SU329397A1 - ACOUSTIC LEVEL - Google Patents

Description

The invention relates to a technique for measuring the level of a liquid, and is intended primarily for the tele-measurement of the level of water in irrigation canals, reservoirs and the level of ground Bod in observation wells.

Acoustic liquid level meters are known that contain electroacoustic transducers fixed by a tube immersed in liquid, which serves as a waveguide.

The impulse sent by the transducer is passed down through the waveguide and reflected from the surface of the liquid. The transit time of the pulse (back and forth) is the measure of the level of the liquid. To correct the speed of sound propagation in the waveguide (taking into account the parameters of the medium), reflectors placed along the height of the waveguide, made in the form of metal plugs, are used.

The methods used in the well-known acoustic times of pulsed level gauges are not suitable for level gauges operating in the autocirculation mode, since, in order to ensure a stable autocirculation mode for the probe pulses (self-starting), it is necessary, first, to exclude multiple reflection of the sound pulse from the intermediate reflector and - second, to provide in the feedback circuit, covering the emitter and receiver, the blocking of pulses reflected or intermediate (calibration) reflector in order to self-start Istemi followed was only imnulsa:, ennymi poisons from the liquid surface,

For this purpose, the fixed partial pro-intermediate reflector of the proposed level gauge is made in the form of a side branch with an adjustable length, for example, a threaded piston, the feedback target includes a symmetric trigger connected at the input to the driver of rectangular electric pulses, but the output is with a probe pulse formation circuit.

When the sound passes through the branch point, if you smoothly change the length / closed side branch from O to l / 4, then you can adjust the intensity of the sound reflected from it from O to max (l - wavelength) to achieve a steady receiving only one, the first, reflected from the side branch of the pulse.

In the output signal of the autocirculation terminal in this case, an impulse from the intermediate reflector appears between the probe tube and the reflections from the surface above them. In order to ensure a steady self-launch of the system. We only use the mirror, reflecting from the surface of the liquid, to avoid the formation of a probe pulse, impulses are excluded, preventing from the inclusion of, for example, a symmetric trigger. The receiving device records the time of the sound pulse passing from the radiator to the surface of the water and back (NPO: rational measurement level and medium parameters) and to a fixed reflector and vice versa (pronunciating only the medium parameters). The true value of the measured level is determined by the ratio of these time values. The division of the two time intervals is easily accomplished by well-known methods and. In the known acoustic autocirculation level gauges, the day of the feedback covering the emitter and receiver comprises an amplifier, an immersing driver, and a circuit for forming probe pulses. FIG. 1 The block-functional scheme of the proposed acoustic level gauge is shown; in fig. 2 - time diagram of his work. An acoustic level gauge contains 1 meter measuring tube 1 with a side branch 2 and a regulator of its length, for example, a threaded pipe 5 at La from the radiator 4 and receiver 5 fixed on the tube. The feedback circuit consists of amplifier 6, forming square rectangular pulses 7 , symmetric trigger 8 and probe formers pulses 9. Transmitting semi-kit 10, communication lines and receiving nukomilekt 11, connected through the separation of signals 12 with the division unit 13, to the output of which is connected a digital electronic counter imp lsov 14, provide the remote transmission and converting the level value to a number. The gauge works as follows. When the device is turned on, the emitter 4 sends a sounding impulse 15 into the measuring tube / probe (see Fig. 2). Receiver 5 receives a probing impulse, a partially reflected pulse from the side branch 2 and then a more powerful imchulse reflected from the surface of the liquid (16. These impulses are formed into rectangular pulses 17 by the former 7 and are simultaneously fed to the transmitting half set 10 and to the counting input of a symmetric trigger 8 previously set to the state "O. Trigger 8 is transferred to the state" 1 by the leading edge of the first (probe) pulse, and to the state "About the leading edge of the pulse reflected from the lateral branch The output signal 18 of the trigger 8 is fed to the input of the circuit for forming a DUIX pulse pulse .9, which is also triggered by the front pulse 18, the sound lock, and the emitter 4 (15). Thus, the self-starting mode is sustained only by pulses reflected from the surface of: the liquid. 17 through the transmitting half-set 10 and the communication line to the receiving half-set //, where the signal is amplified and formed. From the set of a large half-set // the signal enters the signal separation unit J2, where the periods Tae (8) and tx are separated (19, Block 12 can be built, for example, on two series-connected symmetric triggers with counting inputs. The selected signals 17 and 18 enter the dividing unit, where the output of the division of time intervals is produced, and the result is output to an electronic digital controlled pulse counter, which records the value of the measured level through the medias in the decimal system. ADDITIONAL CIRCULATION SYSTEMS Acoustic level gauge containing a measuring tube with an intermediate partial reflector, an oscillating circuit, electro-acoustic transducers and receiving-transmitting semi-sets with a communication line that, in order to obtain reflection of the sound pulse from the reflector and ensuring stable autocirculation mode; the fixed partial intermediate reflector is made as a side branch with an adjustable length, for example, as a threaded piston, and tnoj communication enabled symmetrical trigger input connected by a generator of rectangular electric impulses, and by output - with the probe pulse generating circuit.

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