Instrumentation for time-resolved measurement of ultrasound velocity deviation

An inexpensive digital data acquisition unit is described which has the capability to record ultrasound velocity variations up to 20 m/s in ultrasound velocity at rates up to 1000 readings per second. No calibration procedures are required. The intrinsic velocity resolution of the unit is less than 1 part in 10/sup 6/; however, the short-term frequency instability of the phase-locked loop instrument used as a velocity sensor limits the overall resolution to 1 part in 10/sup 5/.<
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