Abstract: Highly reliable, light-weight, and low power-consuming microwave redundancy and re-routing electronic switches suitable for on-board satellite applications permit rearranging of communication paths for up- and down-link communications and re-routing of microwave signals to redundant devices in the event of on-board hardware failures.

Abstract: The quality of reconstructed images is improved by a post-processing method at the decoder which uses codeword-dependent, spatially-varying 2-dimensional filters. The post-filtering, working across block boundaries, reduces coding artifacts and increases the signal-to-noise ratio. The technique is applicable for use with any VQ-based image compression and can also be used in conjunction with image magnification.

Abstract: A sampling method, denoted continuously variable IF sampling (CVIFS), implemented in digital transmission and reception components is characterized by sampling a bandpass signal which is centered at an intermediate frequency f.sub.IF that is related to both the data transmission symbol rate (R.sub.s) and sample rate (NR.sub.s) by integer ratios. Moreover, the CVIFS method is characterized in that the sample rate NR.sub.s is constrained to be four times the IF center frequency, and both the sample rate NR.sub.s and the IF center frequency are constrained to be within a range of a factor of 1.5 of their maximum values. To maintain this high sample rate as the data symbol rate is lowered, a "gear shifting" technique is utilized whereby the integer number of samples-per-symbol, N, is increased as the symbol rate decreases. Moreover, the sample rate NR.sub.s is always between 3.0 to 4.5 times the maximum data symbol rate (R.sub.smax), and the IF center frequency is always between 3/4 to 9/8 times (R.sub.

Abstract: A rechargeable electrochemical battery having a solid organic electrolyte and a thin film cathode and anode. In particular, the battery employs a proton-conducting organic polymer which is a mixture of a strong acid and a base polymer, a thin film anode containing a hydride alloy, and a thin film cathode containing a NiO.sub.x active material. The battery is rechargeable and capable of fast discharging and recharging. Further, the battery can be hermetically sealed in a case.

Abstract: A digital despreader and downconversion technique useful for spread spectrum communications receivers digitally tracks a timing phase of a PN sequence without the need for steering an external hardware clock. An additional benefit of the technique is the use of a receive filter matched to the bandlimited transmit chip sequence prior to despreading which reduces the amount of noise present after despreading. A narrowband filter also permits the use of a single A/D converter in the receiver, IF sampling at a relatively low sample rate compared to other techniques. A method for reducing a total number of computations required thereby facilitating implementation in a single custom digital integrated circuit is also described.

Abstract: In an asynchronous transfer mode (ATM) system, interleaved cells are formed at the transmit end by combining into each interleaved cell certain bits from each of plural different original ATM cells, the interleaved cells are transmitted over the communications link, and then deinterleaved at the receive end. Any bursty errors occurring on the communications link will, after deinterleaving, be spread out over multiple original ATM cells, maximizing the error correction for ATM cells and error detection for AAL capability and minimizing loss of data. The C1 byte in the Physical Layer Convergence Protocol (PLCP), which indicates the location of end of the PLCP frame, is protected against the burst errors by replication of C1 byte through inserting them in the growth bytes Z1 through Z4.

Abstract: An ISDN Satellite Switch (ISS) is disposed between ISDN user equipment (e.g., an ISDN PBX) and a satellite network, to extract and process the ISDN signaling information originated from the ISDN user equipment, allocate an appropriate satellite capacity for the user service request, generate signaling response messages to the originating user, generate messages to be transmitted over a satellite signaling channel to the corresponding ISS connected to the destination user, and provide an appropriate Protocol Conversion Function (PCF), when necessary for a certain class of data protocols. A destination ISS, after receipt of these messages, generates ISDN incoming call signaling messages to be sent to the called user.

Abstract: Interference from other users in a CDMA Spread Spectrum system is cancelled by constructing a single reference sequence which is representative of the spreading sequences of all users in the system. Interference from the other users can be cancelled without each receiver employing a separate decorrelator for every other user in the system and having an accurate estimate of the received power level of every transmitted signal.

Abstract: An enhanced nonlinear signal processor for RFI suppression using either biased null zone amplifier or a biased inverting limiter. Two or more nonlinear interference processors are connected in cascade. As a result, a deliberate tracking error, selected to provide only a small amount of relative interference rejection, is introduced into each processor. The effect of each stage is cumulative until some limit to performance improvement, determined by the input/output characteristic of each stage, is reached. The benefits of this discovery are increased dynamic range capability (higher levels of interference-to-wanted signal ratio can be fully rejected), simplification of gain control, and increased flexibility in hardware implementation options resulting from reduced sensitivity to RFI tracking error.

Abstract: A dual polarized printed circuit antenna operating in dual frequency bands. A first array of radiating elements radiates at a first frequency, and a second array of radiating elements radiates at a second, different frequency. Separate power divider arrays are provided for each array of radiating elements, and the overall structure is provided in a stacked configuration.

Abstract: A codec uses a number of different signal processing techniques to improve audio compression. These techniques include (1) dynamically varying the size of the processing block to match the duration of the signal over which the audio signal can be considered to be substantially constant, (2) reducing the power gain of the LPC coefficients to reduce leakage of coding noise from one block into the following block, (3) allocating bits to the residual signal in accordance with both objective and subjective criteria, and (4) computing a modified residual signal to take into account the zero input response of the synthesis filters to the reconstruction noise of past blocks.

