JPS61195032A - System for detecting troubled repeater - Google Patents

Abstract

PURPOSE:To detect easily which a repeater is troubled by checking output signals when two switches are sequentially turned off and on with the aid of the output of a control circuit which receives a signal for controlling an electric power source switch. CONSTITUTION:A signal subjected to frequency-shift keying by a signal, which turns off and on the number of the repeater and the switch SW1 through a terminal station equipment 20 at the transmission side and then turns off and on the switch SW2, is transmitted, at first, to the repeater 30 nearest to the equipment 20, for instance, and then relays farther from the equipment 20 one after another. The signal is taken out by the BPF 16 of the control circuit 15 of the repeater, amplified by an amplifier 17, and detected by an FSK detector 18. If said signal is for its own relay, a decoder 19 turns off and on the switch SW1 according to the signal. If a terminal station equipment 21 at the reception side cannot receive the signal at the time of turning off the switch SW1, the error amplifier 7 of the repeater concerned if sound to be troubled. If the signal cannot be received at the terminal station 21 at the time of turning off the switch SW2, a main amplifier 2 is detected to be troubled.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is a repeater using a feedforward amplifier used in a CATV system, etc., in which either the main amplifier or the error amplifier of the feedforward amplifier is damaged. This invention relates to an improvement in a method for detecting a faulty repeater in the event of a failure.

This feedforward amplifier will be explained using FIG. 2.

FIG. 2 is a block diagram showing the circuit configuration of the feedforward amplifier, which includes an error detection loop having paths a and b shown in the figure, and an error injection loop consisting of paths C and d.

In the figure, 1, 4, and 6.9 are hybrid circuits, 2 is a main amplifier, 3.8 is a delay line, 5 is an attenuator, and 7 is an error amplifier.

In FIG. 2, an input signal is applied from an input terminal IN, and is branched into a main amplifier 2 and a delay line 3 in a hybrid circuit 1.

The signal amplified by the main amplifier 2 is branched by the hybrid circuit 4, and a portion thereof reaches the hybrid circuit 6 via the attenuator 5.

Further, a part of the input signal branched at the hybrid circuit 1 reaches the hybrid circuit 6 via the delay line 3.

These two signal paths are shown in FIG. 2 as path a and path b.

When these two signals are input from the hybrid circuit 6 to the error amplifier 7, the phase is rotated by 180 degrees.
The signals are inverted by the hybrid circuit 1 or the main amplifier 2, adjusted by the delay line 3, and adjusted by the attenuator 5 so that their absolute values are equal.

Therefore, the input to the error amplifier 7 is only the noise component from the main amplifier 2, and this noise component is amplified by the error amplifier 7 along the path d and reaches the output terminal OUT via the hybrid circuit 9.

On the other hand, the output of the main amplifier 2 is the hybrid circuit 4° delay line 8
It reaches the output terminal OUT via the hybrid circuit 9 via the path C.

Regarding the transmission amount of these paths c and d, in the same manner as above, by making the absolute values equal and reversing the phase relationship by 180 degrees, the transmission amount reaches the output terminal OUT via path C at the point of the output terminal OUT. The noise component in the main signal (i.e., the output of the main amplifier 2) can be completely canceled by the opposite-phase noise component supplied from the output section of the error amplifier 7, and the noise component in the A small signal output can be obtained.

However, even if the main amplifier 2 becomes a source of failure, the main signal will still be transmitted to the hybrid circuit 1. Delay line 3° hybrid circuit 6. Error amplifier7. The main signal is transmitted through the hybrid circuit 9 and there is no fluctuation in the output level, and even if the error amplifier 7 becomes a source of trouble, the main signal is transmitted through the hybrid circuit 1. Main amplifier 2. Hybrid circuit 4. Delay line 8. The signal is transmitted via the hybrid circuit 9 and there is no fluctuation in the output level.

However, the feedforward condition is no longer satisfied and distortion deteriorates.

CAT repeater using this feedforward amplifier
When used in a V system, etc., as shown in FIG. If the main amplifier 2 or the error amplifier 7 of the feedforward amplifier of a device is disconnected due to a fault, it is desired to provide a faulty repeater detection method that can easily detect which repeater is faulty. ing.

[Conventional technology]

FIG. 4 is a block diagram showing the configuration of a conventional repeater.

In the figure, 10 is a feedforward amplifier, 11° and 12 are power separation filters, 13 is an equalizer, and 14 is a power supply section.
Throughout the following description, the same reference numerals indicate the same functions.

In FIG. 4, the input signal is transmitted through the power separation filter 11
The signal is transmitted through an equalizer 13 for equalizing line loss, amplified by a feedforward amplifier 10, and outputted through a power separation filter 12.

