SU1402963A1 - Device for determining systematic phase error of amplitude and phase meters - Google Patents

Abstract

The invention relates to electrical measuring equipment, namely, devices for determining the systematic phase error of amplifiers. The purpose of the invention is to expand the frequency range. A distinctive feature of the device is the frequency independence of the phase shift of the averaged transmission coefficient. The device contains a measuring generator I harmonic signal and the block 8 of the switch. A matching splitter 2, a reactive dynamic divider (D) 5 voltage and a voltmeter 9 are entered into the device. The count of the cyclic switching of the elements to. Output D 5 forms a series of stresses associated with a known relationship. During calibration, phase-measuring equipment is connected to the input and output buses D 5. The description provides examples of the implementation of the D 5 and the switching unit 8. 2 hp f-ly, 6 pcs. (L

Description

Yu

with

OS

with

The invention relates to electrical measuring equipment, namely, devices for determining the systematic phase error of amplifiers in the frequency range from kilohertz to units of megahertz.

The purpose of the invention is to expand the frequency range.

FIG. Figure 1 shows a block diagram of a device for determining the systematic phase error of amplifiers; in fig. 2 - types of reactive elements; in fig. 3 is a more functional scheme of a reactive dynamic voltage divider; in fig. A - equivalent scheme of connecting one reactive element to; divider elements; FIG. 5 shows the structure of the board; in fig. 6 a, b, c - the state of the branches of the reactive dynamic voltage divider at different positions of the controlled keys in fig. 6d are vector diagrams of the complex transfer coefficients of the indicated divider for its various states and the result of summing up with N 4.

The device (Fig. 1) contains a measuring generator 1 of a harmonic signal, the output is connected to the input of a matching splitter 2, the first output of which is connected to terminal 3 for connecting the reference input of a turnable amplifier 4, and the second output to the input of a reactive dynamic voltage divider 5, the output of which is connected to terminal 6 for connecting the measuring input of a rotatable amplifier 4, N control inputs of said divider 5 are connected to the corresponding outputs 7 of the switching unit 8, the control output matching splitter 2 is connected to a voltmeter 9.

The reactive dynamic voltage divider 5 (Fig. 3) contains N reactive elements 10.1, 10.2 ... 10.N whose first terminals are connected to the output bus of the divider 5, and the second terminals to the corresponding N outputs of controlled keys 11.1, 11.2 .. .11.N the first inputs of which (normally closed with the exit of keys) are connected to the bus. zero potential, the second inputs (normally open with output) are connected to the input bus 12 of the divider 5, and the control inputs of the control keys are control

0

five

0

five

ABOUT

five

0

five

0

five

input inputs of the divider 5 and are connected to the corresponding outputs 7.1, 7.2 ... 7.N of the switching unit 8.

Switching unit 8 contains a generator of 13 rectangular impulses, the output connected to the counting input of the counter 14, allowing its input through the key 15 with latching position (for example, a toggle switch) is connected to the zero potential bus, and the outputs of the counter 14 are connected to the corresponding decoder 16 inputs , the output buses of which are connected via N matching 17.1, 17.2 ... 17.N to the corresponding N control outputs 7.1, 7.2 ... 7.N of the switch block.

The harmonic measurement generator 1 (Fig. 1) includes a serially connected master oscillator 18, a matching element 19 and an adjustable output voltage amplifier 20,

The matching splitter 2 contains a divider 21, the first arm of which is the first output of the splitter 2, and the second arm through the passage element 22 is connected to the second output of the splitter 2. To the output of the passage element 22 is connected i through the probe 23 to the control outlet of the splitter 2.

The device works as follows.

The signal of the measuring generator 1 passed through the matching splitter 2, in the form of a reference signal with a constant amplitude and phase, is fed to the first input of the amplifier 4 (terminal 3).

From the other output of the matching coupler, the measurement signal is fed through the reactive dynamic voltage divider 5 to the second input of the amplifier 4 (terminal 6),

The N control inputs of the reactive dynamic divider are sequentially and cyclically supplied with control signals from the corresponding outputs of the switching unit 8, providing the necessary change in the amplitude and phase of the measuring signal at terminal 6,

A voltmeter 9 is connected to the third output of the splitter to control the amplitude of the signal at the measuring output of the matching splitter 2.

U

The main role in the work of the calibrator is played by the reactive dynamic

voltage divider

A reactive dynamic voltage divider operates as follows.

