Correlation Detection Circuit for Ultrasonic Echo Cross-Talk Rejection
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Solution Overview
Problem
In ultrasonic distance measurement systems, interference from multiple transmitters operating nearby each other causes cross talk and autocorrelation noise, making it difficult to reliably determine the distance to objects using echo detection in applications like vehicle collision avoidance and parking assistance.
Innovation Solution
Implementing a unique modulation code for each transmitter and using a correlator with a reference signal generation technique to detect echoes, where the correlator compares the received signal with the modulation pattern, and a confidence reference level is generated to suppress noise and accurately identify echoes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple ultrasonic transmitters operate nearby each other, then coverage area and detection capability are improved, but cross talk and interference increase making distance determination difficult
Solution Approach 1:
The patent segments the ultrasonic transmission by assigning unique modulation codes to different transmitters. Each transmitter operates in the same frequency range but uses distinct coded sequences, allowing receivers to identify and process only the intended transmitter's signal while filtering out others, thus maintaining reliable distance measurement across multiple concurrent transmitters
Solution Approach 2:
The patent changes the modulation parameter of the ultrasonic signals by using different modulation codes for different transmitters. This parameter differentiation allows multiple transmitters to coexist without interference, as each receiver can selectively detect signals matching its assigned code while rejecting others, resolving the contradiction between expanded coverage and measurement reliability
2Productivity
If multiple transmitters operate concurrently, then system productivity and detection speed are improved, but cross correlation noise and false detection increase
Solution Approach 1:
The patent segments the signal space by assigning unique modulation codes to different transmitters. This segmentation allows concurrent operation of multiple transmitters without cross correlation noise, as each receiver can selectively process only its designated transmitter's signal, maintaining high detection speed while eliminating false detections
Solution Approach 2:
The modulation code acts as an intermediary that enables multiple transmitters to operate concurrently without interference. By embedding unique codes in each transmitter's signal, the system allows simultaneous high-speed detection while the codes serve as mediators that prevent cross correlation noise and false detections
Data Source
AI summary
In an embodiment a semiconductor device correlates a received signal with a known pattern. A correlation output is used as a basis for forming a confidence reference level. The confidence reference level and the correlation output are compared to identify a peak in the received signal indicating that a present signal state of the received signal contains the known pattern.