Abstract: The interference detection and characterization system of this invention supports modern communication systems which have to contend with a variety of intentional and unintentional interference souces. As an add-on to existing communications equipment, the invention employs novel signal processing techniques to automatically detect the presence of communications channel irregularities in near real-time and alert the attending operator. Information provided to the operator through a user-friendly interface is used to characterize the type of interference and its degree of severity. Once characterized, the information is used by the operator to take corrective actions including the activation of alternative communication plans or, in some instances, mitigation of the interference. Since output from the system of this invention lends itself well to expert system and neural network environments, such systems could be employed to further aid the operator.

Abstract: A demodulator apparatus for demodulating a data bearing broadcast signal in the absence of mixers and without incurring quantization errors. The apparatus incorporates a receiver for receiving a broadcast signal and producing therefrom a predetermined intermediate carrier frequency (F.sub.IF), transversal filter connected to receive the intermediate carrier frequency F.sub.IF has N active stages and tap weight means at each of said stages for entering a tap weight sequence to yield maximum correlation energy when desired alignment occurs to thereby make phase and frequency agreement between local timing and the received signal, and the frequency F.sub.IF is sampled at a clock rate (F.sub.s) of: ##EQU1## wherein F.sub.IF is the intermediate frequency and K is a scaling factor which is related to the number of carrier cycles per stage, the transversal filter includes a charge coupled device having the N active stages.

Abstract: A precise ranging and timing system using pseudo-noise bandwidth synthesis to provide precise orbit determination for geosynchronous and low earth orbit satellites, navigation of low earth orbiting satellite through signals transmitted through geosynchronous satellites and precise time-transfer. The system includes a novel signal structure which is comprised of disjoint, narrow band, spectral components spread over a wide bandwidth. The number of spectral components, their individual bandwidths, and their specific spectral locations over the end-to-end spread bandwidth determine the ultimate capabilities and performance achievable.

Abstract: Decoding performance of threshold-decodable forward-error-correcting codes is improved through the use of three methods. These methods employ measurements of received-digit reliability, and extended examination of syndrome digits. The first disclosed method allows correction of most partially-masked channel errors. These errors are not corrected in the prior art. The second and third disclosed methods correct almost all channel correctable with prior art, but furthermore disable action by the decoder in most cases where prior art would erroneously alter an information digit that had been received correctly.