RU1840768C - Device for measurement of frequency-phase characteristics of hydroacoustic instruments - Google Patents

Abstract

FIELD: hydroacoustic engineering.

SUBSTANCE: invention is related to the field of hydroacoustic metering equipment and may be used for measurement of frequency-phase characteristics in continuous and pulse mode. Technical result is achieved by the fact that in device comprising digital phase metre with matching circuits, receiving track with frequency converters in its channels and generator of fixed frequencies, outlet voltages of which are strictly connected to each other by frequency and phase, and which is connected to frequency converters of receiving track, one of outlet of fixed frequencies generator is connected to outlets of phase metre matching circuits.

EFFECT: reduced measurement time.

14 dwg

Description

The invention relates to hydroacoustic measuring technique and can serve to measure the frequency-phase characteristics in a continuous and pulsed mode.

A known device that performs the task of measuring the frequency-phase characteristics, contains a transmitting generator and a receiving path, consisting of an amplifier and a phase meter. For example, a similar system is described in the book of Electromechanical and Electronic Phase Meters by I.M. Vishenchuk, A.F. Kotyuk and L.Ya. Mizyuk, published in 1962 on page 189. In hydroacoustics, measuring systems containing the same basic units are common. For example, a generator made according to the standard scheme is used as a transmitting path, a two-channel amplifier and a phase meter with a constant measuring time are described in the receiving path, described in the article by N.P. Polyakov "Methodological errors of digital phase meters with a constant measuring time", placed in the journal " Instruments and experimental equipment "No. 3, 1959, as well as in B.I. Shvetsky's book" Electronic measuring instruments with digital readout ", publishing house" Technique ", 1964, p. 135.

The transmitting generator 1 ÷ 4/1 / serves as a source of signal supplied to the measured object 5/1 /. A two-channel amplifier with double frequency conversion 6 ÷ 17 / Fig. 1/ raises the level of the measured signals and converts the operating frequency of the device into one constant, second intermediate frequency, while maintaining the phase shift between the output signals the same as that of the working signals.

A digital phase meter 18 ÷ 23 / Fig. 1/ measures the phase angle and displays it digitally.

A disadvantage of the known device is the large measuring time determined by the measuring time of the phase meter. The reason for the increase in this time is the incoherence of the measured signals, measuring time pulses and counting pulses of the phase meter.

Reducing the duration of the measuring time of the device is the main objective of the invention, which is achieved by creating coherence between the measured signals, the measuring time and the counting pulses. Coherence between the above signals is created by introducing instead of the three constant frequency generators 2, 17, 23 (Fig. 1/) included in the known device, one new generator 20 (Fig. 2/), which generates three signals that are tightly coupled in frequency and phase.

The introduction of a new auxiliary generator instead of the three old ones ensures the achievement of the goal - reducing the measuring time of the device.

DESCRIPTION OF THE SUGGESTED DEVICE.

Figure 1 is a block diagram of a prototype of the proposed device.

It includes a transmitting generator 1 ÷ 4, the measured object 5 and the receiving path 6 ÷ 23.

The dashed transmitting generator includes:

1 - tunable frequency generator

2 - fixed frequency generator

3 - frequency converter transmitting generator

4 - power amplifier with a bandpass filter.

The receiving path consists of a two-channel superheterodyne amplifier with double frequency conversion 6–17 and a phase meter with a constant measuring time of 18–23. The two-channel amplifier marked with a dotted line includes:

6, 7 - preamplifiers

8, 9 - the first frequency converters

10, 11 - amplifiers of the first intermediate frequency

12, 13 - second frequency converters

14, 15 - amplifiers of the second intermediate frequency

16 - tunable frequency generator of a two-channel amplifier

17 - fixed-frequency generator of a two-channel amplifier.

The phasometer marked with a dashed line with constant measuring time includes:

18 - shapers and pattern matching

19 - counting indicator device

20 - match pattern

21 - match pattern

22 - frequency divider

23 - generator of counting pulses.

Figure 2 shows a block diagram of a new device.

This scheme includes a transmitting generator 3, 4, a measured object 5, a receiving path, including a two-channel superheterodyne amplifier 6–15 and a phase meter with a constant measuring time of 18–22. Elements of the circuit 3 ÷ 15, 18-22 are the same as in the scheme of figure 1. In the block diagram of the new device did not include the generators 2, 16, 17, 23 shown in the prototype of Fig. 1 Instead of the generators 2, 17, 23 / Fig. 1/, a generator of hard-connected frequencies was introduced into the block diagram of Fig. 2 and pulses 24, and the functions of the generators 1, 16 / Fig. 1/ are performed by the generator 1 / Fig. 2/, common to the entire device.

