SU611147A1 - Apparatus for determining the moment of medium transition from one state to another - Google Patents

Description

radio outputs and the output to the sawtooth voltage generator connected by the first input of the comparator, the output of which is connected to the second input of the trigger and to the first input of the time selector, the second input of which is connected to the output of the forcing device and the output to the second input of the comparator through two successively connected integrator.

The drawing shows a functional diagram of the described device consisting of a probe 1 pulse generator, a measuring transducer 2, a wideband amplifier 3, a driver 4, a trigger 5, a sawtooth voltage generator 6, a comparator 7, a time selector 8, integrators 9 and 10,

The device works as follows. .

The probing generator 1 produces short square pulses that go to the measuring transducer 2, where they are converted into acoustic pulses that pass through the sample under study, again converted into electric oscillations fed to the broadband amplifier 3, and then to the driver 4.

The pulse of the probe generator 1 is also fed to the input of the trigger 5 and starts it.

The leading edge of the trigger pulse 5 starts a sawtooth voltage generator b, the pulse of which is fed to the first input of the comparator 7, where it is compared with the reference voltage supplied to the second input of the comparator from the output of the integrator 10. When the sawtooth and reference voltages are equal, the comparator 7 produces a pulse that flips trigger 5. The delay time of the pulse at the output of the comparator 7 is equal to the propagation time of the acoustic pulse through. The pulse from the output of the comparator 7 is also fed to the time selector b, in which two rectangular selector pulses are generated one after the other. The second input of the temporary selector receives a pulse from the output of the imaging device 4.

Depending on the temporal position of the pulse at the output of the driver 4 relative to the selector pulses at the output of the temporary selector B, a constant voltage of positive or negative polarity (error signal) is generated. This voltage, through the two integrators 9 and 10, controls the operation of the comparator 7, changing the signal at its second input until the signal at the output of the time selector 8 becomes zero.

The use of two integrators is necessary to obtain a tracking system with second-order astatism, which greatly improves the measurement accuracy and system stability. The voltage V at the output I of the integrator 10 is proportional to the time I of the acoustic pulse propagating through the sample G KV, where K is the constant of the circuit. The voltage V at the output And the integrator 9 is proportional to the first derivative of the voltage V, in time

dVi

VdT

Thus, at the moment of breaking the curve of the temperature dependence of the ultrasound velocity at the output of TI of the integrator 9, there is a pulse, the temporal position of which corresponds to the moment of the bend. The voltage V, at the output of the integrator 9 is proportional to the second derivative of the voltage Vj over time

v-.

-Ji

The use of the described system makes it possible to determine with high accuracy the instant of transition of the medium from one physical state to another by the change in the dependence of the ultrasound velocity on temperature. This makes it possible to increase the expressiveness of conducting time-consuming physical experiments.

Claims (2)

Invention Formula A device for determining the moment of medium transition from one physical state to another, containing a probe radio pulse generator connected to the input of the measuring transducer whose output is connected to serially connected broadband amplifier and driver, characterized in that, in order to automate the process of determining break points on the temperature dependence curve of the ultrasound speed and improve accuracy, it is equipped with a two-input trigger, sawtooth generator; a comparator with two inputs time selector with two inputs and two integrators. In this case, the first entry .trigger; connected to the generator output of sounding radio pulses, and the output to a sawtooth generator, for example, connected to the first input of the comparator, the output of which is connected to a second trigger input and to the first input of the time selector, the second input of which is connected to the output of the trigger, and the output to the second input of the comparator through two series-connected integrators. To Sources of information taken in. attention in the examination: Ni 1. USSR authorship certificate 286364, cl. 01 H 5/00, 1968. 2. USSR authorship certificate 441456, cl. Q01, H 5/00, 1972.