SU1328945A1 - Device for calibration of resonance hydrophones - Google Patents

Abstract

The invention relates to acoustic measurements. The purpose of the invention is to increase the accuracy of graduation in a compact basin by eliminating the effect of excitation signals and reducing the after-signal of a hydrophone. The measured reflected signal is fed to the non-inverting input of the differential amplifier B, and the output of the latter will be a reflected signal suitable for measurement by the recorder 9. In the current measurement mode through the graduated hydrophone, the switch 10 is switched to the Up position. During the excitation of the hydrophone by the signal of the radio pulse generator 1, a non-inverting input of the differential amplifier 8 receives a signal Up proportional to the current passing through the hydrophone. The signal from the output of the differential amplifier 8 is measured by the recorder 9. 2 Il. (RG) 4 cl

Description

This invention relates to acoustic measurements and can be used to measure the parameters of resonant hydrophones.

The purpose of the invention is to improve the accuracy of graduation in a compact pool by eliminating the effect of excitation signals and reducing the after-sound of a hydrophone.

Fig. I is a block diagram of a device for calibrating resonant hydrophones; 2, timing diagrams for the operation of the device.

The device contains a generator 1 radio pulses, the driver. 2 control pulses, first 3 and second 4 switches, variable resistor 5, one-shot 6, reference resistor 7, differential amplifier 8, recorder 9, measurement mode switch 10 with control input II of the first 12 and second 13 contact groups, terminals 14 and 15 connect a resonant hydrophone.

Shaper 2 consists of detector 16, one-shot 17, element OR 18, and the output of detector 16 is connected directly and through one-shot 17 to the first and second inputs of element OR 18, respectively, the input of detector 16 is the input of shaper 2, and the output of element OR 18 The first output of the former 2, the second output of which is the output of the detector 6.

 The input of the driver 2 is connected to the output of the generator 1 and through the first key 3 to the control input 11 of the switch 10, the first and second outputs of the driver 2 are connected via a one-shot 6 and directly to the control inputs of the first 3 and second 4 keys, the control input 11 of the switch 10 connected via a variable resistor 5 and a second switch 4 to the case, the amplifier 8 is connected by an inverting input to the output of the generator 1 and through the first group 12 of the switch 10 to the case, the non-inverting input of the amplifier 8 is connected via the second group of contacts 13 Another terminal of the resistor 7, with which and terminals 14 and 1.5 of the connection of the resonant hydrophone are connected to the control input 11 of the switch 10. The output of the amplifier 8 is connected to the input of the recorder 9,

289452

The device dp calibration of resonant hydrophones works as follows.

In the mode of measuring the voltage of the reflected signal, the radio pulses (Fig 2a) from the output of the generator 1 radio pulses arrive simultaneously at the input of the switch 3, the controller forms 2, and the inverting input of the amplifier 8 forms the video control pulse duration

+ t,

3.1

(Fig. 26), which

enter the control input of the key 3, which, under the action of the control pulses, passes into the saturation state, as a result, from the generator 1 to the graduated hydrophone and to the non-inverting input of the differential amplifier 8, excitation pulses are received (fig. 2d). the radio control pulses, the excitation pulses and the hydrophone after-sound signal come through the switch 3 on the inverting input of the amplifier 8,

Thus, the same signal to the inverting and non-inverting inputs of amplifier 8 during () nocTjmaeT, thus preventing the passage of interfering excitation radio pulses and after-talk signal to the recorder's input 9, During () the hydrophone connects through the saturated key 3 to the output of generator 1, therefore, the attenuation of the hydrophone after-sound signal occurs earlier because of the shunt effect of the output impedance of generator 1,

Further attenuation of the after-sounding signal of the calibrated hydrophone occurs during (h. J) Formation of the one-shot signal 6. (Figure 2b), the one-shot 6 is triggered by shaper 2 on the falling edge of the radio pulse of the generator 1, the output switch one-shot 6 key 4 is injected into saturation, t. e. parallel to the hydrophone, a variable resistor 5 is connected. Due to the bypassing action of the resistor 5, the after-sounding hydrophone signal is completely attenuated before the measured reflected signal arrives at the hydrophone at time t, (fig. 2d).

For a particular type of hydrophone, it is necessary to select the optimal resistance value

2g shows the attenuation of the after-sounding signal of the calibrated hydrophone, where f, is the constant of the decay time of free oscillations, is the time constant with regard to the shunting effect of the output pulse of the 1 pulse generator, Cj is the time constant with regard to the shunt effect variable resistor 5,

Before the measured reflected signal arrives at the hydrophone, the keys 3 and A are switched to the high-impedance state, as a result of which the low-impedance output of the radio pulse generator 1 is disconnected from the hydrophone and the hydrophone is switched off via the key 4. Thus, the measured reflected signal is fed to a non-inverted input differential amplifier 8,

Due to the fact that the excitation signals of the hydrophone and the after-effects of i are compensated, the output of the differential amplifier 8 has a reflected signal (Fig 2d) suitable for measurement by the recorder 9,

In the mode of current measurement through a graduated hydrophone switch 1 O

is transferred to} Ir position, the inverting input of the differential amplifier 8 is connected to the housing, and the non-inverting input is connected to the reference resistor 7, At; passing through the hydrophone, the signal from the output of the differential amplifier 8 is measured by the recorder 9,

Comparison of results of graduation of a batch of six hydrophones using the method of self-reciprocity on a prototype

five

0

five

0

five

0

five

The proposed device, with the result obtained using the measuring device, gave a discrepancy of no more than ± 10%. At the same time, the sensitivity of an exemplary hydrophone is determined on an exemplary calibration unit of the second bit, in which the reciprocity method is implemented.

Claims (1)

Invention Formula A device for calibrating resonant hydrophones containing a generator of radio pulses, a reference resistor connected to the case by one output, a switch and an amplifier and recorder connected in series, characterized in that, in order to improve the accuracy of calibration in a small pool, a control pulse driver was inserted, two keys one-shot, variable resistor, while the input of the driver of the control pulses is connected to the output of the generator of radio pulses and through the first key with the control input the switch, the first and second outputs of the control pulse shaper are connected via a single vibrator directly to the control inputs of the first and second keys, respectively; to the output of the radio pulse generator and through the first switch group to the case, the non-inverting input of the amplifier is connected via the second contact group to another output of the reference relay stories, and with which a switch control input coupled yushnm connecting terminals resonant hydrophone. t FIG 2