SU1700378A1 - The method of fixation of the moment of acoustic signal entering and device for its realization - Google Patents

Abstract

The invention relates to a measurement technique and can be used in acoustic measuring devices for determining level. The purpose of the invention is to improve the measurement accuracy. The method of determining the fluid level is to convert the acoustic signal into an electrical one, generate a first reference signal and compare it with a mono-magnetic one, generate a second reference signal by inverting the electrical signal and generate an output signal when the electrical and second reference signals are equal. When an acoustic signal reflected from a liquid arrives at receiver 1, it is converted into electrical amplified by amplifier 2, after which, if the electric signal reaches the first reference signal, comparator 3 generates a pulse setting trigger 4 to state 1. The electrical signal is inverted by inverter 7 and fed to the second input of the comparator 5, the first input of which receives an electrical signal directly. The second comparator is triggered when the equality of the direct and inverse signals is reached. When the comparator 5 is triggered, the single-vibrator 6 is activated and the trigger 4 returns to the initial state. 2 sp.f-ly, 2 ill. (L

Description

The invention relates to a measuring technique and can be used in acoustic measuring devices, for example, in ultrasonic speed testers.

The aim of the invention is to improve the accuracy of measurements

The method of fixing the moment of arrival of the acoustic signal is carried out as follows. The acoustic signal is converted into an electrical one, the first reference signal is formed and compared with it.

electric, form a second reference signal by inverting the electric signal and, in case the latter exceeds the reference level, generate an output signal at the moment of equality of the electric and second reference signal obtained by inverting the electric signal.

FIG. 1 shows a block diagram of a device implementing the method; in fig. 2 - time diagram of his work.

The device for fixing the moment of arrival of the acoustic signal (, 1) contains successively connected receiver 1, amplifier 2, first comparator 3, trigger 4, second comparator 5 and one-shot 6 connected by an input to the output of amplifier 2 and the first input of the comparator 5, and the output to the second the input of the latter, the inverter 7, the D input of the trigger 4 is connected to the bus 8 of the power supply, and the R input to the output of the single vibrator 6, which is the output 9 of the device.

When an acoustic signal arrives at the receiver 1, it is converted into an electric signal and amplified by amplifier 2, after which, if the amplified electric signal 10 (Fig. 2) reaches the threshold of the reference signal 11 of the comparator 3, the latter generates a square pulse 12 trigger 4 to state 1 (position 12 in FIG. 2). If the signal 10 does not reach the trigger threshold 11 of PE 2, then this will indicate that interference has occurred or the acoustic signal has not reached the required level, PE 3 does not operate and the device as a whole (or did not reach the optimum acoustic signal) does not perceive the interference. The output signal 13 of the trigger 4 is gated for the comparator 5. Thus, it is prepared to operate at the falling front of the amplified electrical signal 10, i.e. when it reaches the reference level 11.

The electrical signal 10 is inverted by an inverter 7 (signal 14) and is fed to the second input of the comparator 5, the first input of which receives the signal 10 directly. Thus, the comparator 5 is triggered upon reaching equality of the forward 10 and the inverse 14 signals, moreover, on their falling front. Obviously, this will happen when both signals reach the value O, i.e. with the maximum slope of the signals. In addition, due to the oncoming movement of signals 10 and 14, the slope of the differential signal at the input of the comparator 5 is doubled, which makes it possible to increase the accuracy of determining the signal arrival time, i.e. accuracy of the device. When the comparator 5 is triggered, the odnovibrator b is activated and the trigger 4 returns to the initial state (zero), since its R-input is connected to the output of a single b. b. Strobe signal from strobe

the input of the comparator 5 is removed (since the trigger 4 returns to the O state), therefore, all possible noises and interference following the signal are not perceived by it. So

this way the noise immunity of the device increases

The pulse duration 16 of the one-shot is chosen equal to the minimum pause, for example, at the maximum possible

the upper level of the liquid when using the device in the gage operating in the autocirculation mode (prototype) between the positive half-waves of the acoustic signal, which eliminates the effect of interference (even exceeding the signal level) between the signals. When the next acoustic signal arrives at the device input, the process repeats.

Instead of inverter 7, a paraphase amplifier (not shown) connected to the first and second inputs, respectively, to the output of amplifier 2 and the common bus (second power supply bus), and the first and second outputs, respectively to the first and second inputs of the comparator 5, can be used while the first input of the latter is disconnected from the input of the amplifier 2.

Claims (2)

1. A method of capturing the moment of arrival of an acoustic signal, including converting an acoustic signal into an electrical signal, comparing a reference signal with an electrical signal, obtaining an additional reference signal and generating an output signal with equal electrical and additional reference signal, characterized in that To improve accuracy, an additional reference signal is obtained by inverting an electrical signal. 2. A device for fixing the moment of arrival of an acoustic signal containing a power source, a series-connected receiver, amplifier, threshold element, delay unit, comparator and one-shot, characterized in that, in order to improve accuracy, an inverter is input whose input is connected to the amplifier output, and the output to the corresponding input of the comparator, and the delay unit is designed as a trigger, the reset input of which is connected to the output of the single vibrator, and information input to the power source. 3 C5 E | 7 2 3 5 L  -about