SU1190306A2 - Parameter meter of two-port phase-frequency characteristics - Google Patents

Abstract

PHASE FREQUENCY PARAMETER CHARACTERISTICS FOUR-POLES CHARACTERISTICS on auth.St. No. 1002983, characterized in that, in order to improve measurement accuracy, three adders, a linear approximation unit and an integrator are entered into it, and the output of the selective phase meter is connected to the integrator and the first adder inputs, the second input of which is connected to the output of the unit measuring the signal propagation time, and the output of the first adder is the output of the meter, the integrator output is connected to the first input of the second adder, the second input of which is connected to the second output of the linear block approximation, and the output of the second adder is connected to the first input of the third adder, the second input of which is connected to the output of the selective phase meter, and the output of the third adder is the second output of the meter. Co o co o ed

Description

The invention relates to a measurement technique, can be used to measure the nonlinearity and tilt of the phase-response characteristics (phase response) of the quadrupole and the channels 5 of the communication line, and is an improvement to the author. No. 1002983.

The aim of the invention is to improve the measurement accuracy.

FIG. Figure 1 shows the structure of the meter; in fig. 2 is a block diagram of a linear approximation unit; in fig. 3 is a timing diagram for the operation of a linear approximation unit. 15

The meter of FIG. 1) contains a serially connected oscillator 1, a probing generator 2 of a discrete set of frequencies, a device 3 for phase-phasing multi-frequency signals, a first reference generator 4 of a discrete set of frequencies, a unit 5 for measuring the signal propagation time, the second input of which 25 is connected to the output of the second reference generator 6 of a discrete set of frequencies and with one of the inputs of the selective phase meter 7, block 8 linear approximation, integrator JQ tor 9, adders 10-12, first 13 and second 14 terminals of the meter for connecting and investigated the quadrupole 15.

In this way, the linear approximation block 8 is designed as a trigger 16 with separate inputs, a frequency divider 17 with a division factor equal to N, a frequency divider 18 with a division factor equal to 40 A / 64, element 19 EXCLUSIVE OR with a pr my and inverse outputs of elements 20 and 21 coincidence, a reversible counter 22 with two counting inputs and a pre-45 code installation, dividers 23 and 24 with variable division factors, a reversing counter 25 with one counting and one control inputs, a reversing counter 50 26 with two with etnymi inputs, a digital multiplier 27 by a constant B, and an algebraic adder 28.

The meter works as follows.55

The harmonic signal of master oscillator 1 triggers the probing generator 2 of a discrete set of frequencies. The multi-frequency signal of generator 2 is fed to the input of a quadrupole under test 15. The measurement signal from the quadrupole 15 is a discrete set of harmonics of the signal of the master oscillator 1, limited by the passband of the quadrupole under study 15. All components of this set received phase increments corresponding to the total phase response of the four-pole 15.

The measuring signal is fed to one of the inputs of the selective phase meter 7 and simultaneously to the input of the reference generator 6. The generator 6 generates a signal identical to the signal at the output of the generator 2 and is fed to the second input of the selective phase meter 7. The signal of the generator 6 is separated from the signal of the generator 2 by time t delays of the probing signal in the quadrupole 15 and therefore the selective phase meter 7, in which the phases of the like components of discrete sets of harmonics at its inputs are compared, will register only the nonlinear part of U S ehpolyusnika 15.

The signal of generator 2 is also fed to the input of the device 3 of mutually multiphasing multi-frequency signals, which starts the reference generator 4, as well as monitoring and maintaining the synphase of the same frequency components of the signals at the outputs of oscillators 2 and 4. As a result, the output signals of oscillators 2 and 4 are the same under the form and coincide in time, i.e. in-phase. Each of these signals leads the generator 6 output signal by time i. The time t is measured using block 5, for which you can use either a time interval meter or a linear frequency response slope meter.

To eliminate the error due to the instability of the starting moment of the generator 6, a linear approximation block 8 is connected to the output of the selective phase meter 7, in which the corrections AX and% are determined, which are used to refine the values measured by the selective phase meter 7 and block 5. Amendments & {{ and fltp ,, ow 3

The parameters of the 11 fraction fraction QQ + и1i, which are used to approximate the nonlinear part of the phase response, measured by a selective phase meter 7. The method of determining the parameters IQ and A depends on the choice of the approximation criterion. When choosing the rms criterion most often used in practice, the utfg and bi parameters are found by minimizing the sum

l ..2

P

L. u4 ((OKb (bq o + & tkii).

Z

where type is the numbers of the lower and upper harmonics of the probing signal in the passband of the quadrupole under study 15, / 2 || - the frequency of the master oscillator i.

Differening the last sum of Ha & lfo and LH and equating the obtained expressions to zero, we obtain a system of equations whose solution has the form:

P

 U-kU4K / si5I

  k M y

LUTS (UC / N-iink, iCrw

where N mn + l is the number of harmonics

signaling signal - in the passband

quadrupole 15J lc (m + n) / 2 - arithmetic average

the meaning of the numbers of these

harmonics.

Consequently, the definition of the it corrections is reduced to performing arithmetic operations on the numbers ATN {1 n, t + 1, .... , n), which does not cause fundamental difficulties

Block 8 linear approximation (Fig. 2) works as follows

To the input of block 8 from the output of the selective phase meter 7 information signals and the Sign are received, as well as the reset and number sync signals. The signal uqi is a sequence of short pulses, the number of which in the kth sample is equal or directly proportional to utf. Signal signal equals lo030b4

unity, if Atfj, 0, and logical zero, if A (. The Reset Signal is a short pulse that is generated in

5 is a selective phase meter before the start of each cycle of N measurements, and the Signal Number is a short pulse that is generated before each of the N measurements in the cycle. These signals are present in a selective phase meter, the principle of operation of which is based on sequential heterodyne frequency conversion and direct quantization of time intervals,

15 directly proportional LR).

