Automotive Radar Range Resolution via Orthogonal Code Segmentation
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Solution Overview
Problem
Automotive radar systems face limited range resolution due to the sampling rate constraints of conventional analog-to-digital converters, which is a challenge in applications requiring high precision, such as parking assistants and occupant detection.
Innovation Solution
The method involves modulating continuous radar waves with orthogonal codes and transmitting them with a constant time lag, allowing for improved range resolution by digitally converting received signals at a sampling rate equal to the modulation frequency, and decoding individual range information to determine the distance between the radar system and objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional analog-to-digital converters with standard sampling rates are used, then device complexity and cost are reduced, but range resolution is limited
Solution Approach 1:
The patent segments the radar signal into multiple orthogonal codes (e.g., first code, second code, third code) that are transmitted sequentially with time lags. Each code is processed separately through its own ADC path, allowing the system to achieve fine range resolution by analyzing the time lags between code receptions rather than requiring a single high-speed ADC to capture all details simultaneously.
Solution Approach 2:
The patent employs periodic transmission of orthogonal codes in a sequential manner, where each code is transmitted after a specific time lag. This periodic segmentation of the signal allows the ADC to operate at standard sampling rates while the range resolution is enhanced through the periodic structure and correlation analysis of the transmitted and received codes.
2Measurement precision
If multiple orthogonal codes are transmitted sequentially with time lags, then range resolution is improved by a factor of n, but transmission time is increased
Solution Approach 1:
The patent performs preliminary modulation of orthogonal codes onto radar waves before transmission. By pre-encoding the time lag information into the orthogonal code structure, the system eliminates the need for post-transmission time measurement, thereby reducing overall processing time while maintaining the range resolution enhancement.
Solution Approach 2:
The patent creates multiple copies of the radar signal, each modulated with different orthogonal codes and transmitted with specific time lags. These copies are then processed in parallel through separate ADC paths, allowing the system to achieve high range resolution without requiring all copies to be transmitted simultaneously, thus managing transmission time effectively.
Data Source
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AI summary
A method of operating a modulated continuous-wave radar system at least comprises steps of transmitting (38), with a modulation frequency, a plurality of n modulated continuous radar waves that represent mutually orthogonal codes towards a scene with a potential object to be detected, wherein the transmitted modulated continuous radar waves of the plurality of modulated continuous radar waves are consecutively transmitted with a constant time lag (τ) given by one nth of a period of the modulation frequency; digitally converting (44) a plurality of reflected and received radar signals with a sampling rate (l/ts) that is equal to the modulation frequency; decoding (46) individual range information for each received radar signal; and determining (48) a range between the radar system and the object on the basis of the decoded individual range information.