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GPS receiver apparatus

  • US 4,968,981 A
  • Filed: 10/11/1989
  • Issued: 11/06/1990
  • Est. Priority Date: 10/12/1988
  • Status: Expired due to Term
First Claim
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1. A GPS receiver apparatus for receiving radiowaves from a plurality of GPS satellites and determining a receiving position where said radiowaves are received by the apparatus, and the time thereof, on the basis of pieces of information involved in the received radiowaves, the apparatus comprising:

  • (a) analog-to-digital converting means for converting to a digital signal an analog signal delivered from a radio frequency signal processing means which has received the GPS radiowaves;

    (b) PN code generator means for generating the same PN code as that inherent to radiowaves from any GPS satellite among the plurality of the GPS satellites;

    (c) shift register means for converting the PN code generated in said PN generator means to n PN codes each shifted in their phases by 1/2 bit, and substantially simultaneously delivering those phase-shifted n PN codes;

    (d) signal generator means for generating a first signal of a predetermined frequency and a second signal shifted in its phase by 90°

    from the first signal;

    (e) a plurality of first phase comparators each of said first phase comparators having two input terminals, one of which is connected to an output terminal of said shift register means and the other of which is connected to an output terminal of said analog-to-digital converting means, said first phase comparators comparing said outputs from said shift register means and said analog-to-digital converting means;

    (f) a plurality of second phase comparators connected to said first phase comparators, respectively for receiving outputs of said first phase comparators, and for receiving said first and second signals from said signal generating means;

    (g) a plurality of counters for integrating output signals delivered from said second phase comparators; and

    ,(h) control means for receiving a signal delivered from said plurality of counters and for delivering a control signal for acquiring a GPS satellite signal.

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