FMCW Radar Scanning With Non-Equidistant Sampling for Doppler Ambiguity
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Solution Overview
Problem
Chirp sequence FMCW radars face limitations in Doppler dimension scanning rates, leading to aliasing effects and ambiguous target speed determinations, and suffer from interference issues, especially in MIMO systems, with existing solutions being computationally complex and costly.
Innovation Solution
A radar system employing non-equidistant scanning rates and sweep rates for baseband and frequency-modulated signals, using diverse scanning frequencies and sweep rates to enhance unambiguous target speed determination and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If equidistant time intervals between FMCW signals are used, then computational efficiency is improved, but Doppler scanning rate is limited
Solution Approach 1:
The patent applies non-equidistant time intervals between FMCW signals in a sequence, making the time interval dynamic rather than fixed. This allows the radar system to achieve higher Doppler scanning rates while maintaining target detection capability, resolving the contradiction between computational efficiency and Doppler scanning rate.
Solution Approach 2:
The patent changes the time interval parameter between consecutive FMCW signals from a fixed equidistant value to variable non-equidistant values. This parameter change enables the system to increase the Doppler scanning rate without sacrificing the ability to process signals computationally.
2Productivity
If multiple radars transmit simultaneously, then system productivity is improved, but interference between radars increases
Solution Approach 1:
The patent assigns different non-equidistant time interval patterns to different radar systems, creating local quality differences in their signal sequences. This allows multiple radars to operate simultaneously with reduced mutual interference, as each radar's signal has a unique temporal structure that can be distinguished by receivers.
Solution Approach 2:
The patent establishes predetermined non-equidistant time interval sequences for radar signals before transmission. This preliminary structuring of signal timing allows receiving systems to distinguish between multiple simultaneous radars, reducing interference effects before they manifest as measurement errors.
3Loss of time
If sweep duration is reduced, then measurement time is improved, but hardware complexity increases
Solution Approach 1:
The patent uses periodic FMCW signal sequences with non-equidistant time intervals between repetitions. This periodic structure allows the system to use longer effective measurement times through signal averaging while keeping individual sweep durations short, thereby reducing hardware complexity requirements while maintaining fast measurement capability.
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 efficient, unambiguous target speed determination and reduced interference, allowing computationally efficient processing and simultaneous transmission on multiple channels in MIMO systems.
Implementation Method 1
at least one mixer for mixing the receive signal sequence with the transmit signal sequence and for forming N baseband signals
Implementation Method 2
at least one signal detection device, which is configured to receive (and particularly to detect) a receive signal sequence reflected on an object structure
Implementation Method 3
The speed dimension is also called Doppler dimension (because of Doppler frequency)
Data Source
AI summary
The invention relates to a radar system, particularly a primary radar system, comprising at least one signal generating device (SGEN), which is configured to generate and to emit a transmit signal sequence, at least one signal detection device, which is configured to receive and to detect a receive signal sequence reflected on an object structure, at least one mixer (MIX) for mixing the receive signal sequence with the transmit signal sequence and for forming N baseband signals sb(n, t), where n=1 . . . N, and at least one scanning device (ADC), which is configured to scan the N baseband signals at scanning frequencies fs(n), wherein at least two, preferably at least three, further preferably all of the N scanning frequencies fs(n) differ from each other.