Wireless measurement system and measurement method of multi-node resonant surface acoustic wave sensor

Abstract

The invention discloses a wireless measuring system and measuring method for a multi-node resonant surface acoustic wave sensor. The wireless measuring system is characterized in that corresponding tothe frequency band of each resonant surface acoustic wave sensor, a reader transmitting circuit transmits excitation signals of multiple frequency bands at the same time through a plurality of localoscillation sources to simultaneously measure the resonance frequencies of a plurality of sensors. Moreover, a reader receiving circuit directly performs the band-pass sampling on the amplified and filtered radio frequency echo signals, and then performs frequency-domain interpolation on the Fourier-transformed echo spectrum information. Compared with the conventional reader that measures the resonant frequency of each sensor with a single local oscillation source by polling, the measurement real-timeness is greatly improved, and the measurement precision is improved by a frequency-domain interpolation method. Besides, because the reader receiving circuit adopts the direct band-pass sampling method of the radio frequency signal, the down-conversion circuit is not needed, not only the structure is simple and the cost is low, but also the signal-to-noise ratio is improved.

Description

Technical field: [0001] The invention relates to a wireless measuring system and a measuring method of a multi-node resonant surface acoustic wave sensor, belonging to the field of wireless sensing. Background technique: [0002] Surface acoustic wave devices can be used as sensors, which can be divided into two types: resonant type and delay type in terms of structure, as figure 1 with figure 2 shown. The resonant surface acoustic wave device is composed of a piezoelectric substrate, an interdigital transducer, and a reflective grating. The reflective gratings at both ends of the interdigital transducer are arranged in a dense array to form an acoustic resonant cavity. The delayed surface acoustic wave device is composed of a piezoelectric substrate, an input interdigital transducer, and an output interdigital transducer. When the surface acoustic wave device is used as a sensor, the surface acoustic wave propagation velocity and piezoelectric material parameters change...

AI Technical Summary

Problems solved by technology

When the number of nodes is large, the polling time becomes longer, which affects the real-time performance of the measurement

[0007] (2) For differential nodes, due to the time difference between the polling method and the measurement of two differential sensors, in the case of rapid changes in the object to be measured, not only will the measurement result have a large error, but also cannot accurately monitor the The dynamic change process of the measured object

[0008] (3) The traditional reader receiving link usually adopts a down-conversion structure, which not only has a complex circuit structure and high cost, but also has problems such as increased noise and reduced signal-to-noise ratio

For the method of Fourier transform spectrum measurement, due to the limitation of spectrum resolution, the estimation accuracy of resonance frequency is low; if the resonance frequency estimation method of frequency sweep measurement intensity is used, it is necessary to improve the estimation accuracy by subdividing the step frequency. Then the polling time of multiple nodes will be dramatically longer, and the real-time performance of the measurement will be further affected

Images