Doppler Radar Interference Suppression Using Reference Signal Cancellation
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Solution Overview
Problem
Doppler radar detection technology is hindered by external interference such as co-channel interference, aliased adjacent-channel interference, and baseband/IF-band interference from sources like fluorescent lamps and electronic device noise, which current systems struggle to effectively suppress.
Innovation Solution
A radar detector system comprising a radar transmitting device, a radar receiving device, an analog-to-digital converter, and a digital processing unit that detects interference components in the environment by transmitting and receiving radar waves with and without interference, generating reference and main signals, and adjusts these signals to suppress interference using interference parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Doppler radar detection technology is used for motion detection, then motion detection capability is improved, but the system is susceptible to external interference such as co-channel interference, aliased adjacent-channel interference, and baseband/IF-band interference from fluorescent lamps and electronic devices
Solution Approach 1:
The system performs preliminary interference detection by capturing a reference signal during a first time period when the radar signal is not transmitted. This reference signal characterizes the interference environment before the actual motion detection occurs, allowing the system to prepare interference cancellation parameters in advance. The digital processing unit then uses this pre-acquired interference information to suppress interference in the main signal during the second time period when motion detection is performed.
Solution Approach 2:
The patent introduces a reference signal as an intermediary element that mediates between the interference environment and the main radar signal. This reference signal serves as a representative model of the interference, which is then processed to generate interference parameters that are applied to cancel interference in the main signal. The digital processing unit acts as a mediator that transforms the reference signal into interference suppression parameters and applies them to the main signal processing.
2Object-affected harmful factors
If interference suppression is implemented by detecting interference components and deducting them from received signals, then interference reduction is improved, but the system complexity increases due to additional signal processing requirements
Solution Approach 1:
The system implements periodic interference detection and cancellation by alternating between two time periods: a first time period for acquiring reference signals when radar transmission is suspended, and a second time period for main signal processing when radar transmission occurs. This periodic structure allows the system to systematically update interference characteristics and apply cancellation in a rhythmic manner, making the complex processing manageable and organized.
Solution Approach 2:
The patent creates a copy of the interference environment through the reference signal, which replicates the interference characteristics present during main signal acquisition. Instead of directly analyzing the complex main signal for interference, the system works with this simplified copy (reference signal) to extract interference parameters, thereby reducing processing complexity while maintaining effective interference suppression.
3Measurement precision
If reference signals are acquired during periods when radar signals are subdued, then interference parameter accuracy is improved, but the detection time increases due to additional acquisition periods
Solution Approach 1:
The system maintains continuous useful action by efficiently utilizing all time periods: during the first time period when radar transmission is subdued, the system continuously acquires and processes reference signals to track interference changes; during the second time period when radar transmission occurs, the system simultaneously performs motion detection and applies interference cancellation. This continuous operation across both time periods maximizes the utility of each moment while maintaining accurate interference parameter updates.
Solution Approach 2:
The system applies partial interference cancellation by selectively removing interference components from the main signal rather than processing the entire signal from scratch. The digital processing unit uses the reference signal to identify and remove only the interference portions, leaving the useful radar signal intact. This partial action approach reduces the overall processing time compared to complete signal re-analysis while maintaining detection accuracy.
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
Effectively reduces or eliminates interference in radar signals, enhancing the accuracy of motion detection by isolating interference components and improving signal quality, thereby improving the reliability of Doppler radar systems.
Implementation Method 1
a radar transmitting device (110) configured to transmit a first wireless signal
Implementation Method 2
Doppler radar detection technology is widely applied in motion detection for vehicle proximity detection
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A radar detector (800) includes a radar transmitting device (110), a radar receiving device (120), an analog-to-digital converter (ADC) (130), and a digital processing unit (140). The radar transmitting device (110) transmits a first wireless signal. The radar receiving device (120) receives a second wireless signal to generate an analog reference signal (ASr) in response to the first wireless signal subdued from being transmitted, and receives a third wireless signal to generate an analog main signal (ASp) in response to the first wireless signal not subdued from being transmitted. The ADC (130) generates a digital reference signal (Sr) according to the analog reference signal (ASr), and generates a digital main signal (Sp) according to the analog main signal (ASp). The digital processing unit (140) adjusts the digital or analog main signal (Sp, ASp) according to the digital reference signal (Sr).