Integrated microwave sensors for cavity-length measurement in machine engineering

Megej, A.; Beilenhoff, K.; Schüßler, Martin; Ziroff, Andreas; Mottet, B.; Yilmazoglu, Oktay; Mutamba, K.; Hamann, Claudia; Baican, R.; Hartnagel, H.L.

doi:10.1109/tmtt.2002.805148

Cited by 5 publications

(1 citation statement)

References 7 publications

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“…Ranging and thermometry methods based on laser [ 1 , 2 ] and imaging [ 3 , 4 ] technologies are constrained because light can only travel in straight line, so it is unsuitable for lengthy, curved underground pipeline applications. Ultrasonic and microwave ranging [ 5 , 6 ] and thermometry [ 7 , 8 ] methods require considerable power for long-distance measurements due to their shorter wavelengths and faster attenuation, while increased power means an increased size of the sensor, and hence they are inconvenient for such application, particularly for small diameter conduits. The acoustic method has its advantages over the mentioned techniques above.…”

Section: Introductionmentioning

confidence: 99%

A Time-of-Flight Estimation Method for Acoustic Ranging and Thermometry Based on Digital Lock-In Filtering

Liu

Zhou

Zhang

et al. 2022

Sensors

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Accurate ranging and real-time temperature monitoring are essential for metrology and safety in electrical conduit applications. This paper proposes an acoustic time-of-flight (TOF) estimation method based on the digital lock-in filtering (DLF) technique for conduit ranging and thermometry. The method establishes the relationship between the frequency and the time domain by applying a linear frequency modulated Chirp signal as the sound source and using the DLF technique to extract the first harmonic of the characteristic frequencies of the transmitted and received signals. Acoustic TOF estimation in the conduit is then achieved by calculating the mathematical expectation of the time difference between each characteristic frequency in the time-frequency relationship of the two signals. The experimental results with enhanced noise interference on different conduit lengths and various temperature conditions, proved that the proposed DLF method can establish a robust linear time-frequency relationship according to the characteristics of the Chirp signal, and the measurement accuracy of TOF has also been confirmed. Compared to the conventional method, the DLF method provides the lowest absolute error and standard deviation for both distance and temperature measurements with an enhanced robustness.

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