SU788401A2 - Device for measuring residual fading in occupied telephonic channels - Google Patents

Description

(54) DEVICE FOR MEASURING RESIDUAL DECAY IN EMPLOYED TELEPHONE CHANNELS

one

The invention relates to telephony and can be used to measure the residual attenuation in busy telephone channels without interrupting the transmission of an information signal.

According to the main author. St. No. 566368, a device for measuring the residual attenuation in occupied telephone channels is known, comprising on the transmitter side a measuring signal generator, the output of which is connected to the input of the communication channel through the first matching adder, while the second input of the first matching adder is connected to the first subscriber unit. the receiving side — a level meter, a filter, a second subscriber unit and series-connected pause analyzer and a key stage, the control input of which is connected to the output of the communication channel, also two control units and a series-connected compensation generator and a second matching adder, the second input of which is connected to the output of the communication channel and the input of the filter, the output of which is connected to the input of the pause analyzer, and the output of the key stage is connected to the inputs of the compensation generator connected to the input of the level meter, and the output of the second matching adder is connected to the second subscriber unit 1.

However, this device has a low measurement accuracy and does not exclude the influence of the measurement signal on the information signal.

The purpose of the invention is to increase the measurement accuracy while reducing the influence of the measurement signal on the information signal.

The goal is achieved by the fact that a reference driver

., signal, generator trim control unit, amplitude detector and additional key stage, while the output of the second matching adder through an additional key stage, the second input of which is connected to the output of the analyzer

20 pauses, connected to the input of the amplitude detector and with additional inputs of the control units, the input of one of which is connected to the output of the key stage through

a shaper of the reference signal, the second input of which is connected to the output of the compensation generator, the inputs of which are connected to the outputs of the control units via the generator adjustment control unit, the control input of which is connected to the output of the amplitude detector.

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

The device contains on the transmitting side a measuring signal generator 1, a first matching adder 2 and a first subscriber unit 3, on the receiving side - a compensation generator 4, a reference signal generator 5, an amplitude detector 6, a level meter 7, a filter 8, a second subscriber unit 9, an analyzer 10 pauses, a key stage I, two control units 12 and 13, an additional key stage 14, a second matching adder 15, a generator adjustment control unit 16, as well as a communication channel 17.

The device works as follows.

At the initial moment of time, when there is no speech signal and at the time of any pause, the analyzer 10 generates a signal opening the key stage 11 and an additional key stage 14. Filter 8 suppresses the measurement signal at the input of the analyzer 10 pauses. Through the open key stage 11, the measuring signal of the generator 1 from channel 17 is fed to block 12 and to the driver 5, to the second input of which the signal of the compensation generator 4 arrives. In addition, the signal of the compensation generator 4 is fed to the input of the second matching adder 15, where it compensates the measuring signal from Oscillator 1. Since compensation occurs incomplete, an uncompensated signal appears at the output of the second matching adder 15. Shaper 5 aligns the amplitudes of the input signals and subtracts them. At the output of the imaging unit 5, a signal is obtained whose phase is equal to half the phase difference between the input signals. This signal is fed to one of the inputs of block 13. Simultaneously, through the open additional key stage 14, the uncompensated balance of the measuring signal from the output of the second matching adder 15 is fed to the inputs of the amplitude detector 6, block 13 and block 12. In the amplitude detector 6, a signal is generated indicating uncompensated balance of the measuring signal. In block 13, the phase deviation of the uncompensated signal from the phase of the reference voltage is measured. The signal proportional to this deviation corresponds to the deviation of the level of the signals of the compensation and measuring signals. In block 12, the measurement of the phase deviation of the measuring and uncompensated signals is measured. From the output of the amplitude detector 6 and blocks 13 and 12

Signals indicating the presence of an uncompensated remainder, deviations of the amplitudes and phases of the measuring and compensating signals are received at the corresponding inputs of the block 16, which performs the required tuning of the compensation generator 4 in amplitude and phase until the value of the uncompensated signal becomes zero. The signal of the compensation generator 4 is also fed to the meter 7, which, at a known level of the measuring signal at the output of the generator 1, allows measuring the residual attenuation in channel 17.

If a useful information signal from the first autonomous device 3 appears in channel 17, the analyzer 10 closes the key stage 11 and the additional key stage 14, interrupts the measurement signal from the output of channel 17 and the uncompensated signal from the output of the second matching adder 15 to the amplitude detector 6 and blocks 12 and 13, which, through block 16, rearrange the compensation generator 4. Block 16 fixes to the next pause the values of the level and phase of the compensation generator 4, co) corresponding to the previous sync tions. The meter 7 continues to measure the signal level of the compensation generator 4.

The proposed device provides

high measurement accuracy of residual for tumani in busy telephone channels and

and completely eliminates the influence of the measuring signal on the useful speech signal.

Claims (1)

Invention Formula A device for measuring 1 I of residual attenuation in busy telephone channels by aut. St. No. 566368, characterized in that, in order to improve measurement accuracy while reducing the influence of the measuring signal on the information signal, the shaper of the reference signal, the generator trim control unit, the amplitude detector and the additional key stage are input, while the output of the second matching adder is connected via the additional key stage, the second input of which is to the pause analyzer an amplitude detector input and with additional block inputs control, the input of one of which is connected to the output of the key stage through the shaper of the reference signal, the second input of which is connected to the output of the compensation generator, the inputs of which are connected to the outputs of the control units through the generator adjustment control unit, the control input of which is connected to the output of the amplitude detector. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 566368, cl. H 04 B 3/48, 1975 (prototype).