Abstract: The present invention relates to a wireless PBX network wherein direct sequence spread spectrum multiple access is used for voice and data communications to support a plurality of local-local and local-external calls. The present wireless PBX arrangement comprises a plurality of local user transceivers using a first separate unique chip sequence patterns for information communication and a second common chip sequence pattern for call-set up; and a central PBX comprising (a) a plurality of PBX transceivers, each of which uses a separate first chip sequence pattern which is matched to a corresponding local user transceiver; (b) a switching means for interconnecting local users to each other or to an external network via the associated PBX transceivers; and (c) a call set-up receiver responsive solely to initial call set-up information sent by any user using the second common chip sequence pattern.

Abstract: The present invention relates to a technique for automatically cataloging and storing pictorial and/or written sections of information in the form of, for example 35-mm slides, X-rays, store catalog pages, etc. in a database for subsequent retrieval by end users of the database. In accordance with the present technique, a bar-code label, including a unique bar-code, is assigned and affixed to each piece or section of information to be separately stored in the database. Each section of information is sequentially fed into a recording arrangement where (a) the bar-code versus a brief description of the information section is recorded in a computer memory, (b) an image of the pictorial and/or written information section is transformed into a video signal and recorded on a separate location of a video tape or disk, and (c) the location of the video signal on the video tape or disk for each section of information is recorded in the computer memory with the associated bar-code and brief description.

Abstract: The present invention relates to a dynamic resource allocation technique for multiple users of a channel that employs variable coding and associated redundancy to provide a maximum data rate for various demand conditions while simultaneously providing a maximal margin that is matched to the current demand condition. For such technique, each first data rate input signal is synchronized to a second higher data rate, the synchronized signals are then separately demultiplexed for propagation along separate paths and encoded in a separate variable rate coder (VRC). The output from each VRC is stored in a separate bus interface which contends for a common bus when full. A rate controller maintains the activity on the common bus at a minimum level by either monitoring (1) the activity on the bus, (2) the rate the bus interfaces are filling up, or (3) both (1) and (2) above, and in response thereto to transmit control signal to the VRCs to appropriately vary the codes and redundancy used.

Abstract: The present invention relates to a bootstrapping cross-polarization canceler which includes a noise-blanking limiter in the path before a correlation detector, and a processor which uses the output from the correlation detector to provide cross-polarization cancellation continuously or just during an outage condition where orthogonally received signals from a communication path include error rates which exceed a predetermined threshold. Alternatively, the processor can use the output of a pseudo error detection, which detects the error rate of the orthogonally received signals, when the error rates in the received signals are below the predetermined threshold in order to achieve convergence and cross-polarization cancellation in the canceler during a non-outage period.

Abstract: Eye violation detectors which provide either one of a "graded" or "half-graded" eye violation indicator technique. More particularly, the eye violation detector for practicing the "graded" technique provides an eye violation region in one or more eyes of a multiple eye pattern which is uniformly disposed on either side of the center of each of one or more eyes of the multiple pattern and includes a different amplitude in each of the eye patterns of interest. The eye violation detector for practicing the "half-graded" technique provides an eye violation region in one or more eyes of a multiple eye pattern which is disposed on only one side of the center of each of one or more eyes, except for the center eye of the multiple eye pattern, and includes a different amplitude in each of the eye patterns of interest.

Abstract: The present invention relates to an antenna arrangement for correcting for astigmatism is a beam which is linearly scannable in a first principal plane of the antenna arrangement. The antenna arrangement comprises a parabolic or torus main reflector and a feed arrangement for producing first and second astigmatic phase centers which lie along first and second focal lines, respectively, in the first principal plane and match first and second astigmatic phase centers required by the main reflector to produce a linearly scannable plane wave.

Abstract: The present invention relates to a cross-polarization equalizer/canceler which simultaneously performs cross-polarization equalization/cancellation in a tapped delay line (TDL) matrix. More particularly, the present equalizer/canceler receives the first and second orthogonally polarized digital signals on separate paths which are each split into a straight through and cross-over paths that include a TDL matrix comprising a separate TDL, with a predetermined number of complex taps, in each of the paths. The individual complex taps are appropriately adjusted in response to control signals from a tap adjusting means which derives the appropriate control signals from current tap signals and computed gradients derived from a predetermined algorithm. Accurate data decisions, however, are not needed.

