SU879508A1 - Device for four terminal network amplitude frequency characteristic tolerance control - Google Patents

Description

(54) DEVICE FOR ADMISSION CONTROL OF AMPLITUDE-FREQUENCY CHARACTERISTICS OF FOUR-POLES

I

The invention relates to a measuring technique and can be used to verify the characteristics of amplifying apparatus.

A device for determining frequency characteristics is known, which comprises a series-connected oscillating frequency generator, a monitored device and an indicator, for example, a cathode ray tube (CRT) D1.

The drawback of the device is the low measurement accuracy due to errors in the readout of values on the measuring grid printed on the screen of a CRT.

It is also known a device for observing the amplitude-frequency characteristics of the ESSF) and its field of tolerances on a CRT screen, which contains a sweep frequency generator, a controlled device, a matching amplifier, an indicator, a converter.

frequency voltage and two tolerance adjusters 2.

A disadvantage of this device is the low accuracy of the measurements due to the instability of the analog elements of the tolerance adjusters.

The aim of the invention is to improve the accuracy of control of the frequency response.

The goal is achieved by the fact that a device for tolerance control of the frequency response, containing a controlled oscillator, to the output of which one of the device inputs, the tolerance code setter and the indicator is connected, a voltage-code generator, a digital readout unit, a code comparison unit, a setter are entered. frequency code, nominal level code setter and control unit, the first output of which

Claims (2)

20 is connected to an input of the frequency code setting unit, one of the outputs of which is connected to the frequency indicator, and the second output of the frequency code setting indicator is connected to the control input of the controlled generator, to one of the inputs of the control unit and to the setting output of the tolerance code, to the output connected to one from the inputs of the comparison unit CODOE whose output is connected to the second input of the control unit, the third input of which is connected to the control input of the Start and Stop devices, and the second output of the control unit is connected to the control input of the converter voltage code, the input of which is connected to the second input of the device, and the output of the voltage converter is connected to the indicator input directly and through a digital subtraction unit with the second input of the code comparison unit, while the second input of the digital subtraction unit is connected to the output of the setter of the nominal code of the first level . The drawing shows a block diagram of the device. The device contains a frequency code generator 1 sequentially connected in a ring, a controlled oscillator 2 controlled by a quadrupole; 3, the voltage-code converter 4, the digital subtraction unit 5, the code comparison unit 6 and the control unit 7, the setting unit 8 of the nominal level code, the setting unit 9 of the tolerance code, the frequency indicator indicator 10 and the measurement result indicator. The device works the following way. The unit 8 sets the code of the nominal signal amplitude against which the frequency response is checked, and the unit 9 sets the error tolerance codes for the frequency ranges, and the unit 1 sets the frequency code at which the signal amplitudes must correspond to the nominal level (for the audio equipment, this frequency is equal to 1000 Hz). Block 7 trans: is operated in a steady mode of operation, while blocking control pulses into the setpoint controller is blocked and it constantly issues the set frequency code. By the Start signal, the block 7 is switched to the operating mode and enables the converter 4 to work. After that, by the signal Stop unit 7 is transferred to a non-operating state and it is switched to automatic operation. Unit 1 set the code of the initial frequency. On the Start signal, the block 7 enters the working state. Block 7 can be performed in various circuit variants, in particular, it can be a trigger with input logic, a pulse generator having a control input, and a pulse shaper for triggering the converter, or a multiple-input trigger and asymmetric multivibrator, or a combination of these options. According to the signal from block 7, the setting device 1 sequentially supplies the generator 2 with frequency codes, using which the generator synthesizes sine-wave signals with a constant amplitude and supplies them to the input of a controlled two-pole network. The frequency range sampling step is determined by the class of the device being monitored and the required accuracy of the AFC control and is set by the setting device 1. The signals from the quadrupole 3 output are digitized by the converter 4, and the resulting codes are fed to one of the inputs of the digital deduction unit 5, the second input of which receives the code nominal level The difference between the codes from the output of block 5, the corresponding non-uniformity of the frequency response at the checked point of the frequency range, is compared by block 6 with the error tolerance codes from the setpoint 9, which changes their values depending on the frequency section to be tested. If the difference of the codes exceeds the set value, then block 6 issues a signal to block 7 and the test stops. In this case, the indicators 10 and P indicate the frequency and the result of measuring the amplitude of the signal at this frequency. If the frequency response of a controlled quadrupole is within the established tolerances, then the test continues. After checking the upper cut-off frequency setting unit. 1 passes the signal to block 7 and the test ends. So, for example, when using PNAs of middle class accuracy per 10 bits, the device allows to obtain a control accuracy of about 0.1. The unit of the tolerance code, and the indicator, characterized in that, in order to increase the control accuracy, a voltage-code converter, a digital subtraction unit, a code comparison unit, a master controller are entered into it. and the frequency, the setting unit of the nominal level code and the control unit, the first output of which is connected to the input of the setting unit of the frequency code, one of the outputs of which is connected to the frequency indicator, and the second output of the setting unit of the frequency code is connected to the control input of the controlled generator, with one of the inputs control unit fO ff 84 and with the input of the unit of the tolerance code, the output connected to one of the inputs of the code comparison unit, the output of which is connected to the second input of the control unit, the third input of which is connected to the control input of the Start and Stop devices, and the second output of the control unit is connected to the control the input of the voltage converter-code, the input of which is connected to the second input of the device, and the output of the voltage converter is connected to the indicator input directly and through a digital subtraction unit to the second input of the code comparison unit, at the same time, the second input of the digital subtraction unit is connected to the output of the setpoint adjuster of the nominal level. Sources of information taken into account in the examination 1. Japanese Patent No. 50-23992, cl. ON BUT, 1975. 2. The patent of Germany No. 2060148, cl. G 01 R 27/28, 1970 (prototype).