JPH071934B2 - CATV repeater - Google Patents

Description

The present invention relates to a CATV repeater forming a part of a CATV network.

(Prior Art) When a trunk transmission line in a conventional CATV network is configured by cascade-connecting repeaters, each repeater disconnects the transmission line between the repeater located immediately below the repeater itself. The data processing unit incorporated in the repeater transmits the determination result to the central monitoring station via the upstream transmission line. The central monitoring station was able to know the disconnection point of the trunk transmission line by the operation of each repeater.

(Problems to be Solved by the Invention) In a conventional repeater, when each repeater is connected in cascade to form one trunk line, as described above, the relay device immediately below the trunk line sends the signal in the upstream direction. Since the pilot signal is judged, only disconnection of the trunk transmission line can be detected.

By the way, in an actual CATV network, since a plurality of branch transmission lines are extended from each repeater, there has been a drawback that conventional repeaters cannot detect disconnection of the branch transmission line.

An object of the present invention is to provide a CATV repeater capable of detecting disconnection of a branch transmission line branched from its own repeater.

(Means for Solving the Problems) In order to achieve the above object, CATV repeaters according to the present invention are connected in cascade to form a part of a CATV network, and a CATV monitored by one central monitoring station. In the repeater, the central monitoring station takes in the amplitude-modulated pilot signal which is constantly transmitted in the downward direction, detects the modulated pilot signal, and outputs the modulated signal in the upward direction. Modulation signal sending means for receiving the modulated signal sent in the upstream direction from the repeater located immediately below the trunk line, and first judging means for judging the presence / absence of the signal, and branching branched from the own repeater. A second determination unit that receives a modulated signal transmitted in the upstream direction from a repeater located immediately below the line and determines the presence or absence of the signal, and the results of the first and second determination units are electronically recorded. , Send to the central monitoring station The data processing unit has a data communication function.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a block diagram showing a repeater according to the present invention.

The central monitoring station 31 is a repeater 3 that is cascade-connected to the trunk transmission line 32.
3, monitoring the repeater 34 and the repeater 51.

The repeater 33 takes in the amplitude-modulated pilot signal, which is always transmitted from the central monitoring station 31 in the downward direction, through the combiner 35 and the band-pass filter 36 for taking out only the frequency component of the pilot signal. Then, the modulation signal is detected by the detection unit 37 which is composed of only passive elements. The modulation signal detecting means corresponds to a portion formed by the combiner 35, the band pass filter 36, and the detector 37. This signal is constantly transmitted to the upstream trunk transmission line 32 via the coupler 38 and the coupler 35 which are modulation signal transmitting means. The pilot signal is passed through the amplifier 39 and the combiner 40 in the repeater 33 to the repeater 34.
Since it has also been transmitted to the relay unit 34, the modulation signal component of the pilot signal is also transmitted in the up direction in the repeater 34 as well.

The modulated signal transmitted from the repeater 34 passes through the combiner 40, the amplifier 41, and the distributor 42 in the repeater 33, and is input to the signal detection unit 43 that determines the presence or absence of the modulated signal.

The first judging means is composed of the combiner 40, the amplifier 41, the distributor 42 and the modulation signal detector 43.

Further, since the pilot signal sent from the central monitoring station 31 is also sent to the subordinate repeater 51 connected to the branch transmission line 50 branched from the repeater 33 through the amplifier 39 and the combiner 49, the subordinate relay is performed. The device 51 constantly sends out a modulated signal of the pilot signal in the upstream direction of the branch transmission line 50. The second judging means is composed of a combiner 49, an amplifier 48 and a modulation signal detector 46. This signal passes through the combiner 49 and the amplifier 48 in the repeater 33 and is input to the signal detector 46.

The outputs of the signal detection unit 43 and the signal detection unit 46 are sent to the data processing unit 44, and the contents thereof are electronically converted and sent in response to a request from the central monitoring station 31.

The modulated signal demultiplexing unit 47 in the repeater 33 transmits the service signal in the upstream direction to the trunk line, but does not mix the modulated signal on the branch transmission line 50 sent by the repeater 51 with the modulated signal on the trunk line 32. Works like.

When the branch transmission line 50 branched from the repeater 33 is disconnected, the repeater 33 can detect the disconnection of the branch transmission line by judging that there is no output from the modulation signal detection unit 46. is there.

(Effect of the Invention) As described above, according to the present invention, the central monitor takes in the amplitude-modulated pilot signal sent in the downward direction, sends it to the branch transmission line, and the relay device immediately below the branch transmission line. Has added to each repeater a function to detect the presence or absence of a modulation signal sent in the upstream direction in response to this pilot signal, so that it becomes possible for the central monitoring station to detect the disconnection of the branch transmission line, and the CATV network This has the effect of facilitating maintenance and management.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a CATV network repeater according to the present invention. 31 ... Central monitoring station, 32 ... Main transmission line 33,34,51 …… Repeater 35,38,40,49 …… Coupler 36 …… Bandpass filter, 37 …… Detector 39,41,48 ...... Amplifier, 42 …… Distributor 43,46 …… Modulation signal detection unit 44 …… Data processing unit, 45,47 …… Removal unit 50 …… Branch transmission line

Claims (1)

[Claims] 1. A part of a CATV network is cascade-connected to form 1
In the CATV repeater monitored by the central monitoring station of the station, the modulation signal for taking in the amplitude-modulated pilot signal that is constantly transmitted in the downward direction by the central monitoring station, and detecting this to detect the modulated signal. Detecting means, modulation signal sending means for sending the modulated signal in the upward direction, and receiving the modulated signal sent in the upward direction from a repeater located immediately below the main line, and determining the presence or absence of the signal 1 determination means,
Second determining means for receiving the modulated signal transmitted in the upstream direction from the repeater positioned immediately below on the branch line branched from the own repeater and judging the presence or absence of the signal, and the first and second judgments A CATV repeater comprising a data processing unit having a data communication function of electronically transmitting the result of the means and transmitting the result to the central monitoring station.