Correlation system for pseudo-random noise signals
First Claim
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1. A system for correlation of a first coded digital signal having a clock frequency with an identical coded digital signal of unknown time delay which is bi-phase modulated on a suppressed carrier signal, without recovery of the suppressed carrier signal, comprising:
- means for inverting alternate bits of the first coded digital signal for providing a PN* signal having a frequency component at one-half the clock frequency of the first coded signal;
means for generating an estimated carrier signal;
means for modulating said estimated carrier signal with said PN* signal;
means for mixing said modulated signal with the identical coded signal of unknown time delay;
means for squaring said mixed signal for providing a coded signal having a clock frequency equal to the clock frequency of the first coded signal; and
means for controlling the phase of the first coded signal with said squared signal for correlating the first coded signal with the identical coded signal of unknown time delay.
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Abstract
An improved correlation system for coded signals wherein a signal is known in pattern but is unknown in timing and is bi-phase modulated on a suppressed carrier signal and correlation is accomplished with a time reference signal without the necessity for search and coherent recovery of the suppressed carrier signal.
46 Citations
18 Claims
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1. A system for correlation of a first coded digital signal having a clock frequency with an identical coded digital signal of unknown time delay which is bi-phase modulated on a suppressed carrier signal, without recovery of the suppressed carrier signal, comprising:
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means for inverting alternate bits of the first coded digital signal for providing a PN* signal having a frequency component at one-half the clock frequency of the first coded signal; means for generating an estimated carrier signal; means for modulating said estimated carrier signal with said PN* signal; means for mixing said modulated signal with the identical coded signal of unknown time delay; means for squaring said mixed signal for providing a coded signal having a clock frequency equal to the clock frequency of the first coded signal; and means for controlling the phase of the first coded signal with said squared signal for correlating the first coded signal with the identical coded signal of unknown time delay. - View Dependent Claims (2, 3, 4, 5)
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6. A system for correlation of a first coded digital signal having a clock frequency with an identical coded digital signal of unknown time delay which is bi-phase modulated on a suppressed carrier signal, without recovery of the suppressed carrier signal, comprising:
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means for converting the first coded digital signal for providing a modified coded digital signal having a frequency component at one-half the clock frequency of the first coded digital signal; means for combining said modified coded digital signal with said coded digital signal of unknown time delay; means for squaring said combined modified coded digital signal and coded signal of unknown time delay for providing a combined signal having a frequency component at the clock frequency; and means for controlling the phase delay of the first coded digital signal with said squared signal for correlating the first coded digital signal with the coded digital signal of unknown time delay. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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14. A method for correlating a first coded digital signal having a clock frequency with an identical coded digital signal of unknown time delay which is bi-phase modulated on a suppressed carrier signal, without the necessity for recovery of the suppressed carrier signal, comprising the steps of:
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converting the first coded digital signal to a modified coded digital signal haivng a frequency component at one-half the clock frequency of the first coded digital signal; combining said modified coded digital signal with the coded digital signal of unknown time delay; squaring said combined signal to provide a combined signal having a frequency component at the clock frequency; and controlling the phase delay of the first coded digital signal with said squared signal for correlating the first coded digital signal with the coded digital signal of unknown time delay. - View Dependent Claims (15, 16, 17, 18)
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Specification