Radar system and method with saturation detection and reset

Patent metadata

Field	Value
Publication number	US-2016266239-A1
Application number	US-201514829980-A
Country	US
Kind code	A1
Filing date	Aug 19, 2015
Priority date	Mar 15, 2015
Publication date	Sep 15, 2016
Grant date	—

Abstract

The embodiments described herein provide a radar device and method that can provide improved sensitivity. In general, the embodiments described herein provide a saturation detector and reset mechanism coupled to a radar receiver. The saturation detector is configured to detect saturation events in the radar receiver, and the reset mechanism is configured to reset at least one filter unit in the radar receiver in response to detected saturation events. As such, the embodiments can facilitate improved radar sensitivity by reducing the effects of saturation events in the radar receiver.

First claim

What is claimed is:

1 . A radar device comprising:
at least one transmitter unit configured to transmit a radar signal; at least one receiver unit configured to receive a reflection of the radar signal, wherein the receiver unit comprises at least one filter unit configured to filter the received radar signal and at least one amplifier unit configured to amplify the received radar signal; a saturation detector coupled to the at least one amplifier unit and configured to detect a saturation event the at least one amplifier unit; and a reset mechanism configured to reset the at least one filter unit of the receiver unit in response to a detected saturation event.

2 . The radar device of claim 1 wherein the at least one transmitter unit is configured to modulate the radar signal with frame periods and inter-frame periods, and wherein the reset mechanism is configured to reset the at least one filter unit of the receiver unit in response to the detected saturation event by resetting the at least one filter unit during a next inter-frame period.

3 . The radar device of claim 2 wherein the at least one transmitter unit is configured to increase frequency of the radar signal between an initial frequency value and a higher frequency value during frame periods and decrease the frequency of the radar signal to the initial frequency value during inter-frame periods.

4 . The radar device of claim 2 wherein the at least one transmitter unit is configured to decrease frequency of the radar signal between an initial frequency value and a lower frequency value during frame periods and increase the frequency of the radar signal to the initial frequency value during inter-frame periods.

5 . The radar device of claim 1 wherein the saturation detector is configured to extract a common mode voltage from the received radar signal and to compare the extracted common mode voltage to a threshold voltage to detect a saturation event in the at least one amplifier unit.

6 . The radar device of claim 1 wherein the received radar signal is a differential radar signal, and wherein the saturation detector is configured to extract a positive common mode equivalent voltage and a negative common mode equivalent voltage from the differential radar signal, and wherein saturation detector is further configured to compare the positive common mode equivalent voltage to a variable threshold voltage and to compare the negative common mode equivalent voltage to the variable threshold voltage to detect a saturation event.

7 . The radar device of claim 1 wherein the at least one filter unit comprises a capacitor, and wherein the reset mechanism is configured to reset the at least one filter unit by removing excess charge from the capacitor.

8 . The radar device of claim 1 wherein at least one filter unit comprises a capacitor, a resistor, and a switch device in series with a switched resistor, wherein the switched resistor has a resistance less than the resistor, and wherein the reset mechanism is coupled to the switch device and is configured to reset the at least one filter unit by switching on the switch device to decrease an equivalent time constant of the at least one filter unit.

9 . The radar device of claim 1 wherein the reset mechanism is further configured to receive a frequency modulation control signal, the frequency modulation control signal indicating a start of an inter-frame period in the transmitted radar signal.

10 . The radar device of claim 9 wherein the reset mechanism is configured reset the at least one filter unit of the receiver unit subsequent to a delay period after the indicated start of the inter-frame period in the transmitted radar signal.

11 . The radar device of claim 10 wherein the delay period is a predetermined fixed period based on a propagation delay at a maximum range of the radar device.

12 . The radar device of claim 10 wherein the radar device is further configured to determine a distance to a detected object, and wherein the delay period is a dynamically determined period based on the determined distance to an object and a propagation delay at the determined distance.

13 . A radar device comprising:
at least one transmitter unit, the at least one transmitter unit configured to transmit a radar signal, wherein the radar signal is a frequency-modulated continuous-wave (FMCW) signal modulated with frame periods and inter-frame periods; at least one receiver unit, the at least one receiver unit configured to receive a reflection of the radar signal, the at least one receiver unit including at least one filter unit configured to filter the received radar signal and at least one amplifier unit configured to amplify the received radar signal; a saturation detector coupled to the at least one filter unit and configured to detect a saturation event in the at least one amplifier unit and assert a saturation detection signal in response to the detected saturation event; and a reset mechanism configured to receive the saturation detection signal and a frequency modulation control signal, the frequency modulation control signal indicating a start of a next inter-frame period, the reset mechanism configured to reset the at least one filter unit a delay period after the indicated start of the next inter-frame period in response to the saturation detection signal being asserted in a current frame period.

14 . A method of operating a radar device comprising:
receiving a reflection of a radar signal at a receiver unit, the receiver unit including at least one filter unit configured to filter the received radar signal and at least one amplifier unit configured to amplify the received radar signal; detecting a saturation event in the at least one amplifier unit; and resetting the at least one filter unit of the receiver unit in response to a detected saturation event.

15 . The method of claim 14 further comprising transmitting the radar signal, and wherein the transmitting the radar signal comprises modulating the radar signal with frame periods and inter-frame periods, and wherein the step of resetting the at least one filter unit of the receiver unit in response to the detected saturation comprises resetting the at least one filter unit during a next inter-frame period.

16 . The method of claim 14 wherein the step of detecting the saturation event in the at least one amplifier unit comprises extracting a common mode voltage from the received radar signal and comparing the extracted common mode voltage to a threshold voltage.

17 . The method of claim 14 wherein the at least one filter unit comprises a capacitor, and wherein the step of resetting the at least one filter unit comprises removing excess charge from the capacitor.

18 . The method of claim 14 wherein the step of resetting the at least one filter unit of the receiver unit in response to the detected saturation event comprises resetting a delay period after an indicated start of a next inter-frame period in the transmitted radar signal.

19 . The method of claim 18 wherein the delay period is a predetermined fixed period based on a propagation delay at maximum range of the radar device.

20 . The method of claim 18 wherein the delay period is a dynamically determined period based on a determined distance to an object and a propagation delay at the determined distance.

Assignees

• Freescale Semiconductor Inc

Inventors

• Pavao-Moreira Cristian
• Delbecq Dominique
• Goumballa Birama

Classifications

• G01S13/08

  Systems for measuring distance only (indirect measurement G01S13/46) · CPC title

• G01S7/354 Primary

  Extracting wanted echo-signals (Doppler systems G01S13/50) · CPC title

• G01S7/023

  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 title

• G01S7/4021

  of receivers · CPC title

• G01S13/931

  of land vehicles · CPC title