JPH0461554B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a line condition monitoring method for monitoring the condition of the line in a signal transmission system using a coaxial line such as a CATV system.

[Prior art and its drawbacks]

The general configuration of the CATV system will be explained with reference to FIG. The television signal produced by the head end device 11 is sent to the coaxial line 12, and then transmitted on the line 12 while being amplified by line loss compensation amplifiers 13a to 13e arranged at appropriate intervals. Distribution of the television signal to the subscriber's home 14 is performed by an amplifier 1 having a branch output terminal.
This is done via a branch 15 connected to 3e. Power is supplied to the amplifiers 13a to 13e by transforming a commercial AC voltage of 100V from 30V to a low voltage of 60V using the power supply devices 16a and 16b, and transmitting this through the coaxial line 12. Here, each power supply device 16a, 16b has 1
It is common to drive a plurality of amplifiers (for example, two to three) per unit.

In a CATV system configured in this way,
A track condition monitoring device will be installed to quickly respond to failures in each device or track. In other words, a track condition monitoring device is a system that monitors the corresponding monitoring items within each device, instead of having to go out to the location where the device is installed and measure the condition of the line, such as the strength of the TV signal or the operating voltage of each part of the device. This is a system that automatically measures and transmits the data to the system administrator via a line. In the system shown in Fig. 2 above, instructions are sent from the central monitoring device 17 connected to the head end device 11 to each device through the downward direction of the bidirectional line by band division, and replies from each device, that is, various measurement data. is sent back to the central monitoring device 17 through the upstream direction of the bidirectional line. This allows the centralized monitoring device 17 to display or issue an alarm as necessary.

In the power supply devices 16a and 16b, when the commercial AC power supply is out of power, the inverter circuit powered by the storage battery, which is normally in a charged state, is activated to generate alternating current, which is then supplied to the line to power the CATV. Maintaining system functionality. In other words, such a power supply device is called an uninterruptible power supply device.

In this uninterruptible power supply, the time during which the storage battery can continue discharging is usually about two hours, and it is necessary to restore the commercial power supply within this time. Therefore, it is necessary to notify the central monitoring device 17 of the power failure status as soon as possible.

Here, in particular, the conventional state monitoring method for the power supply system will be explained with reference to FIG. Vessel 2
2 to the line 12, the central monitoring device 1
The presence or absence of a power outage is detected by exchanging data with 7. Note that the amplifier device 13 receives alternating current power from the power supply device 16, transmits this power onto the line 12, and also serves to supply power to other amplifier devices. Each amplifier device also includes a monitoring signal transmitting/receiving device 23, and similarly exchanges monitoring data such as signal levels with the central monitoring device 17.

However, the conventional condition monitoring method as described above has the following drawbacks.

Since it is necessary to incorporate the supervisory signal transmitting/receiving device 21 in the power supply device 16 in addition to the amplifier device 13, the cost increases.

Since it is necessary to allocate a branch 22 to each power supply device 16 and connect it to the line 12, the wiring becomes complicated and the loss of the branch 22 is added to the line 12, resulting in signal attenuation.

[Purpose of the invention]

The present invention was made in view of the above-mentioned drawbacks, and an object of the present invention is to provide a line condition monitoring method that makes it possible to perform highly reliable power outage detection without complicating the transmission/reception system for the central monitoring device. .

[Key points of the invention]

In other words, the line condition monitoring system according to the present invention includes an uninterruptible power supply that generates a power supply voltage of a commercial frequency during normal times and a power supply voltage of a frequency different from the commercial frequency during a power outage, and changes in this power frequency are detected on the amplifier device side. The system is configured to detect this information and transmit it to the central monitoring device.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an extracted power supply section implementing the line condition monitoring method of the present invention. In the figure, 12 is a coaxial line for transmitting television signals;
31 is an uninterruptible power supply, 32 is an amplifier, 33 is a power frequency detection circuit, 34 is a monitoring signal transmitting/receiving device, and 35 is a branch.

The uninterruptible power supply 31 normally steps down commercial AC power through a transformer and transmits the power to the amplifier 32 and coaxial line 12. During a power outage, the uninterruptible power supply 31 converts the DC voltage obtained from the storage battery through an inverter circuit. It is converted into an alternating current voltage and then switched and transmitted to the amplifying device 32 and coaxial line 12. In this case, during a power outage, the power frequency of the AC voltage converted via the inverter circuit is 60Hz if it is normally 50Hz.
Also, if it is 60Hz, it can be changed to 50Hz. Here, in Japan, the amplifier device 32 that receives the power supply is normally designed to operate at either 50 Hz or 60 Hz, so switching of the power supply frequency can be performed without any problem.

The power supply frequency detection circuit 33 detects the frequency of the power supply voltage supplied from the uninterruptible power supply, and this power frequency detection information is high-frequency modulated by the supervisory signal transmitting/receiving device 34 and sent from the branch 35 via the upstream line. and is transmitted to the central monitoring device 17 (see FIG. 2).

That is, when the uninterruptible power supply 31 enters a power outage state and switches to an inverter circuit using a storage battery as a power source, an AC voltage with a frequency different from that of the commercial AC power supply during normal operation is generated, and the AC voltage is generated through the amplifier 32. Power is supplied to the line 12. Then, the amplifier 3
The power frequency detection circuit 33 inside the power supply frequency detection circuit 2 detects fluctuations in the power frequency due to a power outage, and this frequency fluctuation information is sent to the central monitoring device 17 ( (See Figure 2). Then, the centralized monitoring device 17 detects the presence or absence of a power outage at the installation location of each power supply device by knowing this fluctuation in the power supply frequency. In other words, the central monitoring device 17 can know that if the frequency is equal to the commercial frequency, it is in a normal state, and if the frequency is different from this, it is in a power outage state.

Therefore, the line condition monitoring system described in the above embodiment has the following advantages compared to the conventional monitoring system.

There is no need to incorporate a monitoring signal transmitting/receiving device into the uninterruptible power supply, reducing costs.

There is no need to allocate a branch to each uninterruptible power supply, wiring is simple, and signal loss due to the branch is eliminated.

Since multiple amplifiers are normally driven by a single uninterruptible power supply, if the frequency information of the power supplies monitored in each amplifier is compared with each other, reliability of power outage determination can be improved. I can give you sex. That is, in this case, even if power supply frequency fluctuation information is transmitted to the central monitoring device due to a failure in some of the monitoring signal transmitting/receiving devices or frequency detection circuits, this information will not be mistakenly received as power outage information.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to realize a line condition monitoring system that has an extremely simple configuration and can detect a power outage with high reliability.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an extracted power supply section of a CATV system implementing a line condition monitoring system according to an embodiment of the present invention, FIG. 2 is a block diagram showing the general configuration of the CATV system, and FIG. The figure is a block diagram showing a conventional line condition monitoring system. 11... Head end device, 12... Coaxial line, 17... Central monitoring device, 31... Uninterruptible power supply, 32... Amplifying device, 33... Power frequency detection circuit, 34... Monitoring signal transmitting/receiving device, 35 ……
Turnout.

Claims (1)

[Claims] 1. In a line condition monitoring system for transmission lines in which a centralized monitoring device is installed on the transmission system management side, a power supply device that generates a power supply voltage at a commercial frequency during normal operation and a power supply voltage at a frequency different from the commercial frequency during a power outage. , a frequency detection circuit that detects a change in the power frequency of the voltage generated by the power supply device;
A line condition monitoring system characterized by comprising a transmitting device that modulates detection information of a power supply frequency detected by the frequency detection circuit into a high frequency signal and transmits it to a monitoring device via the transmission system.