The input voltage, which is a harmonic oscillation with a complex amplitude Ujx, is applied to the bus 12. When the keys 11.1 ... 11.N (in Fig. 3 from left to right) are sequentially switched, each element 10.1, ..N is alternately for a time one switch is connected to the first bus 12. In FIG. 6a, b, c show the states of the branches of the divider 5 with its sequential switching. The first two states (in Fig. 6 from top to bottom correspond to the sequential erasing of the first two keys 11.1 and 11.2, and the last state - to the operation of the last key 11.N. During N switching times, the average value of the output voltage Ucp. M to the output- terminal 6 turns out to be

| K, | e

,, G: | KPE.

 and

8X

(3)

B1

Kjle

) (fi

 ZtZ3 ... Zi + ZiZi |, N + Z, Zt ... ZN-i -ijZj,., Zfj + Z, ZjZj + ZiZ .., Zf (.

 i (4)

where Zj is the i-th impedance

divider element 5. Going over to the trigonometric form of complex numbers, we assume that the initial phase of the input voltage is zero, i.e.

 lUbxIe 1U

in

(five)

From expressions (3) and (4) we get

N

 th eblxi Ugfcix 1 + .. .Ugb, xN) (1)

6X1

Uex N

de Ucp N is the average value of the complex amplitude of the output voltage over the time of N cycles;

N is the number of cycles equal to the number of reactive elements 10.1 ... 10.N; complex voltage amplitude at the input; complex voltage amplitude at the output during the i-ro cycle time (i 1, 2, ... N). Considering that

and

Bh

and

9Ш

and

OUT i

 UexK, - UBX 1K, 1

,

Where

K - is the complex transfer coefficient of the divider 5 during the 1st cycle; | K, - |, H, - the modulus and phase of the transmission coefficient K-,

expression (1) can be represented in a complex form;

Ug, (lK, + iK.le

thirty

35

8x

eleven

AND

AND

and-

eitxi

in

sin, sinvf.0 (9)

50

gg

Expressions (8) and (9) describe the relationships between the phase shifts, input and output voltage modules, introduced by the reactive divider 5 in its various states. From the expressions it follows that the sum of the active components of the output voltages is equal to the magnitude of the input voltage, and the sum of the reactive components of the output voltages is zero. The obtained relationships are explained in the vector diagram of complex transfer factors K, ... K for the four states of the divider 5, consisting of four reactive elements 10.1 ... 10.4 with arbitrary complex resistance (Fig. 6d). Each transmission coefficient K ... K is designated as

vector, the modulus of which corresponds to the modulus of the coefficient, and the angle of inclination relative to the horizontal axis - the phase of the transfer coefficient. As can be seen in the diagrams, the total vector N

H1K; K, + Kj + K, + K has 1

length equal to one, and is located along the real axis, which illustrates the fulfillment of conditions (8) and (9),

The obtained relations (8) and (9): are frequency-independent, so: as they do not depend on the resistances; elements 10.1 ... 10.N divider 5.: The name is this property and is supposed to be the basis of the device operation . Unit 8 provides a consistent generation of control switching pulses that control the operation of the keys 1. one. . , 1 .N, included in divider 5.

The initial state of the keys 11j1 ... 11.N is shown in FIG. 3

After turning on the power supply, the generator 13 of the pr-angular impulses of the block 8 starts working; and the score-: Chick 14 is in the zero state (previously cleared). By manually pressing the key 15 with latching, the counter 14 begins to fill with pulses from the generator 13, and at its output there appears a binary code corresponding to the number of received pulses. The binary code is fed to the input | of the cipher 16, the output of which bn is converted into a unipolar code, b ensuring consistent excitation of the output buses of the decoder 16. The duration of the pulses at the outputs of the decoder 16 is equal to the period of the generator 13.

The pulses of equal duration from the outputs of the decoder 16 sequentially through the coordinators 17.1 ... 17.N levels of block 8 are fed to the control 1s Key inputs 11.1 ... 11.N in divider 5, ensuring their switching to the Pulse width time. By pulse action, the keys return to their original state. By sequentially switching the keys, the terminals 10.1 ... 10.N are alternately connected to the bus 12 to form the Divider Branch 5. After issuing N pulses from the output of block 8, the counter 14 is reset to the zero state and starts to fill up again, the cycle through

repeats. Ll stop switching, you must disable the key 15 to block the counter 14.

Elements I0.1 ... 10.N - inductance, capacitance or their compounds (Fig. 2) are used as reactive elements. The main requirement for the selection of elements for inclusion in the composition of the divider 5 is their small size and proper structural arrangement on the board (Fig. 5).

From a consideration of the equivalent circuit for incorporating any one element 10 in FIG. 4 that the total impedance of the upper branch (between bus 12 and terminal 6) is equal to

20

2, g-4 8 - Z, + Z, 4.

 F

(ten)

five

0

five

where Z., is the total impedance between busbars 12 and terminal 6 for the upper branch;

Zg - the impedance of the connecting wires of the upper branch;

Z JJ, is the impedance of the first pair of key contacts;

Z. J is the total impedance of the key 11; Z p - the impedance of the resistive element 10. The total impedance of the lower branch (between the bus common and terminal 6) with a different position of the key 11 is equal to

40

0-4 H kl Pl

(eleven)

five

0

five

where is z

- the impedance of the connecting wires of the lower branch;

 Z C - the impedance of the second pair of contacts of the key 1 1.

