Abstract: A transmitter circuit for transmitting a sine wave modulated with digital data, where the sine wave includes a clock signal, and a receiver circuit for demodulating the transmitted sine wave, where the receiver circuit extracts the clock signal and the digital data from the sine wave. The transmitter circuit includes digital logic components that allow the transmitted sine wave to include at least one bit per cycle of the sine wave, and the receive circuit includes digital logic components that allow the clock signal and the digital data to be extracted from the sine wave. In various embodiments, the transmitted sine wave includes one bit per cycle, one bit per half cycle, multiple bits per cycle and multiple bits per half cycle.

Abstract: A modulation channelization, demodulation and error-control system based on orthogonal bipolar spreading vectors is provided that permits a variable information rate to be transmitted without inducing envelope fluctuations and which permits multiple access without requiring the transmitter amplifier to support the combined information rate of all users. The modulation system uses the Hadamard matrix vectors to form communication channels. The information rate on any channel may be doubled by using half the vector length to transmit information. The vector that is not orthogonal-in-the-half to the rate-doubled vector is deactivated. Similarly, higher information rates may be provided through truncation of the transmission vector and the elimination of the resultant non-orthogonal vectors. The system provides biorthogonal coding in addition to multirate communication.

Abstract: A microstrip-to-microstrip RF transition circuit that employs a wide microstrip line transition to a short co-planar waveguide section. In one embodiment, a first microstrip line and a first ground plane are patterned on a top surface of a semiconductor wafer, and a second microstrip line and a second ground plane are patterned on a bottom surface of the wafer. A signal via is formed through the wafer and makes electrical contact with the first and second microstrip lines. Likewise, at least one ground via is formed through the wafer and makes electrical contact with the first and second ground planes. A widened portion of the microstrip line is positioned between extended portions of the respective ground plane so that a slot is provided between the widened portion and the extended portion.

Abstract: A modulation channelization and demodulation system based on orthogonal bipolar spreading vectors is provided that permits a variable information rate to be transmitted without inducing envelope fluctuations and permits multiple access without requiring the transmitter amplifiers to support the combined information rate of all users. The modulation system uses the vectors of a Hadamard matrix to form communication channels. The information rate on any channel may be doubled by using half the vector length to transmit information. The vector that is not non-orthogonal-in-the-half to the rate-doubled vector is preferably deactivated. In the same fashion, higher information rates may be provided through truncation of the transmission vector and the elimination of the resultant non-orthogonal vectors. A multi-channel receiver including a Fast Hadamard Transform structure comprised of controllable modified logic cells for performing the multi-rate communication of the present invention is illustrated.

Abstract: A power amplifier circuit (40) that includes an error correction loop (44) having a lower IP3 error correction amplifier (54) than a main power amplifier (46) in a main signal path (48). A first attenuator (52) in the error loop (44) attenuates the RF signal, and provides more attenuation of intermodulation products in the RF signal and about the same attenuation for a main frequency of the RF signal for each dB of attenuation. The error amplifier (54) amplifies the attenuated RF signal from the first attenuator (52). A second attenuator (56) in the error loop (44) attenuates the RF signal from the error correction amplifier (54). A phase shifter (58) phase shifts the RF signal from the second attenuator (56). A coupler (50) couples the amplified RF signal and the phase shifted RF signal to cancel out intermodulation products in the amplified RF signal.

Abstract: A correlative error detection system (60) for a signal equalizer (10) that corrects a distorted communications signal. The detection system (60) correlates a sequence of bits in a signal from an FFE and/or a DFE processor (12, 14) with a predetermined sequence of correlation values. The detection system (60) includes a summing network (66) that sums the correlated signals. If the sequence of signal bits matches the sequence of correlation values, then the summed correlated signal will include a signal maxima. A peak detector (76) detects and holds the signal maxima so that a slow speed weight computer (40) can process the signal values to set weight values in the processors (12, 14). By knowing how often the sequence of bits that match the correlative values should occur in a random bit stream for an undistorted signal, the weight computer (40) can set the weight values to provide that magnitude of the bit sequence.

