Spread spectrum radar with leak compensation at baseband
First Claim
1. A radar apparatus, comprising:
- (a) radar signal transmit and receive means for simultaneously transmitting and receiving a modulated continuous wave (CW) signal;
(b) means for generating a transmit code for modulating said CW signal prior to transmission thereof;
(c) means for demodulating said CW signal after reception thereof to provide a received echo of said transmit code at baseband;
(d) means for subtracting an attenuated replica of said transmit code from said received echo at baseband, thereby mitigating signal leakage from transmit to receive paths within said radar apparatus; and
(e) means for correlating a delayed replica of said transmit code with said received echo at baseband after subtraction to provide an intermediate output of said radar apparatus.
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Accused Products
Abstract
A spread spectrum radar system, characterized in that the receive radar signal is mixed down to baseband and applied to leak cancellation means for subtracting therefrom an attenuated delayed version of the transmit radar signal to provide a reflected receive radar signal with improved signal-to-noise ratio for further processing and to prevent receiver saturation. The radar allows the capture of the range and speed of identified targets, and facilitates a determination of the target'"'"'s direction. It exhibits an inherent immunity to electromagnetic interference, and is relatively undetectable by radar detectors. The system is easily reprogrammable for different range resolutions and permits Doppler processing to be independent of the angle between radar signal and the track of the target.
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Citations
16 Claims
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1. A radar apparatus, comprising:
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(a) radar signal transmit and receive means for simultaneously transmitting and receiving a modulated continuous wave (CW) signal;
(b) means for generating a transmit code for modulating said CW signal prior to transmission thereof;
(c) means for demodulating said CW signal after reception thereof to provide a received echo of said transmit code at baseband;
(d) means for subtracting an attenuated replica of said transmit code from said received echo at baseband, thereby mitigating signal leakage from transmit to receive paths within said radar apparatus; and
(e) means for correlating a delayed replica of said transmit code with said received echo at baseband after subtraction to provide an intermediate output of said radar apparatus. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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- 11. A spread spectrum radar system having simultaneously operating transmit and receive paths, characterized in that said system includes means for mixing down received radar signals to baseband and applying them to leak cancellation means for subtracting therefrom an attenuated replica of baseband transmit radar signals to provide reflected receive radar signals with improved signal-to-noise ratio at baseband for further processing, and to prevent saturation of the radar system due to signal leakage from its transmit path into its receive path.
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15. A method of processing reflected received radar signals, comprising the steps of:
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(a) detecting a target induced first Doppler frequency-shift (f1) associated with a first distance range (R1);
(b) detecting a target induced second doppler frequency-shift (f2) associated with a second range (R2); and
(c) computing velocity (V) of the target reflecting said reflected received (d) radar signals from f1, R1, f2, R2 and the wavelength (A) of said radar signals. - View Dependent Claims (16)
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Specification