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JP-7855367-B2 - Radar system and received signal processing method

JP7855367B2JP 7855367 B2JP7855367 B2JP 7855367B2JP-7855367-B2

Inventors

  • 林 祐吾

Assignees

  • ミネベアミツミ株式会社

Dates

Publication Date
20260508
Application Date
20220228

Claims (8)

  1. A transmitting unit that transmits a wave from a transmitting antenna, A receiving unit that detects an object based on a received signal including reflected waves received by a receiving antenna, A radar system having, The receiving unit is A leakage path component detection unit extracts a detection component that appears at a specific distance in the received signal as a leakage path component of the signal from the transmitting unit to the receiving unit, A representative value acquisition unit obtains a representative value of the leakage path component based on the time-series signal of the leakage path component extracted by the leakage path component detection unit within a predetermined period, A correction unit calculates the ratio of the time-series signal of the leakage path component extracted by the leakage path component detection unit and the representative value of the leakage path component obtained by the leakage path representative value acquisition unit as a fluctuation ratio, and corrects the time-series signal of the detected component appearing in the object detection distance in the received signal using the reciprocal of the fluctuation ratio. Having, Radar equipment.
  2. The aforementioned specific distance is the smallest distance among multiple object detection distances. The radar device according to claim 1.
  3. The leakage path representative value acquisition unit obtains a representative value of the leakage path component by calculating the average value of the time-series signals of the leakage path component within a predetermined period. The radar device according to claim 1 .
  4. The leakage path representative value acquisition unit obtains a representative value of the leakage path component by smoothing the time-series signal of the leakage path component within a predetermined period using a low-pass filter. The radar device according to claim 1 .
  5. In addition to performing short-term corrections on the time-series signal within the predetermined period using the leakage path component detection unit, the leakage path representative value acquisition unit, and the correction unit, Based on the circuit temperature measured by the temperature sensor, a correction is performed to compensate for the long-term gain change of the transmitting and receiving units. A radar device according to any one of claims 1 to 4.
  6. The receiving unit further includes a determination unit that determines the presence or absence of a living organism based on the time-series signal of the detection component appearing in the object detection distance corrected by the correction unit. A radar device according to any one of claims 1 to 5.
  7. A method for processing a received signal performed in a radar device having a transmitting unit that transmits a wave from a transmitting antenna and a receiving unit that detects an object based on a received signal including a reflected wave received by a receiving antenna, The steps include: extracting a detection component that appears at a specific distance in the received signal as a signal leakage path component from the transmitting unit to the receiving unit; A step of obtaining a representative value of the leak path component based on the time-series signal of the extracted leak path component within a predetermined period, The steps include : calculating the ratio of the time-series signal of the leakage path component to the representative value of the leakage path component as the variation ratio, and correcting the time-series signal of the detection component appearing in the object detection distance in the received signal using the reciprocal of the variation ratio; A method for processing received signals, including the processing of received signals.
  8. The further step includes determining the presence or absence of a living organism based on the time-series signal of the detection component appearing in the corrected object detection distance. The method for processing a received signal according to claim 7.

Description

This invention relates to a radar device capable of detecting the presence of living organisms, such as humans, and a method for processing received signals. Conventionally, radar devices that detect the presence or absence of living organisms by capturing weak changes in radio wave propagation associated with the inherent body movements of living organisms (e.g., body movements due to respiration) have been widely proposed (see, for example, Patent Document 1). This type of radar device transmits a transmission signal obtained by upconverting a pulse signal, and receives the signal reflected from the target object as a received signal. The received signal shows amplitude changes indicating the presence of the target object. In particular, when the target object is a living organism, amplitude changes characteristic of living organisms, such as respiration, appear in the received signal. The radar device is designed to detect the presence of living organisms by analyzing these amplitude changes through signal processing. Japanese Patent Publication No. 2020-024185 Block diagram showing the overall configuration of the radar device according to the embodiment.Block diagram showing the configuration of the received signal processing unit.This figure shows the time-series signal that appears at the object detection distance R.This diagram shows the time-series signals appearing at the object detection distance R and the time-series signals appearing at a specific distance R0.Flowchart for explaining the operation of the embodimentThis figure shows the results of frequency analysis of received signals I and Q acquired when a radar device was installed inside an unmanned vehicle. Figure 6A shows the analysis results of the complex received signal before correction by the correction unit, and Figure 6B shows the analysis results of the complex received signal after correction by the correction unit.This figure shows the results of frequency analysis of received signals I and Q acquired when a radar device is installed inside a manned vehicle. Figure 7A shows the analysis results of the complex received signal before correction by the correction unit, and Figure 7B shows the analysis results of the complex received signal after correction by the correction unit. The embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a block diagram showing the overall configuration of the radar device 100 of this embodiment, which detects living organisms using a pulse radar system. The radar device 100 includes a transmitting unit 110 and a receiving unit 120. The transmitter 110 inputs the pulse signal generated by the pulse signal generator 111 to the multiplier 112. The multiplier 110 upconverts the pulse signal using the carrier frequency signal output from the local oscillator 113. The upconverted pulse signal is amplified by the power amplifier (PA) 114 and then transmitted as an electromagnetic wave (transmitted wave) from the transmitting antenna 115. The receiving unit 120 obtains a received signal by receiving electromagnetic waves with the receiving antenna 121. The electromagnetic waves include reflected waves from the transmitted wave reflected by the detection target (living organism). The received signal output from the receiving antenna 121 is input to the multipliers 123 and 125 via the low-noise amplifier (LNA) 122. Furthermore, the carrier frequency signal from the local oscillator 113 is input to multiplier 123, and the carrier frequency signal phase-shifted by the π/2 shifter 124 is input to multiplier 125. As a result, the received signal is down-converted by a so-called orthogonal downshifter, and the I component of the received signal is output from multiplier 123, while the Q component of the received signal is output from multiplier 125. The I and Q components of the received signal are input to the received signal processing unit 130 via a low-pass filter (LPF), respectively. The received signal processing unit 130 detects a component that appears at a position corresponding to the distance of the reflective object based on the received signal, and determines whether the reflective object is a living organism based on the temporal variation of that component. Figure 2 is a block diagram showing the configuration of the received signal processing unit 130. The received signal is converted from analog to digital by the analog-to-digital converter (A/D) 131 and then stored in the storage unit 132. The stored received signal is then extracted as a time-series signal by the leakage path component detection unit 133 and the correction unit 135. The leakage path component detection unit 133 extracts the detected component appearing at a specific distance in the received signal as the leakage path component of the signal from the transmitting unit 110 to the receiving unit 120. Here, the leakage path component refers to components other than those based on r