Abstract: Method for randomly detecting a unique word comprising M bits in a predetermined number of segments within a frame containing L bits of data, where M and L are integers greater than one and wherein M is less than L, includes steps for (a) randomly sampling the data to thereby obtain the segments, (b) comparing a first segment of the segments with the first portion of an actual unique word so as to permit determination of a match between the first segment and the first portion of the actual unique word, (c) when a match is found between the first segment and the respective portion of the actual unique word, comparing a next segment of the segments with the next portion of the actual unique word, (d) when a match is found between the next segment and the next portion of the actual unique word, repeating step (c) until all of the segments are matched with corresponding portions of the actual unique word, and (e) when the comparison of any segment does not result in an appropriate match, returning to step (a) to

Abstract: A facsimile communication system including a first processing circuit, connected to receive a facsimile signal from a first facsimile device, for converting the analog voiceband facsimile signal into a digital code signal representing information carried in the analog voiceband signal, and for transmitting the digital code signal; a second processing circuit, connected to receive the transmitted digital code signal from the first processing circuit, for converting the received digital code signal into an analog voiceband facsimile signal; and a second facsimile device, connected to receive the analog voiceband facsimile signal from the second processing circuit. The digital code signal includes a digital code which is repeated in the digital code signal an integral number of times. In another embodiment, the digital code signal contains another binary code which represents the position, within a data field, when information was first detected by the first processing circuit.

Abstract: A method for compressing a multi-spectral data stream corresponding to an image for a selected one of transmission, as a limited bandwidth transmission using a predetermined band, and data storage includes steps for dividing the image into pixel blocks P in each of N bands, where both P and N are integers greater than one, selecting one of pixel blocks in one of N bands as an anchor band and computing prediction coefficients for relating intensities of each pixel in each P pixel block in the remaining N-1 bands based on the anchor band. A codec apparatus is also described.

Abstract: A common pressure vessel type Ni-H.sub.2 battery having a thermally conductive rack disposed within the pressure vessel and having an outer wall conforming to and in thermal contact with the inner surface of a cylindrical center wall portion of the pressure vessel and a plurality of fins dividing the rack into a plurality of compartments. A Ni-H.sub.2 battery cell is disposed in each of the compartments in thermal contact with adjacent ones of the fins. A plurality of flexure springs extend between racks, providing a radial force on the racks so as to urge the outer walls of the racks into contact with respective portions of the wall of the pressure vessel. A stopper is formed internally of the pressure vessel and a wave spring is disposed between a weld ring provided at the end of the rack opposite the stopper for forcing the racks in the longitudinal direction of the pressure vessel into contact with the stopper.

Abstract: An apparatus for and a method of permitting the in-band negotiation of enhanced capabilities between two or more facsimile interface units (FIUs) by using FIU capabilities control packets containing a plurality of data cells carrying information of the capability negotiation information is disclosed. In operation, a called station identification signal is transmitted from a remodulating FIU together with a special capabilities packet following the end of a line control packet. The calling FIU may issue a response agreeing to or modifying the compatible enhancements by sending its own special capabilities control packet containing compatibility negotiation information. In another aspect of the present invention, an FIU adds a set of data cells to a line control packet to minimize the possibility of data cell alignment due to degraded channel conditions.

Abstract: Before transmitting signals to a receiver, the signals are subjected to adaptive prediction to generate a residual signal for transmission, and the residual signal is then transformed into frequency domain coefficients, the coefficients are grouped together to form vectors, and the vectors are then quantized.

Abstract: A network of personal communications terminals communicating in a CDMA mode includes a reference station for transmitting a pilot tone that is pre-corrected at the reference station and is used at the remaining stations for frequency control, transmit power control and antenna acquisition and tracking. Voice activation is employed to permit the CDMA system to share the satellite transponder power and bandwidth in a fully Demand-Assignment-Multiple-Accessing (DAMA) manner. Burst-mode operation of a voice activated CDMA system is permitted by sending dummy data in the speech pausing period at a reduced (but not zero) power level, and the "near-far" problem inherent in a CDMA system is mitigated by the use of uplink power control.

Abstract: In a flat plate antenna, insertion loss is reduced significantly by providing an extensive waveguide structure at the back of the ground plane of the antenna. Depending on antenna size, the waveguide may feed the antenna at one or a plurality of points. According to a preferred embodiment, the transition from waveguide to stripline is made via a coaxial connection, with a quarter-wave transformation, including mode suppression walls to direct the energy more efficiently. Alternatively, a direct waveguide to stripline transition may be provided. The technique has wide applicability to a number of antenna designs, including single- and dual-polarization structures, and linear and circular polarization operation.

Abstract: Contactless coupling of a low-noise block down-converter (LNB) imbedded within a flat antenna is achieved by mounting the LNB on a power summing/combining network layer of the antenna, and coupling the transition capacitively to the power summing/combining network in a stripline-to-stripline transition. The contactless coupling facilitates antenna manufacture by allowing the rapid testing of the LNB and its final assembly into the antenna.