CDMA Radar Transmission Scheme for Object Detection
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Solution Overview
Problem
Existing radar systems using code division multiple access (CDMA) struggle to distinguish between objects traveling at similar velocities and ranges, leading to masked reflections that hinder accurate detection.
Innovation Solution
A transmission scheme employing a plurality of CDMA radar system transmitters that linearly increase the time duration between sequential transmissions, using frequency modulated continuous wave (FMCW) signals and Hadamard or pseudorandom codes, allowing for improved separation of reflections by processing reflected energy as vectors and decoding every M elements together.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CDMA radar systems use conventional transmission schemes, then multiple transmitters can simultaneously transmit signals, but reflections from objects at similar velocities and ranges become masked and cannot be distinguished
Solution Approach 1:
The patent applies dynamics by making the time duration between sequential transmissions variable rather than constant. Specifically, the time duration is linearly increased across different transmission sequences, creating a dynamic transmission pattern that allows differentiation between reflections from objects at similar velocities and ranges, thereby resolving the masking problem while maintaining simultaneous transmission capability
Solution Approach 2:
The patent changes the parameter of time duration between transmissions from a fixed value to a variable value that increases linearly. This parameter change enables the radar system to distinguish between reflections that would otherwise be masked, improving object detection accuracy while preserving the productivity benefit of simultaneous multi-transmitter operation
2Device complexity
If the time duration between sequential transmissions is kept constant, then the transmission pattern is simple, but reflections from objects with similar characteristics cannot be separated
Solution Approach 1:
The patent introduces dynamics to the transmission pattern by making the time duration variable rather than constant. This dynamic adjustment of time duration provides the necessary complexity to separate reflections from objects with similar characteristics, improving range rate discrimination without excessive complexity
3Productivity
If multiple transmitters transmit simultaneously, then the radar coverage and detection capability are enhanced, but sidelobe interference increases and masks reflections
Solution Approach 1:
The patent uses dynamics by varying the time duration between transmissions to create a pattern that reduces sidelobe interference. The linearly increasing time duration causes sidelobes to appear at different times, reducing their interference with target reflections and enabling better detection coverage from multiple transmitters
Solution Approach 2:
The patent converts the harmful effect of increased transmission density (which causes sidelobe interference) into a benefit by using the variable time duration to spread out sidelobes in time. This allows the system to maintain enhanced radar coverage while reducing the masking effect of sidelobe interference through temporal separation
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
Facilitates the detection of objects at similar ranges and velocities by reducing sidelobe interference, enhancing angular resolution and range rate discrimination, thereby improving the accuracy of object detection in radar systems.
Implementation Method 1
the frame of the transmit signals transmitted by each of the plurality of transmitters is based on a same chirp, which is a frequency modulated continuous wave (FMCW) signal
Implementation Method 2
a receiver of the CDMA radar system to receive reflected energy resulting from reflection of one of more of the transmit signals of one or more of the plurality of transmitters by an object
Data Source
AI summary
A vehicle includes a plurality of transmitters of a code division multiple access (CDMA) radar system to simultaneously transmit a frame of transmit signals. A first time duration between transmissions of a first pair of sequential ones of the transmit signals is linearly increased to a second time duration between transmissions of a second pair of sequential ones of the transmit signals. The vehicle also includes a receiver of the CDMA radar system to receive reflected energy resulting from reflection of one of more of the transmit signals of one or more of the plurality of transmitters by an object. A controller processes the reflected energy to obtain information about the object and to control an operation of the vehicle based on the information.