Figure 3 shows the timing diagrams illustrating the operation of the phase meter with a constant measuring time.

Figure 4 shows a schematic diagram of a generator of tightly coupled frequencies and pulses 24/2 /.

In the circuit diagram, only the wiring of the signal wires is made, the supply wires and the zero bus are not shown in the circuit. The circuit diagram is divided into five functional blocks highlighted by a dotted line.

Crystal oscillator 25, 26 / Fig. 4/, which includes:

25 - generator / Fig. 5/

25 - emitter follower / Fig.6/.

Shaper of counting pulses 27 ÷ 32, which includes:

27 - resonant amplifier / 7 /

28 - oscillatory circuit / Fig. 8/

29 - amplifier-limiter / 9 /

30 - amplifier-limiter / Fig. 10/

31, 32 - emitter followers / Fig.6/.

Frequency divider 33 ÷ 45 / Fig. 4/, which includes:

33 ÷ 42 - trigger / 11 /

43 ÷ 45 - emitter follower / Fig.6/.

The frequency converter 46 / Fig. 4/, its circuit diagram is shown in Fig. 12, and the amplifier-multiplier 47 ÷ 54 / Fig. 4/, which includes: 47, 49, 51 - resonant amplifiers / Fig. 7/

48 - mechanical filter

50 - doubling chain / Fig. 13/

52 - oscillatory circuit / Fig. 8/

53, 54 - emitter followers / Fig.14/.

The task of reducing the measuring time in hydroacoustic can simply be solved, as shown in the appendix, in the case of coherence of the measured signal, measuring time and repetition rate of the counting pulses. These qualities have a new device, a block diagram of which is shown in figure 2. This device includes a transmission path 3, 4 / Fig. 2/, the output terminals of which are connected to the input of the measured object 5 / Fig. 2/ The measured object is usually a hydroacoustic multipole. In this case, a six-terminal device is selected as a generalizing example.

The output terminals of the measured object 5 / Fig. 2/ are connected to the input of a two-channel amplifier with double frequency conversion 6 ÷ 15 / Fig. 2/, the output terminals of which are connected to the inputs of the phase meter 18-22 / Fig. 2/. The new device differs from the device shown in the block diagram of FIG. 1 in that, in order to fulfill the coherence conditions, the generators 2, 23, 17 (Fig. 1/) are replaced by one generator of frequencies and pulses 24 / Fig. 2/, which are rigidly interconnected. .

The outputs of this generator are connected to the frequency converter of the transmitting generator 3/2 /, with the second converters of the two-channel generator 3/2 /, with the second converters of the two-channel amplifier 12, 13/2 / and the coincidence circuit 21 of the phase meter 18-22 / figure 2 /. In this device, the generators 1 and 16 / Fig. 1/ are combined into one 1 / Fig. 2/, its outputs are connected to the frequency converter of the transmitting path 3 / Fig. 2/ and the first frequency converters 8, 9 / Fig. 2/ of a two-channel amplifier . Such a combination of a tunable frequency generator into one generator, in addition to the simplicity of reducing to a constant output frequency in a two-channel amplifier, creates an additional quality - convenience and efficiency when tuning the device to the operating frequency.

In order to create coherence between the input signals of the phase meter and the counting pulses, a generator of hard-coupled frequencies and pulses 24 / Fig. 2/ is introduced into the device, the description of which and the work are given in the appendix. Three output signals of the generator, which are 359 and 360 harmonics of the output frequency of the two-channel amplifier f = 2786 Hz, operate in the device as heterodyne signals and counting pulses. These are two harmonic signals with a frequency of F = 10 ⁶ and ν = 100786 Hz and a signal in the form of counting pulses with a repetition rate of ν = 1002786 Hz. This choice of frequency values due to the design features of the generator 24/2 /. A heterodyne signal of frequency feeds the converter 3 (Fig. 3/) of the transmitting generator, a heterodyne signal with a frequency of F feeds the second converters 12, 13 / Fig. 2/ of a two-channel amplifier, and a pulse signal with a repetition rate ν is used in the phase meter as counting pulses, where on the coincidence circuit 21/2 / and the frequency divider 22/2 /.

