Pseudorandom-noise receiver having automatic switching between regular and anti-jamming modes
First Claim
1. A spread-spectrum receiver comprising:
- A) input circuitry that receives receiver input signals, processes them, and takes raw samples of the results;
B) digitizing circuitry, alternatively operable in anti-jamming and regular modes, for;
i) deriving sample values from the raw samples by comparing them with quantization thresholds that define quantization intervals into which the samples fall and assigning to them sample values indicative of those quantization intervals in accordance with a regular mapping function when the digitizing circuitry is in the regular mode and in accordance with a different, anti-jamming mapping function when the digitizing circuitry is in the anti-jamming mode; and
ii) generating a sample-value signal that represents sample values thus derived;
C) a pseudorandom-sequence generator that generates a pseudorandom-sequence signal that represents a pseudorandom sequence;
D) a correlator that generates a correlator output signal by performing a correlation operation in accordance with the sample-value and pseudorandom-sequence signals; and
E) mode-control circuitry for automatically switching the digitizing circuitry between its regular and anti-jamming modes.
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Accused Products
Abstract
A receiver for pseudorandom noise (PRN) encoded signals consisting of a sampling circuit, multiple carrier and code synchronizing circuits, and multiple digital autocorrelators. The sampling circuit provides digital samples of a received composite signal to each of the several receiver channel circuits. The synchronizing circuits are preferably non-coherent, in the sense that they track any phase shifts in the received signal and adjust the frequency and phase of a locally generated carrier reference signal accordingly, even in the presence of Doppler or ionospheric distortion. The antocorrelators in each channel form a delay lock loop (DLL) which correlates the digital samples of the composite signal with locally generated PRN code values to produce a plurality of (early, late), or (punctual, early-minus-late) correlation signals. The time delay spacing between the (early, late), and (punctual, early-minus-late) correlation signals are dynamically adjusted, such that in an initial acquisition mode, the delay spacing is relatively wide, on the order of approximately one PRN code chip time; once PRN code lock is achieved, the code delay spacing is narrowed to a fraction of a PRN code chip time.
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Citations
16 Claims
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1. A spread-spectrum receiver comprising:
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A) input circuitry that receives receiver input signals, processes them, and takes raw samples of the results; B) digitizing circuitry, alternatively operable in anti-jamming and regular modes, for; i) deriving sample values from the raw samples by comparing them with quantization thresholds that define quantization intervals into which the samples fall and assigning to them sample values indicative of those quantization intervals in accordance with a regular mapping function when the digitizing circuitry is in the regular mode and in accordance with a different, anti-jamming mapping function when the digitizing circuitry is in the anti-jamming mode; and ii) generating a sample-value signal that represents sample values thus derived; C) a pseudorandom-sequence generator that generates a pseudorandom-sequence signal that represents a pseudorandom sequence; D) a correlator that generates a correlator output signal by performing a correlation operation in accordance with the sample-value and pseudorandom-sequence signals; and E) mode-control circuitry for automatically switching the digitizing circuitry between its regular and anti-jamming modes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A spread-spectrum receiver comprising:
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A) input circuitry that receives receiver input signals, processes them, and takes raw samples of the results; B) digitizing circuitry for; i) deriving sample values from the raw samples by comparing them with quantization thresholds that define quantization intervals into which the samples fall and assigning to them sample values indicative of those quantization intervals in accordance with a mapping function; and ii) generating a sample-value signal that represents sample values thus derived; C) level circuitry, operable in regular and anti-jamming modes, for maintaining a regular relationship between the magnitudes of the samples and the quantization thresholds when the level circuitry is in the regular mode and maintaining a different, anti-jamming relationship between the magnitudes of the samples and the quantization thresholds when the level circuitry is in the anti-jamming mode; D) a pseudorandom-sequence generator that generates a pseudorandom-sequence signal that represents a pseudorandom sequence; E) a correlator that generates a correlator output signal by performing a correlation operation in accordance with the sample-value and pseudorandom-sequence signals; and F) mode-control circuitry for automatically switching the level circuitry between its regular and anti-jamming modes. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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Specification