Time duplex apparatus and method for radar sensor front-ends

• US 7,791,530 B2
• Filed: 01/05/2006
• Issued: 09/07/2010
• Est. Priority Date: 01/05/2006
• Status: Active Grant

• Current Assignee: Magna Electronics LLC (Magna International Incorporated)
• Original Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Inventors: Puglia, Kenneth V.
• Primary Examiner(s): Black; Thomas G
• Assistant Examiner(s): Chen; Shelley
• Application Number:
  US11/327,739
• Publication Number:
  US 20070152871A1
• Time in Patent Office: 1,706 Days
• Field of Search: 342/200
• US Class Current: 342/128
• CPC Class Codes: G01S 13/34 using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
• CPC Class Codes: G01S 13/584 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 7/352 Receivers

Abstract

A radar system and method for determining the range and, optionally, the azimuth of a target, while maintaining a high transmitting duty factor is provided. A waveform generator is connected to an antenna aperture by a transmit-receive switch, and the waveform is transmitted for more than half of the period of time of the sum of the transmission period and the receiving period. For a frequency-modulated continuous-wave waveform (FMCW), the receiver may be turned on for short intervals at a rate which is at least the Nyquist rate for the signal received from at target. A monopulse or frequency-scanned antenna may be used to determine azimuth as well as range.

Claims

1. A radar, comprising:

a waveform generator;

a transmit-receive switch; and

a mixer;

wherein the waveform generator produces a frequency modulated continuous-wave (FMCW) signal;

the transmit-receive switch is in a transmit state for a duration greater than or equal to 95 percent of a sum of a duration of the transmit state and a duration of a receive state; and

an initial sample rate of a received signal is an inverse of a sum of the duration of the transmit state and the receive state, wherein the initial sample rate is greater than twice a differences frequency between an output of the waveform generator and a received signal from a maximum unambiguous range.

2. The radar of claim 1, wherein the FMCW signal has at least one of a positive or a negative time rate of change of frequency.

3. The radar of claim 1, wherein an output of the waveform generator is applied to an input of the mixer for at least a portion of the duration when the transmit-receive switch is in the receive state.

4. The radar of claim 1 wherein an output of the waveform generator is applied to an antenna when the transmit-receive switch is in the transmit state.

5. The radar of claim 1, further comprising a signal amplifier connected to an output of the mixer, wherein the signal amplifier has a frequency selective filter with an output response at one of the sum or difference frequency of the waveform generator and a received signal.

6. The radar of claim 1, wherein the sampled output of the mixer is processed by a signal processor to determine at least a range of a target.

7. The radar of claim 6, wherein the signal processor is adapted to perform a spectral analysis of an output of the frequency selective filter.

8. The radar of claim 1, further comprising:

an antenna assembly.

9. The radar of claim 8, wherein one antenna assembly is used in the transmit state and in the receive state.

10. The radar of claim 8, wherein the antenna assembly is configured to have at least two antenna radiation patterns.

11. The radar of claim 10, wherein the antenna assembly has at least a sum and a difference pattern, the sum pattern connected to the waveform generator during the transmit state, and the sum and the difference pattern connected to the mixer during the receive state.

12. The radar of claim 8, wherein the antenna assembly is configured so that an azimuth of maximum response varies with transmitted frequency.

13. The radar of claim 1, wherein a difference frequency signal is formed between a waveform generator output waveform and the received signal.

14. The radar of claim 13, wherein the duration of the difference frequency signal is determined by the duration of the waveform generator output waveform at an input to a mixer.

15. The radar of claim 13, wherein the difference frequency signal is filtered and is sampled by an analog-to-digital converter.

16. The radar of claim 1, wherein the waveform generator produces a signal that is phase modulated by a pseudo-random (PN) code sequence comprised of chips.

17. The radar of claim 16, wherein a signal processor is adapted to perform a cross-correlation between the pseudo-random (PN) code sequence and an output of the mixer.

18. The radar of claim 16, wherein the output of the mixer communicates with a signal processor, the signal processor determining at least a range of a target.

19. The radar of claim 1, wherein the initial sample rate of the received signal is determined at an output of the mixer.