RU1835054C - Sound speed meter - Google Patents

Abstract

The invention relates to acoustic control techniques and can be used to control the propagation speed of acoustic vibrations in liquid media. The aim of the invention is to improve the accuracy of measurement. The principle of operation of the meter consists in the following balancing of the transit time of the medium under investigation by acoustic vibrations with a duration of a time interval proportional to the period of the output frequency of the meter. Improving the accuracy of the meter is achieved by stabilizing the pulsations of the output frequency at a minimum level. 2 silt

Description

The invention relates to acoustic control techniques and can be used to control the propagation speed of acoustic vibrations (sound) in liquid media.

The purpose of the invention is to improve measurement accuracy.

Figure 1 shows a block diagram of an inventive meter; Fig. 2 is a timing chart illustrating the operation of the flowchart.

The sound velocity meter, the block diagram of which is shown in Fig. 1, contains a recorder 1 connected by an input to the input of a frequency divider 2 and the output of a controlled oscillator 3 connected by an input to an integrator 4, the output of the master oscillator 5 is connected to the input of the generator of exciting pulses b, the output of the current source 7 is connected to the first input of the current chopper 8, connected first

the input to the output of the frequency divider 2, the pulse distributor 9 is connected by the first output to the control input of the 10-bit key, the second input of which, combined with the output of the chopper 8, is connected to the first time input by the capacitor 11, connected by the second output to the output of the key 10, grounded, the second the output of the distributor 9 is connected to the second control input of the chopper 8, the electro-acoustic transducer 12, immersed with the reflector 13 in the medium under study, is connected to the output of the generator 6, combined with the input of the boundary read 14 pulses connected by the output to the input of the comparator 15 of the receiving signal, the second current source 16, combined at the input with the source 7, comparing the block 17, connected by the first input to the first time output of the drive capacitor 11, the output of the comparing block 17 is connected to

With

ate about

to

(AND)

the first input 9 of the trigger 18, connected by the first, second output to the inputs of the same name RS-flip-flop 19, the output of which is connected to the input of the integrator 4, the output of the comparator 15 is connected to the first input of the second pulse distributor 20, the output of the current source 16 is connected to the first input the second current chopper 21, connected by the output to the first input of the second key 22 bits, the second input of which is connected to the first output of the distributor 20, connected by the second output to the second input of the current chopper 21, the second time sets the capacitor 23, sub equipped with the first, second, leads parallel to the first input and output of the key 22 connected to the ground bus, the first output of the capacitor 23, combined with the output of the chopper 21 and the first input of the key 22, is connected to the second input of the comparison unit 17, the second input and the third output of the distributor 9 combined and connected; They are connected to the first input of the 24 And element, the second input of which is connected to the combined second input and the third output of the distributor 20, the output of the 24 And element is connected to the combined second input of the trigger 18 and the input of the correcting pulse generator 25, the output of which is connected to the combined third inputs of the distributors 5, 20 and RS flip-flop 19.

As a recorder 1, for example, it is possible to use an electronically-counted frequency meter of type 43-34, and the tap-changer 2 is made on and / with 584 IE9.

The meter works as follows.

The pulses 26 of the master oscillator 5, operating with a constant frequency {2.5 kHz), are fed to the input of the excitation pulse generator b, which generates short shock excitation pulses (27-1) that act on the transducer 12 of the meter. An acoustic pulse formed upon excitation of the transducer 12, after sensing the medium and reflection from the reflector 13, will be partially received by the transducer 12 in the form of an electrical receiving signal (27-П), and partially reflected from the front surface of the latter, the medium will again be sensed after reflection from the reflector 13 the Converter 12 in the form of a second electrical receiving signal (27-W). Duration t between two receiving

signals (27-P, 27-UJ) will be equal to gp,

where I. is the length of the acoustic base of the electro-acoustic transducer: C is the speed of sound in the medium.

The signals from the output (input) of the converter 12 after being limited in amplitude by the limiter 14 are normalized in amplitude and duration by the comparator 15 (28-1,

28-P; 28-W). Pulse 28-1 is caused by shock excitation; pulses 28-P and 28-III are received signals. The indicated pulse train acts on the counting input C of the distributor 20.

The pulse 28-1 at the output 1 of the distributor 20 generates a signal 30 of a high logical level, which, acting on the control input - V key 22, causes the closure of its switching input and

5 exits. This provides a shunt of the terminals of the capacitor 23 and its discharge. In this case, the switching input and the input of the chopper 21 are in the open state and the current of the source 16 does not cause a drop

0 voltage at the closed terminals of the switch 22. The introduction of the current chopper 21. Allows to reduce the residual voltage on the capacitor 23 during discharge to a minimum value (2-4 hV) and .. therefore, to ensure its slight changes when exposed to external factors.

Pulses (28-П) at the output 2 of the distributor 20, a signal 31 of a high logical level is formed and the shunting of the terminals of the capacitor 23 is stopped, since a low-level c-needle will act on the control input of the key 22, Signal 31, acting on the control input V chopper 21, will cause 5

pushing his commuting input and output. This will lead to the charge of the capacitor 23, the current lie, and an increase in the voltage thereon with a constant slope (diagram 32 - Fig. 2).

0 By a pulse 28-Ш at the output 3 of the distributor 20, a high-level signal 33 is formed and the charge of the capacitor 23 is stopped (the switching input and output of the interrupter 21 is opened, since the low-level signal will act on the control input V of the latter).

