Method for evaluating similarity of signals having a carrier frequency offset
First Claim
1. An apparatus for evaluating the similarity of multi-mode radar signals detected by a passive receiver said apparatus comprising a means to determine the differential phase of pairs of received signals, one signal of each pair being a currently received signal and the other a previously received signal, and means for fitting a straight line to the differential phase of pairs of signals wherein the slope of the line gives the frequency offset between signals and the mean square error between the actual phase-time data and the straight lines indicates the similarity of the signals.
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Abstract
A method and apparatus for evaluating the similarity of multi-mode radar pulses detected by a passive ESM receiver. The method consists of fitting a straight line to the differential phase of pairs of received signals, one signal of a pair being a currently received signal pulse and the other a previously received signal pulse, by a best least squares fit method. The slope of that straight line gives the frequency offset between the signals and the mean square error between the actual phase-time data and the straight line indicates the similarity of the signals. A second measure of the similarity of the signals can be obtained by applying statistical tests for serial correlation in the difference between the phase-time data and the straight line.
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Citations
21 Claims
- 1. An apparatus for evaluating the similarity of multi-mode radar signals detected by a passive receiver said apparatus comprising a means to determine the differential phase of pairs of received signals, one signal of each pair being a currently received signal and the other a previously received signal, and means for fitting a straight line to the differential phase of pairs of signals wherein the slope of the line gives the frequency offset between signals and the mean square error between the actual phase-time data and the straight lines indicates the similarity of the signals.
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3. An apparatus for evaluating the similarity of multi-mode radar signals detected by a receiver comprising:
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(1) means for estimation of the differential phase between two complex baseband radar signals detected by the receiver; (2) means for providing a least squares estimation of carrier frequency offset Δ
fc between detected signals from said estimation of the differential phase and a weighting parameter Ψ
(nT); and(3) means for determining a cost function C from said estimation of the differential phase between the signals, their frequency offset Δ
fc and the weighting parameter Ψ
(nT), wherein C is a measure of the similarity between pairs of signals. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 20, 21)
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18. An apparatus for evaluating the similarity of multi-mode radar signals detected by a receiver wherein an antenna for receiving radar signals is connected to the receiver which has a tuner for received signals and a demodulator for those signals with at least one analog-to-digital converter providing digitized in-phase and quadrature signal data of received radar signals, the apparatus comprising:
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(1) a buffer memory to which the digitized in-phase and quadrature signal data is directed, that data being also applied to an endpointing and thresholding circuit that determines sequences of signal samples corresponding to individual pulses which is applied to the buffer memory where the received digitized signal data is stored; (2) the memory being connected to a phase estimation processor which provides an estimation of the differential phase between pairs of signals from the memory, outputs of the phase estimation processor being directed to at least one analysis processor with (3) said at least one analysis processor providing a least squares estimation of carrier frequency offset Δ
fc that is forwarded to at least one statistical analysis processor which determines a cost function C providing a measure of the similarity of modulation between pairs of signals. - View Dependent Claims (19)
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Specification