Ultrasonic distance measuring algorithm based on digital filtering and digital envelope extraction

Abstract

The present invention provides an ultrasonic distance measuring algorithm scheme suitable for engineering application and based on digital filtering and digital envelope extraction. A Butterworth IIRdigital band-pass filtering algorithm is employed at an output end of an ADC; an output portion of the digital band-pass filtering algorithm is taken as input of a rectifier algorithm, and the rectifier algorithm is employed to filter signals located at a negative half axis in echoes and remain signals located at a positive half axis; and an envelope detection algorithm is employed at an output ofthe rectifier algorithm, the envelope detection algorithm and a downsampling algorithm are commonly configured to extract envelope information of the positive half axis, and a Butterworth IIR digitallow-pass filtering algorithm is employed at a comprehensive output of a filtering and envelope extraction algorithm to filter Gaussian noise. The algorithms mentioned above comprises five concrete steps that: the Butterworth IIR digital band-pass filtering algorithm, the rectifier algorithm, the envelope detection algorithm, the downsampling algorithm and the Butterworth IIR digital low-pass filtering algorithm. Signal processing can be performed at an internal portion of a main control chip without the help of external processing devices, a point tracing method configured to calculate echo transition time and a threshold point tracing integration algorithm are provided through combination of features of the integration algorithm, and the two algorithms are employed to accurately record echo arrival time and save peripheral equipment resources of a main controller.

Description

Technical field: [0001] The invention proposes an ultrasonic ranging method of digital filtering and digital envelope extraction, which is used to improve the accuracy of the ranging system. The processing method adopts full digitization, envelope digital filtering, digital extraction envelope, and digital peak point search. It is suitable for reversing radar, drones, sweepers and other fields. Background technique: [0002] 1. Ultrasonic energy consumption is slow during the transmission process, and it propagates in a straight line. When it encounters obstacles, it will be diffracted and reflected. It has high adaptability to extreme external environments such as haze weather, sandstorm weather, rain and snow weather; At the same time, ultrasonic waves are not affected by the transmission medium, can propagate in gas, liquid, and solid, and can transmit a long distance in the medium, which is an ideal measurement medium for distance measurement systems. [0003] 2. The b...

AI Technical Summary

Problems solved by technology

[0003] 2. The band-limiting filter and envelope detection in the traditional ultrasonic ranging system are designed as the hardware circuit of the resistance-capacitance coupling circuit. Instability, it is difficult to be used in actual engineering production

At the same time, if the center frequency of the ultrasonic ranging system changes, the internal resistors and capacitors need to be replaced again, which is inconvenient for the integrated ranging system and increases the hardware cost

The traditional envelope detection algorithm is processed by the correlation operation of the pseudo-random sequence. Considering the complexity of FFT and other operations in the correlation operation and the symbol length of about 500μs, it is not suitable for short-range embedded ranging systems

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