Interleaved Radar Signals for Unambiguous Speed and Distance
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Solution Overview
Problem
Existing radar systems for detecting road users and vehicle relative speed face ambiguities in distance measurement due to the Doppler effect when objects are moving, requiring multiple signal periods and complex evaluation processes, which prolong measurement time and demand significant computational resources, especially in complex traffic scenarios.
Innovation Solution
The method involves emitting two interleaved signals with zero frequency difference between their signal sections, allowing parallel ambiguity lines in the distance/speed coordinate system, enabling direct and unambiguous relative speed determination and subsequent distance calculation, simplifying evaluation without extending measurement time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple signal periods are used to eliminate ambiguities in distance measurement, then measurement precision is improved, but measurement time increases
Solution Approach 1:
The radar signal is divided into multiple signal periods, each with different chirp slopes. By segmenting the measurement into multiple phases with distinct signal characteristics, the system can resolve distance-speed ambiguities more efficiently than using a single long measurement period, thereby reducing total measurement time while maintaining precision.
Solution Approach 2:
The system employs periodic transmission of chirp signals with varying slopes across different periods. This periodic action with systematic variation allows the radar to accumulate unambiguous distance and speed information through multiple cycles, achieving high measurement precision without requiring excessively long continuous measurement times.
2Measurement precision
If multiple signal periods with different chirp slopes are used to resolve ambiguities, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system dynamically adjusts the chirp slope for each signal period based on a predefined sequence. This dynamic variation in signal parameters allows the radar to encode multiple measurement dimensions (distance and speed) into the temporal structure of the signals, enabling high measurement precision while keeping the transmitter and receiver hardware relatively simple.
Solution Approach 2:
The invention changes the chirp slope parameter systematically across different signal periods. By varying this key signal parameter in a controlled manner, the system can disambiguate distance and speed measurements without requiring complex additional hardware, thus improving measurement precision with moderate increases in control and evaluation complexity.
3Measurement precision
If complex evaluation processes are used to handle multiple signals, then measurement precision is improved, but computational resources required increase
Solution Approach 1:
The system performs preliminary correlation processing between received signals and locally generated reference chirp signals to extract phase information before conducting full ambiguity resolution. This preliminary action pre-processes the data in a way that simplifies subsequent computational steps, reducing the overall computational power needed while maintaining high detection precision.
Solution Approach 2:
The evaluation process uses copied reference chirp signals (locally generated copies of transmitted signals) to perform correlation and phase extraction. By comparing received signals against these precise local copies, the system can accurately determine object distance and speed with relatively simple computational operations, avoiding the need for complex algorithms.
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 allows for simplified and efficient evaluation of relative speed and distance, reducing computational demands and measurement time, even in complex situations, using two interleaved signals, which is sufficient for most cases, and enhances the sensitivity of speed determination.
Implementation Method 1
a plurality of objects be reliably detected and that it is also possible to assign said objects a correct relative speed
Implementation Method 2
it is possible to determine the transit time of the emitted, reflected and once more received signal, from which a determination of distance results
Data Source
AI summary
The invention relates to a method for determining the distance (R) and relative speed (v) of at least one object remote from an observation point, comprising the following method steps: continuous transmission of at least one first and one second electromagnetic signal in each case of a signal period (Tchirp) from the observation point; the signals consist of signal portions (bursts) having a constant frequency and a predetermined equal duration, wherein the signal portions of a signal cover a predetermined modulation range by means of frequency steps; the signals are transmitted interlaced in that signal portions of the different signals follow one another in time, wherein a frequency hop occurs between the successive signal portions of different signals, receiving the signals reflected by the object as an echo signal and carrying out a mixed operation with the transmission signal for transformation of the received signal into the baseband in a common analog channel; carrying out an analog-to-digital conversion and sampling the received signal portions of the echo signals and extraction of at least one sampling value for each signal portion; separately evaluating the sampling values for the different echo signals of the different emitted signals by means of a Fourier transformation stage and determining the frequency of the peaks corresponding to signal portions and determining a phase difference between the echo signals of the transmitted signals, characterised in that the signal portions of the second signal (B) are transmitted by means of the same frequencies as corresponding signal portions of the first signal (A).