Design Of Wireless Sweep Si-B-C-N Temperature Sensor Signal Detection System Based On LabVIEW

Si-B-C-N temperature sensor is a wireless passive sensor that is made of PDC high temperature ceramic matrix.It is based on the principle of microwave resonator.When the ambient temperature changes,the dielectric constant of the sensor will change,which causes the resonant frequency of the internal cavity to shift.In this thesis,designed a set of wireless sweep signal Si-B-C-N temperature sensor signal detection system based on LabVIEW for testing the coupling relationship between resonant frequency and ambient temperature,according to the basic working principle of Si-B-C-N temperature sensor combine with microwave transmission/reflection measurement method.In this thesis,using graphical programming language control NI PXIe-5644 R vector signal generator(VSG),NI PXIe-5665 vector signal analyzer(VSA)and NI PXIe-6363 data acquisition card(DAQ)and other hardware to make a program design by using of virtual instrument technology.In hardware,the system consists of sweep signal generation module,transmission channel conversion module,echo signal receiving module and real-time temperature acquisition module.Adopting LabVIEW software control VSG sent 5.5~5.8GHz band constant frequency signal,generated 11.0~11.6GHz band constant sweep signal after making the frequency twice times by HMC573LC3 B frequency multiplier in the sweep signal generation module.The swept signal is transmitted to the Si-B-C-N temperature sensor in a way of wired to wireless through the three-port ring and coaxial waveguide converter in the transmission channel conversion module.The sensor feeds back the echo signal to the coaxial waveguide after time delay.the echo signal is received and taken high speed AD sample by the echo signal receiving module.The real-time temperature acquisition module collects the real-time temperature corresponding to the resonant frequency of the Si-B-C-N temperature sensor.In software,obtaining the echo frequency of the Si-BCN temperature sensor at different temperatures after performing the singularity and Butterworth filtering to the received echo signal.Obtaining the real-time temperature of sensor after making median filter and mean processing to the real-time temperature data collected.After obtaining the sensorresonant frequency and real-time temperature information,the relationship between the resonant frequency of the Si-B-C-N temperature sensor and the real-time temperature is obtained by using the resonant frequency-real-time temperature fitting in the way of least squares method and Bisquare method.After the local debugging of the swept signal source,the echo signal and the real-time temperature acquisition and processing,and the resonant frequency-real-time temperature fitting module are completed,wireless sweep signal Si-B-C-N temperature sensor signal detection system based on LabVIEW is carried out system joint debugging finally.The results of experiment show that the response time of the Si-B-C-N temperature sensor is 12 us nearly.The resolution of the Si-B-C-N temperature sensor is 0.0024?/kHz and the signal detection system has a measurement accuracy of 1.2? in the range of 30 ?~350 ?.