JPS63316587A - Signal selecting system for catv system - Google Patents

Abstract

PURPOSE:To transmit a signal of a specific channel to a specific terminal equipment by allowing a controller to control the switching of 1st and 2nd switches based on a command signal sent from the center side. CONSTITUTION:When a switching contact of the switches 16, 21 exists on a position shown by a solid line, a broadcasting signal sent from the center side through an I/O terminal 11 is branched by a branch 12 and the branched output is outputted from a branching terminal 14 to a specific terminal equipment through the switches 16, 21 and an I/O terminal 26. Although the branched output is entered from a branching circuit 15 to the controller 28, a command for instructing the switching of the switches 16, 21 is not included in the branching output, so that the switch 28 outputs no switch control signal. In case of including the command for instructing the switching of the switches 16, 21 in the broadcasting signal, a switch control signal is outputted from the controller 28 and the transmission of a signal of a specific channel is interrupted by a filter 27. Thus, signals can be transmitted and interrupted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a CΔTV system, and more particularly to a signal selection circuit that passes or blocks a specific channel signal sent from the center side.

[Conventional technology]

Conventionally, switch circuits and the like have been provided in CATV systems to block crossover noise in uplinks, but they have not been put to practical use as signal selection circuits that pass or block signals of specific channels.

Furthermore, filters to prevent pilot signals from flowing into the uplink were manually plugged in or plugged off, and were not controlled from a central location.

Furthermore, a system in which a specific channel of downlink signals is selected for each terminal device requires a scrambler at the center, and a descrambler at the terminal device.

[Problem that the invention seeks to solve]

As mentioned above, in order to be able to select a specific channel signal for each terminal device, conventional systems require a scrambler at the center and a descrambler for each terminal device, which increases costs. There was a problem.

The present invention was made in view of these circumstances, and
To provide a signal selection circuit for a C A TV system capable of transmitting a signal of a specific channel to a specific terminal device or blocking the transmission thereof with a simple configuration and at low cost without using any special equipment. The purpose is to

[Means for solving problems]

The signal selection circuit of the CATV system according to the present invention includes a duplexer that demultiplexes broadcast signals sent from the center side, and a demultiplexer that receives the demultiplexed output of one of the demultiplexers and selects one of the two transmission lines. a first switch that switches the transmission path;
A second switching device that is connected to the switching device through the two transmission lines, and outputs the signal sent from the center side to the terminal device by switching the transmission line to either one of the two transmission lines. a filter that is provided on one of the two transmission lines and that blocks the passage of a certain channel signal or attenuates the signal, and receives the branched output of the other branching filter, The controller is configured to control the first and second switching devices to switch to one of the two transmission paths on the same transmission path side based on the command signal included in the demultiplexed output.

In the above configuration, the controller controls switching of the first and second switching devices based on the command signal sent from the center side, so that the broadcast signal sent from the center side to the terminal device side is passed through as is, or Its passage can be blocked or its signal attenuated. Therefore, it is possible to send a signal on a specific channel to a specific terminal device without using any special equipment such as a scrambler or descrambler.

〔Example〕

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

FIG. 1 shows the configuration of a signal selection circuit for a CATV system according to the present invention. In the figure, a signal selection circuit 10 includes a branching filter 12 for branching a broadcast signal input manually via an input/output terminal 11 connected to the center side, and a branching filter 1.
a switch 16 that switches and outputs the demultiplexed output of one of the two transmission lines 32.34 to either one of the transmission lines 32.34; a switch 21 that switches the transmission line to
4j, and a controller 28 that receives the other branched output of the duplexer 12 and controls the switching of the switch 16, 21.

In the above configuration, when the switching contacts of the switching devices 16 and 21 are at the positions shown by solid lines, the broadcast signal sent from the center side via the input/output terminal 11 is split by the splitter 12, and the The wave output is transferred from the branch terminal 14 to the switch 17.
, the transmission line 32, the switch 21, and the input/output terminal 26, the signal is output to a specific terminal device. At this time, the demultiplexed output is taken into the controller 28 from the demultiplexer terminal 15 of the demultiplexer 14 via the input terminal 29, but this demultiplexed output receives a command signal instructing switching of the switch 16.21. Since it is not included, a control signal for performing switching control is not output from the controller 28 to the control terminal 20.25 of the switching device 16.21.

On the other hand, if the broadcast signal manually inputted from the input/output terminal 11 includes a command signal instructing switching of the switching device 16.21, the controller 28 switches the signal to the control terminal 20.25 of the switching device 16.21. A control signal for controlling is output, and the switching contact of the switching device 16.21 is switched to the switching terminal 19.24 side. As a result, the broadcast signal output from the duplexer 24 is transferred to the filter 27 of the transmission path 34 from the switching device 16.
, the switching device 21, and the input/output terminal 26 to the terminal device side. At this time, the filter 27 blocks transmission of the signal of the specific channel or attenuates the signal, so that the specific terminal device connected to the input/output terminal 26 is unable to receive the specific channel.

〔Effect of the invention〕

As explained above, the present invention includes a transmission path that transmits broadcast signals from the sensor side to the terminal device side, and a transmission path that allows the broadcast signals to pass through as is, and a transmission path that blocks the transmission of broadcast signals of specific channels, or The transmission line provided with a filter for attenuating the signal is configured to be switchable by a switch, and the switch is controlled by a controller based on a command signal sent from the center side. Therefore, according to the present invention, it is possible to transmit the broadcast of a certain specific channel to the terminal device or to block the signal thereof at low cost without using any special equipment such as a scrambler or a descrambler.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a signal selection circuit for a CATV system according to the present invention. 10... Signal selection circuit, 11.26... Input/output terminal, 12... Duplexer, 16.21... Switcher, 27... ...filter, 28...controller.

Claims (1)

[Claims] A splitter that splits broadcast signals sent from a center side; A switch is connected to the first switch via the two transmission lines, and by switching the transmission line to either one of the two transmission lines, the signal sent from the center side is sent to the terminal device. a second switching device for outputting the signal to a specific channel; a filter provided on one of the two transmission lines to block a signal of a certain channel from passing through or attenuate the signal; A controller that receives the other branched output and controls the first and second switching devices to switch to the same transmission line side of one of the two transmission lines based on a command signal included in the other branched output. CAT characterized by having
V system signal selection circuit.