Abstract: The present invention relates to a technique for infusing and maintaining a gas-in-glass fiber. In the present technique, a length of an optical fiber, e.g., a single mode fiber, is placed in a pressure vessel with the ends of the fiber protruding from the vessel walls through seals. The vessel is then partially or fully filled with a medium, such as a gas or water, and the vessel sealed. In one embodiment, a container, including both the predetermined gas under pressure and a rupture disc in a container wall, is disposed within the vessel. Pressure is then applied to the sealed vessel until the rupture disc implodes and releases the gas for subsequent infusion. In a second embodiment, the predetermined gas is introduced into the vessel from an outside pressurized source until a first predetermined pressure is obtained within the vessel. A predetermined amount of additional pressure from a second pressure source is then supplied to the vessel until a second predetermined pressure is reached in the vessel.

Abstract: The present invention relates to a broadband variable attenuator comprising a two- or three-section transmission line with a separate PIN diode bridging each of the two gaps between the adjacent ends of the transmission line sections. The two PIN diodes are disposed in series opposition and the first, second and third transmission line sections are connected to a diode variable biasing source to cause (a) substantially a total reflection of an input signal to the attenuator for a bias below a first value, (b) substantially a total transmission of an input signal through the diodes for a bias above a second value, and (c) a selected amount of both partial reflection and partial transmission of an input signal for a bias value between the first and second values. The broadband variable attenuator can be implemented using microstrip, stripline or coaxial technology without the need of d-c isolation capacitors or applique resistors while providing a maximum insertion loss under zero bias conditions.

Abstract: The present invention relates to a scanning beam antenna comprising a doubly-curved main reflector, a doubly-curved subreflector and at least one linear array feed. The main reflector is doubly-curved in two planes to produce a separate first focus for each feed in a first plane in front of the subreflector and a separate second focus for each feed in a second orthogonal plane behind the subreflector. The subreflector is curved to refocus each second focus of the main reflector to coincide with the image line of a first axis on the reflecting surface of the main reflector in the first plane. Each feed array is disposed at a separate secondary focus of the combination of the main reflector and subreflector. The resulting antenna provides very little phase error due to aberrations as each beam is linearly scanned.

Abstract: The present invention relates to a QPSK modulator or demodulator for modulating two different input bit streams with a subharmonic pump carrier signal to produce an appropriately encoded QPSK output signal. The subharmonic pump carrier signal used is a submultiple of a predetermined microwave or millimeter-wave carrier frequency. The QPSK modulator or demodulator is capable of being fabricated on a planar substrate using appropriate stripline filters and a mixer diode in each of an in-phase and quadrature signal path. A fin line arrangement, also capable of fabrication on the substrate, can be used to introduce an appropriately phased subharmonic pump carrier signal into each of the in-phase and quadrature signal paths before each mixer diode.

Abstract: The present invention relates to a horn antenna which provides minimized cross-polarization in the far field of the antenna. The antenna arrangement comprises a horn including four walls wherein a first pair of opposing concentric conic walls are associated with a common longitudinal axis, and a second pair of opposing planar walls are aligned radially to the common longitudinal axis of the cones. The walls taper down from an offset parabolic main reflector to intersect a common apex corresponding to a focal point of the main reflector. The longitudinal axis of the horn is arranged at a predetermined angle to the common longitudinal axis of the cones to minimize cross-polarization in either one or both of the TE.sub.01 or TE.sub.10 modes in the far field of the antenna.

Abstract: The present invention relates to an antenna arrangement for reducing multipath fades. The antenna arrangement comprises a curved main reflector disposed confocally with one focal point of a subreflector, and a feed arrangement. The feed arrangement comprises at least a pair of feed horns and a selectively movable plate reflector disposed between the feed horns and the subreflector along a feed axis of the antenna arrangement. The feed horns are disposed adjacent each other with the aperture of each of two feed horns covering one-half of the image of the main reflector. By selectively orienting the plate reflector so that one of the two multipath beams arrives with its central ray disposed orthogonal to the aperture of the feed horns, the contribution from each half of this beam received at each feed horn, for a particular frequency band, is equal and can be subtracted from the other half beam signal to cancel its effect without the need for an equalizer.

