SU121820A1 - Measuring device for monitoring the residual attenuation of a telephone channel - Google Patents

Description

Measuring devices for monitoring the residual attenuation of a telephone communication channel are known, which contain a sinusoidal voltage generator used as a sensor for controlling the ziir signal of a tonal frequency transmitted over the channel under test. During the measurement of the residual attenuation of the channels, these devices are turned off: D both end points. In addition, the measurement accuracy is not sufficiently high, and the measurement process itself is not automated.

In the device described, these shortcomings are eliminated by the npyH.MstiCHiiCM phase detector, which detects the pilot and auxiliary reference signals, a phase shifter used for combining both signals in phase, and a pilot frequency indicator, which makes it possible to send a pilot signal to the line in the presence of a speech signal; the use of an integrator switched on at the output of the phase detector, which increases the accuracy of measurements in the conditions of interference, and a relay switch, which is automatically triggered when the start pulse arrives.

The block diagram of the described device is shown in the drawing.

A measuring sinusoidal signal with a frequency of 1600 Hz, whose level is 5-6 times lower: the average normal transmission level, comes from the output of the measuring generator / into the low-frequency path at one end of the measuring channel 2. More intense oscillations of the transmitted voice messages are superimposed on this signal , because the channel is not turned off during the measurement - At the other end of the channel, speech signals are filtered out using narrow-cavity resonant y-3 and the signal selected by this amplifier gives # 121820

from one of the inputs of the phase detector 4. The signal from the generator 1 is fed through the tone wiring channel 5 through the amplifier 6 and the phase shifter 7 to the second input of the phase detector 4. The output of the phase detector is proportional to the amplitude of the measuring signal .

The voltage of the speech signals at the output of narrowband amplifier 5, whose average frequency bandwidth is 1600 Hz, is a sinusoidal oscillation, the phase of which with the same probability can take any value from 0 to 2P. As a result, the interference voltage produced by the speech signal at the output of phase detector 4 will take on both positive and negative values with the same probability. The voltage from the output of the phase detector 4 is fed to the input of the indicator 5. Which averages this voltage over a certain time interval. At a sufficiently large interval of averaging, the effect of speech signals appears to be close to zero, due to their mutual compensation. The effect of the effect of the measuring signal turns out to be equal to a certain specific value proportional to the amplitude of this signal. The voltage from the output of the indicator is fed to the measuring device 9, which can be used as a needle indicator.

To fully automate the measurement, a device switch 10 is used in the described device, which, after the integration period has elapsed, returns the measurement circuit to its original position, i.e., removes the voltage from the output of indicator 8, preparing the circuit for the new measurement. The measuring device automatically registers the residual attenuation value of the channel and, if it deviates from the norm, it signals the maintenance personnel with the help of alarm 11. In order to fully automate the process of monitoring the residual attenuation of a multichannel system, it is necessary to ensure that the system’s channels are not disconnected for measurement. The synchronization of the operation of all elements of the measuring and switching devices, as well as the fixing of the moment of counting, is carried out from the primary electric clock of the VNIIM. The time required to monitor each channel is about three minutes.

Subject invention

Claims (3)

1. A measuring device for monitoring the residual attenuation of a telephone channel, but to which a sinusoidal measuring voltage of a control signal of a tonal frequency is transmitted, characterized in that, in order to control the residual attenuation without interrupting communication operation and measuring at the receiving end of a constant voltage line current, the value of which is proportional to the amplitude of the measuring signal, it uses a phase detector that detects the control and auxiliary reference signals, the phase shifter, with which The signals are aligned in phase, and the control frequency indicator. 2. The device according to claim 1, characterized in that, in order to eliminate the effect of interference on the pilot signal, an integrator is included, connected at the output of the phase detector. 3. The device according to paragraphs. 1 and 2, characterized in that, for the purpose of fully automating the measurement, a relay switch is applied, which is triggered by the start pulse.