SU934784A1 - Acoustic level gauge - Google Patents

Description

Caught by errors in the operation of the useful signal extraction unit, which lead to a breakdown in the search and tracking of the useful signal and to an increase in the gain of the receiving unit to the maximum value.

The purpose of the invention is to improve the operational reliability of the device under conditions of intense interference. ,

This is achieved by introducing a threshold unit and an AND logic element into the Acoustic level gauge, the input of the threshold unit being connected to the output of the receiving unit, the output of the threshold unit connected to one of the inputs of the logic element I, the other input of which is connected to the output of the decision unit, and output element And is connected to the input of the gain control.

The drawing shows a structural diagram of the proposed acoustic level gauge.

The level gauge contains a generator 1, to the output of which a reversible electroacoustic converter 2 is connected and the input of the receiving unit 3, to the output of which the useful signal extraction unit is connected, the outputs of which are connected to the decision unit 5 and to the measuring node 6. The device also contains the threshold unit 7 AND 8 and the gain control 9. The threshold unit 7 is connected to the output of the receiving unit 3 by a faulty input, the output together with the output of the decision block 5 is connected to the inputs of the logical element 8. And the output of the AND element 8 is connected to ode regulator gain 9t kotor1y, in turn, its output connected to the control input receiving unit 3. The acoustic transmitter operates

in the following way.

Generator 1 produces radio pulses with a given filling frequency, which are applied to converter 2, where they are converted into sound pulses of the same frequency. Having reflected from the controlled surface, the sound pulses return to the transducer 2 and in it are converted into electrical impulses. One transducer perceives extraneous noise and a scattered signal.

The sum signal perceived by the electroacoustic transducer is fed to the input of the receiving unit 3, where it is amplified. From the output of block 3, the amplified signal is fed to the input of the block k of the extraction of the useful signal and to the input of the threshold block 7

The unit of selection of the useful signal by multiple comparisons of the position of each pulse in a few adjacent repetition periods of the useful signal finds the useful signal and switches from the search mode to the tracking mode of the useful signal, while selecting it from the total signal. At the moment of transition of the useful signal extraction unit to the accompanying mode, the decision block 5 is triggered, switches on the measuring node 6 and issues a single signal to the AND 8 element. If at the same time the amplitude of the useful signal at the output of the receiving unit 3 exceeds the threshold of block 7, then from the output of this block to the element And the second single signal will be given. As a result, a single signal will be fed to the gain control 9 of the receiving unit 3 and it will begin to reduce the gain of the receiving unit until the amplitude of the useful signal at the input of the threshold unit 7 reaches its threshold. After this threshold is reached, the single signal from the output of block 7 is replaced by zero, the output signal of the element 8 comes to zero. In this case conditional control 9 will begin to smoothly increase the gain of the receiving unit 3 until the amplitude of the useful signal again reaches the threshold threshold of the threshold unit. .

Thus, if there is a single signal from the decision block 5 at the input of the element And 8, the gain control 9 will maintain the amplitude of the useful signal at the output of the receiving unit 3 almost unchanged, regardless of the conditions of propagation and reflection of sound in the industrial apparatus and the measured distance.

The threshold unit 7 determines the ratio between the amplitudes of the signals applied to the useful signal extraction unit and the automatic gain control system. The threshold of block 7 is selected in such a way that even with sufficiently deep fluctuations of the amplitude of the useful signal in the block of the selection of the useful signal, there is practically no loss of the useful signal and the tracking mode is not broken.

In conditions of very strong interference, when the signal-to-noise ratio is close to one, the useful signal in block k

the selection of the useful signal is periodically lost, the block goes from the tracking mode to the search mode, and the decisive block 5 is triggered and outputs a zero signal to the AND 8 element. At the same time, the gain control 9 will gradually increase the gain of the receiving unit 3 until the desired signal is again found among the interference pulses. The decisive unit 5 at the same time issues a single signal per element AND 8.

four

7 v

AND

/ V

Claims (1)

ACOUSTIC LEVEL METER, containing a generator, to the output of which a reversible electro-acoustic transducer and a receiving unit are connected, to the control input of which an amplifier is connected