SU720377A1 - Device for measuring relative non-linearity of amplitude response - Google Patents

Description

I

The invention relates to electrical measurement techniques and can be used to measure the relative non-linearity and non-identity of the amplitude characteristics of various four-port networks over a wide frequency range.

A panoramic meter is known from a carrier non-linearity of amplitude characteristics of four-port circuits containing a high-frequency generator connected in series, a modulator, a test four-pole circuit, an output divider, a switch, the second input of which is connected to the modulator output, a controllable element, an amplitude detector, a selectable amplifier, a synchronous detector, , direct current amplifier, cathode ray tube, adder, and error signal fl,

The disadvantage of the meter - low ability and low measurement accuracy (about 2%).

Also known is an amplitude response meter containing a series-connected input source, a continuously varying voltage converter in stepwise varying, an input divider, a test pole circuit, an output divider, a switch, an amplifier, a detector, a phase inverter, a second switch, the second input of which is connected with detector output, integrator, key, vertical deflection amplifier, cathode ray tube, as well as a reference quadrupole, whose input is connected to the output of the transducer the smoothly varying voltage bar in a stepwise variable through a controlled correction divider, and the output to the switch 2.

The disadvantage of the meter is significant in total, the fault and the impossibility of direct measurement.

The purpose of the invention is to expand the functionality of the device.

The goal is achieved by the fact that, in a meter that contains an input signal source, the output is connected through a controlled divider to the first input and to the input of the reference four

of the pole, the output of which is connected to one of the switch inputs, the other input of which is connected to the second input of the device through the output divider, and the switch output via a serially connected amplifier and detector to the input of the recording indicator, the indicator of the recording indicator is connected to the control input of the amplifier adjustable, and the register indicator is made in the form of a voltage-frequency generator &, the output of which is connected to the input of the switch, the first output of which is connected through numbers a new counter with the input of a recording-recording device, and the second one - with one of the inputs of the frequency comparison unit, the other one, whose input is connected to the output of the reference frequency generator,

The drawing shows a block diagram of the device.

The device contains an input signal source 1, a controlled divider 2, a quadrupole under investigation 3, a standard: a quadrupole 4, an output divider 5, a switch 6, a controlled amplifier 7, a detector 8, a voltage converter 9, a switch U, a reversible pulse counter 11. the frequency comparison unit 12, the reference frequency generator 13, the device 14 and the recording indicator 15,

The device works in two modes

In the first mode, the inputs of the reference 4 and the investigated 3 quadrupoles receive a voltage varying in time according to a stepwise law with the help of a controlled divider 2. Switch 6 performs a duration of each step connecting to the input of the controlled amplifier 7 respectively output voltages reference circuit: - four pole and four output divider When connecting the output of the reference quadripole 4 to the amplifier 7, the output of the voltage converter into frequency 9 through the switch 10 is connected to the comparison unit Frequency 12, which controls the transfer ratio of the controlled amplifier 7 until the frequency at the output of the voltage converter at frequency 9 becomes equal

NOY, at the frequency GO received from the reference frequency generator 13 “So. Thus, the output voltage of the reference four-port 4 is normalized. When the frequencies supplied to the frequency comparison unit 1 coincide, the switch 1O switches the output of the voltage converter 9 to the input of the reversing counter 11, which during the counting time T will sweep; number of pulses N

biriVU. ,,

where K K KgHg is the coefficient () of the transmission of the corresponding block transmissions.

After the expiration of the counting time T, the input of the amplifier 7, the value of the transmission coefficient of which remains equal to that obtained in the first rhenium mode, connects the output of the divider 5; and the reversible counter 11 switches 1 s to the subtraction. In the second mode, during TQ, the number of pulses Ng will pass to the counter 11

,,. K, .K.K, .K..a)

considering expression (1), expression (2) takes the following form

M ggr V5 .- (i)

As a result of the subtraction on the counter - 11 numbers will remain

N N, -N.) ")

four

which will go to the digital register-registering device 14. The transition of the state of the reversible counter to zero is recorded by the digital counting-registering device 14 by changing the sign of the display. The resulting difference in the number of pulses is equal to the relative nonlinearity of the studied four-field axis 3 at a given signal level at its Input relative nonidentical

the amplitude characteristics of the studied 3 and 4 reference quadrupole

kikov. Similar operations are repeated at each following step. As follows from the expression (4), the errors of amplifier 7, detector 8 and convert voltage-frequency 9 into the measurement result do not enter, and the frequency instability influences the measurement error

f Q And time counting TQ. In the case of full multiplicity

gr P

C5)

instability fo and Td does not affect

measurement error.

Claims (2)

Claim 1. A relative non-linearity meter of amplitude characteristics, containing an input source, an output connected via a controlled divider to the first input of the device and to the input of a reference four-pole network, the output of which is connected to one of the inputs of the switch, the other input of which through the output divider is connected to the second input of the device, and the switch output through a series-connected amplifier and detector to the input of a recording indicator, characterized in that, in order to extend the functionality Tey, the output of the recording indicator is connected to the amplifier input, made adjustable. 2. The meter according to claim 1, is different in that the recording indicator is designed as a voltage-frequency converter, the output of which is connected to the input of the switch, the first output of which is connected through a digital counter to the INPUT of the switch, the first output of which is connected a digital counter with the input of a registering device, and a second output with one of the inputs of the frequency comparison unit, the other input of which is connected to the output of the reference frequency generator. Sources of information taken into account in the examination 1. Author's certificate of the USSR N9 311213, cl. G 01 R 23/20, 02.08 L1, 2. USSR Author's Certificate No. 296060, class, G 01 R 27/28, 12.11,71 (prototype).