation (BBC), tolerance is growing in some regions of Bulgaria, and there are gay bars and clubs in Sofia (n.d.).
In 1 August 2006 correspondence with the Research Directorate, the Executive Director of the Queer Bulgaria Foundation indicated that texts of law that discriminated against sexual minorities had all but disappeared over the previous two years. The Executive Director added that only part of the Constitution (and the corresponding article in the Family Code), which defines marriage as a "sacred union between a man and a woman," discriminates against gays and lesbians (Queer Bulgaria 1 Aug. 2006).
According to the Public Relations Officer of BGO Gemini, Bulgaria's Protection Against Discrimination Act
provides protection against discrimination on the grounds of sexual orientation in the fields of employment, health care, and education, recruitment to the military, housing, accommodation, and a range of services available to the public (5 Aug. 2006; see also Bulgaria 1 Jan. 2004, Art. 4).
The Act defines sexual orientation as heterosexual, homosexual or bisexual orientation (Bulgaria 1 Jan. 2004, Add. Provisions 1). However, the Public Relations Officer also stated that two factors hinder the effectiveness of the Protection Against Discrimination Act: a lack of awareness of the law among sexual minorities and in society in general, and a lack of experience in implementing anti-discrimination legislation among the institutions that are mandated to uphold the Act (5 Aug. 2006). The Executive Director of the Queer Bulgaria Foundation stated that it was too early to assess the effect that the Act would have on sexual minorities (1 Aug. 2006).
Government and state authorities
According to BGO Gemini's Public Relations Officer, the Bulgarian Commission for Protection Against Discrimination, which was created in the fall of 2005 to enforce the anti-discrimination Act, has yet to fulfil its mandate (BGO Gemini 5 Aug. 2006).
While the exact number of sexual orientation cases handled by the anti-discrimination Commission could not be found among the sources consulted by the Research Directorate, BGO Gemini reports that 13 of the 194 complaints handled by the Commission between 2005 and March 2006 had to do with disability, sexual orientation or age (26 Apr. 2006).
In August 2005, various media sources reported that, in response to pressure from the local Orthodox Church, the Mayor of the Black Sea resort of Varna decided to cancel a number of public awareness events that were to take place as part of the country's first-ever gay pride parade (The Irish Times 26 Aug. 2005; AFP 24 Aug. 2005; IHF 2006; AP 24 Aug. 2005). According to a BGO Gemini representative cited in an Associated Press (AP) article, the event was allowed to proceed but only indoors; BGO Gemini said it planned to launch a lawsuit against the Orthodox Values committee, which had campaigned for the parade's cancellation (ibid.).
A February 2006 press review by the Bulgarian News Agency (BTA) reports that supporters of Volen Siderov, the leader of the Ataka parliamentary party, called for the re-introduction of capital punishment for homosexuality (BTA 1 Feb. 2006).
On 1 August 2006, the Executive Director of Queer Bulgaria Foundation noted that, so far, no federal politicians were openly gay and that Bulgarian Socialist Youth was the sole federal party to actively support sexual minority rights in Bulgaria. However, other sources indicate that Ivelin Yordanov, a member of the Socialist Party (Têtu 9 Nov. 2005), was the first Bulgarian politician to come out (ibid.; Bulgayria 11 Feb. 2004). In addition, an uncorroborated article found on Bulgayria's Web site notes that the New Time Party (Novoto Vreme) announced its intention to support sexual minority rights, including an undefined "partnership bill" (14 June 2005).
Although the Public Relations Officer of BGO Gemini indicated that the organization frequently receives complaints of discrimination from sexual minorities, she also stated that she had not heard of any such complaints being made to the police (BGO Gemini 5 Aug. 2006).
On 19 May 2005, the Sofia News Agency reported that the Bulgarian Commission for Protection against Discrimination had taken on the case of an ethnic-Albanian gay man who said he was verbally and physically abused by police because of his ethnicity and sexual orientation. Further or corroborating information on this incident could not be found among the sources consulted by the Research Directorate within time constraints.
In April 2005, the Queer Bulgaria Foundation reported that it had "won the first case for discrimination based on sexual orientation [against] St. Kliment Ohridsky Sofia University," which had reportedly prevented four gay men from accessing the university's athletic centre because of their sexual orientation (Queer Bulgaria Foundation 25 Apr. 2005). The Regional Court of Sofia ruled that the university must pay each man 500 leva [roughly CAN$371 (XE.com 10 Aug. 2006)] in compensation and grant the men access to the gym (Queer Bulgaria Foundation 25 Apr. 2005).
According to the Executive Director of the Queer Bulgaria Foundation, the army continues to treat homosexuality as an "aberration" and homosexuals are exempt from military conscription; in addition, safeguards against discrimination are reportedly difficult to monitor and enforce in the Bulgarian military, both prior to and following enrolment (1 Aug. 2006). This information could not be corroborated by the Research Directorate.
According to uncorroborated information found in Country Reports on Human Rights Practices for 2005, Bulgarian sexual minorities "were often refused employment on the grounds of sexual orientation or fired after revealing their sexual identity" (8 Mar. 2006, Sec. 5).
Non-governmental organizations (NGOs)
In addition to BGO Gemini and the Queer Bulgaria Foundation, other advocates of sexual minority rights in Bulgaria include the Bulgarian Helsinki Committee, the Bilitis Resource Centre of Lesbians and Bisexual Women, and the gay sports clubs Tangra and Dolphin (Queer Bulgaria 1 Aug. 2006).
