Target detection method and device for wideband unambiguous pulse Doppler radar
First Claim
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1. A method for detecting a target with a wideband Doppler radar, comprising the steps of:
- transmitting a burst of N coherent pulses with a low pulse repetition frequency,a wideband of said N coherent pulses corresponding with a high range resolution δ
R, which is a measure of radar range bin width,a pulse repetition period and pulse burst duration of said N coherent pulses being restricted such that a migration in target distance, as represented by a progression in range of an observed target echo between a first and a last repetition of said burst, is greater than the radar range bin width, for a target having a speed equal to an ambiguous speed detectable by the Doppler radar;
receiving and sampling a return signal;
searching samples of the return signal corresponding to each repetition period of said burst of N coherent pulses for each radar range bin and each speed hypothesis of a real speed of the target;
Doppler analyzing the samples for each radar range bin and speed hypothesis and obtaining N signal values corresponding with a fine target speed value having a greater resolution than each of the speed hypotheses; and
extracting information elements on each detected targetfrom a rank of a range bin corresponding with a distance of the target, andfrom the fine target speed value of the Doppler analyzing step and a corresponding speed hypothesis that gives an unambiguous speed of the target.
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Abstract
Coherent bursts of N wideband, low repetition frequency width-modulated pulses are transmitted, and they are received with pulse compression and then sampling. For each range gate and each speed hypothesis, a selection is made of the corresponding samples of N repetitions of a burst after compensation for the migration in distance. On each set of N samples, for a given speed hypothesis, a Fourier transform and a threshold-setting operation are performed. The distance and the unambiguous speed of the detected targets are then extracted.
28 Citations
8 Claims
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1. A method for detecting a target with a wideband Doppler radar, comprising the steps of:
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transmitting a burst of N coherent pulses with a low pulse repetition frequency, a wideband of said N coherent pulses corresponding with a high range resolution δ
R, which is a measure of radar range bin width,a pulse repetition period and pulse burst duration of said N coherent pulses being restricted such that a migration in target distance, as represented by a progression in range of an observed target echo between a first and a last repetition of said burst, is greater than the radar range bin width, for a target having a speed equal to an ambiguous speed detectable by the Doppler radar; receiving and sampling a return signal; searching samples of the return signal corresponding to each repetition period of said burst of N coherent pulses for each radar range bin and each speed hypothesis of a real speed of the target; Doppler analyzing the samples for each radar range bin and speed hypothesis and obtaining N signal values corresponding with a fine target speed value having a greater resolution than each of the speed hypotheses; and extracting information elements on each detected target from a rank of a range bin corresponding with a distance of the target, and from the fine target speed value of the Doppler analyzing step and a corresponding speed hypothesis that gives an unambiguous speed of the target. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A wideband Doppler radar for detecting a target, comprising:
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means for transmitting a burst of N coherent pulses, including means for transmitting and receiving said N coherent pulses corresponding with a high range resolution δ
R, δ
R being a measure of radar range bin width, andmeans for restricting a pulse repetition period and pulse burst duration of said N coherent pulses such that a migration in target distance, as represented by a progression in range of an observed target echo between a first and a last repetition of said burst, is greater than the radar range bin width δ
R, for a target having a speed equal to an ambiguous speed detectable by the Doppler radar;means receiving and sampling a return signal; means for searching samples of the return signal corresponding to each repetition period of said burst of N coherent pulses for each radar range bin and each speed hypothesis of a real speed of the target; means for performing a Fourier transform on the samples selected by the means for searching so as to obtain a fine speed value; means for comparing the fine speed value with a predetermined threshold and for detecting a presence of the target; and means for extracting information on distance and unambiguous real speed of each detected target after detecting said presence of the target.
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Specification