JPH03210881A - Relay system for catv and its relay amplifier - Google Patents

Abstract

PURPOSE:To prevent signal interruption of a transmission line at downstream to a faulty location by bypassing an amplifier when a signal level of its output terminal is decreased abnormally and increasing the amplification factor of the amplifier when a signal level to an input terminal reaches an abnormally low level. CONSTITUTION:When an amplifier is faulty, a through-means is active and a signal inputted in a level of 70dBmuV is not amplified but sent as it is. Then double amplification is implemented in an amplifier of a next stage to keep a signal level of a normal transmission system. When the relay amplifier 12 is faulty, the through-means is active in the relay amplifier 12 is active and a fault signal amplifier means of the relay amplifier 13 is active.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applied to a repeater amplifier used in a CATV transmission line. In particular, the present invention relates to means for preventing signal disconnection on a CATV transmission line when an amplifier fails.

〔overview〕

The present invention is a repeating amplifier in which a plurality of repeat amplifiers are inserted in a CATV transmission line, and the system bypasses the device in which the fault has occurred and increases the amplification factor of the amplification section of the device in the lower stage. This also allows signals to be transmitted normally.

[Conventional technology]

Conventionally, this type of repeater amplifier amplifies and corrects the signal level attenuated due to cable loss in the transmission path.

[Problem to be solved by the invention]

Conventional relay amplifiers like this have the disadvantage that if one unit on the CATV transmission line fails, the signal will be cut off on the transmission line below the failure point, and the TV signal will not be transmitted to the TV receiver in each home, making it impossible to provide service. There is.

SUMMARY OF THE INVENTION An object of the present invention is to provide a repeater amplifier which eliminates such drawbacks and can prevent signal disconnection in a transmission line below a failure point.

[Means to solve the problem]

The first aspect of the present invention is to provide a repeating amplifier in which a plurality of amplifiers are inserted into a CATV transmission line and the gains of the amplifier sections included in each of the plurality of amplifiers are approximately equal, and the signal level at the output terminal of the relay amplifier is monitoring means for detecting an abnormal decrease in
A bypass control means for closing the input terminal of the own device and the output terminal of the own device to bypass the same when the monitoring means detects an abnormal drop in the signal level and extremely reducing the gain of the amplifying section. It is characterized by having the following.

A second aspect of the present invention is a repeating amplifier in which a plurality of repeating amplifiers are inserted into a CATV transmission line, and a monitoring means for detecting an abnormal decrease in a signal level at an input terminal of the repeating amplifier, and a signal level When an abnormal decrease in the signal level is detected, a new amplifying section is connected in cascade to the amplifying section of the white field width amplifier, the gain of which is approximately equal to the gain of the amplifying section, and the monitoring means detects that the signal level is at a normal value. The detection period is characterized by the provision of a switching means for bypassing this new amplification section.

A third invention of the present invention includes a plurality of relay amplifiers,
In the CATV repeating system in which this repeating amplifier is inserted, one repeating amplifier has a monitoring means for detecting an abnormal drop in the signal level at the output terminal of its own device, and a monitoring means for detecting an abnormal drop in the signal level at the output terminal of its own device. A bypass control means that sometimes closes and bypasses between the input terminal of the own device and the output terminal of the own device and extremely reduces the gain of the above-mentioned amplifier section, and is cascade-connected to the one repeating amplifier. The other relay amplifier includes a monitoring means for detecting an abnormal drop in the signal level at the input terminal of the own device, and a sub-connection to the amplifier section of the white field amplifier when this monitoring means detects an abnormal drop in the signal level. During the period when the fault signal amplification section 3, which is a new amplification section whose gain is approximately equal to the gain of the amplification section, and the monitoring means detect that the signal level is a normal value, this new amplification section The present invention is characterized by comprising a switching means for bypassing the amplifying section.

[Effect]

When the signal level at the output terminal of the device drops abnormally, this device is bypassed and the signal is sent to the lower device via this bypass path. Furthermore, when the signal level at the input terminal of the device reaches an abnormally low value, the amplification factor of the amplifier section is increased to provide a signal at a normal level to the output terminal.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment. This embodiment uses a relay amplifier output terminal level monitoring/through signal control device 1, a through signal line 7, and a through signal line 7 as a signal through means for sending a through signal from an output terminal to a next-stage relay amplifier when an amplifier fails. , an output terminal level monitoring line 8, and further monitors the signal sent through from the previous stage when the previous stage relay amplifier fails,
The input terminal level monitoring/switching signal control device 2, the input terminal level monitoring line 9, and the fault signal amplification means perform double amplification and switch between the AGC means and the MGC means to prevent signal disconnection. 3, a switching means 4 that selects the fault signal amplification section when a fault occurs, a switching means 5 that normally selects the AGC means and switches to the MGC means when a fault occurs, and a switching control device that simultaneously controls the switching means 4.5. 6
Equipped with.

