Ultrasonic Sensor Signal-to-Noise Ratio Determination
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Solution Overview
Problem
Existing methods for determining the signal-to-noise ratio of ultrasonic sensor echoes in motor vehicles are inaccurate due to correlation noise, which affects the identification of target echoes and distinguishes them from interference signals.
Innovation Solution
A method that involves encoding transmission signals with a code word, decoding received signals by correlating them with a reference signal, and determining the signal-to-noise ratio by analyzing noise within specific segments of the correlation signal, ignoring correlation noise to obtain the actual noise level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If correlation decoding is used to decode received signals, then signal identification capability is improved, but correlation noise increases and degrades signal-to-noise ratio measurement accuracy
Solution Approach 1:
The correlation signal is divided into multiple signal segments in the time domain. The noise value is determined by analyzing only the signal segment containing the target echo, while excluding other segments that contain correlation noise. This segmentation allows the system to isolate the relevant signal information from the harmful correlation noise, thereby maintaining accurate signal-to-noise ratio measurement while preserving signal identification capability.
2Reliability
If correlation decoding is applied to distinguish target echoes from interference signals, then signal discrimination ability is improved, but measurement accuracy deteriorates due to correlation noise influence
Solution Approach 1:
The invention extracts and removes the harmful correlation noise from the correlation signal by identifying and excluding the signal segments containing correlation noise. Only the signal segment with the target echo is used for noise value determination. This extraction process separates the useful signal discrimination information from the harmful correlation noise, enabling accurate measurement while maintaining signal discrimination ability.
Solution Approach 2:
The invention applies local quality analysis by examining different segments of the correlation signal with different characteristics. The signal segment containing the target echo has different properties (higher amplitude, specific temporal pattern) compared to segments containing correlation noise. By focusing the noise value determination on the specific local region with the target echo, the system achieves accurate measurement without being degraded by correlation noise present in other regions.
3Ease of manufacture
If the entire correlation signal is used to determine noise value, then computational simplicity is maintained, but measurement accuracy is degraded due to inclusion of correlation noise
Solution Approach 1:
The correlation signal is segmented into multiple time-domain segments, and the noise value is determined by analyzing only the specific segment containing the target echo rather than the entire signal. This selective analysis reduces the amount of data processing required compared to analyzing the complete correlation signal, while simultaneously improving measurement accuracy by excluding correlation noise from other segments.
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 precise determination of the signal-to-noise ratio, improving accuracy in identifying target echoes and distinguishing them from interference, without the influence of correlation noise, enabling reliable detection of vehicle-external objects.
Implementation Method 1
The ultrasonic sensors operate on the basis of the echo delay principle: the distance measurement is effected using ultrasonic technology by means of an echo delay method or echo sounding method
Implementation Method 2
the ultrasonic sensor transmits a transmission signal—ultrasound—and receives a received signal, which is the transmission signal reflected by a vehicle-external object
Implementation Method 3
a predetermined code word is impressed on the transmission signal, for example using modulation
Implementation Method 4
The received signal is decoded by correlating same received signal with a reference signal and this correlation provides a correlation signal
Implementation Method 5
the relative speed between the motor vehicle and the object causes a frequency shift in the ultrasonic signal on account of the Doppler effect
Data Source
AI summary
The invention relates to a method for determining the signal-to-noise ratio (20) of a target echo (11) from a received signal (UE) received from an ultrasonic sensor (3) of a motor vehicle (1), in which: a transmission signal is transmitted in encoded form, the received signal (UE) is decoded and decoding involves the received signal (UE) being correlated with a reference signal and the correlation provides a correlation signal (UK), and the target echo (11) is detected in the correlation signal (UK), wherein the signal-to-noise ratio (20) is determined by determining a value (21) of the noise in the received signal (UE) on the basis of the correlation signal (UK) and, in so doing, dividing the correlation signal (UK) into a multiplicity of signal segments (17a to 17e) and determining the value (21) of the noise solely on the basis of signal values for that one of the signal segments (17a to 17e) that contains the target echo (11).