The reset signal is set in the trigger 16. The same signal writes the number k-m + 1 to the reversing counter 22 and resets to 0.

20 all the remaining counters and dividers of the block 8 of the preset circuit of the Dividers and counters of the block 8 in FIG. 1 not shown).

The direct output of the trigger 16 is connected to one of the inputs of the matching element 20, and the inverse output to one of the inputs of the matching element 21. Therefore, after setting the trigger 16 in O, the element 20 is closed, and the element 21 is opened. Since the output of element 21 is connected to the subtracting input of counter 22, in the latter the mode Subtraction is set. When entering the first

pulse Number -from counter 22, the unit is subtracted and the code E is set in it (l. This code is fed to the pre-set inputs of dividers 23 and 24, filled,

for example, on K155IE8 chips. Thus, dividers 23 and 24 set the division factors equal to the ratio 64 / (k-m). Inputs Choice of crystal dividers

23 and 24 are connected respectively to the direct and inverse outputs of element 19 EXCLUSIVE OR. Therefore, at any time one of these dividers is open and the other is closed.

during the first measurement, the Sign is equal to the logical unit (Fig. 3. Therefore, at the direct output of element 19 there will also be a signal of a logical unit, and at the inverse output of the same element - a signal of logical zero.

Under these conditions, the divider 24 will be open, connected by its output to the subtractive input of the reversible counter 2.6. Consequently, during the first measurement, dividers 18 and 24 will receive (km) & subtracting input of counter 26 (pulses, i.e. negative number (mk) will be recorded in counter 26) When the second pulse arrives, the number in counter 22 sets the code k-rt) -l. During the second measurement, the Sign signal is equal to a logical zero, therefore an open divider 23 and a closed divider 24, i.e. (km,) u (f, / A pulse and the number (ra-k) u (pn, / A- {mHk) u4m, / A, etc., will be recorded in the meter 26 for the first measurement) to the summing input of the counter 26. When the k-th pulse arrives, the number in the counter 22 is set to zero, and a short pulse appears at its registration output zero, which arrives at the installation input into 1 flip-flop 16. The flip-flop 16 flips and delivers the resolving potential to the coincidence element 20 simultaneously locking the matching element 21. After that, the counter 22 is transferred to the Summing mode. During the k-ro measurement The presets for divisors 23 and 24 are affected by the code of O, both dividers are locked and there are no pulses at the inputs of counter 26. Thus, multiplication Ha is performed (k -k 0. When a +1 pulse is received, the number 1 is set in the counter 22 therefore, summing or subtracting (depending on the potential of the signal Sign) inputs pulses to the counter 26. Next, over 24 measurements to 24 of one of the inputs of the counter 26 ((pulses, etc.) Thus, after M measurements in the counter 26 register number h (. at the same time, the number 2G is locked at the output of the counter 25, since at its counting input, through the divider 17, bursts of pulses with the number of pulses on the k-th batch equal to Dsrc are received. Counter 25 is reversible and therefore performs the algebraic addition of the numbers LСрх. The counter 25 mode is controlled by a signal. The digital multiplier 27 serves to determine the value of BvB and can be executed on integrated circuits K53SHK1P. The value of bCfo is determined using an algebraic adder 28, which is easily implemented on an integrated circuit chip K155IMZ or K155IPZ. The division factor of divider 18 is chosen to be equal to the ratio A / 64 due to the fact that the frequency of the pulses at the outputs of dividers 23 and 24 (K155IE8 chips) is equal to f. b1X U where M is the code combination on the V-inputs of K155IE8 microcircuits. In our case, If-1. Due to this, the operation of multiplying the numbers & i) j by the weighting factors k-k with the simultaneous division of these numbers by the constant A. is implemented. Block 8 has two outputs. From the first output, a signal proportional to ui ;, is fed to the input of the adder iO, where it is used to refine the time t, measured with the aid of block 5, in accordance with the expression. The same signal is fed to the input of the integrator 9, in which frequency integration is performed. A proportional signal from the integrator 9 output (, is fed to one of the inputs of the adder I1. A signal proportional to L tf d acts on the second input of the adder 11. This signal comes from the second output of the block 8. Signal proportional to the sum of itfo + iT.y , (, from the output of the adder 11 is fed to one of the inputs of the adder 12, where it is used to refine the nonlinearity of the phase response measured by the selective phase meter 7, in accordance with the expression ID, i) C (w,) C). Thus, the nonlinearity of the phase response, registered at the output of the adder 12, does not contain a linear L to. and a constant value | c of the composition due to the instability of the starting moment of the generator 6 and the instability of the parameters of the quadrupole under study 15. In addition, the propagation time of the signal, measured with the correction l1, does not depend on these factors either.

but

/ "G

Sign

LGV

28

27

AT

J

Claims (1)

MEASURING PARAMETERS OF PHASE-FREQUENCY CHARACTERISTICS OF FOUR-POLE VOLTAGE No. 1002983, characterized in that, in order to increase the measurement accuracy, three adders, a linear approximation unit and an integrator are introduced into it, while the output of the selective phase meter through the linear approximation unit is connected to the inputs of the integrator and the first adder, the second input of which is connected to the output of the unit measuring the propagation time of the signal, and the output of the first adder is the output of the meter, the integrator output is connected to the first input of the second adder, the second input of which is connected to the second output of the linear approximation block mation and the output of the second adder is connected to a first input of a third adder, a second input coupled to an output of the selective phase meter, and the output of third adder is the second output of the meter. 1190306 ²