Acoustic signal processing device and method for detecting concentration of trace binary-component gas

Abstract

The invention discloses an acoustic signal processing device and method for detecting the concentration of trace binary-component gas. The method comprises the following steps: a digital signal processor (DSP) controls a programmable logic device (CPLD) to generate pseudorandom phase-coded pulse signal, the signal is divided to two ways and then converted to ultrasonic signals by two ultrasound transmitting transducers, the ultrasonic signals are transmitted simultaneously, the ultrasonic signals separately passes through the clean gas in a measurement cavity and the binary-component gas in another measurement cavity to transmit, an A / D converter is used to convert analog continuous signal to digital discrete signal, the DSP adopts the digital signal processing algorithm for processing, and the concentration of binary-component gas can be calculated according to the formula of gas concentration and phase difference. The device of the invention has simple structure and easy operation, the pseudorandom signal both has high time product and band width product, and the roughly detected time delay and accurately detected phase position are combined together to obtain the accurate measurement result of non-fuzzy phase position, thus increasing the measurement accuracy of the concentration of trace binary-component gas.

Description

technical field The invention belongs to the technical field of gas detection and signal processing, and relates to the electronic detection of gas concentration, in particular to the electronic detection of the concentration of trace binary mixed gas. Background technique At present, spectrometers and other equipment are generally used to detect the concentration of trace binary mixed gases, but the measurement cost is high and cannot be widely used. The patent number is ZL200510037936.2, and the patent titled "Transmitter for Measuring Sulfur Hexafluoride Gas Concentration and Its Measurement Method" is that the synchronously transmitted ultrasonic waves reach the receiving end through two equidistant channels, one channel is a trace SF 6 Mix gas with air; the other channel is air as a reference, measure the phase difference and sound propagation time of the two received signals at the receiving end, and substitute into the formula to calculate sf 6 Gas concentration valu...

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Problems solved by technology

At present, spectrometers and other equipment are generally used to detect the concentration of trace binary mixed gases, but the measurement cost is high and cannot be widely used

The patent number is ZL200510037936.2, and the patent titled "Transmitter for Measuring Sulfur Hexafluoride Gas Concentration and Its Measurement Method" is that the synchronously transmitted ultrasonic waves reach the receiving end through two equidistant channels, one channel is a trace SF 6 Mix gas with air; the other channel is air as a reference, measure the phase difference and sound propagation time of the two received signals at the receiving end, and substitute into the formula to calculate sf 6 Gas concentration value, this measurement method eliminates the need for sound velocity compensation due to changes in ambient temperature, and simplifies the measurement process, but the disadvantages of this measurement method are: 1. The processing signal uses a counter to measure phase and time, and the measurement accuracy is limited Due to the sampling time interval, it is susceptible to interference; 2. Using continuous wave signals or long and short pulse signals, the detection accuracy is low; 3. In order to avoid phase ambiguity, the signal phase difference of the two channels is limited within 360 degrees, and the optional measuring device The length and ultrasonic frequency are limited, which also affects the measurement accuracy

Since the accuracy of acoustically detecting the concentration of trace binary mixed gases is mainly determined by the phase measurement accuracy and the propagation time measurement accuracy, to improve the phase measurement accuracy, it is necessary to use a narrow-band long pulse signal, and to improve the propagation time measurement accuracy, a wide-band short pulse signal is required. For the current common signal measurement, it is contradictory and difficult to implement the method of requiring longer signal duration and wider bandwidth

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