Abstract: A cluster of communications platforms can comprise a master platform and support platforms. The master platform can partition a data block into data partitions and transmit the data partitions via a short range transmitter to the support platforms. Each support platform can include a high power storage device for powering long range burst transmissions of a subset of the data partitions to a distant receiver. Burst transmissions of data partitions by the same support platform can be separated by a charging time period that allows a high power storage device in the support platform to charge from a relatively low average power Pa a relatively high power burst PB that is sufficient to transmit one of the data partitions to a distant receiver.

Abstract: A radio signal transmission technique includes selecting a sample rate from a plurality of predefined sample rates so that the radio signal is contained entirely within a Nyquist zone corresponding to the sample rate. A digitized signal is converted to an analog signal, spectrally enhanced, and passed through a selected one of a plurality of selectable bandpass filters to form the radio signal.

Abstract: The perceived sample rate at which a DAC can operate can be increased by allowing multiple DACs to process different portions of a digital signal in parallel. In this way, the outputs of multiple DACs can be combined into a single analog signal to achieve the desired speeds and resolutions of the analog output. This parallel processing can be implemented using a time-interleaving technique or a sub-band reconstruction technique. Pre-distortion can be applied to the digital input signal to compensate for degradation detected in the analog output signal. By applying pre-distortion, waveforms having high sampling rates can be efficiently generated.

Abstract: A return-to-zero control signal for controlling a modulator can be generated from two separate streams. A first data stream can include a pulse for each logical one that appears in an input data stream, while a second data stream can include a pulse for each logical zero that appears in the input data stream. The first and second data streams can be combined in a manner that yields the return-to-zero control signal. The first and second data streams can be generated in digital circuitry, such as an FPGA, to minimize the analog path for generating the return-to-zero control signal.

Abstract: A cluster of communications platforms can comprise a master platform and support platforms. The master platform can partition a data block into data partitions and transmit the data partitions via a short range transmitter to the support platforms. Each support platform can include a high power storage device for powering long range burst transmissions of a subset of the data partitions to a distant receiver. Burst transmissions of data partitions by the same support platform can be separated by a charging time period that allows a high power storage device in the support platform to charge from a relatively low average power Pa a relatively high power burst PB that is sufficient to transmit one of the data partitions to a distant receiver.

Abstract: A wedge shaped scimitar radio frequency (RF) antenna can include a lip, an RF signal feed connected to the lip, a base, and a back surface. The antenna can also include a convexly curved outer surface that extends from the lip to the back surface. The convexly curved outer surface can be wedge shaped from the back surface of the antenna to the lip. The antenna can also include a concavely curved outer surface that extends from the lip to the base of the antenna, and the concavely curved outer surface can be wedge shaped from the base of the antenna to the lip.

Abstract: A radio frequency (RF) horn can include an interior surface with an inner geometry comprising irregular, aperiodic corrugations and/or undulations. The pattern of the inner geometry can excite higher order modes simultaneously in two RF signals each at a different frequency that combine with fundamental modes of the signals to produce substantially Gaussian profiles of the two signals at the output aperture of the horn. Even though the signals are at different frequencies, the illumination pattern of both signals on a reflector antenna at which the horn is directed can be substantially the same.

Abstract: A digital signal processing (DSP) apparatus is used for processing a plurality of different signals. The DSP apparatus includes a DSP module configured to perform a DSP algorithm on samples of the signals. The DSP apparatus also has a parameter memory that includes a plurality of memory cells. The parameter memory has a signal number input and a parameter output. The parameter output is connected to the DSP module. The parameter memory is configured to output to the parameter output a parameter corresponding to a signal identifier at the signal number input.

Abstract: The peak-to-average power ratio of an input signal can be reduced prior to amplification. This reduction in the peak-to-average power ratio can be accomplished without adding significant intermodulation distortion to the input signal. The resulting input signal can therefore have a peak-to-average power ratio that does not exceed the output backoff of the amplifier thereby preventing the amplifier from being operated in saturation and, as a result, minimizing the intermodulation distortion added by the amplifier. The peak-to-average power ratio of an input signal can be reduced using two stages of signal clipping. By employing two stages, the intermodulation distortion introduced to the input signal as it passes through the stages is minimized. Also, because this two-stage approach does not attempt to account for intermodulation distortion introduced by the downstream amplifier, it can be implemented without any prior knowledge of the amplifier's transfer function or any output monitoring scheme.

Abstract: A digital electronic message comprising datawords to be transmitted in a communications system can be encoded prior to transmission using an asymmetric error detection coding scheme. The coding scheme is asymmetric because the coding scheme includes multiple codeword groups each with a different minimum coding distance. The codewords in a group having a greater minimum coding distance can correspond to datawords that have a relatively high susceptibility to transmission errors. The codewords in a group having a lesser minimum coding distance can correspond to datawords that have a relatively low susceptibility to transmission errors.

