A radar system and method for realizing dynamic and static cooperative detection
By using two directional planar antennas and a reference signal source in a radar system, the problem of traditional Doppler radar being unable to detect stationary targets is solved, achieving high-sensitivity detection of stationary targets, avoiding detection blind spots, and featuring a simple structure and low power consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANCHONG SKY MICROWAVE
- Filing Date
- 2026-03-10
- Publication Date
- 2026-05-29
AI Technical Summary
Traditional Doppler radar cannot detect stationary targets, creating a detection blind spot. It is especially in situations where people are sitting quietly reading in front of a lamp, looking at their phones while sitting on the toilet, or elderly people who have fallen and are unable to move or are unconscious, and therefore cannot detect the presence of the target.
Two adjacent directional planar antennas are arranged on the same hardware platform. Doppler signals and difference frequency signals are distinguished by frequency and phase difference. A reference signal source is introduced to detect stationary targets when there are no moving targets. The existence of stationary targets is determined by analyzing the difference frequency signal.
It enables the detection of both moving and stationary targets on the same hardware platform, enhances the detection sensitivity of stationary targets, reduces the false trigger rate, and has a simple structure and low power consumption.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of radar signal processing and target recognition technology, specifically relating to a microwave radar system capable of distinguishing between moving and stationary targets and achieving continuous and accurate detection in a stationary state. Background Technology
[0002] Traditional Doppler radar motion detectors typically use a single transmit / receive antenna or a shared antenna. Their detection area is affected by transmit power, antenna gain, radiation pattern, and detection threshold, generally exhibiting a fan-shaped or hemispherical coverage with a relatively wide detection range. Traditional Doppler radar has advantages such as high sensitivity, fast response, and simple structure in detecting moving targets. However, its fundamental principle dictates that it cannot generate effective intermediate frequency signal output for stationary targets (such as sitting, squatting, or immobile individuals). This constitutes a serious detection blind zone in certain application scenarios, such as when a person is sitting and reading under a lamp, using a mobile phone while sitting on the toilet, or an elderly person who has fallen and is unable to move or is unconscious. Traditional radar will be unable to detect the target's presence, creating a detection blind zone. To address these issues, this radar system proposes a dynamic and static collaborative detection mechanism. While retaining the original motion detection capability, it also includes stationary target detection functionality, achieving blind-zone-free, full-coverage inspection capabilities. Summary of the Invention
[0003] The present invention aims to provide a radar system and method that can realize motion detection and stationary target presence detection on the same hardware platform, overcoming the defect of traditional Doppler radar that cannot detect stationary targets.
[0004] The core of this invention lies in: The system's two adjacent directional flat panel antennas work together on the same hardware platform. Figure 1 The radiation areas of the two directional flat panel antennas overlap to form a coincident detection area. The signals transmitted by the two antennas have frequency and phase difference, thus distinguishing the intermediate frequency signal into the Doppler signal generated by motion and the difference frequency signal of the stationary reflecting object.
[0005] When the system's Doppler radar antenna does not detect the Doppler signal of a moving target, a reference signal source is activated to transmit a reference microwave signal. This signal, after being reflected by a stationary target, mixes with the local oscillator signal to generate an intermediate frequency (IF) signal. By analyzing the frequency difference and intensity of this signal, the presence of a stationary target is determined, thus enhancing the detection sensitivity for stationary targets.
[0006] The working mechanism of introducing a reference signal source and cooperative detection 1. When the Doppler intermediate frequency of a moving person or object disappears, the cooperative radar activates the reference signal source. The reference signal source can operate in two modes: 1) The reference source generates a frequency difference with the radar's main frequency at a fixed frequency (with a frequency difference from the radar's main frequency). 2) The reference source operates in a frequency conversion mode, generating a frequency difference with the main frequency. 3) Doppler signal and reference signal operate in a time-division multiplexing manner. Second: When the cooperative radar does not detect the Doppler intermediate frequency of a moving target, it operates at the main frequency while simultaneously starting the reference signal source to operate at a fixed frequency. The radar detects the intermediate frequency signal generated by the mixing of the local oscillator signal and the reference signal, thereby determining the presence of a stationary person or object.
