Moving Object Detection Circuit Using IF Mixing for Accurate Ranging
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Solution Overview
Problem
Existing object detection technologies face challenges in reducing DC offset and flicker noise when using microwave transceivers to detect moving objects, which affects the accuracy of distance measurement.
Innovation Solution
A moving object detection circuit that employs a mixing circuit, analog-to-digital conversion, and a distance detecting unit with time domain to frequency domain analysis and spectral peak selection to generate detection results, using intermediate frequency carrier signals to mitigate DC offset and flicker noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If direct conversion of I/Q signals is used to extract phase information, then the detection process is simplified, but DC offset and flicker noise cannot be easily reduced
Solution Approach 1:
The patent introduces an intermediate frequency (IF) carrier signal as a mediator between the RF carrier and baseband signals. By performing mixing operations at the IF stage rather than direct I/Q conversion, the system can effectively separate and filter out DC offset and flicker noise components while preserving the useful signal, thus resolving the contradiction between processing simplicity and measurement accuracy
Solution Approach 2:
The patent changes the frequency parameter by using IF carrier signals at a non-zero intermediate frequency instead of direct baseband conversion. This frequency shift allows the signal spectrum to be separated from the DC and low-frequency noise regions, enabling effective noise reduction while maintaining detection accuracy
2Device complexity
If conventional mixing circuits are used, then the circuit structure is simple, but DC offset and flicker noise from the transmitter to the receiver cannot be reduced
Solution Approach 1:
The patent uses IF carrier signals as an intermediary stage between transmission and reception. The mixing circuits mix the received RF signal with the IF carrier, and subsequent mixing with another IF carrier brings the signal to baseband. This two-stage mixing process with IF as intermediary effectively separates the signal from DC offset and flicker noise, reducing harmful factors without significantly increasing circuit complexity
Solution Approach 2:
The patent extracts the useful signal from the mixed signal by performing spectral peak analysis in the frequency domain. By transforming the time-domain signal to frequency domain and identifying spectral peaks, the system extracts only the relevant signal components while leaving behind DC offset and flicker noise, thus removing harmful factors from the detection process
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
The solution effectively reduces the influence of DC offset and flicker noise, improving the accuracy of distance measurement for moving objects by isolating and processing the signal components corresponding to moving objects from static objects and leakage.
Implementation Method 1
a first mixing circuit for mixing the radio frequency (RF) carrier signal and the first analog signal to generate a second analog signal
Implementation Method 2
The time domain to frequency domain analysis unit is configured to generate at least one frequency domain signal according to the first signal and the second signal
Data Source
AI summary
A moving object detection circuit for detecting movement information of a measured object. The moving object detection circuit includes a mixing circuit, an analog-to-digital conversion circuit, a mixing unit, and a distance detecting unit. The mixing circuit mixed the RF carrier signal and a first analog signal to generate a second analog signal. The first analog signal is generated by a signal reflected from the measured object. The analog-to-digital conversion circuit coupled to the mixing circuit for generating a digital signal according to the second analog signal. The mixing unit mixed an IF signal and a first/second IF carrier signal to generate a first/second signal. The distance detecting unit generated a detection result according to the first signal and the second signal. The detection result is corresponding to a distance between the measured object and the moving object detection circuit.