JPS623954Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a tap-off used in a CATV system.

In a CATV system, a TV signal received by an antenna is amplified by a relay amplifier, etc., and then the signal is finally distributed to each home using a tap-off circuit having several output terminals.

Conventionally, this tap-off is performed by branching an input signal by transformers 1 and 2, and then branching the input signal to four subscriber terminals 4, 5, and 2 by a distribution circuit 3, as shown in FIG.
Although the TV signal is output to terminals 6 and 7, transformers 1 and 7 are installed so that even if signals are sent to these terminals from the subscriber side, they will not be output to adjacent subscriber terminals or tap-off input terminals 8, etc. A ratio of 2 is set.

The present invention modifies a portion of such a tap-off so that signals such as an intercom or an emergency bell can be exchanged between subscribers connected to the same tap-off.

FIG. 2, in which the same parts as in FIG. 1 are denoted by the same reference numerals, is an embodiment of the tap-off of the present invention, and other parts than the wiring diagram near the subscriber terminal are the same as those in FIG. 1 and are therefore omitted. In Fig. 2, the subscriber terminals are connected by a capacitor C, and a filter F is inserted in the output circuit to each terminal in the tap-off to pass the TV signal and block lower frequency signals. There is.

The tap-off of the present invention with the above configuration can transmit buzzer and intercom signals of several hundred kilohertz between the subscriber terminals 4, 5, 6, and 7, and since this is not output to the tap-off input terminal side, it is possible to transmit TV signals. It does not interfere with transmission.

Moreover, since it is only necessary to modify a part of the tap-off circuit, the modification cost is low, and the system can be easily used multiplexed without requiring any special method such as a two-way communication system.

[Brief explanation of the drawing]

FIG. 1 is a conventional tap-off connection diagram, and FIG. 2 is a tap-off connection diagram of the present invention, in which 4, 5, 6, and 7 are subscriber terminals, C is a capacitor, and F is a filter.

Claims (1)

[Scope of utility model registration request] In a tap-off that is connected to the line of a CATV system and outputs TV signals to two or more subscriber terminals, each of the terminals is coupled to each other by a capacitor, and in the output circuit to each terminal in the tap-off, A tap-off for CATV, characterized in that a filter is inserted to block signals in frequencies lower than the TV signal.