MIMO Radar Chirp Phase Coding for Signal Orthogonality
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing radar systems face ambiguities in determining object information such as distance, speed, and direction due to interference between target signals from objects with different velocities at the same distance, particularly in MIMO radar systems using multiple transmitters.
Innovation Solution
The method involves specifying unique phase shift values for multiple transmit signals to ensure orthogonality, allowing for simultaneous operation of multiple transmitters, reducing interference, and enabling accurate determination of object information through two-dimensional Fourier transforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple transmitters send signals simultaneously into the monitoring area, then the productivity and detection speed of the radar system are improved, but signal interference occurs between target signals from objects with different velocities at the same distance
Solution Approach 1:
The patent applies parameter changes by assigning different phase shift values to each transmitter signal. Specifically, each transmitter is assigned a unique phase shift amount (e.g., 0°, 45°, 90°, 135°) that modulates the transmitted signal. This parameter differentiation allows multiple transmitters to operate simultaneously while maintaining signal distinguishability, thereby resolving the interference problem while preserving high detection speed.
Solution Approach 2:
The patent employs asymmetry by using different phase shift values for different transmitters rather than uniform phase shifts. The phase shift amounts are specifically chosen to be asymmetric (different from each other), creating unique signal signatures for each transmitter. This asymmetric encoding enables the receiver to distinguish between signals from different transmitters even when they reflect off objects at the same distance, eliminating signal interference while maintaining simultaneous operation.
2Reliability
If phase modulation is applied to encode multiple transmit signals, then signal orthogonality and reduced interference are achieved, but the device complexity increases
Solution Approach 1:
The patent uses parameter changes by modifying the phase parameter of the transmitted signals through phase modulation. Each transmitter applies a specific phase shift value to its signal, creating orthogonal signal patterns. This approach achieves reliable signal differentiation and orthogonality while maintaining relatively simple modulation logic, as it only requires phase angle adjustments rather than more complex modulation schemes.
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 efficiency of radar systems by minimizing signal interference, enabling reliable detection and resolution of object information, particularly in high-resolution scenarios with multiple transmitters.
Implementation Method 1
a radar system, in which at least four transmitters send signals in the form of chirps
Implementation Method 2
at least one first transmit signal and at least three other transmit signals are generated from a frequency-modulated continuous wave signal
Implementation Method 3
at least one receiver, at which at least one object is at least one object, receives the reflected echoes of the signals as received signals
Implementation Method 4
the at least three other transmitted signals are each encoded by means of phase modulation relative to the at least one first transmitted signal, wherein the respective phase positions of the at least three other transmitted signals are incremented or decremented from one chirp to the next by a respective constant phase shift amount
Implementation Method 5
the received signals are subjected to at least one two-dimensional discrete Fourier transform; at least one target signal is determined from the result of the at least one two-dimensional discrete Fourier transform
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
The invention relates to a method for determining at least one piece of object information about at least one object sensed by means of a radar system and to a radar system. According to the method, transmission signals in the form of chirps are transmitted by at least three transmitters in each case in chirp sequences in a monitoring region of the radar system. Echoes of the transmission signals reflected at the at least one object are received as reception signals by means of at least one receiver and, if necessary, are brought into a form that can be used by an electronic control and/or evaluation device. The reception signals are subjected to at least one two-dimensional discrete Fourier transformation. At least one target signal (ZS1_a, ZS2_a, ZS3_a, ZS4_a, ZS1_b, ZS2_b, ZS3_b, ZS4_b) is determined from the outcome of the at least one two-dimensional discrete Fourier transformation. At least one piece of object information is determined from the at least one target signal (ZS1_a, ZS2_a, ZS3_a, ZS4_a, ZS1_b, ZS2_b, ZS3_b, ZS4_b). On the transmitter side, at least one first transmission signal and at least two other transmission signals are generated from a frequency-modulated continuous wave signal and simultaneously transmitted into the monitoring region of the radar system by means of a separate transmitter in each case. The at least two other transmission signals are each encoded by means of a phase modulation in relation to the at least one first transmission signal. The respective phase positions of the at least two other transmission signals are each incremented or decremented from one chirp to the next by a constant phase shift amount. Different phase shift amounts are used for the at least two other transmission signals. The respective phase shift amounts for the at least two other transmission signals are specified such that for at least three of the transmission signals, including the at least one first transmission signal, the differences in amount between the phase shift amounts of two of the at least three transmission signals are different.