JPS6156525A - Circuit level compensating system - Google Patents

Abstract

PURPOSE:To compensate the loss of a circuit accurately and economically by controlling automatically the amplification degree of a signal information amplifier in response to the difference between the level of an incoming pilot signal and the reference level of a pilot signal for comparison. CONSTITUTION:A certain kind of signal information is transmitted from an exchange station 1 at the transmission side via an input circuit 7. Then a transmitter 2 supplies a signal information current to a hybrid amplifier 25 via a BPF21. At the same time, the pilot signal is also supplied to the amplifier 25 from a pilot signal oscillator 22 via a level controller 23 and an HPF24. Thus the amplifier 25 transmits both the signal information and the pilot signal at a time to a circuit 3. A receiver 4 obtain a difference level C between the output level B of a pilot signal detecting filter 41 and the reference level A of a level controller 43 through a differential transformer 44. The level C is supplied to a compensating amplifier 48 via an amplifier 45 and a rectifier circuit 46. Therefore the signal information current contained in a signal spectrum sent from the circuit 3 and supplied to the amplifier 48 via a BPF47 is compensated by the amplifier 48 for its circuit loss component and then outputted to an exchange statioin 5 at the reception side via an output circuit 6.

Description

TECHNICAL FIELD The present invention relates to a line level compensation system, and more particularly to a line level compensation system that automatically compensates for loss of signal information due to lines in a communications switching network.

(Prior Art) In communication switching networks that have become increasingly complex in recent years, it has become necessary to automatically compensate for line losses in transmitted signal information. On the other hand, since conventional communications switching networks are relatively simple, line losses are assumed to be fixed, and compensation for them is not particularly necessary.

(Object of the Invention) The object of the present invention is to eliminate the above-mentioned need by knowing the line loss at the receiving end from the level of the pilot signal transmitted together with the signal information from the sending end and adjusting the amplification of the signal information amplifier. Another object of the present invention is to provide a hitherto unknown line level compensation system that automatically compensates for line losses in a complex communications switching network.

(Number of grooves according to the invention) According to the present invention, the transmitting end side that sends signal information to the line is provided with a transmitting means for transmitting a pilot signal having a constant frequency and a constant level together with the signal information, and A line characterized in that the receiving end side of the line is equipped with adjusting means for adjusting the amplification degree θ11 of the signal information amplifier based on the level difference obtained by comparing the level of the pilot signal arriving from the line with a reference level. A level compensation scheme is obtained.

(Example) Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of a telephone switching network showing an embodiment of the line level compensation method of the present invention, and FIGS. 2 and 3 are circuit block diagrams showing an example of the transmitting device and receiving device in FIG. 1, respectively. FIG. 4 is a diagram showing an example of the frequency spectrum of signal information sent from the transmitter in the M2 diagram.

In Figure 1, the telephone switching network is a general transmitting exchange 1.
, a transmitting device 2 connected to this via an input line and transmitting a pilot signal of a constant frequency and a constant level along with signal information to line 3, and a pilot signal generated internally to determine the level of the pilot signal arriving from line 3. The gain of the signal information amplifier is 8! by comparing it with the reference level and detecting the level difference. It consists of a receiving device 4 that performs i-setting, and a general receiving exchange 5 connected to this via an output line 6. Next, in FIG. 2, a transmitting device 2 is connected to an input line 7. A bandpass filter 21 for signal information current, a pilot signal oscillator 22, a level adjuster 23 that adjusts the level of the pilot signal from the pilot signal oscillator 22 to a constant level serving as a reference, and a bypass filter 24 that passes the output thereof. and a mixing amplifier 25 that mixes and amplifies the outputs of the bandpass filter 21 and the bypass filter 24 and transmits the mixed amplified signal to the line 3.

