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HF high data rate modem

  • US 5,097,485 A
  • Filed: 10/10/1989
  • Issued: 03/17/1992
  • Est. Priority Date: 10/10/1989
  • Status: Expired due to Term
First Claim
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1. A high frequency modem comprising:

  • a transmitter comprising (a) phase generator means for processing digital words that comprise data that is to be transmitted and for converting the digital words into a series of corresponding phase encoded digital signals, each successive phase encoded digital signal having a phase relationship with respect to the preceding phase encoded signal such that the currently processed signal has its phase component incremented by the phase value of the preceding processed digital word; and

    (b) digital synthesizing means coupled to the phase generator means for processing the phase encoded signals and generating a series of digital signals that have individual frequencies randomly selected from a predetermined set of frequencies, and whose respective phases correspond to the phases of the respective phase encoded signals, and wherein the frequency dwell time is significantly less than the multipath differential times of arrival, and such that further occurrences of the same frequency occur no more frequently than the maximum multipath differential times of arrival; and

    a receiver comprising demodulation means for demodulating the frequency hopped, digital phase shift keying signals and providing digital words which comprise the information transmitted by the transmitter.

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