SU1613972A1 - Calabrator of coefficient of intermodulation distorsions - Google Patents

Abstract

The invention relates to a measurement technique and can be used in devices for checking and adjusting intermodulation distortion meters. The aim of the invention is to improve the accuracy of the formation of the output signal with the desired intermodulation distortion factor. The intermodulation distortion coefficient calibrator includes a generator of 1 sinusoidal signals, a detector of 2 average values, a balanced modulator 3, an adder 4, an attenuator 5, a detector of 6 root-mean-square values, a comparator 7, an adjustable amplifier 8, and a generator of 9 sawtooth signals. 1 il.

Description

W /) (

SP

C5

oo with to

The invention relates to a measurement technique and can be solved in devices for checking and adjusting the intermodule meters — Sch10NN distortions with

The purpose of the invention is to increase the accuracy of the formation of the output signal with the required intermodulation distortion factor.

The drawing shows a functional diagram of the calibrator of the intermodule coefficient of common distortions. The calibrator contains a generator of 1 sinusoidal signal, a detector of 2 average values, a balanced modulator 3, an adder 4, an attenuator 5, a detector of 6 rms values, a comparator 7, an adjustable amplifier 8 and a generator 9 of a sawtooth signal, while the output of the generator of a sinusoidal signal is connected to the input detector 2 averages and the first input of the adder 4, the output of which is connected to the output bus, and the second input. - with the code of the attenuator 5, the input of which is connected to the input of the detector 6 rms values and the output of the adjustable amplifier 8, the input of which is connected to the output of the balanced modulator 3, and the control input - to the output of the comparator 7, whose inputs are connected to the outputs of the detectors 2 and 6 mean and rms values, and

the inputs of the balanced modulator 3 are connected to the outputs of the generators 1 and 9 of sinusoidal and sawtooth signals about

The balance modulator 3 can be performed, for example, on a 526PS1o microcircuit. As a generator of 9 sawtooth signals, you can use, for example, special-shaped signal generators of the type Gb-33, G & -34

and dro

The intermodulation distortion coefficient calibrator operates as follows.

From the output of the generator 1 sine

Sigal U high frequency f signals are fed to the first input of a balanced modulator 3, to the second input (modulating) of which a sawtooth U is fed. A low frequency of the first harmonic f from the generator output -9 and L O U (-, t +

+ g sin6nf, t Output spectrum of the balanced modulator 3 content combinational components with frequencies mf. ± nf, (,. The signal U combinational frequencies passes through an adjustable amplifier 8, which is included in the automatic level control system, which also includes a detector of 2 average values detector 6. rms values and comparator 7 o The output signal U of adjustable amplifier 8 is converted by detector 6 into the corresponding constant voltage, which is fed to the second input of comparator 7. Output signal V Generator 1 is also converted by a detector 2 into a corresponding constant voltage, which is fed to the second input of the comparator 7. The output of the comparator 7 is a mismatch signal that acts on the control input of the adjustable amplifier 8 until the voltage of the signals and and 1) 4 will not be equal in root-mean-square values.

The signal and combinational clock passes through a passive attenuator 5 with a transmission coefficient K ,, to the second input of the passive output adder 4, to the first input of which is fed the original sinusoidal signal V of high frequency f. The output of the calibrator is determined by

and

elbtx

(t) U / t) h - KqU (t) Ug (2)

TO

Th "l

whose coefficient is equal to

 UECOO% - -100 100 K., (3)

 U1 U-, where and, U4 and Ug- are the rms values of the voltages of the corresponding psycho signals, i.e.

K value, but equal to the coefficient of transmission Kd attenuator 5

In the particular case, the frequency f and f of the signals And, and U ,. can be equal, i.e. f, 2 f. Then the spectrum of the input signal U-j balanced mod51613972

Ltor 3 contains spectral components with frequencies f ± nf, m. harmonics of the frequency f of the signal U. With an accurate calibration of the levels of the output signals U |. and generators 1 and 9 relative to each other, the output signal Uj of the balanced modulator 3 has a fixed harmonic value of K. Therefore, in this case, the harmonic of the calibrator output signal can also be normalized.

Thus, the introduction of new elements and connections makes it possible to more accurately form the output signals with the given values by decreasing (practically excluding) the content in the signal of the combination frequencies of the components with frequencies f

and 2..

Formula of Invention

Intermodulation distortion coefficient calibrator, containing

the adder, the output of which is connected to the output bus, the first input - with the output of the sine-wave generator, the input of the average detector and the first input of the multiplier, and the second input - with the output of the attenuator, the input of which is connected to the input of the rms detector

values and output of an adjustable amplifier, the control input of which is connected to the output of a comparator, whose inputs are connected to the outputs of detectors of average and rms values, characterized in that, in order to improve accuracy, a sawtooth signal generator is added to it, the output of which is connected to the second

the input of the multiplier, the output of which is connected to the input of the adjustable amplifier, while the multiplier is made in the form of a balanced modulator,

Claims (1)

FIELD OF THE INVENTION An intermodulation distortion coefficient calibrator comprising an adder whose output is connected to the output bus, the first input to the output of the sine wave generator, the input of the average detector and the first input of the multiplier, and the second input to the output of the attenuator, the input of which is connected to the input of the detector of rms jq values and the output of an adjustable amplifier, the control input of which is connected to the output of the comparator, the inputs of which are connected to the outputs of the detectors of medium and rms iCal values, characterized i in that, to improve accuracy, it is further introduced sawtooth signal generator whose output is connected to a second. 20 by the input of the multiplier, the output of which is connected to the input of an adjustable amplifier, while the multiplier is made in the form of a balanced modulator.