[0007] Innovation Dual-mode collaborative working mechanism: Motion detection and stationary detection share the same set of hardware, resulting in a simple structure; Low-power design: The stationary detection mode is activated only when there is no movement, avoiding continuous transmission; Stationary target recognition capability: By using reference signal reflection and difference frequency analysis, the presence of stationary human bodies or objects can be determined; Strong anti-interference capability: The judgment of stationary targets is based on dual verification of frequency difference and intensity, resulting in a low false trigger rate. Attached Figure Description
[0008] Figure 1 This is a schematic diagram of the radar system. On the main board, there is a directional flat-panel radar antenna (main radar and coordinating radar) on the left and right sides. Figure 2 When there are no people or objects in front of the sensor, the analysis unit continuously receives a fixed difference frequency signal. Figure 3 This is a diagram of pulse signals (low power), showing two different difference frequency signals. Figure 4 This is a diagram of a continuous wave signal; Figure 5 This is a schematic diagram showing a person or object moving in front of the sensor. Figure 6 The image shows the Doppler motion signal received by the analysis unit; Figure 7 This is a schematic diagram showing the situation when there is a non-moving object in the detection area; Figure 8 When the Doppler does not detect motion signals, the reference source generates a difference frequency using the local oscillator signal of the main radar. The intermediate frequency signal generated by mixing the local oscillator signal with the reference signal is shown in the figure. Detailed Implementation
[0009] This invention includes: Antenna unit: includes main radar and coordinating radar, with both radar antennas operating in the same frequency band (e.g., 5.8 GHz, 10.525 GHz, 24 GHz), and the distance between the two antennas is 5-500 mm; Receiver unit: Used to receive reference signals transmitted from the antenna and signals reflected back from moving targets, and mix them with the local oscillator signal of the receiver unit to generate an intermediate frequency signal; Signal processing unit: Extracts the Doppler component from the difference frequency signal and determines motion events.
[0010] Under the motion detection mechanism, the main radar continuously transmits and receives signals, while the cooperative radar serves as the receiving channel for Doppler signal detection; the reference signal source remains inactive. When the cooperative radar does not detect any motion signals, the system switches to stationary detection mode, activates the reference signal source, and transmits a reference microwave signal. This signal, reflected by a stationary target, is received by the main radar and mixed with the local oscillator signal to generate an intermediate frequency (IF) signal. The signal processing unit analyzes the frequency difference and intensity of the IF signal to determine the presence of a stationary target.
Claims
1. (Apparatus, Independent Claim): A radar system for achieving coordinated dynamic and static detection, characterized in that, include: Two adjacent directional flat panel antennas are used to form a forward detection area; One main radar unit is used to transmit local oscillator signals and receive reflected signals; A cooperative radar unit is used for Doppler motion signal detection and to activate a reference signal source when there is no motion signal. A signal processing and control unit for switching operating modes and analyzing intermediate frequency signals. The system's operating modes include: Motion detection mode: Cooperative radar detects Doppler signals, reference signal source is turned off; Stationary detection mode: When the cooperative radar does not detect any motion signal, it activates the reference signal source, transmits a reference signal, which is reflected by the stationary target and received by the main radar and mixed to generate an intermediate frequency signal; The signal processing unit determines the presence of a stationary target by analyzing the frequency difference and intensity of the intermediate frequency signal.
2. Referring to claim 1: The apparatus according to claim 1, characterized in that, The microwave signal operates at frequencies of 5.8 GHz, 10.525 GHz, or 24 GHz.
3. Referring to claim 1: The apparatus according to claim 1, characterized in that, The difference frequency detection scheme includes a pair of radar antennas (main radar and cooperative radar) for transmitting and receiving Doppler signals and reference signals, and the signals are analyzed by a processing unit.
4. Referring to claim 1: The apparatus according to claim 1, characterized in that, The signal processing unit includes a dynamic threshold judgment circuit, which is used to determine whether a target exists based on the energy change of the intermediate frequency signal.
5. Claim 1: The main frequency radar and the cooperative radar work in a time-division manner to determine the motion and stationary state of people and objects.
6. Method, Independent Claim: A motion detection method using the apparatus as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step S1: The system enters motion detection mode, the main radar transmits and receives signals, and detects whether there is a Doppler intermediate frequency signal; Step S2: If a Doppler signal is detected, it is determined that a moving target exists; Step S3: If no Doppler signal is detected, the system switches to static detection mode and starts the reference signal source; Step S4: The reference signal source transmits a signal, and the main radar receives the reflected signal from the stationary target and mixes it with the local oscillator to generate an intermediate frequency signal; Step S5: The signal processing unit analyzes the frequency difference and intensity of the intermediate frequency signal; Step S6: If the intermediate frequency signal is stable and its intensity exceeds the threshold, it is determined that there is a stationary target in the detection area; Step S7: If there is no valid intermediate frequency signal, turn off the reference signal source and return to motion detection mode.