Distance Sensor Noise Injection for Echo Discrimination
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Solution Overview
Problem
Conventional distance-measuring sensors face challenges in accurately distinguishing between true echoes and interfering signals, especially in noisy environments, due to the limitations of 1-bit A/D conversion which destroys signal information and makes it difficult to differentiate weak echoes from noise or objects.
Innovation Solution
The introduction of a noise generator that adds an artificial noise signal to the reception signal before digitization, allowing the sensor to adjust its sensitivity and reliably distinguish between interfering echoes and true echoes by modifying the histogram accumulation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If 1-bit A/D conversion is used to reduce hardware cost, then device complexity is reduced, but measurement precision deteriorates because signal information is destroyed and weak echoes cannot be distinguished from noise
Solution Approach 1:
The patent applies preliminary action by adding artificial noise to the reception signal before A/D conversion. This pre-processing step modifies the signal characteristics in advance, enabling the subsequent 1-bit converter to preserve sufficient information for distinguishing weak echoes from interference. The noise addition occurs before the irreversible quantization process, thereby preventing information loss.
Solution Approach 2:
The patent changes the parameter of the reception signal by adding artificial noise with specific statistical properties (Gaussian distribution, controlled standard deviation). This parameter modification transforms the signal distribution to optimize the performance of 1-bit quantization, allowing the system to maintain measurement precision while using low-cost hardware.
2Device complexity
If conventional pulse methods with comparator threshold are used, then device complexity is reduced, but reliability deteriorates in noisy environments where interference signals cannot be distinguished from weak echoes
Solution Approach 1:
The patent introduces artificial noise as an intermediary element that mediates between the weak echo signal and the binary quantization process. This intermediary noise modifies the probability distribution of the quantized values, creating a statistical signature that allows reliable distinction between echoes and interference through histogram analysis, without requiring complex real-time signal processing.
Solution Approach 2:
The patent implements feedback through histogram accumulation and analysis. The system accumulates quantized signal values over multiple pulses, builds a histogram distribution, and uses this statistical feedback to determine the presence of echoes. This feedback mechanism enables reliable detection in noisy environments by distinguishing echo patterns from random interference based on their statistical properties.
3Measurement precision
If statistical evaluation with histogram accumulation is used to improve signal-to-noise ratio, then measurement precision is improved, but device complexity increases due to requirements for high-speed A/D converters and complex evaluation electronics
Solution Approach 1:
The patent replaces expensive, high-performance A/D converters with inexpensive 1-bit quantizers. Instead of relying on high-resolution single-shot conversion, the system uses multiple low-resolution measurements that are accumulated statistically. This substitution of cheap, simple components for expensive complex ones achieves the same measurement precision through statistical processing.
Solution Approach 2:
The patent performs preliminary noise addition before quantization to ensure that the 1-bit converter operates in an optimal regime. This pre-processing prepares the signal in advance so that simple binary quantization followed by histogram accumulation achieves signal-to-noise improvement without requiring complex real-time evaluation electronics.
4Reliability
If artificial noise is added to the reception signal, then reliability is improved by enabling distinction between interfering and true echoes, but device complexity increases due to the noise generator component
Solution Approach 1:
The patent makes the system self-service by generating the artificial noise internally within the sensor device. The noise generator is integrated into the signal processing chain, and the system uses its own resources to create the necessary noise signal, eliminating the need for external noise sources or complex post-processing additions. The noise is generated, added, and utilized entirely within the device.
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 enhances the sensor's ability to robustly differentiate between interfering and true echoes, reducing measurement errors and preventing false shut-downs, thereby improving the overall reliability and availability of the sensor.
Implementation Method 1
a signal time of flight principle, wherein the time interval between transmission and reception of a signal is converted into a distance by means of the signal speed
Implementation Method 2
a noise generator configured to add a noise signal to the reception signal prior to its digitization in the A/D converter
Data Source
AI summary
A distance measuring sensor (10) for a detection and distance determination of objects (18) in a monitoring area, the sensor (10) having a transmitter (12) for transmitting transmission pulses, a receiver (20) for generating a reception signal from transmission pulses remitted from the monitoring area, an A/D converter (38) for digitizing the reception signal, and a control and evaluation unit (28, 30), which is configured to transmit a plurality of transmission pulses via the transmitter (12), to accumulate the respective reception signals generated by the receiver (20) in a histogram (110), and to determine, from the histogram (110), a reception point in time and thus a measurement value for the signal time of flight from the sensor (10) to the object (18), wherein the sensor (10) comprises a noise generator (40) configured to add a noise signal to the reception signal prior to its digitization in the A/D converter (38).