Quadrature self-injection-locked radar

Patent metadata

Field	Value
Publication number	US-10281561-B2
Application number	US-201715491406-A
Country	US
Kind code	B2
Filing date	Apr 19, 2017
Priority date	Feb 7, 2017
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

A quadrature self-injection-locked radar utilizes a phase shifter to make a oscillation signal operating in two phase modes, and utilizes a frequency demodulator for frequency demodulation and a signal processor for signal processing to eliminate the nonlinear distortion caused by self-injection locked phenomenon. Therefore, the self-injection locked radar can be applied to more cases for detecting displacement variations with any range.

First claim

What is claimed is:

1. A quadrature self-injection-locked radar comprising:
a self-injection-locked (SIL) loop including a voltage-controlled oscillator (VCO), a phase shifter and a transceiver antenna, wherein the VCO outputs an oscillation signal, the phase shifter adjusts a phase of the oscillation signal to operate in two phase modes, and the transceiver antenna radiates the oscillation signal to a subject, wherein the oscillation signal reflected from the subject is received by the transceiver antenna and transmitted to the VCO for bringing the VCO to a self-injection-locked (SIL) state to generate a first self-injection-locked (SIL) signal and a second self-injection-locked (SIL) signal;
a frequency demodulator for receiving the first and second SIL signals, wherein the frequency demodulator demodulates the first and second SIL signals in frequency to obtain a first frequency demodulation signal and a second frequency demodulation signal; and
a signal processor for receiving and computing the first and second frequency demodulation signals to obtain a displacement signal of the subject.

2. The quadrature self-injection-locked radar in accordance with claim 1 , wherein the VCO includes a signal output port and a signal injection port, and the transceiver antenna includes a transmit antenna and a receive antenna, wherein the signal output port is electrically connected with the frequency demodulator and the transmit antenna, the signal injection port is electrically connected with the phase shifter, and the phase shifter is electrically connected with the receive antenna, and wherein the oscillation signal reflected from the subject is received by the receive antenna, phase-shifted by the phase shifter and then transmitted to the signal injection port of the VCO for bringing the VCO to the SIL state.

3. The quadrature self-injection-locked radar in accordance with claim 2 , wherein the phase shifter shifts the phase of the oscillation signal with 90° in one phase mode and shifts the phase of the oscillation signal with 0° in the other phase mode for the oscillation signal comprising 90° phase difference between the two phase modes.

4. The quadrature self-injection-locked radar in accordance with claim 1 , wherein the VCO includes a signal output port and a signal injection port, and the transceiver antenna includes a transmit antenna and a receive antenna, wherein the signal output port is electrically connected with the frequency demodulator and the phase shifter, and the signal injection port is electrically connected with the receive antenna, and wherein the oscillation signal reflected from the subject is phase-shifted by the phase shifter and then transmitted to the transmit antenna.

5. The quadrature self-injection-locked radar in accordance with claim 3 , wherein the phase shifter shifts the phase of the oscillation signal with 90° in one phase mode and shifts the phase of the oscillation signal with 0° in the other phase mode for the oscillation signal comprising 90° phase difference between the two phase modes.

6. The quadrature self-injection-locked radar in accordance with claim 1 , wherein the VCO includes a signal output port electrically connected with the frequency demodulator and a signal output/injection port electrically connected with the phase shifter, and wherein the oscillation signal output from the VCO is phase-shifted by the phase shifter and then transmitted to the transceiver antenna, and the reflected oscillation signal is received by the receive antenna, phase-shifted by the phase shifter and then transmitted to the signal output/injection port of the VCO for bringing the VCO to the SIL state.

7. The quadrature self-injection-locked radar in accordance with claim 6 , wherein the phase shifter shifts the phase of the oscillation signal with 45° in one phase mode and shifts the phase of the oscillation signal with 0° in the other phase mode for the oscillation signal comprising 90° phase difference between the two phase modes.

8. The quadrature self-injection-locked radar in accordance with claim 1 , wherein the frequency demodulator includes a delay element, a quadrature power splitter with a 0° output end and a 90° output end, a first mixer and a second mixer, wherein the delay element and the quadrature power splitter are electrically connected with the SIL loop, the first mixer is electrically connected with the delay element and the 0° output end of the quadrature power splitter, and the second mixer is electrically connected with the delay element and the 90° output end of the quadrature power splitter, and wherein the first mixer outputs a first mixing signal, the second mixer outputs a second mixing signal, and the signal processor receives the first and second mixing signals.

9. The quadrature self-injection-locked radar in accordance with claim 8 , wherein the frequency demodulator further includes a first low-pass filter (LPF) electrically connected with the first mixer and a second low-pass filter electrically connected with the second mixer, and wherein the first mixing signal is transmitted to the signal processor through the first LPF, and the second mixing signal is transmitted to the signal processor through the second LPF.

10. The quadrature self-injection-locked radar in accordance with claim 1 , wherein the signal processor demodulates the first and second frequency demodulation signals by an arctangent demodulation to obtain a demodulation signal.

11. The quadrature self-injection-locked radar in accordance with claim 10 , wherein the arctangent demodulation is presented as formula 1, and S demod (t) is the demodulation signal, S BB,0 (t) is the first frequency demodulation signal, S BB,90 (t) is the second frequency demodulation signal, and α d (t) is a phase variation caused by the displacement of the subject.

S
demod

⁡

(
t
)

=

tan

-
1

⁢

-

S

BB
,
0

⁡

(
t
)

S

BB
,
90

⁡

(
t
)

Assignees

• National Sun Yat Sen University

Inventors

• Wang fu-kang
• Horng Tzyy-Sheng
• Tang Mu-Cyun

Classifications

• G01S7/352 Primary

  Receivers · CPC title

• G01S13/32

  using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated · CPC title

• G01S13/584

  adapted for simultaneous range and velocity measurements · CPC title

• H03L7/24

  using a reference signal directly applied to the generator · CPC title

• G01S2007/358

  Physics · mapped topic