本論文主要目標是建構一個高精確度的超音波距離量測系統，使用雙頻率調制波，結合飛行時間法和相位差法兩種方法，其量測原理類似尺之量測，以飛行時間法測得粗值，再以相位差法作刻度細分及修正，以達到高精確度及高解析度的距離量測。因聲波的傳播速度易受到環境溫度的影響而改變，因而距離量測的準確度降低，如果要得到高精準度的距離量測，則必需依照環境的溫度作校正，所以本論文又發展了一套高精確的溫度量測系統配合超音波測距系統作溫度補償校正，以達到高精確的距離量測值。
首先描述的是以雙頻率調制的超音波距離量測系統及其設計方法，此測距系統使用了一個結合飛行時間法和相位差法的高效率演算法，此演算法兼俱飛行時間法和相位差法兩者的優點，可得到比飛行時間法更準確及比相位差法更遠的距離量測。此測距系統以單晶片微電腦為基礎的雙頻率調制訊號產生器及相位偵測器來記錄及計算飛行時間和兩個相位差，並將量測的距離顯示于LCD或PC，PC只用於校正系統。實驗是在等溫的空氣中進行，以40 kHz及41 kHz為調制頻率，解析度為頻率40 kHz波長的0.05％，實驗的距離範圍超過6000 mm，可得到0.05 mm的準確度。此超音波測距系統的主要優點為高解析度，使用低成本的窄頻寬超音波發射及接收器，並且容易實現與操作。
再描述補償用之溫度量測系統，此系統使用一個時間領域的溫度感測器，可直接將溫度值轉換成相對應的工作週期，本溫度量測系統乃利用此特性，而提出以雙鎖相迴路為主的新設計方法，此雙鎖相迴路的工作原理是模擬游標尺的操作方法來量測工作週期，可消除傳統使用計數器時的一些誤差及在不增加量測脈波頻率下，得到較高的解析度，並以單晶片微電腦去讀取和計算工作週期，如此，溫度值即可很容易借由工作週期量測而求得，並將結果傳送到LCD上顯示。由實驗得到的結果，其解析度為工作週期的1/65280和最大溫度量測誤差為 ±0.05 ℃ 在 -25.5 ℃ 到 102 ℃ 之間，此溫度量測系統主要優點為高解析度、高精確度和低成本。

The main aim of this dissertation is to design a highly accurate ultrasonic distance measurement system. The principle of the ranging system is similar to the operation of using a ruler. At first a coarse measurement is done by time-of-flight (TOF) method, and then a fine measurement by phase shift method is adopted to refine the final result. The sound wave propagation speed in the air depends on the temperature. So, to measure the distance more correctly, it is necessary to revise according to the temperature. Therefore, an accurate temperature measurement system is designed in order to increase the accuracy of the distance measurement for the UDMS.
At first, a highly accurate binary frequency shift-keyed (BFSK) ultrasonic distance measurement system (UDMS) for use in isothermal air is described. This system presents an efficient algorithm which combines both the time-of-flight method and the phase-shift method. The proposed method can obtain larger range measurement than the phase-shift method and also get higher accuracy compared with the TOF method. A single-chip microcomputer-based BFSK signal generator and phase detector was designed to record and compute the TOF, two phase shifts and the resulting distance, which were then sent to either an LCD for display or a PC for calibration. Experiments were done in air using BFSK with the frequencies of 40 and 41 kHz. Distance resolution of 0.05％ of the wavelength corresponding to the frequency of 40 kHz was obtained. The range accuracy was found to be within ±0.05 mm at a range of over 6000 mm. The main advantages of this UDMS system are high resolution, low cost, narrow bandwidth requirement, and ease of implementation.
The second, a method for the temperature measurement system (TMS) using two phase-lock-loops (PLLs) is described. A time-domain temperature sensor can convert the temperature into the duty cycle. The PLL circuit developed to emulate the Vernier caliper to measure the duty cycle is able to eliminate the measuring error and obtain higher resolution without increasing the clock frequency. Then, a single-chip microprocessor is designed to get and compute the duty cycle. Thus, the temperature can be easily computed with the duty cycle, and then sent to a Liquid crystal display (LCD) to display. The experimental results show that the resolution of the duty cycle is 1/65280, and the range of the measured temperature is from –25.5 to 102 ℃ with maximum error ±0.05 ℃ in the TMS. Therefore, the main advantages of this system are high resolution, high accuracy, and low cost.