The value of the voltage across the capacitor 23 at the time of its termination will be determined by the well-known expression LJ23

0 (is T

 where Caz is the capacitance of the capacitor 23.

C23

The signal 33 is supplied both to the input CE of the distributor 20, causing it to be blocked, and to the first input of the logical, element And 24.

The pulses of the frequency-controlled generator 3 through the divider 2 are fed to the counting input C of the distributor 9 (diagram 34 in Fig. 2).

The signal 36 (Fig. 2), formed at the output 1 of the distributor 9, discharges the capacitor 11 through the key 10.

The signal 37 (figure 2), formed at the output 2 of the distributor 9, the interrupter

8 connects the capacitor 11 to the output of the current source 7. This leads to the charging of the capacitor 11 by the current and an increase in the voltage thereon with a constant slope (diagram 38 - Fig. 2).

When the signal 39 - Fig. 2 is generated at the output 3 of the distributor 9, the charge of the capacitor J1 is stopped and the voltage value at it at this time instant is determined by the known expression Vn

 t t

- -ft-. where T is the pulse period at the input

eleven

distributor 9; C is the capacitance of the capacitor 11. The signal 39 (figure 2) is supplied both to the input CE of the distributor 9, causing it to block, and to the second input of the AND gate 24.

The high-level signal 40 (Fig. 2), formed at the output of the And 24 element, when the signals at its inputs coincide, affects both the input C of the trigger 18 and the input of the driver 25 of the correcting pulses.

The signal 40 (Fig. 2), acting on the C-input of the trigger 18, will change its position if a high level signal acts at the output of the comparison unit 17, which will be observed with Vvi Uas. If we assume that he and Sc, then trigger 18 will change its position at T t.

Otherwise (Un U23), the position of the D-flip-flop 18 does not change. The pulse 41 (figure 2), formed at the output of the driver 25, will act on the inputs of the distributors

9 and 20 and read input V of the RS flip-flop 19.

The impact of the pulse 41 (Fig. 2) on the inputs V of the distributors 9 and 20 leads to the installation of the latter in the initial state (at the outputs 0 of the distributors 9 and 20, high-level signals act - diagrams 29 and 35 of Fig. 2).

The impact of the pulse 41 (Fig. 2) on the reading input V of the trigger 19 leads to the formation of the output of the last signal of a high (low) level - if a change in the position of the trigger 18 occurred (did not occur), the signal of a high (low) level will cause an increase (decrease) ) the voltage at the output of the integrator 4, which is input to the controlled generator 3. Moreover, an increase (decrease) in this voltage leads to an increase (decrease) in the frequency f of the oscillations of the latter.

In the steady state operating mode of the meter, 5 conditions Vn U23 (T t) and Un U23 (T t) alternate. In this mode, the averaged values of the indicated stresses (durations) will be equal to I / n, i.e. Un U23 and T g, since T -. where k

0 is the division coefficient of the counter divider 2, and r 7, then f- A L

In the meter circuit, the equality of the currents I and he was achieved by carrying out their identical circuits and using a single reference element (Zener diode D 818 E) for sources 7 and 16, connected between the plus output and the non-inverting inputs of operational source amplifiers (140 2UD20A).

The signal diagram in FIG. 2 is based on the assumption that the distributor 9 starts working earlier than the distributor 20. Otherwise, the picture changes to

5 opposite.

Thus, in the proposed scheme, the positive advantage of the prototype is preserved - the duration is used as a signal of the measuring information

0 time interval between two receiving signals and a further increase in the accuracy of control voltage ripple. The pulsation frequency in this case is set by the master oscillator 5.

5 In addition to the above, in the proposed meter scheme, an increase in the speed was achieved. performance at low speeds of sound due to the fact that the sounding frequency is accepted as maximum and does not depend on the value of the speed of sound.

In the proposed scheme, mm, K-100 meter, the output signal is 140,000-155,000 Hz corresponding to the range of 140,000-155,000 cm / s, the deviation from linearity is not worse than ± 4.5 cm / s (in the prototype ± 6 cm / s). A reduction in the settling time of the output signal by 0.06 s has been achieved compared with the prototype.

Claims (1)

The claims 0 Sound speed meter, containing. connecting the first key in series, the comparing unit, the D-flip-flop, the HC-flip-flop, the integrator, the controlled oscillator, the frequency divider and the first 5 a pulse distributor associated with a first output with a second input of a first key, the output of which is intended for grounding, a first capacitor connected in parallel to the first input and the output of the first key, series-connected generator of exciting pulses, an electro-acoustic transducer, a pulse limiter and a comparator, a current source and a recorder connected to the output of a controlled generator, characterized in that, with the aim of increasing accuracy, it is equipped with the first. a current chopper, the signal input of which is connected to the output of the first current source, the control input - with the second output of the first pulse distributor, and the output - with the first input of the comparator unit, a master oscillator connected to the input of the excitation pulse generator, connected in series with the second current source, the chopper current and a second switch, the output of which is intended for grounding, a second capacitor connected in parallel to the first input and output of the second switch, the second distributor, counting input One of which is connected to the output of the comparator, the first the output is to the second input of the second key, and the second output is to the control input of the second current chopper, and the element And and the pulse shaper are connected in series, the output which is connected to the installation inputs of the RC flip-flop. and pulse distributors, the third outputs of the distributors are connected respectively with their own blocking inputs and inputs of the AND element, the output which is connected to the C-input of the D-flip-flop, the output of the second current chopper is connected to the second input of the comparison unit, and the reference inputs of the current sources are combined.