JPS58207737A - Amplitude limiting system of transmission signal - Google Patents

Abstract

PURPOSE:To suppress an overload of a repeater and to prevent the deterioration in the quality of transmission, by detecting a pilot signal, a monitor signal, and a transmission signal, respectively, and controlling the level of an amplitude limiter with a signal of abnormal value in the detected signals when the level is abnormal. CONSTITUTION:The transmission signal SD, the pilot signal SP and the monitor signal SV are inputted to an automatic amplitude controller 3 via a transmission line 1 and the repeater 2. The signals SD, SP and SV are branched by a hybrid 4 and detected by detectors 6, 9, 11 via suitable BPFs 5, 8, 10, respectively. The detected output of each detector is inputted to a level discriminating circuit 7, and when each signal is normal, a discriminating level is outputted from the circuit 7 and a normal level is given to the operating bias of the limiter 12 at the discriminating level. If any of the signals SP, SV, SD loses the AGC function and a level in which the detected output is higher than the normal value is detected, the circuit 7 increases the limiter operating point of the limiter 12 at the high level, the other signal level outputted from the limiter 12 is suppressed to suppress the overload at the next 13 and succeeding repeaters.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a transmission signal amplitude limiting method for limiting a transmission signal to a predetermined level.

(b) Prior art and problems Generally, a transmission signal has a pilot signal and a monitoring signal. The pilot signal monitors and controls the transmission signal, and the supervisory signal is sent from each repeater that transmits the transmission signal to maintain the transmission system.

If the above pilot signal is disconnected or the repeater has a fault, the monitoring signal from the corresponding repeater is transmitted to the terminal station, and when the terminal station detects a fault, the above transmission signal is transferred from the current transmission system to the backup transmission system. Can be switched.

If you do not have a backup transmission system, the AGC function of each repeater will be lost due to Bicht signal interruption or abnormal decline, the gain of the repeater will increase, and the repeater will be overloaded due to the transmission signal. This may cause the signal to deteriorate or damage the repeater.

To suppress the increase in the level of the transmission signal, the transmission signal is multiplexed, and when a monitoring signal (hereinafter referred to as Sv signal) is added, the transmission signal level increases and overloads the repeater. An amplitude controller is inserted into the terminal station or a predetermined transmission line to prevent the corresponding repeater from being overloaded. However, when the pilot signal is disconnected, the AGC function of each repeater is lost and the repeater becomes overloaded, distorting the transmitted signal and degrading the transmission quality, or damaging the repeater.

As a countermeasure to the above problem, it is possible to use an amplitude limiter, but since the amplitude limiter has an amplitude limit level set for steady-state overload of the transmission signal, it cannot be applied to the above excessive overload. do not have.

Therefore, there is a need for an amplitude limiter that can respond to various level changes of the transmission signal, pilot signal, and 5VGt signal.

(c) Purpose of the Invention In order to solve the above-mentioned drawbacks, the present invention aims to provide a new transmission signal amplitude limiting method that is compatible with changes in the signal levels of each of the K, transmission signal, pilot signal, and Sv multiplied signal. shall be.

(d) Structure of the Invention In order to achieve the above object, the present invention applies an amplitude limiter to a transmission signal to which a pilot signal for controlling the transmission signal and a monitoring signal for a repeater transmitting the transmission signal are added. In a transmission system that limits the number of pilot signals, the signal level is an abnormal value when the signal level is an abnormal value among the detected signals of the 93 pilot signals. The method is characterized in that the operating level of the amplitude limiter is controlled to limit the nuclear transmission signal to a predetermined level.

(e) Embodiments of the Invention The present invention will be explained based on the drawings. FIG. 1 shows a further embodiment of the invention. In the figure, a transmission signal SD, a pilot signal SP, and a GV flaw signal v are input to an automatic amplitude limiting device 3 according to the present invention via a transmission line 1 and a corresponding repeater 2.

In the device 3, the signals SD, SP, SV
Each signal is branched by the hybrid 4 and input to a band pass filter (hereinafter referred to as BPF) adapted to each.

That is, it is detected by the detector 6 through the SD flaw signal BPF'5, and its output is input to the level judgment circuit 7, and the SP multiplied signal BP
The signal is detected by the detector 9 via the F8, and the detected output is input to the level determination circuit 7. Similarly, BP for Sv double signal
The signal is input to the level determination circuit 7 via the FIo-detector 11.

