JPH02272844A - Head end device - Google Patents

Abstract

PURPOSE:To start using a channel translator which stands by when abnormality occurs in an in-use channel translator as in-use without the necessity of a manual operation by installing abnormality detection devices in a switching device. CONSTITUTION:The switching device 2 is provided with a communication line, a switch 20 which is connected to either of respective distribution devices 3a and 3b, respective abnormality detection devices 21 and 22 on an in-use-side and a stand by-side, a state indication part 23 detecting the states of respective channel translators 1a and 1b and a switch driving part 24. The abnormality detection device 21 generates an error signal when the transmission signal of a forward channel outputted from the distribution device 3a and the transmission signal of a reverse channel do not satisfy a prescribed condition, and the state indication part 23 outputs an abnormality signal. Then, it operates the switch driving part 24 and changes over the switch 20. Thus, the channel translator 1b which stands by can be started for use as in-use when abnormality occurs in the in-use channel translator 1a.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a headend device used in cable network communication systems and the like.

(Prior Art) A cable network communication system shown in FIG. 3 is conventionally known as a data communication system.

This system includes a plurality of stations 101, a communication path 102 connecting these stations 101, a headend device 103 connected to one end of this communication path 102, and a communication path 102 connected to one end of the communication path 102.
and a terminator 104 connected to the other end, each station 101
outputs a transmission signal on the forward channel when communicating.

This transmission signal is supplied to the headend device 103 via the branch line 105 and the communication path 102, where it is converted into a reverse channel transmission signal, returned to the communication path 102, and taken into each station 101.

However, this system had the following problems.

That is, the headend device 103 has two channel translators 106a and 106b, two distributors 107a and 107b connected to these, and one of the channel translators 106a and 106b via these distributors 107a and 107b. and a changeover switch 108 that connects the communication path 102 to the communication path 102 as the current communication path.

Further, the changeover switch 108 is composed of a mechanical coaxial switch or a coaxial relay, and when the currently used channel translator, for example, the channel translator 106a, goes down, the operator manually switches it to use the other channel translator 106b. Therefore, not only does switching between the channel translators 106a and 106b require human intervention, but also there is a problem in that it takes too much time to recover from a failure.

(Purpose of the Invention) The present invention has been made in view of the above-mentioned circumstances, and it is possible to replace a channel translator that is on standby when an abnormality occurs in a channel translator currently in use without requiring human labor. The purpose of the present invention is to provide a headend device that can be put into use as an active device.

(Summary of the Invention) In order to achieve the above object, the head end device according to the present invention has the following configuration. That is, in a switching device that designates one of a plurality of channel translators as currently in use, there is provided a detection unit that detects whether or not the input signal and output signal of the currently used channel translator correspond; and a switching device that connects another channel translator to the cable of the cable network communication system as the current channel translator when it is detected that the input signal and output signal of the channel translator currently in use do not correspond to each other. It is characterized by

(Embodiments of the Invention) Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a block diagram showing a first embodiment of a head end device according to the present invention.

The headend device shown in this figure includes two channel translators 1a and 1b, a switching device 2 that connects one of these channel translators la and lb to a communication path of a cable network communication system, and this switching device 2. and each channel translator 1a
, 1b, respectively.

The distribution device 3a outputs the forward channel transmission signal from the output terminal 4b when it is input to the input/output terminal 4a, and outputs it from the input/output terminal 4a when the reverse channel transmission signal is input to the input terminal 4C. a distributor 4 which receives the forward channel transmission signal which is output from the output terminal 4b of the distributor 4 and supplies it to the input terminal 7 of the channel translator 1a and the input terminal 10 of the switching device 2. 6 and the input terminal 4 of the distributor 4 by taking in the transmission signal of the reverse channel output from the output terminal 8 of the channel translator 1a.
The switching device 2 includes a distributor 9 that supplies signals to the switching device 2 and the input terminal 11 of the switching device 2.

Similarly to the distribution device 3a, the 1 distribution device 3b includes three distributors 4, 6, and 9, and transmits the forward channel transmission signal inputted to the input/output terminal 4a of the distribution device 4 to the input terminal 7 of the channel translator 1b. and the input terminal 12 of the switching device 2, and the channel translator 1b.
The transmission signal of the reverse channel outputted from the output terminal 8 of is supplied to the input terminal 13 of the switching device 2.

It is output from the input/output terminal 4a of the distributor 4.

Each of the channel translators la and lb includes a receiving section that receives a forward channel transmission signal inputted to the input terminal 7, a signal generating section that generates a signal of a predetermined frequency, and an output of the signal generating section and It includes a frequency conversion section that mixes the output of the frequency conversion section and generates a reverse channel transmission signal, and a transmission section that takes in the output of this frequency conversion section and outputs it from the output terminal 8.

Further, the switching device 2 connects the communication path and each of the distributors 23.3b.
a switch 20 that connects one of the above, an abnormality detection device 21 on the active side, and an abnormality detection device 22 on the standby side,
A state indicating section 23 that detects the state of each channel translator 1a, 1b based on the output of each of these abnormality detection devices 21, 22, and a switch driving section that drives the switch 20 according to the detection result of this state indicating section 23. It is equipped with 24.

The abnormality detection device 21 includes a signal receiving section 25 that receives the forward channel transmission signal supplied from the distribution device 3a, and a decoder section 26 that converts the forward channel transmission signal received by the signal receiving section 25 into frame data. , a signal receiving section 27 that receives the reverse channel transmission signal supplied from the distribution device 3a, a decoder section 28 that converts the reverse channel transmission signal received by the signal receiving section 27 into frame data, and each of these decoders. The frame data check section 29 determines whether or not the channel translator 1a is normal based on the outputs of the sections 26 and 28, and generates an error signal and supplies it to the status indicating section 23 when the channel translator 1a is not normal.

