Radar Phase Difference Folding Resolution Using Dual-Frequency Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Radar devices face challenges in accurately estimating target direction due to phase difference folding issues when the interval between receiving antennas exceeds a wavelength, leading to ambiguity in phase difference measurements and reduced receiving levels near the detection range boundary.
Innovation Solution
A radar device configuration that includes a transmission unit transmitting signals of two different frequencies and a reception unit with two receiving antennas, where a control unit determines phase folding by calculating phase differences between signals received by each antenna, allowing precise estimation of target direction without antenna interval reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the interval between receiving antennas is increased to half wavelength or longer, then the detection region can be expanded, but phase difference folding occurs causing inability to distinguish target direction
Solution Approach 1:
The patent uses multiple transmission frequencies to create different wavelength ratios between transmitted signals. By transmitting at least two frequencies with different wavelengths and comparing phase differences across these frequencies, the system resolves phase folding ambiguity while maintaining the ability to detect targets across an expanded angular range.
Solution Approach 2:
The patent adds a frequency dimension to the traditional single-frequency phase difference measurement. By measuring phase differences at multiple frequencies and using the ratio relationship between them, the system transforms a one-dimensional ambiguous measurement into a multi-dimensional unambiguous determination.
2Measurement precision
If multiple transmission antennas are used to estimate target direction with receiving level difference, then target direction can be determined, but the configuration becomes complicated
Solution Approach 1:
The patent makes the single receiving antenna system perform multiple functions by processing signals at different frequencies. The same receiving antenna that captures the signal also provides phase difference information across multiple frequencies, eliminating the need for separate transmission antennas while achieving target direction determination.
Solution Approach 2:
The patent creates virtual transmission antenna effects by using frequency multiplication. The phase difference measurements at different frequencies act as copies of the spatial information that would be obtained from multiple physical transmission antennas, achieving the same directional information with simpler hardware.
3Adaptability or versatility
If the detection direction range is expanded, then more targets can be detected, but the receiving level is lowered near the boundary making level difference estimation difficult
Solution Approach 1:
The patent changes the measurement parameter from receiving level difference to phase difference ratio across frequencies. This phase-based measurement remains reliable even when receiving levels are low near the detection boundary, avoiding the signal-to-noise problems that plague level-based methods in extended detection ranges.
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 high-precision estimation of target direction by distinguishing phase differences and preventing performance deterioration, even when antenna intervals exceed the wavelength, by using frequency differences to resolve phase folding ambiguities.
Implementation Method 1
The radar device is configured to transmit and receive frequency-modulated electromagnetic waves, thereby estimating a distance from the radar device to the target having reflected the electromagnetic waves
Implementation Method 2
The radar device can calculate the target direction (an arrival direction of the electromagnetic wave) by a phase difference of the reflected waves (reflected electromagnetic waves) received by the two adjacent antennas. The phase difference is generated due to a difference of path lengths (path length difference) from the target to the respective antennas.
Data Source
AI summary
There is provided a radar device. A transmission unit includes a transmission antenna for transmitting a signal of a first frequency and a signal of a second frequency. A reception unit includes a first receiving antenna and a second receiving antenna for receiving a first signal obtained by bouncing the signal of the first frequency off a target, and a second signal obtained by bouncing the signal of the second frequency off the target. A control unit determines folding of a first phase difference, based on the first phase difference between the first signal received by the first receiving antenna and the first signal received by the second receiving antenna, a second phase difference between the second signal received by the first receiving antenna and the second signal received by the second receiving antenna, and a difference between the first phase difference and the second phase difference.