Computer Controlled Resonator Measurements with a 12-Liter Pyrex Sphere and a 100-Liter Titanium Sphere

摘要

A microcomputer controlled spherical resonator apparatus has been developed for acoustic studies of liquids at 5-500 kHz. A programmable frequency synthesizer producing frequencies in steps down to 1 microHz is used as the source. The received signal is fed into a programmable tuned amplifier, and demodulated. A/D conversion is made with a high-speed sample-and-hold digital voltmeter via a multiplexing scanner. The system allows for very detailed mode mapping of the sphere by accumulating amplitude data both while the sphere is being driven and after a specified decay time interval, along with recording of temperature. The experimental resonance frequencies have been compared with those predicted theoretically and decay rates of a large number of resonances measured. The amplitude decay can be followed through 70 dB with reproducibility within + or - 0.2 dB/s under favorable conditions. The system is also used for cylindrical resonators. (Author)