Abstract: A method for decoding forward error correction (FEC) encoded data. A stream of units of FEC encoded bits are received, where the units are derived from a transmitted signal, where each unit represents a one-bit data value, and where each unit includes correctness bits. Preferably, the stream of units of FEC encoded bits are decoded by using the quality level of bits to perform soft-decision convolution decoding on the stream of units of FEC bits, where the soft-decision convolution decoding produces, for block decoding, a stream of symbols made up of bits. Subsequences of units that are prone to erroneous soft-decision convolution decoding are detected by determining, for the sub-sequences whether the distribution of quality bits indicate the units are below a threshold level of correctness, and by comparing characteristics of that distribution to a given set of characteristics predetermined to be prone to result in incorrect decoding.

Abstract: A bit quality evaluator receives a sequence of bits. The bit sequence is provided to a decoding device that performs soft decision convolutional decoding on the sequence of bits. An off track event detector detects an occurrence of a trellis decode path change during the convolutional decoding operation and identifies a first symbol proximate corresponding to the occurrence of the trellis decode path change. An erasure decision circuit identifies at least the first symbol for erasure. The output of the first decoder and the erasure decision circuit are received at a second decoder, which decoder decodes the output of the first decoder after erasing at least the first symbol. The erasure decision circuit may also identify additional symbols for erasure using performance measures of the trellis decode path and using quality measures of the sequence of bits.

Abstract: A wideband receiver comprises a comb limiter combiner wherein the limiting is conducted by digitization and frequency excision in the frequency domain. The received signal is divided up into sub-bands by a bank of bandpass filters having contiguous pass bands spanning the entire receiver range. In each sub-band the band limited signal is digitized and subjected to digital signal processing. A threshold is set such that any frequency with a magnitude that exceeds the threshold is excised in the frequency domain. When converted back to the time domain, the high-power interference frequencies will no longer be present, thereby leaving only the low-power noise and the desired signal.

Abstract: A bit quality evaluator receives a sequence of bits. A quality measure is assigned to each bit within the sequence. The bit sequence and the quality measures are provided to a decoding device that performs soft decision convolutional decoding on the sequence of bits using the quality measure. An off-path detector detects an occurrence of a trellis decode path change during the convolutional decoding operation and identifies a first symbol proximate corresponding to the occurrence of the trellis decode path change. An erasure decision circuit identifies at least the first symbol for erasure. The output of the first decoder and the erasure decision circuit are received at a second decoder, which decoder decodes the output of the first decoder after erasing at least the first symbol. The erasure decision circuit may also identify additional symbols for erasure based on performance measures of the trellis decode path and the quality measure of the sequence of bits.

Abstract: A comb limiter combiner for front end filtering reduces bit error rates with an increased reception range. Notch filters are tuned to suppress interfering frequency-hopped signals. An output comb filter suppresses out-of-band intermodulation products generated by any non-linear devices (such as limiters and the notch filters) in each of the comb limiter combiner sub-bands. Sensitivity is further increased by the use of cryogenically cooled high temperature superconductor components for the filters, amplifiers, and limiters used in each sub-band.

Abstract: A method for decoding forward error correction (FEC) encoded data. A stream of units of FEC encoded bits are received, where the units are derived from a transmitted signal, where each unit represents a one-bit data value, and where each unit includes correctness bits. Preferably, the stream of units of FEC encoded bits are decoded by using the quality level of bits to perform soft-decision convolution decoding on the stream of units of FEC bits, where the soft-decision convolution decoding produces, for block decoding, a stream of symbols made up of bits. Subsequences of units that are prone to erroneous soft-decision convolution decoding are detected by determining, for the sub-sequences whether the distribution of quality bits indicate the units are below a threshold level of correctness, and by comparing characteristics of that distribution to a given set of characteristics predetermined to be prone to result in incorrect decoding.

Abstract: A method for decoding forward error correction (FEC) encoded data. A stream of units of FEC encoded bits are received, where the units are derived from a transmitted signal, where each unit represents a one-bit data value, and where each unit includes correctness bits. Preferably, the stream of units of FEC encoded bits are decoded by using the quality level of bits to perform soft-decision convolution decoding on the stream of units of FEC bits, where the soft-decision convolution decoding produces, for block decoding, a stream of symbols made up of bits. Subsequences of units that are prone to erroneous soft-decision convolution decoding are detected by determining, for the sub-sequences whether the distribution of quality bits indicate the units are below a threshold level of correctness, and by comparing characteristics of that distribution to a given set of characteristics predetermined to be prone to result in incorrect decoding.

