SU1465823A1 - Device for measuring parameters of phase demodulator - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure the transition time of a phase demodulator when it is affected by a phase jump and amplitude, a transmission coefficient, and a detector characteristic of the phase demodulator and its zero offset. The aim of the invention is to reduce the measurement time. For this purpose, a shaper 3 signal is additionally entered into the device, four switches 2, 5, 15 and 16 and two keys 13 and 14. In addition, the device contains an oscillator 1, a divider 4 frequencies, attenuators 6 and 7, a phase shifter 8, the subject LD 9 Phase meter 10, And oscilloscope, millivoltmeter 12, terminals 17-20. Using phase shifter 8, various values of the initial phase are set, then the detector characteristic of PD 9 is measured, which is used to determine the transmission coefficient of PD 9. 1 Il. (L

Description

The invention relates to a measurement technique and can be used to measure the transition time of a phase demodulator (PD) when exposed to a phase or amplitude jump, transfer coefficient and detector characteristics of the phase demodulator and its offset. YU

The purpose of the invention is the reduction of measurement time.

The drawing shows a structural diagram of the installation.

The installation comprises an oscillation generator 1 15, a first switch 2, a signal shaper 3, a frequency divider 4, a second switch 5, a first 6 and a second 7 attenuators, a phase shifter 8, a tested phase 20 demodulator 9, a phase meter 10, an oscilloscope 11, a millivoltmeter 12, the first 13 and second 14 keys, third 1.5 and fourth 16 switches, first 17, second. 18 and third 19 terminals

The device operates as follows.

When measuring the transition time of PD 9, switch 2 is set to position 2, and switches 15 and 16 are set to the closed position. '' The signal from the oscillation generator 1 is fed to the installation terminal 17, the inputs of the attenuators 6 and 7, and to the first input of the phase meter 10. The switch 5 includes voltage E to the frequency divider 4, the output of which generates a signal supplied to the control input of the key 13, which is translated to the closed position. At the same time, the signal at the output Q of the frequency divider 4 is absent and the key 14 is in the Open position. The signal from the oscillation generator 1 is supplied through a series-connected attenuator 6, a switch 15 and a key 13 to the installation terminal 18. The signal from the terminal 19 of the installation setup for connecting the test phase demodulator and the fourth terminal 20 of the device for connecting the voltage source E. Moreover, the output of the oscillation generator 1 is connected to 30 inputs of the signal shaper 3, attenuators 6 and 7, the first input of the phase meter 10 and the first terminal 17 of the installation for connecting the test PD 9, the second terminal 18 of which is connected to the second input of the phase meter 10, the synchronization input of the oscilloscope 11 and the outputs of the keys 13 and 14, the control antiphase inputs of which are connected to the cell stvuyuschim outputs frequency divider 4. The output of the signal shaper 3 is connected to the first fixed contact of the switch 2, the second fixed contact of which is connected via the switch 5 to the installation terminal 20 for connecting the voltage source E. The movable 'contact of the switch 2 is connected to the input of the frequency divider 4. Terminal 19 of the setup for connecting the test PD 9 is connected to the signal input of the 1 G oscilloscope and the input of the millivoltmeter 12. The output of the attenuator 6 through the switch 15 is connected to the input of the key 13. The output of the attenuator 7 is connected through the phase shifter 8 and non-: 'switch 16 is connected to the input key 14.

It is connected to the input of the multivoltmeter, where it is registered. According to the readings of the millivoltmeter 12 and the phase meter 10, by adjusting the attenuator 6, the required signal amplitude at the input of PD 9 is set. Then switch 5 is switched to the Open position. In this case, a signal is generated at the output Q of the frequency divider 4, which is fed to the control input of the second key 14 and sets it to the closed position. The signal from the output of the attenuator 7 through a series-connected 40 phase shifter 8, switch 16 and key 14 is supplied to the installation terminal 18. The signal from the terminal 19 of the installation is fed to the input of a millivoltmeter 12, where it is registered. Based on the readings of a millivoltmeter 12 and a phase meter, the amplitude and initial phase of the signal at the input of the PD 9 are set. After that, the switch 2 is turned to position 1. In this case, the transition process of the PD 9 from the phase and amplitude signal is observed on the oscilloscope 11 screen. The transient time is measured on the screen of the oscilloscope taking into account the calibration elements of the sweep scale of the oscilloscope + dograph.

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When measuring the transfer coefficient, the detection characteristics of the PD 9

1 and its zero offset, switch 2 is moved to position 2. Switch 5 and 15 are set to the open position. According to the readings of a millivoltmeter 12 and a phase meter 10, the required values of the signal amplitude at the input of PD 9 are set.

Using phase shifter 8 sequentially set various values of the initial phase of the signal. In this case, the readings of the millivoltmeter 12 connected to the output of the PD 9 are noted each time. Thus, the detection characteristic of the PD 9 is measured. Using this, the transmission coefficient of the PD 9 is determined as the ratio of the maximum voltage recorded by the millivoltmeter 12 to the amplitude of the input signal. The zero shift of the PD <9 detector characteristic is determined as the difference "-4, _... , where φ _3χ0 is the value of the initial phase 2 of the signal at which zero readings of the millivoltmeter 12 are recorded.

Claims (1)

Claim ; A device for measuring the parameters of a phase demodulator containing an oscillator, the output of which. connected to the inputs of the first and second attenuators, with the first input of fa465823 4 meters and the first terminal of the device for connecting the test phase demodulator, the second terminal is connected to the second input of the phase meter and to the synchronization input OSCILLO! - rafa, the third terminal of the device for the phase demodulator is connected to the steel input of the oscillator θ 'of the graphograph and the input of a millivolmeter, a phase shifter and a frequency divider, characterized in that, in order to reduce the measurement time, a signal former is introduced into it, four switches la and two key again ^r 'a, the output of the oscillator through the generator signal is coupled to a first fixed contact of the first switch, the second fixed contact which via a second switch coupled to the fourth terminal device to connect a voltage source, the movable contact of the first switch via a frequency divider coupled to antiphase control inputs of the first and second keys, the output of the first attenuator through a third-series switch connected in series and the first key is connected to the input ohm of the oscilloscope synchronization, the output of the second attenuator through a phase shifter connected in series, the fourth switch and the second key are connected to the output of the first key.