That is, in this embodiment, a plurality of repeating amplifiers each having substantially the same gain in the amplifying section included in each repeating amplifier are inserted into a CATV transmission line, and one of the plurality of repeating amplifiers has an output of its own. A monitoring means for detecting an abnormal drop in the signal level at the terminal, and when the monitoring means detects an abnormal drop in the signal level, the input terminal of the own device and the output terminal of the own device are closed and bypassed. It is also equipped with an output terminal level monitoring/through signal control device 1, which is a bypass control means for extremely reducing the gain of the amplifying section, a through signal line 7, and a switching means 5, which are cascade-connected to the one relay amplifier. The other relay amplifiers include an input terminal level monitoring/switching signal control device 2 which is a monitoring means for detecting an abnormal drop in the signal level at the input terminal of the own device, and when this monitoring means detects an abnormal drop in the signal level. A fault signal amplifying section 3 is a new amplifying section which is connected in series to the amplifying section of the own amplifier and whose gain is approximately equal to the gain of the above amplifying section.
and switching means 4 for bypassing this new amplification section during a period when the monitoring means detects that the signal level is at a normal value.

Next, the operation of this embodiment will be explained. When the own amplifier fails, the through means works and transmits the manually generated signal at 70 dBμV without amplifying it.

Then, the next stage amplifier performs double amplification to maintain the signal level of the normal transmission system.

FIG. 2 is a block diagram showing a CATV transmission line. If the relay amplifier 12 fails, this relay amplifier 12
In this case, the through means works, and in the relay amplifier 13, the failure signal amplification means works.

〔Effect of the invention〕

As explained above, in the present invention, the signal is transmitted to the faulty amplifier as if it were through one cable, and the signal is transmitted to the next-stage amplifier at two levels, which is the level that should be manually transmitted there. Since the level is amplified twice to bring it to the normal level before the failure, it has the effect of preventing signal interruption.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a block configuration diagram showing the configuration of a CATV transmission line. 1... Output terminal level monitoring/through signal control device, 2
...Input terminal level monitoring/switching signal control device, 3...
・Failure signal amplification unit, 4.5... switching means, 6...
Switching control device, 7... Through signal line, 8... Output terminal level monitoring line, 9... Input terminal level monitoring line, 10
...Center head end, 11-13...Relay amplifier.

Claims (1)

[Claims] 1. In a repeating amplifier device in which a plurality of repeating amplifiers are inserted into a CATV transmission line and the gains of the amplifier sections included in each of the plurality of repeating amplifiers are approximately equal, an abnormal decrease in the signal level at the output terminal of the repeating amplifier device; a monitoring means for detecting an abnormal decrease in the signal level; and when the monitoring means detects an abnormal decrease in the signal level, the input terminal of the own device and the output terminal of the own device are closed to bypass it, and the gain of the amplification section is maximized. 1. A relay amplifier comprising a bypass control means for reducing the size. 2. In a repeater amplifier in which a plurality of relay amplifiers are inserted into a CATV transmission line, there is a monitoring means for detecting an abnormal drop in the signal level at the input terminal of the own device, and a monitoring means that automatically detects an abnormal drop in the signal level when the monitoring means detects an abnormal drop in the signal level. A new amplifying section is connected in cascade to the amplifying section of the amplifier, and the gain thereof is approximately equal to the gain of the amplifying section. 1. A relay amplifier comprising: a switching means for bypassing a section of the relay amplifier. 3. In a CATV relay system in which multiple relay amplifiers and these relay amplifiers are inserted, one relay amplifier has a monitoring means for detecting an abnormal drop in the signal level at the output terminal of its own device, and this monitoring means. comprising a bypass control means for closing the input terminal of the device and the output terminal of the device to bypass the device when the device detects an abnormal decrease in the signal level, and extremely reducing the gain of the amplifying section; The other relay amplifiers connected in cascade to the one relay amplifier described above have a monitoring means for detecting an abnormal drop in the signal level at the input terminal of the own device, and a self-control device when the monitoring means detects an abnormal drop in the signal level. A new amplifying section is connected in cascade to the amplifying section of the amplifier, the gain of which is approximately equal to the gain of the amplifying section, and during the period when the monitoring means detects that the signal level is at a normal value, this new amplifying section is A relay system for CATV, characterized in that it is equipped with a switching means for bypassing the section.