To eliminate the influence of connecting wires and contacts of keys 11 on the values of switched reactances, these circuits must be made symmetrical, i.e.

Z

7 l / 7 7 / J J / jf,, 1

K t

WHAT ensures equality

Z 11- {Z o-J

(12) (13)

11D

Thus, the total switched impedance formed from the resistance of the element 10, the resistance of the wires and the contacts of the key 11, is the same for the two positions of the key 11. The circuits of the divider 5 are symmetrical (FIG. 5), and the switches with the same co - resistance of switched channels (for example, on field-effect transistors

or reed relays).

I

Determining the systematic normness of the amplifier is carried out by measuring the control voltmeter and the amplifier itself. Using the amplifier the measurement of the phase difference between the signals at the inputs and the determination at terminal 6 of the amplitude; s of the measuring signal during each cycle. Reference sign

and

ewxll

1C

exit i

and

8x

i A,

, + in v ,, +

 uiM w is the phase difference between the harmonic signals at the inputs of the amplifier and the amplitude measured in the i-ro cycle of the divider 5.

Represented the value of the measured phase difference form

uzm

where (f is the phase of the transfer coefficient of the divider 5 during the i-ro cycle; D1 is the systematic error

phase measurement,: expression (16) can be written

 sin h

Ujivn

„(Sine / .cos dtf +

) 1 and -1

+ cost /, sin 4 Lf)

N lUgbixil

Cos / 5

eleven

and

5X

sin if. +

The voltage on terminal 3 of the amplifier A is kept constant. The measurement results are read from the output indicators of the calibrated amplification meter, the input voltage of the divider 5 is measured by a voltmeter 9.

Thus, after all N switches of divider 5, the amplitude ratios must be determined

and

Ri-ift

and.

Bhxn

(14)

and phase shift measured by the amplification meter

meas 1 meas 1 t I N (i5)

According to the measurement results (14) and (15), the constant component of the measurement error of the phase LL is defined as the algebraic sum

ttlX N

-Sin l vjjMN BX

(sixteen)

 Llueiix l

+ sin 1 2-7; costf. A. (17)

 Bx

Taking into account the properties of the divider 5, described by expressions (8) and (9), we obtain

sin dlf A finally

/ It / arcsin A,

(18)

(nineteen)

Thus, the sought systematic error 41 of the verified amplification meter 4 is determined through the known number A obtained from the results of N measurements. For small values of error

.(20)

The main technical and economic advantage of the proposed device in comparison with the known ones is a significant expansion of the operating frequency range. Frequency independence of the average transmission coefficient allows the use of

; device As a wide-range meter, systematic phase errors when 1 testing amplifiers, this eliminates the need for using some stable precision elements,

Claims (3)

Invention Formula 1. A device for determining the systematic phase error of amplifiers, containing a measurable harmonic wave generator, switching unit and terminals for connecting an amplifiable to be tested, differing from the fact that, in order to extend the frequency range, a matching a splitter, a voltmeter, and a reactive dynamic divider, for example, with the first output of the matching splitter connected to the terminal of the connection of the reference input of the output amplifier, the second output with the input su- dynamic voltage divider whose output is connected to a terminal for sub {slyucheni measuring input power metal - amplifazometra direct and control guides yhody said divider - to soot- etstvuyuschimi peregspyu- 1eni output unit, the measuring generator garmo12 Ugx  1 0-2L W-W goshch output signal is connected to the input of a matching splitter, the test output of which is connected to a voltmeter, 2. The device according to claim 1, characterized in that the reactive dynamic voltage divider contains N reactive elements, the first terminals of which are connected to the output of said divider, and the second terminals to the corresponding outputs of N controlled keys, the first inputs of which are connected with a common bus of zero potential, and the second terminals with the input of the said divider, the control inputs of the control keys are the control inputs of the reactive dynamic voltage divider. I. 3. The device according to claim 1, characterized in that the switching unit comprises a generator of rectangular pulses, the output of which is connected to the counter input of the counter, allowing its input through a key with position fixing is connected by a zero potential bus, and the outputs of the counter are connected to the corresponding decoder inputs. The N output buses of which are connected via N level adapters to the outputs of the switching unit. - / 1 0-2L W-W afvx 7 / 7.2 gz /five pgcht fa & c 12 ////// Jxj 7 /////////// nr, l | g, x. i / ///////// y //// F G7. / I P n / (; 7-2 „p fab. 12 v / ////////////// 7 Jrj / ff-jj : S irni I and a 7 th " a 2irj F f F 73 / (7-3 „P n  7.U. q n fi8.5 Q J2 FIG. 6