Abstract: A wideband receiver comprises a comb limiter combiner wherein the limiting is conducted by digitization and frequency excision in the frequency domain. The received signal is divided up into sub-bands by a bank of bandpass filters having contiguous pass bands spanning the entire receiver range. In each sub-band the band limited signal is digitized and subjected to digital signal processing. A threshold is set such that any frequency with a magnitude that exceeds the threshold is excised in the frequency domain. When converted back to the time domain, the high-power interference frequencies will no longer be present, thereby leaving only the low-power noise and the desired signal.

Abstract: A comb limiter combiner for front end filtering reduces bit error rates with an increased reception range. Notch filters are tuned to suppress interfering frequency-hopped signals. An output comb filter suppresses out-of-band intermodulation products generated by any non-linear devices (such as limiters and the notch filters) in each of the comb limiter combiner sub-bands. Sensitivity is further increased by the use of cryogenically cooled high temperature superconductor components for the filters, amplifiers, and limiters used in each sub-band.

Abstract: Units of forward error correction (FEC) encoded bits each represent a one-bit data value and include correctness bits that together reflect a probability that the one-bit data value represented by the unit is correct. The units of FEC encoded bits are decoded by using the correctness bits to perform soft-decision convolution decoding on the units of FEC bits. Block code symbols that are prone to having been erroneously decoded via soft-decision convolution decoding are identified by determining whether the convolutional decoder “changes its mind” as indicated by a trellis decode path change during the convolutional decoding such that the last state of a lowest cost path after the path change does not agree with the penultimate state of a lowest cost path immediately prior to the path change. Such a path change indicates that the data input to the convolutional decoder is so corrupted so as to be substantially unlikely to be correctly decoded by the convolutional decoder.

Abstract: Units of forward error correction (FEC) encoded bits each represent a one-bit data value and include correctness bits that together reflect a probability that the one-bit data value represented by the unit is correct. The units of FEC encoded bits are decoded by using the correctness bits to perform soft-decision convolution decoding on the units of FEC bits. Block code symbols that are prone to having been erroneously decoded via soft-decision convolution decoding are identified by determining whether the convolutional decoder “changes its mind” as indicated by a trellis decode path change during the convolutional decoding such that the last state of a lowest cost path after the path change does not agree with the penultimate state of a lowest cost path immediately prior to the path change. Such a path change indicates that the data input to the convolutional decoder is so corrupted so as to be substantially unlikely to be correctly decoded by the convolutional decoder.

Abstract: A method for decoding forward error correction (FEC) encoded data. A stream of units of FEC encoded bits are received, where the units are derived from a transmitted signal, where each unit represents a one-bit data value, and where each unit includes correctness bits. Preferably, the stream of units of FEC encoded bits are decoded by using the quality level of bits to perform soft-decision convolution decoding on the stream of units of FEC bits, where the soft-decision convolution decoding produces, for block decoding, a stream of symbols made up of bits. Subsequences of units that are prone to erroneous soft-decision convolution decoding are detected by determining, for the sub-sequences whether the distribution of quality bits indicate the units are below a threshold level of correctness, and by comparing characteristics of that distribution to a given set of characteristics predetermined to be prone to result in incorrect decoding.

Abstract: A method and apparatus for decoding forward error correction (FEC) encoded data. A stream of units of FEC encoded bits are received, where the units are derived from a transmitted signal, where each unit represents a one-bit data value, and where each unit includes correctness bits that together reflect a level of probability that the one-bit data value represented by the unit differs from corresponding bits in the signal before it was transmitted. The stream of units of FEC encoded bits are decoded by using the quality level of bits to perform soft-decision convolution decoding on the stream of units of FEC bits, where the soft-decision convolution decoding produces, for block decoding, a stream of symbols made up of bits.

Abstract: A comb limiter combiner for frequency-hopped communications includes an input signal coupler for coupling to a receiving antenna and distributing the antenna signal to a bank of input bandpass filters. The input bandpass filters have contiguous passbands that comprise the total receiver bandwidth. Each input bandpass filter is connected to a limiter having a threshold substantially equal to the limiting threshold of the receiver. Each limiter is connected to an output bandpass filter similar to the corresponding input bandpass filter to remove out-of-band intermodulation products generated by the limiter. The bank of output bandpass filters is connected to an output signal coupler for coupling to the front end of the receiver.

Abstract: The present invention is a Comb linear amplifier combiner (CLAC) apparatus that allows one or more transmitters to transmit through one transmit antenna. The CLAC apparatus passes low powered transmit signals through a bank of bandpass filters. The transmit signals then pass through Class A amplifiers which amplify the transmit signals to the full transmit power. The full transmit power signals then pass through a second bank of bandpass filters. The transmission signals are then transmitted through a single transmission antenna.