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Delay-locked loop circuit in spread spectrum receiver

  • US 5,062,122 A
  • Filed: 09/28/1988
  • Issued: 10/29/1991
  • Est. Priority Date: 09/28/1988
  • Status: Expired due to Term
First Claim
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1. Spread spectrum receiver including a terminal for a received spread spectrum signal and a delay locked loop circuit for holding the synchronization of a despread signal with the received spread spectrum signal, the circuit comprising:

  • a voltage control oscillator for generating a clock signal;

    a despread signal generator controlled by said clock signal for generating a first despread signal and second despread signal, the first despread signal being shifted in phase by one bit to the second despread signal;

    first correlation means for producing a first signal representative of a correlation of the received spread spectrum signal with the first despread signal;

    second correlation means for generating a second signal representative of a correlation of the received spread spectrum signal with the second despread signal;

    a subtracter for generating a signal representative of a subtraction between said first and second correlation representative signals;

    a positive feedback amplifier for amplifying said subtraction representative signal which is applied to said voltage control oscillator as a control signal; and

    a window comparator with a predetermined window width for in response to the subtraction representative signal for producing a lock signal when the subtraction representative signal is positioned within the window width and an unlock signal when outside the window width.

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