An ultrasonic, continuous wave, computerhyphen;controlled, reflection bridge spectrometer has been developed with offhyphen;thehyphen;shelf components. This spectrometer can be used for measurements of the velocity of sound and acoustic attenuation, sampledhyphen;cw acoustic modes, and nuclear acoustic resonance. The frequency range of the spectrometer is from 5 to 400 MHz with only phase shifter, bandhyphen;pass filter, and sample probe tuning changes. Sensitivity of the spectrometer over a wide range of power from 0.01 mgr;W to 1 W in a 50hyphen;OHgr; system is as good as that of marginal oscillators used in nuclear acoustic resonance. The spectrometer can be used to measure ultrasonic phase velocity to within plusmn;0.0001percnt; and the ultrasonic attenuation to within plusmn;0.1percnt; for a low attenuating composite resonator kept at a constant temperature.
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