Radar Built-In Self-Test via Secondary Modulation
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Solution Overview
Problem
RF radar systems face challenges in detecting parasitic signal paths between the transmitter and receiver, leading to increased crosstalk, receiver saturation, and inaccurate object detection due to high 1/f noise and parasitic paths, which are difficult to detect using existing methods.
Innovation Solution
A built-in self-test (BIST) mechanism using secondary modulation is implemented, where the chirp signal is modulated independently during a dedicated self-test mode, generating a twice-modulated output signal with frequencies above the high-pass filter cut-off, allowing for detection of parasitic paths by analyzing spectral components in the low-frequency signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional radar operation mode is used, then object detection function is maintained, but parasitic paths and crosstalk cannot be detected
Solution Approach 1:
The radar system performs self-diagnosis by executing a built-in self-test (BIST) procedure. The transceiver conducts parasitic path detection using secondary modulation and spectral analysis of its own transmitted and received signals, eliminating the need for external test equipment or additional detection systems.
Solution Approach 2:
The system alternates between normal object detection mode and BIST mode in periodic intervals. During BIST mode, the radar transmits test signals with secondary modulation and analyzes spectral components to detect parasitic paths, then returns to normal operation, ensuring continuous monitoring without permanent mode change.
2Reliability
If high-pass filter is used to reduce 1/f noise, then noise is reduced, but parasitic paths with frequencies below cut-off cannot be detected
Solution Approach 1:
The system applies secondary modulation to the transmitted chirp signal, which shifts the spectral components of the signal to frequencies above the high-pass filter cut-off frequency. This parameter change in signal frequency allows parasitic paths to be detected despite the presence of the high-pass filter that blocks low-frequency 1/f noise.
Solution Approach 2:
Secondary modulation acts as an intermediary mechanism that bridges the gap between the high-pass filter's frequency blocking and the need to detect parasitic paths. By modulating the signal at a frequency above the cut-off, the system enables detection while the filter continues to block harmful low-frequency noise.
3Device complexity
If transmitter and receiver are in close proximity, then system integration is improved, but crosstalk and receiver saturation increase
Solution Approach 1:
The BIST mechanism provides feedback about the isolation level between transmitter and receiver by detecting parasitic paths through spectral analysis. When crosstalk or parasitic signals are detected above threshold levels, the system can alert operators or adjust operation to maintain reliable performance despite close proximity integration.
Solution Approach 2:
Instead of relying solely on physical isolation mechanisms (mechanical separation, shielding structures), the system uses signal processing and spectral analysis to detect and compensate for crosstalk effects, replacing physical isolation requirements with electronic detection and analysis 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
The BIST effectively detects parasitic paths and ensures proper isolation between the transmitter and receiver, preventing receiver saturation and improving the accuracy of object detection by identifying and addressing crosstalk issues in real-time.
Implementation Method 1
generating a chirp signal based on a local oscillator (LO) signal, wherein the LO signal is a frequency-modulated continuous-wave (FMCW) signal
Implementation Method 2
transmitting the output signal on a transmitting antenna of the radar device
Implementation Method 3
receiving an echo signal on a receiving antenna of the radar device
Implementation Method 4
downmixing an amplified version of the echo signal with the LO signal to produce a low frequency signal
Data Source
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AI summary
Radar device (200) and a method of operating the radar device, the radar device having a transmitter(105,110,115) and a receiver (120,125,130), the method including: generating a chirp signal based on a local oscillator signal, wherein the LO signal is a frequency-modulated continuous-wave signal; secondary modulating the chirp signal to produce an output signal; transmitting the output signal on a transmitting antenna (115) of the radar device; receiving an echo signal on a receiving antenna (120) of the radar device; downmixing an amplified version of the echo signal with the LO signal to produce a low frequency signal; and outputting an error detection signal based on spectral components of the low frequency signal, wherein the spectral components correspond to the secondary modulating.