Abstract: The present invention relates to an antenna arrangement which includes a polarization diplexer capable of bidirectionally directing two orthogonally polarized signals along one path in the far field of the antenna arrangement and along two separate paths in the near field for interception along at least one of the paths by an array of feed elements. The array is arranged to provide a fixed linear phase taper along one axis across the array to produce or intercept a beam squinted at an angle 90 degrees-.alpha. to the face of the array and including a signal polarized in a first direction. Phase shifting means selectively produce a linear phase taper along a second axis across the face of the array orthogonal to the first axis to cause the beam to traverse a predetermined arc in the far field of view.

Abstract: The present invention relates to a Time Compression Multiplexing (TCM) technique for transmitting three consecutive television picture signals from a television picture source during the time period normally used to send one television picture signal. More particularly, three consecutive lines or fields from a TV signal source are compressed into an ordinary line or field period, respectively, by sending one line or field as is, but time compressed, in one portion of a line or field period and sending two other lines or fields as differential signals, also time compressed, to occupy two separate and different portions of the same line or field period as is used by the first one line or field. With such technique it is possible to send three consecutive line or field signals from each of three separate colocated or non-colocated TV sources on a Time Division Multiple Access (TDMA) basis.

Abstract: The present invention relates to an FET power amplifier whose transfer characteristics are parabolic or have a pronounced parabolic region. The amplifier is capable of linear operation due to a drain electrode bias network which includes a pair of serially connected quarter-wave transmission line sections connected at one end thereof to the drain electrode, and the interconnection point of the two quarter-wave transmission line sections is connected to both (a) a bias supply which causes the FET to operate over at least a portion of the parabolic region and (b) to a means which prevents envelope-induced drain bias voltage variations and presents a short-circuit to the drain terminal at a second harmonic of the input signal.

Abstract: The present invention relates to a technique for the Time-Frequency-Multiplexing (TFM) of three television signals. More particularly, three fields of a TV signal are sent simultaneously to a remote receiver by transmitting one field as is in the baseband of a standard television system signal while the other two fields are transmitted as differential signals, quadrature amplitude modulated onto a subcarrier frequency above baseband. The two differential signals can comprise two field differential signals or a frame and a field differential signal. Arrangements are also provided for transmitters and receivers for implementing the present technique.

Abstract: The present invention relates to a near-instantaneous companding coder wherein the peak a-c amplitude of an input signal is measured over a block of K samples. Each of the K samples is coded into an n-bit quantized sample code word based on a step size quantizing control signal determined from the measured peak a-c amplitude. The step size quantizing control signal, and other overhead information such as parity, sync, etc., are formed into a K-bit overhead word and transmitted serially by adding a separate bit of K-bit overhead word to each of the corresponding K n-bit quantized sample code words associated with an immediately prior block of K sample code words. At the remote decoder, the received K-bit overhead information word is stored and used to decode the next subsequent block of K received n-bit quantized sample code words.

Abstract: The present invention relates to a transmitter and a receiver for use in a digital communication system which are capable of transmitting and receiving, respectively, a single duplex analog signal channel, such as, for example, a voice channel, and limited short asynchronous data bursts. The transmitter portion includes an encoding means which uses an adaptive companding algorithm in the encoding process while the receiver portion includes a decoding means using the same synchronized algorithm in the decoding process. The transmitter and receiver at each end of a communication channel also include a signaling interface which can interrupt the coding and decoding process to transmit and receive, respectively, an occasional data burst without upsetting the synchronization of the adaptive companding algorithm states at both ends of the channel.

Abstract: The present invention relates to a cross-polarization cancellation arrangement for digital radio channels wherein the cancellation arrangement comprises a canceller section and an equalizer section in cascade which operate at baseband. The canceller section includes both a main lobe estimator and detection circuits. The estimator provides a preliminary estimate of the main lobe of the pulse response in each of the two received orthogonally polarized signals. The detection circuits take each of the estimator means output signals, relating to each received polarized signal, and generates therefrom error control signals for adaptively updating the main lobe estimate signals from the estimator and also to provide an output signal which is used to cancel the interferer main lobe in the received oppositely polarized signal. The equalizer section then mitigates intersymbol and cross-rail interference in each of the orthogonally received signals.