FM Pulse Radar Adaptive Range Gate Measurement
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Solution Overview
Problem
Conventional FMCW radar devices face challenges in accurately determining distance and relative velocity, especially when multiple targets are present, due to errors in beat signal combination and correspondence, and struggle with optimal modulated frequency settings, particularly in cases of short and long distances.
Innovation Solution
A radar device employing an FM pulse system with frequency modulation, pulsed signal transmission, and adaptive measurement time periods in each range gate for Fourier transform input, allowing for optimal distance and relative velocity resolution by adjusting sampling timing and measurement time periods based on distance to the target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed measurement time period is used for all range gates, then the device complexity is reduced, but the measurement precision deteriorates because optimal resolution cannot be achieved for both short and long distances
Solution Approach 1:
The measurement time period is made dynamic by changing it according to the range gate being used. For short distance range gates, a longer measurement time period is applied to achieve high relative velocity resolution, while for long distance range gates, a shorter measurement time period is used to achieve high distance resolution. This dynamic adaptation resolves the contradiction by allowing optimal resolution in each range gate without requiring a single complex fixed configuration.
Solution Approach 2:
Different measurement time periods are assigned to different range gates based on their specific requirements. Short distance range gates receive longer measurement time periods for velocity resolution, while long distance range gates receive shorter measurement time periods for distance resolution. This local differentiation allows each part of the system to have the quality needed for its specific function, resolving the contradiction between overall precision and complexity.
2Measurement precision
If a single modulated frequency is used for all distances, then the device complexity is reduced, but the measurement precision deteriorates because optimal frequency settings cannot be achieved for both short and long distances
Solution Approach 1:
The modulated frequency is made dynamic by changing it according to the range gate. Lower modulated frequencies are used for short distance range gates to achieve high relative velocity detection accuracy, while higher modulated frequencies are used for long distance range gates to achieve high distance resolution. This dynamic frequency adjustment resolves the contradiction by allowing optimal frequency selection for each distance range.
Solution Approach 2:
Different modulated frequencies are assigned to different range gates based on their distance characteristics. Short distance range gates use lower frequencies optimized for velocity measurement, while long distance range gates use higher frequencies optimized for distance measurement. This local optimization resolves the contradiction between velocity accuracy and distance resolution.
3Measurement precision
If measurement time period is increased for high resolution, then the measurement precision is improved, but the productivity deteriorates because the measurement cycle becomes longer
Solution Approach 1:
Long measurement time periods are applied only to short distance range gates where high relative velocity resolution is needed, while short measurement time periods are applied to long distance range gates where distance resolution is the priority. This localized application of long measurement periods minimizes the overall impact on measurement speed while maintaining high resolution where required.
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 approach enables improved accuracy in distance and relative velocity measurements by setting high resolution in short distances and low resolution in long distances, reducing errors and improving correspondence determination between beat signals and targets.
Implementation Method 1
frequency modulation means for making a frequency modulation of a frequency of a transmission radio wave with a modulation signal of a triangular wave
Implementation Method 2
the signal, being the transmission signal reflected at the target and received by a receiving antenna 315 undergoes a time delay due to the distance and a frequency deviation corresponding to the relative velocity
Implementation Method 3
the signal, being the transmission signal reflected at the target and received by a receiving antenna 315 undergoes a time delay due to the distance
Implementation Method 4
measurement time changing means for setting a measurement data used as an input of Fourier transform based on sampling data obtained by the sampling means
Data Source
AI summary
A radar device of FM pulse system, in which a pulsed radio wave with frequency modulated is transmitted or received, to calculate a distance to a target 203 and a relative velocity, comprising: range gate setting means 205 for determining a sampling timing every time a predetermined time period has passed from a transmission timing; sampling means 206 for making a sampling in a frequency up zone or frequency down zone in each range gate; and measurement time changing means 207 for setting a measurement data used as an input of Fourier transform based on sampling data obtained by the sampling means 206, and when letting a time period required to make a sampling of all measurement data a measurement time period, changing the measurement time period in each range gate. An optimum distance resolution and relative velocity resolution can be set based on the distance to a target.