Signals with frequencies ν and F _n are supplied to the converter of the transmitting generator 3 / Fig. 2/ from the generator pos.24 / Fig. 2/ and from the tunable frequency generator 1 / Fig. 2/. The frequency F _n lies in the range 1009786 ÷ 1302786. The signal from the output of the converter 3/2 / comes to the power amplifier with a band-pass filter 4/2 /. An amplifier with a filter isolates and amplifies the lower side frequency, which lies in the range of 7–300 kHz. From the power amplifier, the signal is supplied to the measured object 5/2 /. From the measured object, the phase-shifted signals arrive through the preamplifiers 6, 7 / Fig. 2/ to the first frequency converters 8, 9 / Fig. 2/. A signal of frequency F _n is supplied to the same converters from a tunable frequency generator 1 / Fig. 2/. After conversion by the amplifiers of the first intermediate frequency, a lower side frequency equal to the frequency ν is allocated. The frequency signal ν is mixed in the second frequency converters 12, 13 / Fig.2/ with the frequency signal F _get. = 10 ⁶ Hz coming from the generator pos.24 / Fig.2/. Amplifiers of the second intermediate frequency 14, 15 emits a constant frequency f = 2786 Hz. The phase shift between the signals remains the same as at the input of the amplifier, i.e. it is equal to the angle introduced by the measured object 5/2 /.

Signals with frequencies f and ν, interconnected in accordance with the formula ν = Cf, where C is a constant, are fed to a phase meter with a constant measuring time of 19 ÷ 22 / Fig. 2/. The signal in the form of counting pulses with a repetition rate ν from the generator 24 (Fig. 2/) is supplied to the coincidence circuit 21 of Fig. 2 and to the frequency divider 22 (Fig. 2/), and signals with a frequency f are supplied to the shapers and the coincidence circuit 18 / Fig. .2 /, where pulses of duration τ are generated, which are proportional to the phase between the signals.

Further, from these and counting pulses, on a coincidence circuit 21 / Fig. 2/, a series of packets of pulses is formed, with the repetition rate of packets f, the duration of the packet τ and the number of pulses in the packet N, with N = φ °, in the case C = 360 one pulse will be correspond to one degree. A series of these pulses is fed to the coincidence circuit 20 / Fig. 2/.

Схема совпадений выделяет один пакет, который поступает на счетно-индикаторное устройство 19 /фиг.2/, где фиксируется результат.Pulses of a constant measuring time with a duration formed by a frequency divider 22 (Fig. 2/) are fed to the same circuit

The coincidence scheme allocates one packet, which arrives at the counter-indicator device 19 / Fig. 2/, where the result is recorded.

In the layout developed on the basis of this proposal, the phase angle is measured in the operating frequency range of 7 ÷ 300 kHz. Indications on a digital display device are counted to an accuracy of one degree within 0 ÷ 360 °.

APPENDIX

Theoretical part.

A digital phase meter with a constant measuring time has two drawbacks that limit its use in sonar measurement technology. The first drawback is the low upper limit of the operating range, which, according to various sources, lies in the range from 20 to 100 kHz.

In the device / Fig. 1/, this disadvantage is eliminated by the use of a superheterodyne amplifier. The second drawback is the large measuring time θ, lying in the range from 0.1 s to 10 s, caused by the incoherence of the measuring time and the signals under study.

равными частоте и периоду исследуемых напряжений. Длительность τ пропорциональна сдвигу по фазе между исследуемыми сигналами.In the phase meter 18 ÷ 23 / Fig. 1/, using the formers and coincidence circuit 18 / Fig. 1/, rectangular pulses of duration τ, with a frequency f and a period are generated

equal to the frequency and period of the studied voltages. The duration τ is proportional to the phase shift between the studied signals.

На выходе делителя частоты 22 /фиг.1/ образуется прямоугольный импульс длительностью θ, служащий для управления схемой совпадения 20 /фиг.1/. Таким образом, на счетно-инидикаторное устройство 19 /фиг.1/ в течение постоянного измерительного времени θ поступит θf пакетов.These pulses open the coincidence circuit 21 / Fig. 1/, so that packets with the filling frequency with counting pulses ν and the period arrive at the coincidence circuit 20 / Fig. 1/

At the output of the frequency divider 22 / Fig. 1/, a rectangular pulse of duration θ is formed, which serves to control the matching circuit 20 / Fig. 1/. Thus, the counting-indicator device 19/1 / within a constant measuring time θ will receive θf packets.

