Fast Frequency Hopping Radar Waveforms with Continuous Phase Modulation
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Solution Overview
Problem
Radar systems face performance degradation due to external interference and power coupling issues, particularly in automotive and robotic applications, where conventional step frequency waveforms are inadequate in managing high power interference and multiple antenna support.
Innovation Solution
A radar system that transmits and receives a specific waveform with a frequency generation method and modulation techniques to enhance robustness against interference, using random permutation patterns and continuous phase modulation to suppress auto-correlation sidelobes and power saturation, and incorporates filter bank receivers with both analog and digital components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional step frequency waveforms are used, then the radar system is simple to implement, but the system performance degrades due to external interference and power coupling issues
Solution Approach 1:
The patent implements dynamic frequency hopping where the radar waveform continuously changes frequency across multiple sub-bands according to a pseudo-random pattern. This dynamic frequency variation allows the system to avoid interfering signals by hopping to clean frequency sub-bands, thereby improving robustness against external interference while maintaining manageable system complexity through structured frequency management.
Solution Approach 2:
The patent changes the frequency parameter dynamically by dividing the total bandwidth into multiple sub-bands and selectively activating different sub-bands based on a pseudo-random hopping pattern. This parameter change approach enables the radar to adapt to interference conditions by switching frequency sub-bands, improving reliability without requiring complete system redesign.
2Measurement precision
If high power is used to improve signal detection, then detection capability improves, but power coupling issues and nonlinearities increase
Solution Approach 1:
The patent segments the total frequency bandwidth into multiple independent sub-bands. By transmitting signals in distributed frequency sub-bands rather than concentrating power in a single frequency, the system achieves better detection capability through frequency diversity while reducing power coupling effects. The segmentation of frequency resources allows high total power to be distributed across multiple sub-bands, mitigating nonlinearities in the transmit signal path.
Solution Approach 2:
The patent introduces frequency hopping as an intermediary mechanism between the transmitter and receiver. The pseudo-random frequency pattern acts as a mediator that separates the transmitted and received signals in frequency domain, allowing high power transmission while using the known frequency pattern to correlate and recover the signal at the receiver, thereby managing power coupling issues.
3Reliability
If frequency hopping is implemented to avoid interference, then robustness improves, but phase discontinuities cause nonlinearities in the transmit path
Solution Approach 1:
The patent implements periodic frequency hopping where the radar systematically cycles through different frequency sub-bands in a predetermined pseudo-random pattern. This periodic structure ensures that frequency transitions occur at regular intervals with controlled phase relationships, maintaining phase continuity across frequency hops. The periodic nature allows the system to achieve interference avoidance through frequency diversity while managing phase discontinuities through structured transition management.
4Ease of manufacture
If simple frequency tones are used at each step, then the waveform generation is simple, but auto-correlation sidelobes and cross-correlation between multiple antennas increase
Solution Approach 1:
The patent combines multiple frequency tones within each sub-band to create composite waveforms. Instead of using simple single-frequency tones, the system transmits composite signals that occupy multiple frequency components within each sub-band. This composite approach reduces auto-correlation sidelobes and improves cross-correlation performance between multiple antennas while maintaining relatively simple waveform generation through structured frequency composition.
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
The solution provides robustness against unpredictable and high-power interference, improving transmitter amplifier performance and enabling more effective receiver designs, while maintaining power saturation and reducing nonlinearities in the transmit signal path.
Implementation Method 1
The continuous phase characteristic allows for power saturation of the transmitter amplifiers and less nonlinearities from the entire transmit signal path
Implementation Method 2
the radar system uses a radar waveform used to modulate a random differential to the phases between each step of the frequency generator. These random differential phases (or phase transitions) suppress auto-correlation sidelobes between delays of the frequency patterns or cross-correlation between multiple transmitted patterns
Implementation Method 3
an exemplary radar system includes filter bank receivers with both analog and digital components constituting the filter bank
Data Source
AI summary
A radar system that uses fast frequency hopping transmit waveform and filter bank receiver consisting of both analog and digital components. The waveform steps discrete frequency tones with short duration and modulates a continuous phase signal on each tone. The frequency hopping patterns are generated using pseudo-random permutation or low-collision method of anti-causal code shifting. To process waveform at radar receiver, a filter bank is used with squelching switches and controls to reduce distortion from strong signal into the receiver. Using the Strong Return Estimator, the timing of the strong signal is used to control the squelching switches.