SU541120A1 - An autocirculation device for measuring the speed of ultrasound in media - Google Patents

Description

The input delay of the electronic delay 16 with the outputs of the driver 14 trigger pulses and the duty generator 13, and the filter

11former connected to circuit input

12 matches.

The operation of the device is as follows.

The output of the exciting voltage source to the radiating transducer 4 receives the voltage of a certain frequency, which then in a certain randomly chosen time interval changes in steps by a small amount, for example 1-2% of the initial value. This frequency change is achieved by supplying from the output of the driver 14 trigger pulses to the input of the modulator 1 rectangular video pulses, the duration of which is equal to the selected time interval. At the initial moment of time when the modulator 1 of the source has not yet received pulses to change the frequency, a video pulse is triggered from the output of the duty generator 13 to the input of the modulator 1, triggering an electronic time delay by the leading edge, the back edge of which pulses the gating pulse generator 15. From one output of the generator 15, the video pulses come in, and from the other output to the input of the duty generator 13 to lock it. At the same time, transducer 4 converts the source voltages into an ultrasonic wave, which propagates in a controlled environment. After reflection, the signal is applied by the converter 6 and is converted by it into a signal having the same shape as the signal exciting, but with a shift of the first frequency bunch from the impact of the impulse generator 13 on time equal to the time of ultrasound propagation in the controlled medium. After amplification, this signal enters the driver input, where it is normalized in amplitude, detected and filtered in the form of a rectangular pulse, the duration of which corresponds to the duration of the "bunch" of the initial frequency of the receiving signal. Further, this pulse arrives at the second input of the coincidence circuit 12. When the pulses coincide at both inputs of the coincidence circuit 12, a video pulse appears at its output, from which a trigger pulse is formed by the shaper 14, acting simultaneously on the inputs of the modulator 1 and the electronic time delay 16. The device operates cyclically. The following cycles are performed in the same way, but already with the generator on duty 13 locked.

Thus, due to the design and circuit features of the described autocirculation device, it is possible to achieve

compensation for changing the shape of the receiving signal.

The measurement accuracy, especially when measured in environments with high attenuation ultrasound, became higher.

Claims (1)

Invention Formula An autocirculation device for measuring the speed of ultrasound in media containing a source of excitation voltage, a receiving-emitting acoustic measuring transducer connected to its output, an amplifier connected to its input, a receiving acoustic transducer, a pulse shaper, a coincidence circuit, a duty generator, a trigger pulse shaper, a gate generator pulses and electronic time delay, characterized in that, in order to increase accuracy, the source of exciting , made according to the scheme of a continuous monofrequency electrical oscillation generator with a modulator for pulse frequency change, is connected by the modulator input to the junction of the electronic delay input with the trigger pulse generator and the duty generator, and a pulse driver consisting of a frequency discriminator and filter, and keys from the filter to the input of the coincidence circuit.