RADAR RECEIVER AND A METHOD FOR PROCESSING RADAR RETURNS

• US 20090295623A1
• Filed: 03/24/2009
• Published: 12/03/2009
• Est. Priority Date: 06/03/2008
• Status: Active Grant

• Current Assignee: Saab AB
• Original Assignee: Saab AB
• Inventors: FALK, Kent
• Granted Patent: US 7,944,392 B2
• Time in Patent Office: Days
• US Class Current: 342/109
• CPC Class Codes: G01S 13/32 using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
• CPC Class Codes: G01S 7/023 Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36
• CPC Class Codes: G01S 7/0234 Avoidance by code multiplex
• CPC Class Codes: G01S 7/352 Receivers
• CPC Class Codes: G01S 7/356 involving particularities of FFT processing
• CPC Class Codes: G01S 7/36 Means for anti-jamming , e.g. ECCM, i.e. electronic counter-counter measures

Abstract

A method for processing received radar returns of a radiated wide-band arbitrary waveform in a wide-band radar processing system using spectral processing. The received wide-band radar returns are undersampled by using a first sampling rate to obtain an undersampled digital wide-band radar waveform. Spectral processing is performed on the power spectrum of the undersampled digital wide-band radar waveform in order to obtain a discrete ripple frequency power spectrum of the undersampled digital wide-band radar waveform. Ripple frequencies indicating radar targets are located in the discrete ripple frequency power spectrum of the undersampled digital wide-band radar waveform. A radar receiver, a digital wide-band radar processing system and a computer program product.

Claims

1. A method for processing received radar returns (u(t)) of a radiated wide-band arbitrary waveform in a wide-band radar processing system using spectral processing, the method comprising:

undersampling said received wide-band radar returns (u(t)) by using a first sampling rate to obtain an undersampled digital wide-band radar waveform (u_ds[n]);

performing spectral processing on the power spectrum of said undersampled digital wide-band radar waveform (|U_ds(ω

_d)|²) in order to obtain a discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)); and

locating, in said discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)), ripple frequencies indicating radar targets.

2. The method according to claim 1, further comprising:

extracting at least a first radar target information based on said located ripple frequencies in said discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)), wherein said first radar target information is distances to said radar targets.

3. The method according to claim 1, wherein said first sampling rate is selected such that it is below a second sampling rate, wherein said second sampling rate is the sampling rate required by the wide-band radar returns in order to fulfill a Nyquist criteria, and such that a folding factor present in said discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)) is stable, so that said ripple frequencies may be located in said discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)).

4. The method according to claim 1, further comprising:

transforming said discrete ripple frequency power spectrum (F_ds(Ω

_d)) into a velocity domain (Ω

_d, V_d)) using the Fourier transform; and

extracting a second radar target information from said discrete ripple frequency power spectrum (F_ds(Ω

_d)) in the velocity domain ((Ω

_d, V_d)).

5. The method according to claim 4, wherein said second radar target information is the velocity (v_d) of said radar targets.

6. The method according to claim 1, wherein the radiated wide-band arbitrary waveform has a flat frequency spectrum.

7. A radar receiver for processing radar returns in a wide-band radar processing system using spectral processing, the radar receiver comprising:

a receiver arranged to receive radar returns (u(t)) of wide-band arbitrary waveforms radiated by a transmitter;

at least one analog to digital converter operating at a first sampling rate arranged to undersample received wide-band radar returns (u(t)) in order to obtain an undersampled digital waveform (u_ds[n]); and

a processor arranged to

perform spectral processing on the power spectrum of said undersampled digital wide-band radar waveform (|U_ds(ω

_d)|²) in order to obtain a discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)), and

locate, in said discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)), ripple frequencies indicating radar targets.

8. The radar receiver according to claim 7, wherein the radar receiver is arranged to extract at least a first radar target information based on said located ripple frequencies in said discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)), wherein said first radar target information is distances to said radar targets.

9. The radar receiver according to claim 7, wherein said first sampling rate of said at least one analog to digital converter is selected such that it is below a second sampling rate, wherein said second sampling rate is the sampling rate required by the wide-band radar returns in order to fulfill the Nyquist criteria, and such that a folding factor present in said discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)) is stable, so that said ripple frequencies remain may be located in said discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)).

10. The radar receiver according to claim 7, wherein said processor is further arranged to:

transform said discrete ripple frequency power spectrum (F_ds(Ω

_d)) into a velocity domain ((Ω

_d, v_d)) using the Fourier transform; and

extract at least a second radar target information from said discrete ripple frequency power spectrum (F_ds(Ω

_d)) in the velocity domain ((Ω

_d, v_d)).

12. A digital wide-band radar processing system, comprising:

a radar receiver comprising

a receiver arranged to receive radar returns (u(t)) of wide-band arbitrary waveforms radiated by a transmitter,

at least one analog to digital converter operating at a first sampling rate arranged to undersample received wide-band radar returns (u(t)) in order to obtain an undersampled digital waveform (u_ds[n]), and

a processor arranged to

perform spectral processing on the power spectrum of said undersampled digital wide-band radar waveform (|U_ds(ω

_d)|²) in order to obtain a discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)), and

locate, in said discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)), ripple frequencies indicating radar targets.

13. A computer program product for use in a radar receiver, said computer program product comprising:

a computer readable medium; and

computer readable code recorded on the computer readable medium and executable by a processor which when run in the radar receiver causes said radar receiver to perform the steps of;

performing spectral processing on the power spectrum of said undersampled digital wide-band radar waveform (|U_ds(ω

_d)|²) in order to obtain a discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)); and

locating, in said discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)), ripple frequencies indicating radar targets.

11. The radar receiver according to claim 13, wherein said second radar target information is the velocity (v_d) of said radar targets.

14. The computer program product for use in a radar receiver according to claim 13, wherein the computer readable code is further for performing the step of:

extracting at least a first radar target information based on said located ripple frequencies in said discrete ripple frequency power spectrum of said undersampled digital wide-band radar waveform (F_ds(Ω

_d)).

15. (canceled)