| 中文摘要 |
In this article present invention a environment temperature monitoring system using a binary frequency shift-keyed (BFSK) ultrasound. It uses the ultrasonic measurement of the changes in speed of sound in the air to determine the temperature of bulk air. The changes in speed of sound are calculated by combining time-of-flight (TOF) and phase shift techniques. This method can work in a wider range than using phase shift alone and is more accurate than TOF scheme. The system consists of a micro-computer, two-frequency ultrasound generator, power amplifier, preamplifier, gain-controlled amplifier, digital phase meter, and phase shift converter. |
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