SU801274A1 - Device for checking frequency characteristic of group time delay of four-pole networks - Google Patents

Description

(54) DEVICE FOR MONITORING THE FREQUENCY CHARACTERISTICS OF GROUP TIME OF SUB-PLAYING OF SCHREHPOLYAN

The invention relates to communication and can be used when checking for compliance with the frequency response of a group time delay channel and communication devices.

A device is known for controlling the frequency response of a group time for quad-pole powering, containing on its transmitting side a frequency oscillator, the input of which is connected to the quadrupole input, on the forward side, serially connected matching unit, low frequency, low frequency , an amplifier-limiter and a phase detector, another input of which is connected to the output of the amplifier-limiter through a serially connected frequency divider and a phasing unit, another input of the divider Cha Toty connected to the output of the quartz oscillator vyho matching block connected to the input of the frequency converting unit 1 in voltage.

However, this device has a low accuracy and considerable time control.

The purpose of the invention is to improve the accuracy and reduce the time of control.

This goal is achieved by the fact that the first and second comparators, the first and second voltage dividers, the first and second key blocks, the decoder pulse counter, the OR element and the AND element, in which the output of the first comparator is on the receiving side, are entered into the known device; one of the inputs of which is connected to the output of a frequency-to-voltage converter; another input with one of the outputs of the first voltage divider is connected via a serially connected pulse counter, a decoder, and a corresponding output which are connected to the corresponding inputs of the first and second key blocks, and the OR element to one of the inputs of the AND element, the other input of which is connected to the output of the phase detector via a second comparator, the other input of which is connected to one of the outputs of the second voltage divider, the other outputs of which are connected to the corresponding inputs of the second key block, and the outputs of the first voltage divider are connected to the inputs of the first key block, respectively.

The drawing shows a structural electrical circuit of the proposed device.

A device for monitoring the frequency response of the group time of the four-port network contains on the transmitting side a oscillating frequency generator 1 connected to the input of the quadrupole 2, and on the receiving side matching unit 3, demodulator 4, low-pass filter 5, limiting amplifier b, phase detector 7, frequency divider 8, crystal oscillator 9, phasing unit 10, voltage converting unit 11, first comparator 12, OR element 13, pulse counter 14, decoder 15, first key block 16, first divide Either 17 voltages, second block 18, keys, second divider 19 voltages, second comparator 20, and element 21 I.

The device works as follows.

To the quadrupole 2 input, the output of the generator 1 is supplied with an amplitude-modulated measurement signal with a modulation frequency L. On the receiving side, the signal from the output of the quadrupole 2 is fed to the matching unit 3, which provides input matching and signal amplification. This signal is detected by demodulator 4 and fed to a filter 5, which extracts the envelope of the input signal L. The envelope phase carries information about the time (phase) shifts at the current carrier frequency in the quadrupole 2. The envelope signal is converted in limit amplifier 6 into a series of square pulses and fed to the input of the phase detector 7, which is compared in phase with the sequence coming from the divider 8. Divider 8, transform the signal of the crystal oscillator 9, extracts a sequence of rectangular pulses following with a frequency L and coinciding in phase with the envelope of the input signal at the carrier frequency input quadrupole 2 before measurements. Phasing of divider 8 is performed by block 4 10, the input of which receives a signal from the output of limiting amplifier 6.

At the output of the phase detector 7, a constant voltage is selected, the level of which is proportional to the difference in the group delay time at the measured and reference frequency. This voltage is fed to the input of the second comparator 20. From the output of the matching unit 3, the voltage also goes to unit 11, the constant voltage at the output of which varies in proportion to the frequency of the input signal. This voltage is applied to one of the inputs of the first comparator 12, to the other input of which the voltage removed from the first divider 17 is applied. The first divider 17 is controlled by a decoder

 15 using the first block 16. Before

 the beginning of the measurements, when the counter 14 is reset, the output of the first divider 17 is set to the voltage corresponding to the frequency at which

5 the inclusion of the first tolerant granigda. Element 21 I is blocked by a signal from the first output of the decoder 15, passing through element 13 OR.

With increasing signal frequency

0, the constant voltage at the output of block 11 increases, and this voltage exceeds the value of the reference voltage taken from the output of the first divider 17, leads to an abrupt change in the signal level at the output of the first comparator 12. This abrupt change in level changes the state of the counter 14 At the second output of the decoder 15, a signal appears that performs the appropriate switching in blocks 16 and 18. The block is removed from element 21 I. The output of the first divider 17 sets a voltage corresponding to the frequency at which the following tolerance limit is turned on. The output of the second divider 19 sets the voltage corresponding to the tolerance limit, which determines the tolerance of the frequency response of the group delay time at the current frequency of the test signal from its value at the reference frequency. With further

5, by increasing the frequency of the test signal, the voltage switching at the outputs of the dividers 17 and 19 is carried out in a similar way.

To the input of the second comparator 20.

 the output of the phase detector 7 receives a voltage, the level of which is proportional to the difference in the group delay time at the measured and reference frequency, and at its other

Input 5 - voltage corresponding to the tolerance limit. When the tolerance limit signal is exceeded, an abrupt voltage change is observed at the output of the second comparator 20. At the output of element 21, a signal appears indicating that the frequency response of the group latency of the quadrupole 2 does not match the specified norms.

When the test signal leaves the normalized and monitored frequency band, element 21 I is again blocked by a signal from the n + 1 output of the decoder 15 passing through element 13 OR.

 The proposed device allows to fully automate the process of control during panoramic measurements of the frequency characteristics of the group delay time of four-terminal networks and provides high accuracy of control.

Claims (1)

Invention Formula A device for monitoring the frequency response of a quadruple delay group time, containing on the transmitting side a oscillating frequency generator, the output of which is connected to the input of four quadrupole, on the receiving side are series-connected matching unit, demodulator, low pass filter, limiting amplifier and phase detector, the other input of which connected to the output of the amplifier limiter through a serially connected frequency divider and phasing unit; another input of the frequency divider n yield a crystal oscillator, the output of the matching block is connected to the input of a frequency conversion unit ie EM |, characterized in that, in order to increase the accuracy and reduce the monitoring time, on the receiving side its first and second comparators, first and second voltage dividers, first and second key blocks, pulse counter, decoder, OR element and AND element, while on the receiving side of the output of the first comparator, one of the inputs of which is connected to the output O of the frequency-to-voltage conversion unit, the input — with one of the outputs of the first voltage divider, is connected via a series-connected pulse counter, a decoder, the corresponding outputs of which are connected to the corresponding inputs of the first and second key blocks, and an OR element to one of the inputs And, the other input of which is connected to the output of the phase detector through the second comparator, the other input of which is connected to one of the outputs of the second divider, the other outputs of which are connected to the corresponding the inputs of the second 5 blocks of keys, and the output of the first voltage divider are connected to the inputs of the first key block, respectively. Sources of information taken into account in the examination 0 1, Measuring the group lag time and amplitude-frequency characteristics of the IIA. Passport. USSR Ministry of Communications, 1976 (prototype).