With a sufficiently large measuring time θ, the total number of measuring pulses N, counted by a counter-indicator device 19 / Fig. 1/, is proportional to the phase angle and regardless of the frequency of the input voltages

The incoherence of the input signal and the measuring time forces to increase the measuring time in order to increase the accuracy of the measurement. If the measuring time, the measured signal and the repetition rate of the counting pulses are synchronized in frequency and phase, then the measuring time θ can be significantly reduced, namely, to the value of one period of the measured signal. This feature is illustrated by the timing diagrams shown in FIG. 3 and the explanations below.

Diagrams "a" and "b" show phase-shifted measured harmonic oscillations with period T. The diagrams "c" and "d" show pulses corresponding to a "positive" transition through zero of the measured oscillations. Diagram d shows pulses of duration τ proportional to the phase shift between the measured oscillations. Diagram "e" shows the counting pulses following with a period t. Diagram “g” shows packets of counting pulses, the number of which in each packet is proportional to the phase angle between the measured oscillations.

If we rigidly relate in time the period following the counting pulses t through the constant C with the period of the measured oscillations T, we obtain the following dependences

If you choose C = 360,

The number of pulses N, proportional to the angle φ °, is expressed by the formula

For the case θ = T and

That is, for the case C = 360 and θ = T, the measured angle is φ = N, where one pulse corresponds to one angular degree. In other words, the number of counting pulses with a period t that fit into one time interval τ will give a measurement of the angle φ. For measurement, one time interval τ is sufficient and, therefore, one period of the measured oscillations T, which is the minimum necessary measurement time θ. It can be seen from the foregoing that the task of reducing the measuring time can be simply solved in the case of coherence of the measured signal, measuring time, and the pulse repetition rate.

Description of the circuit diagram of a generator of tightly coupled frequencies and pulses.

A schematic diagram of a generator of tightly coupled frequencies and pulses is shown in Fig.4. The nodes included in it are shown in FIGS. 5-14.

In the device, the signals received from the generator of rigidly coupled frequencies and pulses whose frequencies are equal to the 359th and 360th harmonics of the output frequency f = 1786 Hz of a two-channel amplifier are selected as heterodyne signals.

These are the frequencies F = f · 359 = 10 ⁶ Hz and ν = f · 360 = 1002786 Hz.

This choice of auxiliary frequencies is due to the counting speed of the triggers used in the frequency divider 33 ÷ 45 / Fig. 4/, and the use of a standard mechanical filter 48 / Fig. 4/ type EMF-5D- in the amplifier-limiter 27 ÷ 32 / Fig. 4/ 500-0.3С with a passband of 300 Hz and a central operating frequency of 500 kHz.

A crystal oscillator 25, 26 (Fig. 4/) generates a harmonic signal with a frequency ν = 1002786 Hz. This signal is fed to the shaper of the counting pulses 27 ÷ 32/4 /. Through the resonant amplifier 27, 28 and the emitter follower 31, the signal is fed to output 1, from which it is supplied to the transmitting generator. The same signal from the resonant amplifier 27, 28 is fed to the amplifier-limiting cascades 29, 30 (Fig. 4/), from which it is fed to output 2 through the emitter follower 32, and from there it enters the phase meter in the form of counting pulses. The signal from stage 30 is fed to a frequency divider 33-45 / Fig. 4/. The dividing factor of the divider is chosen equal to 720. This value of the coefficient is achieved by inverting feedback from trigger 41 through emitter follower 43 to trigger 35, 36, 39. From triggers 33, 42, signals with frequencies: 501393 Hz and 1393 Hz are supplied respectively through emitter repeaters 44, 45 to the frequency converter 46 / Fig. 4/.

From the output of the frequency converter, the signal is fed to the input of the amplifier-multiplier 47-54 / 4 /.

The resonant amplifier 47, loaded on a mechanical filter 48, produces a lower side frequency of 500 kHz from the bias products, which is doubled by the amplifier 49, 50, and then it is amplified and filtered by the amplifier 51, 52. The second harmonic is selected with a frequency of F = 10 ⁶ Hz through emitter repeaters 53 , 54 is fed to a two-channel amplifier.

Claims (1)

A device for measuring the frequency-phase characteristics of hydroacoustic devices, containing a digital phase meter with matching circuits, a receiving path with frequency converters in its channels and a fixed frequency generator, for example a harmonic generator, the output voltages of which are rigidly interconnected in frequency and phase, and connected to the converters frequency of the receiving path, characterized in that, in order to reduce the measurement time, one of the outputs of the fixed frequency generator is connected to the inputs of the matching circuits f zometra.

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