SU512437A1 - Frequency response meter - Google Patents

Description

5, synchronous detector of side cocTaii.isiocals 6, auxiliary current amplifier 7, first low pass filter 8, divider nan 9, meter ratios 10, switch 11, phase inverter 12, second low pass filter 13, switching unit 14, indicator 15, komnarator 16, a set-level setting circuit 17, a control unit 18, a unit for modulating voltage 19, and a time selector 20, an electronic counter 21.

The meter works as follows.

The frequency of the oscillator 1 is approximately set to the average frequency / o of the four-terminal 4 position on which the modulator 3 starts the amplitude of the modulated oscillation obtained by modulating the oscillations of the generator 1 with the voltage of the generator 2. The amplitude-modulated oscillation consists of three components: the main equal to the frequency of the reference oscillator 1, and two lateral, symmetrically located relative to the main one and separated from it on the frequency axis by an amount determined by the frequency of the oscillator 2. As a result e wobble frequency generator 2 from zero to Qm side frequency components in synchronism will vary in the range from fo to fo-r m, yielding values of transmittance ri- band frequency quadrupole. Passing the quadrupole, the fundamental and lateral components are amplified in accordance with its frequency characteristics and fed to detector 5, which produces spectrum non-transfer to zero frequencies with convolution relative to zero frequency, and DC voltage and low-frequency components at its output Equal to the generator frequency, they will be normal voltages of the corresponding components at the output of the quadrupole.

The constant component is amplified by the DC amplifier 7 and the filter 8 is extracted and through the voltage divider 9 used in the calibration mode to equalize the voltages of the main and side components, is fed to the first input of the ratio meter 10. The side components at the frequency arrive to the input of the LED of the side components 6, to the second input of which through the switch 11, in phase directly and out of phase through the phase inverter 12 oscillations from the generator are received. The switching of the antiphase controls of the detector 6 allows it to produce voltages that are proportional to the lateral components of the amplitude-modulated oscillation, which are fed through the filter 13 to the second input of the ratio meter. From the output of the relationship meter, the voltage, proportional to the ratio of the operating voltage to the side components, is in parallel supplied to the indicator 15 and the comparator I). The block of switching 1presses operates in such a way that in the “EnoRuoiiii” mode of switching on the indicator are observed

two branches frequency characteristics. With a strictly symmetric form, they are merged. The frequency of the oscillator 1 is adjusted to c :: sf max the frequency response at the beginning of the indicator sweep.

In the measurement mode, the switch is in a predetermined steady state, and one indicator of frequency characteristics is displayed on the indicator. Genre filed on

0, the compiler is compared to the voltage of a predetermined level coming from the circuit setting a predetermined level 17. At the moment of equality of these conditions, the comparator outputs a pulse to the control unit 18. At the second

5, the control unit input is supplied with voltage from the modulating voltage unit 19. The control unit generates two pulses delivered to the time selector 20. The first impulse opens the time selector when the generator frequency vanishes, the second impulse closes the time selector when the frequency characteristic reaches the specified level . Thus, the counter 21 passes the number of periods of the generator, equal in magnitude to the width of one branch in hertz. By switching the switch I, the width of another frequency response is measured in the same way. In this case, the inaccuracy of setting the frequency of the generator 1 is not

0 causes an increase in the measurement error of the entire transmission bandwidth. The meter readings are erased by a pulse from the control unit before the next counting cycle begins.

In the meter on the measurement error is not

5 is affected by the instability of the gain of the measured quadrupole because its output measures the ratio of the voltages of the frequency components. This circumstance allows for this meter, in contrast to the known ones, to select the optimum frequency sweep rate only from observability conditions.

The readings of the comparison with the setpoint level, as well as the frequency reading, are performed

5 automatically and independently of the accuracy and other characteristics of the indicator. On the other hand, the display of frequency characteristics on the screen is not interrupted in parallel with high-frequency transmittance measurements.

In the meter, all nodes can be performed on the elemental base created in the industry. In addition, signal processing, starting with detector 6, is carried out at low frequencies and direct current, which allows the use of compact typical nodes and integrated circuits.

Claims (1)

Invention Formula An frequency response meter comprising a modulating voltage block, the outputs of which are connected to the inputs of an oscillographic indicator and oscillating frequency generator, characterized in that, in series with increasing accuracy and automating bandwidth measurement, a modular torus, synchronous reference-frequency detector, DC amplifier, first low-pass filter, voltage divider, ratio meter, the output of which is connected to the indicator input the second output of the synchronous detector of the reference frequency through a synchronous detector of the side components and the second low pass filter connected to the second input of the ratio meter, the first output of the oscillating frequency generator connected to the second input of the module torus, second oscillator frequency generator output connected via a time selector with an electronic counter, the input "reset" of which is connected to the second output of the control unit, and the third output through a phase inverter and directly connected to the first and second inputs of the switch, to the control input of which the switching voltage block is connected, and the switch output is connected to the control input of the synchronous detector of the lateral components, and the second comparator input is connected to the output of the set level circuit, the outputs of the modulating voltage block are connected to the control inputs of the oscillating frequency generator, the horizontal scan of the indicator, the control unit, and the second output of the reference frequency generator is connected to the control im input synchronous detector reference frequency.