Abstract: A radio signal reception technique includes selecting a sample rate from a plurality of predefined sample rates so that the radio signal is contained entirely within a Nyquist zone corresponding to the sample rate. The radio signal is passed through a selected one of a plurality of selectable bandpass filters to provide an analog signal. The analog signal is sampled at the sample rate and converted to a digital signal.

Abstract: A symbol de-mapper can determine soft values for the bits of a complex symbol R that has been transmitted and received at a receiving device. The symbol de-mapper can reduce the number of calculations needed to determine soft values of the bits by limiting the symbols S utilized to calculate the soft values to subsets of the symbols S associated with sectors of symbol rings in the symbol constellation.

Abstract: A digital signal processing (DSP) apparatus can be used to process a serial stream of digital signal samples of a plurality of “n” number of different signals. The DSP apparatus can include a DSP module configured to perform a DSP algorithm on digital signal samples of the signals. The DSP apparatus can have a delay memory with an “n” number of memory cells that each corresponding to one of the signals. The delay memory can also have a digital signal sample input connected to said initial input of said DSP module, a signal-number-in input, a signal-number-out input, and a digital signal sample output connected to said delay input of said DSP module. The delay memory can be configured to store a digital signal sample at the digital signal sample input in a memory cells identified by a signal identifier at said signal-number-in input.

Abstract: Adaptive filtering is used to substantially cancel distortion in radio frequency (RF) signals. Such adaptive filtering can be used in an RF transmitting module to pre-compensate an RF signal with compensation (inverse) distortion to cancel inherent transmission path distortion from the RF signal. Adaptive filtering can also be used in a multi-carrier RF receiving module to cancel from a given carrier signal distortion due to cross talk from adjacent carrier signals. Adaptive filtering in an RF transceiver can be used to cancel from a received RF signal distortion arising from leakage of a transmit signal into the receive path.

Abstract: Stepped radio frequency (RF) reflector antennas are disclosed in which an inner RF reflector is disposed in a central opening of at one or more annular RF reflectors. The RF reflecting surface of the inner RF reflector and the RF reflecting surface(s) of the one or more annular RF reflectors can be shaped and positioned relative to each other to have different focal lengths but nevertheless reflect an RF signal to the same focal plane. The depth of the inventive reflector antenna system can be less than the depth of prior art reflector antennas with a comparable RF aperture.

Abstract: A thin film circuit, particularly desirable for satellite communications, mixes RF and an LO giga-hertz-range input signals to yield an IF signal by splitting the LO and RF signals into two, with a 180 degree phase shift introduced into one of the resulting signals. The LO and RF signals are then each mixed in parallel mixers. The outputs of the mixers have the IF signal with spurious (spur) signals in frequencies that are multiples of the frequencies of the RF or LO signals. The outputs are mixed together so that some of the spur signals cancel each other out and the IF signals are added in phase.

Abstract: A spectral sensing demodulator can include a programmable filter bank and a reconfigurable processor coupled to the programmable filter bank. The programmable filter bank can frequency demultiplex a plurality of frequency division multiplexed channels from a frequency band into a plurality of demultiplexed channels. The reconfigurable processor can include a plurality of reconfigurable resources. Each resource can be alternatively be configured to demodulate a demultiplexed channel and to monitor a demultiplexed channel.

Abstract: A radio frequency (RF) coaxial horn can comprise an inner RF horn disposed inside a larger outer RF horn. An interior surface of the inner horn can comprise a pattern of irregular, aperiodic features that excite modes in first and second RF signals each at a different frequencies that produce substantially Gaussian beam profiles of the first and second signals at the output aperture of the inner horn. The waists of the beam profiles of the first and second signals can be outside the inner horn but inside the outer horn. An interior surface of the outer horn and/or an outer surface of the inner horn can similarly excite modes in a third RF signal at a frequency different than the first and second RF signals to produce a substantially Gaussian beam profile of the third signal at the output aperture of the outer horn. The waist of the beam profile of the third signal can be aligned with the waists of the beam profiles of the first and second signals.

Abstract: Adaptive filtering is used to substantially cancel distortion in radio frequency (RF) signals. Such adaptive filtering can be used in an RF transmitting device to pre-compensate an RF signal with compensation (inverse) distortion to cancel inherent transmission path distortion from the RF signal. Adaptive filtering can also be used in a multi-carrier RF receiving device to cancel from a given carrier signal distortion due to cross talk from adjacent carrier signals. Adaptive filtering in an RF transceiver can be used to cancel from a received RF signal distortion arising from leakage of a transmit signal into the receive path.

Abstract: A conformal lens-reflector antenna system in which a radio frequency (RF) reflector is disposed in a depression in a raised portion of a dielectrical RF lens. The RF reflector can be shaped to reflect RF signals between an RF feed path to the lens and a body of the lens that extends generally laterally away from the raised portion. RF signals having a frequency within a resonant frequency range of the lens can be directed along the RF feed path to the reflector, which can reflect the RF signals into the body of the lens from which the RF signals can radiate. Similarly, RF signals in the resonant frequency range of the lens in space near the lens can resonate in the lens, and the reflector can reflect those signals down the RF feed path.