In October 2005, several NGOs hosted Bulgaria's first gay and lesbian film festival in Sofia (BGO Gemini 29 Sept. 2005; Bulgayria 1 Oct. 2005).
For a list of gay bars, clubs, discotheques, hotels, shops, media and organizations please consult the Web site Bulgayria.com (ibid. n.d.).
This Response was prepared after researching publicly accessible information currently available to the Research Directorate within time constraints. This Response is not, and does not purport to be, conclusive as to the merit of any particular claim for refugee protection. Please find below the list of additional sources consulted in researching this Information Request.
Agence France-Presse (AFP). 24 August 2005. "Municipal Officials Ban Gay Parade in Bulgarian Seaside Resort." (Factiva)
Associated Press (AP). 24 August 2005. "First National Gay Festival in Bulgaria Stirs Angry Reaction." (Factiva)
British Broadcasting Corporation (BBC). N.d. "Bulgaria – Entertainment." Bulgaria. 1 January 2004. Protection Against Discrimination Act. (Office of the United Nations High Commissioner for Refugees Web site) Bulgarian Gay Organization (BGO) Gemini. 5 August 2006. Correspondence from the Public Relations and International Affairs Officer. Bulgarian News Agency (BTA). 1 February 2006. "Press Review: Home Scene." (Factiva) Bulgayria. 1 October 2005. "First Gay and Lesbian Fest in Sofia, Bulgaria." Country Reports on Human Rights Practices for 2005. 8 March 2006. "Bulgaria." United States Department of State. International Helsinki Federation for Human Rights (IHF). 2006. "Bulgaria." Human Rights in the OSCE Region: Europe, Central Asia and North America, Report 2006 (Events of 2005). The Irish Times [Dublin]. 26 August 2005. Daniel McLaughlin. "Bulgaria Bans Country's First Gay Parade in Face of Church Pressure." (Factiva)
Queer Bulgaria Foundation. 1 August 2006. Correspondence from the Executive Director. Sofia News Agency (Novinite.com). 19 May 2006. "Homosexual Complains of Sofia Policeman." (BGO Gemini Web site) Têtu [Paris]. 9 November 2004. Judith Silberfeld. "Premier coming-out d'un homme politique en Bulgarie." XE.com. 10 August 2006. "Universal Currency Converter." Additional Sources Consulted
Internet Sites, including: Amnesty International (AI), Bulgarian Helsinki Committee, Council of Europe (COE), European Country of Origin Information Network (ECOI), Freedom House, Global Gayz, Human Rights Watch (HRW), International Lesbian and Gay Association (ILGA), Open Society Institute, Organization for Security and Co-operation in Europe (OSCE), Sofia Echo.
_____. 26 April 2006. Desislava Petrova. The Commission Against Discrimination's Annual Report.
_____. 29 September 2005. Desislava Petrova. "Gay & Lesbian Fest in Sofia."
_____. 9 March 2005. "Bulgarian Women Are More Tolerant to Homosexuals." (Factiva)
_____. 11 February 2005. "First Youth Gay Organization in Bulgaria – Sensus."
_____. 14 June 2005. "New Time (Novoto Vreme) Political Party Declares Support for Gays."
_____. N.d. "Sofia Gay Guide."
_____. 25 April 2005. "First Anti-Discrimination Case Based on Sexual Orientation Was Won."


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Where There's A Will, There's A Greenway
The last major open air creek without surrounding green space in the city, the Frankford Creek is poised to be lined by a trail and park connecting the Tacony Creek Park, now under construction, and the Delaware River. A feasibility study for the project will begin in 2013 > more
Getting to the Root of the Problem
Urban agriculture needs to be tied to broader strategies of economic development, says Ariel Diliberto in her review of the film "Urban Roots" > more
Frankford Avenue Drawing More Than A Dozen New Projects
With a hotel, theater, market, and new shops and restaurants coming, are the days of drag racing and short dumping over? We survey the scene and talk to some of the developers and observers close to the action > more
In South Philly, Subtly Staking Territory
Exploring the shopping center architecture of Vietnamese Washington Avenue > more


text:
Talking Feather Kit
$7.99Kit includes 12" dowel, fur, feather, sinew, beads, suede lace, and instructions. As the talking feather is passed around, only the person holding it is allowed to speak. Learn More -
Delta Dart Kit
Originally Starting at:
Starting at:$4.99
Build your own rubber-band powered flying machine! Kit includes precut balsa, model airplane paper, propeller assembly, and instructions to make one prop-glider airplane. Measures 12" long with a wingspan of more than 10" Learn More -
Warbonnet Neckerchief Slide Kit
$4.49Scouts will be amazed when, in no time at all, simple safety pins and beads come together to create this replica of a Native American headdress that doubles as a neckerchief slide. Includes pins, beads, and stringing materials. Learn More -
Arrowhead Bear Claw Glow-In-The-Dark Necklace Kit
$4.49Glow-In-The-Dark Necklace Kits. NEW! Fun and easy Native American craft kits feature glow-in-the-dark components for an edgy addition to these string-them-yourself necklaces. Kits include beads, lacing, and instructions. Learn More