Further, in FIG. 3, the receiving device 4 includes a pilot detection filter 41 that detects a pilot signal arriving from the line 3.
, a pilot signal oscillator 42 that generates a comparison pilot signal having the same frequency as the incoming pilot signal, a level adjuster 43 that adjusts the level of its output to a reference level A, and a pilot detection filter 41 that detects the reference level and the pilot signal.
A differential transformer 44 which obtains a difference level 0 by comparing the output level B of It consists of a band pass filter 47 that passes only the signal information current to be transmitted, and a compensation amplifier 48 that amplifies its output and outputs it to the output line 6. The compensation amplifier 48 has a gain adjusted by the output of the rectifier circuit 46. be exposed.

Further, in FIG. 4, the signal spectrum transmitted from the transmitter 2 (shown in FIG. 2) to the circuit !3 (shown in FIG. 2) has a frequency of 0.3 to 3.4 KHz in the signal information band. , 3.5-4.0 KHz pilot signal band.

Next, the operation of this embodiment will be explained.

When a certain signal information is sent from the originating switching center 1 via the input line 7, the transmitting device 2 inputs the signal information current to the mixing amplifier 25 via the bandpass filter 21fi, and also inputs the signal information current to the mixing amplifier 25 via the level adjuster 23° bypass filter. 24
Pilot signal from pilot signal oscillator 22 (frequency 3.5-4.0 KHz) via f mixing amplifier 2
5, the signal information and the pilot signal are sent together from the mixing amplifier 25 to the line 3. The simultaneously transmitted signal information and pilot signal are both level-lossed by the line 3 and arrive at the receiving device 4. In the receiving device 4, the pilot detection filter 411C detects a pilot signal from the incoming signal and inputs it to the differential transformer 44. On the other hand, the comparison pilot signal (
Frequency 3.5~4.0 KHz) also differential transformer 44
is input. The differential transformer 44 obtains a difference level ○ between the output level B of the pilot detection filter 41 and the reference level A, and the amplifier 45 . The signal is inputted to a compensation amplifier 48 via a rectifier circuit 46 . Therefore, the signal information current in the signal spectrum from the line 3 that is input to the compensation amplifier 48 via the bandpass filter 47 is exchanged on the receiving side via the output line 6 after the line loss is compensated for by the compensation amplifier 48. Output to station 5.

According to this embodiment, the receiver 4 uses the pilot signal to learn the loss level of the line 3 and automatically adjusts the gain of the compensation amplifier 48 to I? 11, the influence of line loss can be removed.

Note that although the above explanation has been made for the case of line loss, the same operation occurs in the case of line gain. It goes without saying that the pilot signal frequency may be within or outside the voice band.

(Effects of the Invention) As is clear from the above explanation, according to the recurrent level compensation method of the present invention, the signal information amplifier is amplified according to the difference between the incoming pilot signal level and the reference level of the comparison pilot signal. Since the degree is automatically adjusted, the effect is that the compensation for the loss of glands is carried out accurately and economically. Furthermore, if the present invention is applied to multiplexed lines, further economicalization can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a telephone switching network showing an embodiment of the line level compensation method of the present invention, and FIGS. 2 and 3 are circuit block diagrams showing an example of the transmitting device and receiving device in FIG. 1, respectively. FIG. 4 is a diagram showing an example of the frequency spectrum of signal information sent from the transmitter in FIG. 2. In the figure, 1... the sending exchange center, 2...
...Transmitting device, 3... Line, 4... Receiving device, 5... Receiving exchange, 6...
Output line, 7... Input line, 21.47...
... Bandhus filter, 22.42 ... Pilot signal oscillator, 23, 43 ... Level adjuster, 24 ... Bypass filter, 25 ...
... Mixing amplifier, 41 ... Pilot detection filter, 44 ... Differential transformer, 45 ...
...Amplifier, 46... Rectifier circuit, 48...
...Compensation amplifier. Figure 2, Figure 3, Figure 4

Claims (1)

[Claims] The transmitting end side that sends out signal information to the line is equipped with a transmitting means for transmitting a pilot signal having a constant frequency and a constant level together with the signal information, and the receiving end side of the line is equipped with the pilot signal arriving from the line. 1. A line level compensation system comprising: adjusting means for adjusting the amplification degree of a signal information amplifier based on the level difference obtained by comparing the level of the signal information amplifier with a reference level.