Importance

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Abstract

There is disclosed a high frequency communication system of the type employing a high frequency terminal which terminal can transmit a processed signal in a transmitting mode or process a received signal in a receiving mode which terminal includes a first subsystem for voice processing, including a processor responsive to voice signals to provide a linear predictive coded voice signal at a given data rate which signal is coupled to a data modem subsystem that digitally encrypts said voice signal which data modem subsystem is coupled to a modem processor subsystem capable of processing said encrypted signal for providing frequency hopping, feedback equalization, intersymbol interference cancellation, error correction and interleaving to provide a transmitted signal which is relatively immune to jamming during said transmitting mode which includes a convolutional encoder means included in said modem processor subsystem responsive to said encrypted signal to provide a convoluted signal at a higher data rate than said encrypted signal at an output. There is an interleave buffer having an input coupled to said encoder outputs for interleaving said higher data rate signal according to an interleaving algorithm, a symbol encoder having one input responsive to said interleave signal and one input coupled to a source of PN training signals as stored to provide at an output an encoded signal encoded according to said PN signal which PN training signal differs for each transmitting frequency. This signal is then converted to an analog signal and eventually coupled to a transmitting means for transmitting said signal. The apparatus also contains receiver means which operate to employ improved equalization for a received signal according to said PN training signal blocks.

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First Claim