FM-CW Radar VCO Feedback Calibration for Aging Drift
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Solution Overview
Problem
Conventional FM-CW radar systems fail to properly respond to changes in voltage control oscillator (VCO) characteristics due to aging, leading to inefficiencies in mass production and inspection processes.
Innovation Solution
The implementation of an FM-CW radar system that includes a microcomputer with a look-up table (LUT) for storing modulation control data, which calculates and updates frequency information based on phase information from the VCO, allowing for real-time correction and compensation of VCO frequency drifts using polynomial approximation and time error calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional FM-CW radar systems are used without feedback control, then the device complexity is reduced, but the reliability deteriorates due to inability to respond to VCO characteristic changes caused by aging
Solution Approach 1:
The patent implements a feedback control system where the microcomputer continuously monitors the actual frequency of the VCO and compares it with the target frequency. Based on the frequency deviation detected through phase information from a frequency divider, the microcomputer dynamically adjusts the modulation control voltage to correct VCO frequency drift, thereby maintaining reliable operation despite aging effects.
Solution Approach 2:
The system performs self-calibration by automatically detecting its own frequency deviations and correcting them without external intervention. The microcomputer uses the phase information from the frequency divider to calculate frequency errors and autonomously adjusts the VCO control voltage, enabling the radar system to self-correct aging-related drift.
2Manufacturing precision
If individual adjustment work is performed for each transmit/receive module during delivery inspection, then the manufacturing precision is improved, but the productivity deteriorates due to increased inspection time
Solution Approach 1:
Each transmit/receive module is equipped with a microcomputer that autonomously performs frequency calibration without requiring manual adjustment. The system automatically measures its own VCO frequency characteristics and applies correction values stored in a lookup table, eliminating the need for time-consuming individual adjustment work during inspection while maintaining high frequency accuracy.
Solution Approach 2:
The patent pre-calculates and stores correction values in a lookup table within the microcomputer before the delivery inspection process. During inspection, the system simply retrieves and applies the appropriate correction values based on measured frequency deviations, significantly reducing the time required compared to performing full adjustment procedures for each module.
3Measurement precision
If the VCO frequency is monitored and corrected in real-time, then the measurement precision is improved, but the device complexity increases due to additional monitoring and correction circuitry
Solution Approach 1:
The patent combines the frequency monitoring and correction functions with the existing microcomputer that controls the radar system. The microcomputer utilizes its existing processing capabilities to read phase information from the frequency divider, calculate frequency deviations, and adjust the VCO control voltage, thereby achieving precise frequency monitoring without adding separate dedicated monitoring and correction hardware systems.
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
Enables the FM-CW radar to accurately respond to VCO changes caused by aging, reducing inspection time and enabling feedback control, thus improving production efficiency and accuracy.
Implementation Method 1
a voltage control oscillator that generates an output signal by using a piezoelectric element
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An FM-CW radar includes a high frequency circuit 13 that receives a reflected wave from a target, and a signal processing unit 14 that converts an analog signal generated by the high frequency circuit 13 into a digital signal and detects at least a distance to the target and velocity of the target. The high frequency circuit 13 includes a VCO 4 that receives a modulation voltage from the signal processing unit 14 and generates a frequency-modulated high frequency signal. The signal processing unit 14 includes an LUT 9 that stores default modulation control data. The signal processing unit 14 calculates frequency information from phase information of output of the VCO 4, and updates the data stored in the LUT 9 with correction data that is generated by using a result of the calculation.