The power supplied from the input side is separated by a power separation filter 11, supplies power to a power supply section 14, and is sent to the next stage via a power separation filter 12.

Power is supplied from the power supply section 14 to the main amplifier 2 and the error amplifier 7 of the feedforward amplifier 10.

The input signal is amplified and output via the repeater configured in this manner.

[Problem that the invention seeks to solve]

However, when this repeater is used in a system such as CATV shown in FIG.
Even if the main amplifier 2 or the error amplifier 7 of 0 is disconnected due to a fault, distortion will deteriorate, but the output level will not fluctuate, so
There is a problem in that it is not easy to detect which repeater has a failure in its main amplifier or error amplifier.

[Means for solving problems]

The problem mentioned above is that on the output side of the feedforward amplifier,
a control circuit for receiving a signal for controlling a power switch sent from a terminal device, and a first switch and a second switch are provided in the power supply circuits of the main amplifier and the error amplifier of the feedforward amplifier, respectively; The first . This problem is solved by the fault repeater detection method of the present invention, which sequentially turns off and on the second switch and monitors the output signal.

[Effect]

According to the present invention, when the power of the main amplifier of a certain repeater is turned off, if the terminal equipment on the receiving side cannot receive the signal,
If it is determined that the repeater's error amplifier is at fault, and when the power to the error amplifier is turned off, the terminal equipment on the receiving side cannot receive the signal, then there is a fault in the main amplifier of the repeater. This makes it easy to detect faulty repeaters.

〔Example〕

FIG. 1 is a block diagram showing the configuration of a repeater according to an embodiment of the present invention.

In the figure, 15 is a control circuit, 16 is a bandpass filter, 17 is an amplifier, 18 is an FSK detector, 19 is a decoder, and SWI
, SW2 is a switch, and 14-1 is a power supply section.

The difference between FIG. 1 and FIG. 4 is that a control circuit 15 is provided on the output side of the feedforward amplifier 10, and switches SWI and SW2 are provided in the power supply circuits of the main amplifier 2 and error amplifier 7, respectively. 14-1 supplies power to the control circuit 15.

When detecting a faulty repeater, the transmitting terminal device 20 in FIG. For example, the signal is initially sent to terminal device 2.
The above-mentioned FSK signal is transmitted to the repeater 30 closest to 0 and successively to distant repeaters.

This signal is passed through the bandpass filter 1 of the control circuit 15 of the repeater.
6, the amplifier 17 amplifies the signal, the FSK detector 18 detects the signal, and the decoder 19 first turns the switch SWI off and on based on this signal if it is intended for the local station.

When this switch SWI is turned off, if the signal cannot be received at the terminal equipment 21 on the receiving side, it is determined that the error amplifier 7 of this repeater is at fault, and when the switch SW2 is turned off, If the terminal device 21 on the receiving side cannot receive the signal, it is determined that the main amplifier 2 of this repeater is at fault.

Therefore, it is possible to easily detect which repeater is at fault.

〔Effect of the invention〕

As explained in detail above, according to the present invention, if the main amplifier or error amplifier of the feedforward amplifier of any repeater is disconnected due to a fault, it is possible to easily detect which repeater is at fault. There is a possible effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a repeater according to an embodiment of the present invention, FIG. 2 is a block diagram showing the circuit configuration of a feedforward amplifier, FIG. 3 is a block diagram showing the configuration of a CATV system, and FIG. 4 FIG. 1 is a block diagram showing the configuration of a conventional repeater. In the figure, 2 is a main amplifier, 7 is an error amplifier, 10 is a feedforward amplifier, 11.12 is a power separation filter, 13 is an equalizer, 14.14-1 is a power supply section, 15 is a control circuit, and 16 is a band Pass filter, 17 is an amplifier, 18 is an FSK detector, 19 is a decoder, 20 is a terminal station device on the transmitting side, 21 is a terminal station device on the receiving side, 30 to 3n are repeaters, and SWI and SW2 are switches.

Claims (1)

[Claims] A repeater using a feedforward amplifier includes a control circuit on the output side of the feedforward amplifier that receives a signal sent from a terminal device to control a power switch, and also has a control circuit that receives a signal for controlling a power switch sent from a terminal device, and also has a control circuit that is connected to the main amplifier of the feedforward amplifier. A first switch and a second switch are provided in the power supply circuit of the amplifier, respectively, and the output of the control circuit receives a signal sent from the terminal device to control the power switch.
A method for detecting a fault repeater, characterized in that the first and second switches are turned off and on in sequence, and the output signal is monitored.