Abstract: A fuel cell system that employs a recuperative heat exchanger to provide additional cooling for the compressed charge air applied to the cathodes of the fuel cells in the fuel cell stack. The cathode exhaust gas is applied to the recuperative heat exchanger so that the cathode exhaust gas cools the charge air heated by the compressed air. A cathode exhaust gas expander is provided in combination with the recuperative heat exchanger that uses the energy in the heated cathode exhaust gas to power the charge air compressor. An anode exhaust gas combustor can be provided that burns residual hydrogen in the anode exhaust gas to further heat the cathode exhaust gas before it is applied to the expander.

Abstract: A stand-alone fuel processor (10) for producing hydrogen from a hydrocarbon fuel for a fuel cell engine in a vehicle. The fuel processor (10) includes a primary reactor (14) that dissociates hydrogen and other by-products from the hydrocarbon fuel as a reformate gas. The reformate gas is applied to a WGS reactor (48) to convert carbon monoxide and water to hydrogen and carbon dioxide. The WGS reactor (14) may include an adsorbent for adsorbing carbon monoxide. The reformate gas from the WGS reactor (48) is then sent to a rapid-cycle PSA device (12) for adsorbing the undesirable by-products in the gas and generates a stream of pure hydrogen. A liquid water separator (70) separates water from the reformate gas before it is applied to the PSA device (12). The PSA device (12) uses a portion of the separated hydrogen as a desorbing gas to purify the adsorbent in the PSA device (12). The by-products of the reformate gas can be used as a fuel in a combustor (30) that generates heat for the primary reactor (14).

Abstract: A signal equalizer that employs micro-electromechanical machine devices for the tap weight controllers. The equalizer includes a substrate on which is formed a forward transmission line rail and a return transmission line rail. A cantilever stanchion is also formed on the substrate that runs parallel with the transmission line rails. A series of spaced apart cantilevers are pivotally mounted to the cantilever stanchion, and extend over the transmission line rails to define a gap therebetween. A weight tap line is coupled to each cantilever, and is responsive to a DC weight signal that controls the position of the cantilever to set the gap between the cantilever and the transmission line rails. A distorted signal is coupled from the forward transmission line rail to the return transmission line rail through the cantilevers.

Abstract: A bipolar plate for a PEM fuel cell is disclosed. The plate includes a plurality of channels, wherein the ends of the channels are staggered. The plate also includes a plurality of tunnels, wherein the ends of the tunnels are staggered. The plate further includes a cathode and an anode, wherein a portion of the cathode overhangs a portion of the anode. These staggered/offset features allow for an increase the capillary meniscus of water droplets passing therethrough, allowing for a reduction in the pressure required to move the water through the cell and out to the header volume of the stack.

Abstract: A fuel cell system that employs a procedure for delaying an air purge of a fuel cell stack at system shut-down until the temperature of the stack is reduced below a predetermined temperature. The fuel cell stack includes an anode side, a cathode side, an anode input, a cathode input and an anode exhaust. The system includes a temperature sensor for monitoring the temperature of a cooling fluid flowing through the stack. The anode side of the fuel cell stack is purged at the stack shut-down by directing air from the cathode input line to the anode input line after the temperature of the cooling fluid is reduced to a predetermined temperature.

Abstract: A single-element antenna system that provides a wide bandwidth and consistent polarization over the frequency range to which the antenna is impedance matched. In one embodiment, the wideband antenna system includes two parallel coupled sectorial loop antennas (CSLA) that are coupled along an axis of symmetry. In another embodiment, half of the coupled sectorial loop antenna is electrically coupled to a ground plane, where the antenna includes one pie-slice shaped sector and two arches. In alternate embodiments, sections of the sector can be removed to reduce the weight of the antenna system.