If the above-mentioned SD flaw signal spg7 and SV signal are normal, a normal judgment level is output from the level judgment circuit 7', and this judgment level gives a normal level to the operating bias of the limiter 12. As a result, the hybrid 4
The various signals that have been branched out are shaped to a constant level. Various signals SD and S shaped to a constant level by limiter 12
The P and SV signals are input to the next repeater 13 via the transmission line 1.

When the SP multiplier signal disconnection is detected by the detector 9, the level determination circuit 7 outputs a level higher than the normal value, raises the limiter operating point of the limiter 12, and outputs another signal SD from the limiter 12. Suppress the Sv signal level. This suppression allows the next repeater 13 to reduce the increase in output level due to loss of AGC function due to SP signal disconnection, suppresses overload of repeaters after repeater 13, and Damage or SD damage suppresses signal distortion and prevents deterioration of transmission quality.

When the SP double signal failure occurs before repeater 2, the SD flaw signal is considerably increased before repeater 2, and is further increased by repeater 2, so that the SD flaw signal detector 6 reaches a level higher than the normal value. Based on the detection level, the level judgment circuit 7 outputs a judgment level that is higher than the normal value, and the input operating level point to the limiter 12 is raised, and the various signals SD and SV signals are branched by the hybrid 4. to suppress.

Similarly to the above, the Sv double signal is detected by the Sv double signal detector 11 due to the failure of the faulty repeater, and the detected signal is judged by the level judgment circuit 7, and the judgment output is the output corresponding to the increase in the Sv multiplication signal. On the other hand, by operating the limiter 12 at a high level, the hybrid 4 outputs 8.
Suppress the 04g level.

Thus, when the SP signal is disconnected or the fault occurs, the sv multiplied signal is 5D (=
This prevents repeater overload by suppressing the increase in signals.

FIG. 2 shows a limiter using a diode according to the present invention. In the same figure, 'Ring source 14 is the level determination 1q path 7.
This level is considered to be equivalent to the output voltage of the SD scratch signal SV.
The diode 15.1 is connected to the high and low outputs output from the level judgment circuit 7 for the signal and the SP multiplied signal magnitude.
Give an operating bias of 6. This allows level 1j limits to be made in response to various signal levels.

FIG. 3 shows an example of the input/output characteristics of the automatic amplitude limiting device 1 according to the present invention, where C is the input/output characteristic of the mold 1 when 5P (If signal failure is detected by the detector 9, and B is the repeater Sv at the time of failure
The input/output characteristic of the device 11 when detected by the signal doubler detector 11, A is the input/output characteristic of the device 11 when the SD signal is on the verge of overload, which indicates a substantially normal value.

(f>) More than the effects of the invention, according to the present invention, the transmission signal, pie stomach Xt No. 1, S
It detects the V signal, etc., and controls the limiter's operating level at a level appropriate to the detection level to control various signal levels, thereby preventing damage due to overload of the repeater due to disconnection of the pilot) f1 line, etc. 0, which has the advantage of preventing deterioration of transmission signals.

[Brief explanation of drawings]

FIG. 1 shows an automatic amplitude limiting device 3 according to an embodiment of the present invention, FIG. 2 shows a limiter according to the present invention, and FIG. M3 shows input/output characteristics of the automatic amplitude limiting device. In the figure, 1 is a transmission line, 2.13 is a repeater, 3 is an automatic amplitude limiter, 4 is a hybrid, 5, 8.10 is a BPF, 6
, 9 and 11 are detectors, 7 is a level judgment circuit, 12 is a limiter, 14 is a power supply, and 15.16 is a diode.

Claims (1)

[Claims] In a transmission method in which a pilot signal that controls a transmission signal and a monitoring signal of a repeater that transmits the transmission signal are added and the transmission signal is limited by an amplitude limiter, the pilot signal, the monitoring signal, and the transmission signal are control the operation level of the amplitude limiter with the abnormal value signal when the signal level of the detected three signals is an abnormal value, and transmit the signal. A transmission signal amplitude limiting method characterized by limiting the signal to a predetermined level.