Microwave Doppler Detection with Differential Interference Cancellation
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Solution Overview
Problem
Current Doppler microwave detection methods face challenges in accurately eliminating interference signals with frequency relationships to the local oscillator signal, leading to reduced accuracy in detecting human movement and micro-movements due to the integration and smoothing of signals during filtering, which requires multiple filtering processes and affects the integrity and accuracy of the Doppler intermediate frequency signal.
Innovation Solution
The method involves forming a differential signal form of the Doppler intermediate frequency signal to distinguish and suppress or eliminate common mode and differential mode interference separately, using frequency selective cancellation to remove interference signals with same, adjacent, or harmonic frequency relationships to the local oscillator signal, thereby ensuring the integrity and accuracy of the signal without multiple filtering processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If filtering is used to eliminate interference signals from the Doppler intermediate frequency signal, then interference signals are removed, but the effective signal is also filtered out and integrated, destroying the integrity of the Doppler intermediate frequency signal and making it difficult to ensure the corresponding relationship between output parameters and physical meaning
Solution Approach 1:
The patent segments the interference elimination process into two distinct paths: a first signal path for the Doppler intermediate frequency signal and a second signal path for the interference signal. This segmentation allows selective processing where the interference signal can be filtered without affecting the integrity of the effective Doppler signal, thus resolving the contradiction between removing interference and preserving measurement precision.
Solution Approach 2:
The patent extracts the interference signal from the mixed signal before filtering. By identifying and separating the interference component (which has known frequency characteristics) from the Doppler intermediate frequency signal, the system can apply filtering only to the extracted interference, avoiding the integration and smoothing that would otherwise occur to the effective signal.
2Object-affected harmful factors
If multiple filtering processes are applied to eliminate interference, then interference signals are more effectively removed, but signal delay increases and the immediacy of detection is reduced
Solution Approach 1:
The patent performs preliminary extraction of the interference signal before the main filtering operation. By pre-identifying and separating the interference component, the system eliminates the need for multiple iterative filtering processes, thereby reducing signal delay and improving the immediacy of detection while still achieving effective interference removal.
3Object-affected harmful factors
If the bandwidth of the antenna body is narrowed to filter out environmental interference, then interference signals are reduced, but the detection capability for micro-movements is also reduced
Solution Approach 1:
The patent introduces an intermediary processing stage where the interference signal is extracted and processed separately. This intermediary approach allows the antenna body to maintain its full bandwidth for detecting micro-movements while the extracted interference component is selectively filtered, thus preserving both interference rejection and micro-movement detection capabilities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy and immediacy of Doppler intermediate frequency signal feedback for motion detection, allowing for real-time detection of human activities like breathing and heartbeat, while reducing the need for capacitor components and minimizing signal delay, thus improving the anti-interference performance of the microwave detection device.
Implementation Method 1
The Doppler microwave detection device comprises an antenna body 10P for transmitting and/or receiving microwaves. The antenna body 10P transmits a detection beam corresponding to the frequency of the local oscillator signal fed by a mixer 20P to form a corresponding detection space, and receives a reflected wave formed by the detection beam reflected by an object in the detection space to form a feedback signal generated by the reflected wave. Based on the principle of Doppler effect, the amplitude fluctuation of the Doppler intermediate frequency signal theoretically corresponds to the movement of the object in the detection space.
Implementation Method 2
The mixer 20P receives the feedback signal and outputs a Doppler intermediate frequency signal corresponding to the frequency difference between the local oscillator signal and the feedback signal by mixing and detecting.
Data Source
AI summary
An anti-interference microwave detection method and microwave detection device, wherein the anti-interference microwave detection method can accurately eliminate the interference signal in the environment that have any frequency relationship with the local oscillator signal of the microwave detection device, including same frequency, adjacent frequency, and harmonic frequency, so that it is conducive to improve the feedback accuracy of the Doppler intermediate frequency signal for the detection of the motion of objects in the corresponding detection space, so that it is beneficial for achieving the combined detection of motion characteristics including human movement, micro-movement, breath and hear beat, the detection function of the microwave detection device is diversified and suitable for intelligent detection applications of multifunctional requirements.