Also, like the abnormality detection device 21, the abnormality detection device 22 includes two signal receiving sections 25, 27 and two decoder sections 26.
．． 28 and one frame data check section 29, and generates an error signal when the forward channel transmission signal and the reverse channel transmission signal output from the distribution device 3b do not satisfy a predetermined condition. The information is supplied to the state indicating section 23.

Next, the channel translator switching operation of this embodiment will be explained.

Now, assume that the switch 20 connects the communication path of the cable network communication system and the distributor 3a, and uses the channel translator 1a as the current one and the channel translator 1b as a backup one.

At this time, if the channel translator 1a side is normal, the forward channel transmission signal input from the communication path is input to the channel translator 1a via the switch 20 and the distribution device 3a, where it is converted into a reverse channel transmission signal. After that, the distribution device 3a and the switch 20
The signal is output to the communication path via.

At this time, the forward channel transmission signal and the reverse channel transmission signal are input from the distribution device 3a to the abnormality detection device 21, but if the channel translator 1a is normal, each signal obtained based on these transmission signals is Since the frame data match, the abnormality detection device 21
does not generate an error signal.

Therefore, in this case, the switch driver 24
0 switching is not performed.

Then, the contents of the forward channel transmission signal (contents of frame data) input to the channel translator 1a for some reason, and the contents of this channel translator 1
The content of the reverse channel transmission signal output from a (
frame data contents) no longer match,
When a reverse channel transmission signal is not output from the channel translator 1a within a predetermined time after the forward channel transmission signal is input to the channel translator 1a, the frame data check section 29 of the abnormality detection device 21 determines that the channel translator 1a is abnormal. It determines that this has occurred and generates an error signal.

As a result, the status indicating section 23 outputs a signal indicating that the currently used channel translator 1a has become abnormal, operates the switch driving section 24, and switches the switch 20.

As a result, the channel translator 1a, which had been used as a reserve, is released as a reserve, and the channel translator 1b, which had been on standby as a reserve, is started to be used as a reserve.

In this way, in this embodiment, the content of the forward channel transmission signal input to the channel translator 1a currently in use matches the content of the reverse channel transmission signal output from this channel translator 1a. When the reverse channel transmission signal is not output from the channel translator 1a within a predetermined time after the forward channel transmission signal is input to the channel translator 1a, it is determined that the channel translator 1a has become abnormal. Since the channel translator 1b, which had been on standby as a backup, is now in use, even if the channel translator 1a currently in use becomes abnormal, the backup can be used without interrupting communication. It is possible to switch to channel translator 1b.

FIG. 2 is a block diagram showing a second embodiment of the head end device according to the present invention. In this figure, the same parts as those in FIG. 1 are given the same reference numerals.

The headend device shown in this figure differs from the one shown in FIG.

In this case, the signal detecting section 30 determines whether or not each signal receiving section 25.27 receives a forward channel transmission signal, that is, when a forward channel transmission signal is input to the channel translators 1a, 1b, the signal detecting section 30 determines whether or not each signal receiving section 25, 27 receives a forward channel transmission signal. An abnormality in the channel translators 1a and 1b is determined based on whether or not a channel transmission signal is output.

In this way, in this embodiment, the determination of the content of each transmitted signal is omitted, and the abnormality of the channel translators 1a and 1b is determined simply based on whether there is a transmitted signal of the reverse channel that corresponds to the transmitted signal of the forward channel. Therefore, the configuration of the abnormality detection devices 21 and 22 can be simplified, and the cost reduction of the system can be promoted.

Furthermore, in each of the embodiments described above, when the transmission signal input to and output from the channel translators 1a and 1b becomes abnormal once, these channel translators 1a and 1b
However, an error counting function is added to the frame data check section 29 and signal detection section 30 to determine the frequency (normal A certain value (for example, 1
An error signal may be generated when the value exceeds O-9), thereby making it possible to perform switching in accordance with the reliability required for the entire system.

Further, in each of the embodiments described above, when the channel translator 1a currently in use becomes abnormal, only the channel translators 1a and 1b are switched. This may be confirmed by a lamp display or an alarm sound when switching.

Alternatively, the power to the spare channel translator 1b may be cut off until switching between the channel translators 1a and 1b is performed, and the power may be turned on when the channel translator 1b is used as the current channel translator. can save electricity.

(Effects of the Invention) As explained above, according to the present invention, when an abnormality occurs in the currently used channel translator, the standby channel translator is started to be used as the currently used channel translator, without requiring human labor. be able to.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a first embodiment of the head end device according to the present invention, FIG. 2 is a block diagram showing a second embodiment of the head end device according to the present invention, and FIG. 3 is a general cable network communication FIG. 1 is a block diagram showing an example of a system.

Claims (2)

[Claims] (1) In a headend device equipped with a plurality of channel translators and a switching device that connects one of these channel translators to a cable of a cable network communication system as an active channel translator, the switching device is used as an active channel translator. A detection unit that detects whether the input signal and output signal of the channel translator currently being used correspond to each other, and the detection unit detects whether the input signal and output signal of the channel translator currently being used by this detection unit do not correspond. and a switching device for connecting another channel translator to the cable as the active channel translator when it is detected. (2) When the input signal is input to the currently used channel translator but no output signal is output from this channel translator, the detection unit detects whether the input signal and output signal of the currently used channel translator correspond. The head end device according to claim 1, wherein the head end device determines that the head end device does not.