1. D. Marioli, C. Narduzzi, C. Offelli, D. Petri, ”Digital Time-of flight Measurement for Ultrasonic Sensors.” IEEE Trans. Inst. and Meas., Vol. 41, No.1, pp.93-97, Feb. 1992。
2. M. Parrilla, J.J.Anaya, and C.Fritsch, ”Digital Signal Processing Techniques for High Accuracy Ultrasonic Range Measurement” IEEE Trans. Inst. And Meas. Vol. 40, pp.759-763, Aug. 1991。
3. G. Tardajos, G.G. Gaitano, and F.R.M de Espinosa, “Accurate, Sensitive, and Fully Automatic Method to Measure Sound and Attenuation” American Institute of Physics, Rev. Sic. Instrum., Vol. 65, No.9, pp.2933-2939, Sep. 1994。
4. M. S. Young and Y. C. Li, “ A High Precision Ultrasonic System for Vibration Measurement”, American Institute of Physics, Rev. Sic. Instrum., Vol. 63, No.11, pp.5435-5441, Nov. 1992。
5. J. S. Shoenwald and C.V. Smith, Jr., Proceedings of the IEEE Ultransonic Symposium, P469, 1984
6. Francis E. Gueuning, Mihai Varlan, Christian E. Eugene, and Pascal Dupuis, “Accurate Distance Measurement by an Autonomous Ultrasonic System combining Time-of-Flight and Phase Methods”, IEEE Trans. Inst. and Meas., Vol. 46, No.6, pp.1236-1240, Dec. 1997。
7. C. F. Huang, M. S. Young and Y. C. Li, “Multiple-frequency continuous wave ultrasonic system for accurate distance measurement”, American Institute of Physics, Rev. Sic. Instrum., Vol. 70, No.2, pp.1452-1458, Feb. 1999。
8. Tomonori KIMURA, Shusou WADAKA, Koichiro MISU, Tsutomu NAGATSUKA, Toru TAJIME, and Mitsuhiro KOIKE, “A High Resolution Ultrasonic Range Measurement Method Using Double Frequencies and Phase Detection “ ,IEEE Ultrasonic Symposium, pp.737-741, 1995。
9. Ming Yang, S. L. Hill, and J. O. Gray, “ A Multifrequency AM-Based Ultrasonic System for Accuracy Distance Measurement”, IEEE Trans. Inst. and Meas., Vol. 43, No.6, pp.861-866, Dec. 1994。
10. David Wsbster, “A Pulsed Ultrasonic Distance Measurement System based upon Phase Digitizing”, IEEE Trans. Inst. and Meas., Vol. 43, No.4, pp.578-582, Aug. 1994。
11. Fernando Figueroa, and Enrique Barbieri, “An Ultrasonic Ranging System for Structural Vibration Measurements”, IEEE Trans. Inst. and Meas., Vol. 40, No.4, pp.764-769, Aug. 1991。
12. George S.K. Wong and Tony F.W.Embleton,”Variation of the speed of sound in air with humidity and temperature”, J. Acoust Soc. Am., Vol. 77, No.1, pp.1710-1711, May 1985。
13. E. O. Doebelin, “Measurement System Application and Design,” New York, McGraw-Hill, 1990.
14. D. Rod White, Keith Jones, Jonathan M. Williams, and Ian E. Ramsey, “A Simple Resistance Network for Calibrating Resistance Bridges”, IEEE Trans. Instrum. Meas. Vol. 46, NO. 5, pp.1068-1074, Oct. 1997.
15. Saibal Pradhan, and Susanta Sen, “An Improved lead compensation technique for three-wire resistance temperature detectors,” IEEE Trans. Instrum. Meas. Vol. 48, NO. 5, pp.903 -905, Oct. 1999.
16. Paul Welander, Martin Barmatz, and Inseob Hahn, “A New Small Nano-Kelvin Resolution thermometer for Low-Temperature Experiments”, IEEE Trans. Instrum. Meas. Vol. 49, NO. 2, pp.253-255, April. 2000.
17. Linear products databook, Analog Devices l990/1991
18. Smartec B. V. Specification sheet SMT160-30, www.smartec.nl, 1996.
19. R. E. S. Abdel-Aal, “Digital phase meter updates measurement each cycle”, Electronics, Vol. 22, pp.156-157, 1981.
20. T. S. Rathore and L. S. Mombasawala, “An Accurate Digital Phase Measurement Scheme”, Proceedings of the IEEE, Vol. 72, pp.397-398, 1984.
21. Andria Nemat, “A Digital Frequency Independent Phase Meter”, IEEE Trans. Instrum. Meas. Vol. 39, NO. 4, pp.665-666, Aug. 1990.
22. Andria Nemat, “A High Resolution Digital Frequency Meter for Low frequencies”, IEEE Trans. Instrum. Meas. Vol. 39, NO. 4, pp.667-668, Aug. 1990.
23. H. P. Lio and M. S. Young, “New digital phase meter concept and its application”, American Institute of Physics, Rev. Sic. Instrum., 68(4), No.11, pp.1894-1901, Apr. 1997.
24. S. S. Huang, C. F. Huang, K. N. Huang, and M. S. Young, “ A high accuracy ultrasonic distance measurement system using binary frequency shift-keyed signal and phase detect”, American Institute of Physics, Rev. Sic. Instrum., Vol. 73, No.10, pp.3671-3677, Oct. 2002.