Asymmetric Modulation for Radar Distance and Velocity Measurement
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Solution Overview
Problem
Existing continuous wave radar systems face challenges in accurately determining distance and relative velocity due to ambiguity in phase contributions from modulated reflectors, leading to difficulties in distinguishing the desired reflection from unwanted reflections.
Innovation Solution
The method involves asymmetric modulation of the radar signal at the reflector, allowing for identification of the desired reflected signal through changes in phase or amplitude, which simplifies the determination of distance and relative velocity by providing irregular contributions that can be distinguished from noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If symmetric modulation is applied at the reflector, then the reflection can be enhanced, but phase ambiguity arises making it impossible to determine the correct phase contribution from the modulator
Solution Approach 1:
The patent applies asymmetric modulation where the modulation signal has different amplitude levels during different phases of the modulation cycle. Specifically, the modulation signal applies a first amplitude level during a first portion of the modulation period and a second amplitude level during a second portion. This asymmetry creates an irregular contribution that can be distinguished from the desired reflected signal, allowing the receiver to identify and remove the modulator's phase contribution, thereby resolving the phase ambiguity while maintaining reflection enhancement.
2Measurement precision
If modulation is applied at the reflector to suppress unwanted reflections, then the desired reflection can be easier filtered, but the phase contribution from the modulator creates ambiguity in distance determination
Solution Approach 1:
The patent uses asymmetric modulation with different amplitude levels during different portions of the modulation period. This creates a distinctive irregular contribution in the reflected signal that simplifies the identification process. The receiver can detect the asymmetric pattern and use it to separate the modulated desired reflection from unwanted reflections and to determine the modulator's phase contribution, thereby improving distance determination accuracy without excessive signal processing complexity.
Solution Approach 2:
The patent employs periodic modulation at the reflector, where the modulation signal repeats at a specific modulation period. This periodic action allows the receiver to synchronize with the modulation and systematically process the reflected signal over complete modulation periods. By analyzing the signal characteristics over one or more complete modulation periods, the receiver can accurately identify the desired reflection and determine distance while filtering out unwanted reflections.
3Ease of manufacture
If the modulation signal has equal amplitude throughout the period, then the modulation is simple to implement, but the contribution from the modulator cannot be distinguished from the desired reflection
Solution Approach 1:
The patent implements asymmetric modulation where the modulation signal has different amplitude levels during different portions of the modulation period. Specifically, it applies a first amplitude level during a first portion and a second amplitude level during a second portion. This asymmetry creates an irregular contribution that is easily distinguishable from the desired reflected signal, allowing reliable signal differentiation while maintaining relatively simple modulation implementation.
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 enhances the accuracy and reliability of distance and velocity measurements by clearly differentiating the desired reflection, enabling more precise control in applications such as automatic loading and collision protection systems.
Implementation Method 1
a transceiver device (transmitter and receiver) is arranged on the moving object, and a reflector device is arranged at a fixed reference position. By transmitting a radar signal at radio frequency, i.e. an RF signal, and detecting the reflection thereof it is possible to determine the distance between the transceiver and the reflector.
Implementation Method 2
reflecting the measurement signal by means of a reflector, thereby providing a desired reflected measurement signal
Implementation Method 3
determining at least one of a distance and a relative velocity between the antenna and the reflector by means of the desired reflected measurement signal
Data Source
Figure 1a~1b
Figure 2~3
Figure 4
AI summary
This invention relates to a method for determining at least one of a distance and a relative velocity by means of continuous wave radar measurements. The method includes generating a measurement signal in the form of a continuous wave radar signal; transmitting the measurement signal by means of an antenna (112); reflecting the measurement signal by means of a reflector (118), thereby providing a desired reflected measurement signal; receiving the desired reflected measurement signal; and determining at least one of a distance and a relative velocity between the antenna and the reflector by means of the desired reflected measurement signal. The reflection of the measurement signal involves asymmetrically modulating the measurement signal at the reflector. The determination of at least one of a distance and a relative velocity includes detecting the desired reflected measurement signal among several received reflections of the measurement signal, by means of information added by the asymmetric modulation.