FM-CW radar and method of generating FM-CW signal

Patent metadata

Field	Value
Publication number	US-10520596-B2
Application number	US-201515549477-A
Country	US
Kind code	B2
Filing date	Feb 19, 2015
Priority date	Feb 19, 2015
Publication date	Dec 31, 2019
Grant date	Dec 31, 2019

Abstract

An FM-CW radar includes a high frequency circuit that receives a reflected wave from a target, and a signal processing unit that converts an analog signal generated by the high frequency circuit into a digital signal and detects at least a distance to the target and velocity of the target. The high frequency circuit includes a VCO that receives a modulation voltage from the signal processing unit and generates a frequency-modulated high frequency signal. The signal processing unit includes an LUT that stores default modulation control data. The signal processing unit calculates frequency information from phase information of output of the VCO, and updates the data stored in the LUT with correction data that is generated by using a result of the calculation.

First claim

The invention claimed is:

1. An FM-CW (frequency modulated continuous waves) radar using frequency modulation based on an FM-CW scheme, the FM-CW radar comprising:
high frequency circuitry configured to receive a reflected wave from a target; and
signal processing circuitry configured to convert an analog signal generated by the high frequency circuitry into a digital signal and detect at least a distance to the target and velocity of the target, wherein
the high frequency circuitry includes a voltage control oscillator to generate a frequency-modulated high frequency signal by receiving a modulation voltage from the signal processing circuitry,
the signal processing circuitry includes a look up table to store default modulation control data, and
the signal processing circuitry updates data stored in the look up table in response to change to characteristics of the voltage control oscillator with correction data that is generated by fixing a voltage increment and varying a time increment with use of frequency information calculated from phase information of an output of the voltage control oscillator, wherein

the corrected modulation control data causes the voltage control oscillator to generate a linear frequency-modulated high frequency signal.

2. The FM-CW radar according to claim 1 , wherein the FM-CW radar does not transmit an FM-CW signal until a first round of updating the look up table is completed by calculating the frequency information and performing correction processing.

3. The FM-CW radar according to claim 1 , wherein the signal processing circuitry uses a polynomial approximation to correct the frequency information calculated by phase calculation.

4. The FM-CW radar according to claim 3 , wherein the signal processing circuitry calculates, as an error, a difference along a time axis between data of the frequency information being calculated and waveform data of an ideal frequency line, and uses the calculated error to perform a correction along the time axis by using the calculated error and changing the time increment set to an integer multiple of the minimum time resolution of the signal processing circuitry.

5. The FM-CW radar according to claim 2 , wherein the signal processing circuitry includes a non-volatile memory, and
the signal processing circuitry monitors ambient temperature of a transceiver module including the high frequency circuitry, and stores temperature data obtained by monitoring into the non-volatile memory along with a transmitted frequency of the FM-CW signal.

6. The FM-CW radar according to claim 5 , wherein the signal processing circuitry uses the temperature data stored in the non-volatile memory to determine whether or not the transmitted frequency falls within a preset tolerance, and issues an alarm to a host control circuitry in response to the transmitted frequency falling outside the tolerance.

7. The FM-CW radar according to claim 5 , wherein the signal processing circuitry uses the temperature data stored in the non-volatile memory to determine whether or not the transmitted frequency falls within a range defined by an upper limit and a lower limit, or whether or not a modulation bandwidth of the FM-CW signal falls within a range defined by an upper limit, and issues an error to a host control circuitry in response to the transmitted frequency falling outside the range defined by the upper limit and the lower limit or the modulation bandwidth falling outside the range defined by the upper limit.

8. A method of generating an FM-CW (frequency modulated continuous waves) signal to be transmitted from an FM-CW radar, the FM-CW radar including: high frequency circuitry configured to include a voltage control oscillator generating a frequency-modulated high frequency signal, and signal processing circuitry configured to convert an analog signal generated by the high frequency circuitry into a digital signal and detect at least a distance to a target and velocity of the target, wherein the signal processing circuitry includes a look up table to store default modulation control data, the method including:
calculating frequency information from phase information of a frequency-divided signal from the voltage control oscillator;
performing correction processing in response to change to characteristics of the voltage control oscillator by fixing a voltage increment and varying a time increment by using a result of the calculation of the frequency information and then calculating voltage data required to secure linearity of a transmitted frequency; and
updating a value stored in the look up table by using the voltage data calculated in the correction processing.

9. An FM-CW (frequency modulated continuous waves) radar using frequency modulation based on an FM-CW scheme, the FM-CW radar comprising:
high frequency circuitry configured to receive a reflected wave from a target; and
signal processing circuitry configured to convert an analog signal generated by the high frequency circuitry into a digital signal and detect at least a distance to the target and velocity of the target, wherein
the high frequency circuitry includes a voltage control oscillator to generate a frequency-modulated high frequency signal by receiving a modulation voltage from the signal processing circuitry,
the signal processing circuitry includes a look up table to store default modulation control data, and
the signal processing circuitry updates data stored in the look up table with correction data that is generated by fixing a voltage increment and varying a time increment with use of frequency information calculated from phase information of an output of the voltage control oscillator, and wherein

the FM-CW radar does not transmit an FM-CW signal until a first round of updating the look up table is completed by calculating the frequency information and performing correction processing.

10. The FM-CW radar according to claim 9 , wherein the signal processing circuitry uses a polynomial approximation to correct the frequency information calculated by phase calculation.

11. The FM-CW radar according to claim 10 , wherein the signal processing circuitry calculates, as an error, a difference along a time axis between data of the frequency information being calculated and waveform data of an ideal frequency line, and uses the calculated error to perform a correction along the time axis by using the calculated error and changing the time increment set to an integer multiple of the minimum time resolution of the signal processing circuitry.

12. The FM-CW radar according to claim 9 , wherein
the signal processing circuitry includes a non-volatile memory, and
the signal processing circuitry monitors ambient temperature of a transceiver module including the high frequency circuitry, and stores temperature data obtained by monitoring into the non-volatile memory along with a transmitted frequency of the FM-CW signal.

13. The FM-CW radar according to claim 12 , wherein the signal processing circuitry uses the temperature data stored in the non-volatile memory to determine whether or not the transmitted frequency falls within a preset tolerance, and issues an alarm to a host control circuitry in response to the transmitted frequency falling outside the tolerance.

14. The FM-CW radar according to claim 12 , wherein the signal processing circuitry uses the temperature data stored in the non-volatile memory to determine whether or not the transmitted frequency falls within a range defined by an upper limit and a lower limit, or whether or not a modulation bandwidth of the FM-CW signal falls within a range defined by an upper limit

Assignees

• Mitsubishi Electric Corp

Inventors

• Kurashige Kazunori

Classifications

• G01S13/584 Primary

  adapted for simultaneous range and velocity measurements · CPC title

• G01S7/4008

  of transmitters · CPC title

• G01S7/35

  Details of non-pulse systems · CPC title

• G01S13/931

  of land vehicles · CPC title

• G01S7/4004

  of parts of a radar system · CPC title