Synchronization in FMCW radar systems

Patent metadata

Field	Value
Publication number	US-10649069-B2
Application number	US-201715635659-A
Country	US
Kind code	B2
Filing date	Jun 28, 2017
Priority date	Mar 28, 2014
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

The disclosure provides a radar apparatus for estimating a position and a velocity of the plurality of obstacles. The radar apparatus includes a local oscillator that generates a first signal. A first transmit unit receives the first signal from the local oscillator and generates a first transmit signal. A frequency shifter receives the first signal from the local oscillator and generates a second signal. A second transmit unit receives the second signal and generates a second transmit signal. The frequency shifter provides a frequency offset to the first signal based on a routing delay mismatch to generate the second signal such that the first transmit signal is phase coherent with the second transmit signal.

First claim

What is claimed is:

1. A radar apparatus comprising
a local oscillator configured to generate a first signal;
a first transmit unit configured to receive the first signal from the local oscillator and configured to generate a first transmit signal,
a frequency shifter configured to receive the first signal from the local oscillator and configured to generate a second signal; and
a second transmit unit configured to receive the second signal and configured to generate a second transmit signal, wherein the frequency shifter is configured to provide a frequency offset to the first signal based on a routing delay mismatch to generate the second signal such that the first transmit signal is phase coherent with the second transmit signal.

2. The radar apparatus of claim 1 , wherein the frequency shifter comprises:
a function generator configured to receive a frequency offset value and generates a digital signal;
a digital to analog converter (DAC) coupled to the function generator and configured to generate an analog signal corresponding to the digital signal, and
a mixer configured to multiply the analog signal and the first signal to generate the second signal.

3. The radar apparatus of claim 1 , wherein the first transmit unit comprises:
a first power amplifier coupled to the local oscillator and configured to amplify the first signal to generate the first transmit signal; and
a first transmit antenna unit coupled to the first power amplifier and configured to transmit the first transmit signal received from the first power amplifier.

4. The radar apparatus of claim 3 , wherein the second transmit unit comprises:
a second power amplifier coupled to the frequency shifter and configured to amplify the second signal to generate the second transmit signal; and
a second transmit antenna unit coupled to the second power amplifier and configured to transmit the second transmit signal received from the second power amplifier.

5. The radar apparatus of claim 4 , wherein the routing delay mismatch is estimated from a routing delay from the local oscillator to the first transmit antenna unit, and from a routing delay from the local oscillator to the second transmit antenna unit.

6. The radar apparatus of claim 1 , wherein the first transmit signal and the second transmit signal are scattered by a plurality of obstacles to generate a scattered signal.

7. The radar apparatus of claim 1 further comprising a receive unit, the receive unit comprising:
a receive antenna unit configured to receive the scattered signal;
a low-noise amplifier (LNA) coupled to the receive antenna unit and configured to amplify the scattered signal to generate an amplified scattered signal;
a mixer coupled to the LNA and the local oscillator, the mixer configured to mix the amplified scattered signal and the first signal to generate an IF (intermediate frequency) signal;
an ADC (analog to digital converter) coupled to the mixer and configured to sample the IF signal to generate a sampled data; and
a processor coupled to the ADC and configured to estimate a position and a velocity of the plurality of obstacles from the sampled data.

8. The radar apparatus of claim 1 , wherein the first signal is a ramp segment having a start frequency and a fixed slope.

9. The radar apparatus of claim 8 , wherein the frequency offset is estimated from at least one of the routing delay mismatch and the fixed slope.

10. A method comprising:
generating a first signal;
generating a first transmit signal from the first signal;
providing a frequency offset to the first signal based on a routing delay mismatch to generate a second signal; and
generating a second transmit signal from the second signal, wherein the first transmit signal is phase coherent with the second transmit signal.

11. The method of claim 10 further comprising estimating the routing delay mismatch from a time difference between a time instant when the first signal is generated and a time instant when the first transmit signal is transmitted, and from a time difference between the time instant when the first signal is generated and a time instant when the second transmit signal is transmitted.

12. The method of claim 10 further comprising amplifying the first signal to generate the first transmit signal, and amplifying the second signal to generate the second transmit signal.

13. The method of claim 10 further comprising scattering of the first transmit signal and the second transmit signal by a plurality of obstacles to generate a scattered signal.

14. The method of claim 13 further comprising:
amplifying the scattered signal to generate an amplified scattered signal;
mixing the amplified scattered signal and the first signal to generate an IF (intermediate frequency) signal;
sampling the IF signal to generate a sampled data, and
estimating a position and a velocity of the plurality of obstacles from the sampled data.

15. The method of claim 10 , wherein the first signal is a ramp segment having a start frequency and a fixed slope.

16. The method of claim 15 further comprising estimating the frequency offset from at least one of the routing delay mismatch and the fixed slope.

Assignees

• Texas Instruments Inc

Inventors

• Ramasubramanian Karthik
• Subburaj Karthik
• Bhardwaj Sachin

Classifications

• G01S13/343

  using sawtooth modulation · CPC title

• G01S7/35 Primary

  Details of non-pulse systems · CPC title

• G01S13/726

  Multiple target tracking · CPC title

• G01S2013/0245

  Radar with phased array antenna · CPC title

• G01S13/584

  adapted for simultaneous range and velocity measurements · CPC title