FM-CW Radar VCO Initial Voltage Reset for Velocity Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
FM-CW radars using open loop technology without a phase locked loop (PLL) suffer from a decrease in accuracy of relative velocity measurement due to the history effect of the voltage-controlled oscillator when modulation is performed across multiple bandwidths within the same frame.
Innovation Solution
A radar device that includes a voltage-controlled oscillator generating a frequency-modulated high frequency signal, transmission and receiving antennas, a mixer to generate a beat signal, and a control unit that calculates distance and relative velocity using the beat signal. The control unit ensures that the initial voltage of the triangular wave voltage signal for a second modulation scheme is equal to that of the first modulation scheme during switching within the same frame, thereby eliminating phase changes in the beat signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open loop technology without PLL is used in signal source control, then device complexity is reduced and ease of manufacture is improved, but measurement precision of relative velocity deteriorates due to history effect of VCO
Solution Approach 1:
The patent applies preliminary action by resetting the initial voltage of the triangular wave voltage signal to a reference voltage at the start of each frame before switching between different bandwidth modulation schemes. This preliminary reset action eliminates the history effect accumulation in the VCO, ensuring that phase changes in beat signals are caused only by target motion and not by residual effects from previous modulation schemes, thus maintaining measurement precision while using simple open loop architecture
2Adaptability or versatility
If multiple different bandwidths are used within the same frame for modulation, then adaptability is improved and productivity is enhanced, but measurement precision of relative velocity deteriorates due to phase changes from VCO history effect
Solution Approach 1:
The patent applies preliminary action by resetting the initial voltage of the triangular wave voltage signal to a reference voltage at the start of each frame before switching between different bandwidth modulation schemes. This preliminary reset action eliminates the history effect accumulation in the VCO, ensuring that phase changes in beat signals are caused only by target motion and not by residual effects from previous modulation schemes, thus maintaining measurement precision while using simple open loop architecture
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the bandwidth parameter of the triangular wave voltage signal modulation while maintaining the initial voltage reset to reference voltage. This allows the system to switch between different bandwidths (e.g., wide bandwidth for high velocity resolution, narrow bandwidth for low velocity resolution) within the same frame to adapt to different target scenarios, while the parameter change is performed in a controlled manner that prevents history effect interference
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 solution effectively reduces the decrease in accuracy of relative velocity measurement in FM-CW radars, enhancing the radar's performance by minimizing phase changes in the beat signal.
Implementation Method 1
a voltage-controlled oscillator to generate a high frequency signal frequency-modulated based on a triangular wave voltage signal
Implementation Method 2
a mixer to generate a beat signal having a frequency equal to a frequency difference between the reception signal and the high frequency signal
Data Source
AI summary
A radar device utilizing frequency modulation of a frequency modulated continuous wave type, and includes a voltage-controlled oscillator generating a high frequency signal frequency-modulated based on a triangular wave voltage signal, a transmission antenna emitting the high frequency signal into the air, a receiving antenna receiving, as a reception signal, a reflected wave from a target object, of the high frequency signal, a mixer generating a beat signal having a frequency equal to a frequency difference between the reception signal and the high frequency signal, and a microcomputer calculating distance from the target object and relative velocity with respect to the target object, using the beat signal, and causing the initial voltage of the triangular wave voltage signal corresponding to second modulation scheme to be equal to that corresponding to first modulation scheme at a time of switching from the first modulation scheme to the second modulation scheme.