JPH01320889A - Cable television system - Google Patents

Abstract

PURPOSE:To confirm and test a control function on a cable transmission line being in service by providing a means which transmits a control signal of plural channels including a channel change command onto the cable transmission line at the time of confirming and testing the function of the control signal in a terminal equipment by a center station. CONSTITUTION:A channel of a normal control signal having a frequency FS is used to transmit a test start command from a controller 13a of a center station 10 to a terminal equipment 30n. A test command from the center station 10 is received by a control part 33 through a control signal tuner 32, and the tuning frequency of the control signal tuner 32 is changed from the frequency FS of the channel of the normal control signal to a frequency Ft of the channel of a test control signal. Thereafter, the channel having the frequency Ft is used to transmit an individual control signal destined for the terminal equipment 30n and a multiple-address control signal destined for all terminal equipments from an artificial control part 13b and a modulator 14b of the center station 10 to a cable transmission line 20.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cable television system, also called CATV or the like.

(Conventional technology) CATV (Community antenna)
NA Television) originated from the remote reception of television broadcasts.

However, recently, this CATV is transmitting not only wireless television broadcast programs received by the antenna, but also multiple channels of television video signals, including movie programs played by the center station, local programs created by the center station, etc., using coaxial cables. This has evolved into a format in which the information is delivered to the terminal devices of service subscribers via large-capacity wired transmission lines such as optical cables and optical cables. For this reason, CATV has come to be referred to as a cable television system, or simply cable television, as a broader concept.

Typical cable television systems allow subscribers to subscribe and specify the channels they wish to receive. Typically, there are also channels mixed in that all subscribers can receive unconditionally, such as wireless television broadcast programs received by antennas. Therefore, control signals are sent from the center station to the terminal devices for the purpose of causing each subscriber terminal device to selectively receive only channels that comply with the contract. Control signals for realizing this selective reception function may be sent to individual terminal devices, or may be sent out in a broadcast manner to all terminal devices.

When connecting a new subscriber's terminal device to the transmission line where such cable television system service is currently being provided,
A test to confirm the selective reception function by transmitting and receiving control signals is required. This control signal includes broadcast signals, but
If such a repeatable control signal is sent to a wired transmission line where a service is being provided, the operation of the existing terminal device will be disrupted.

Therefore, in the past, new subscriber terminal equipment was tested by connecting it to a test wired transmission line, or by connecting it to an actual wired transmission line during idle hours when no service was being provided. .

(Problems to be Solved by the Invention) In the above-mentioned conventional cable television system, a test to confirm the control function of a new subscriber terminal device is conducted using a test cable transmission line or an idle time slot. however,
When using a wired transmission line for testing, there is a problem in that the actual operating state cannot be sufficiently simulated. Furthermore, when using free time slots, there are problems such as large constraints on working time.

(Means for Solving the Problems) The cable television system of the present invention is a means for a center station to send control signals of multiple channels including a channel change command onto a cable transmission line during a function confirmation test of control signals in a terminal device. , and is configured to enable confirmation tests of control functions to be performed on a wired transmission line in service using a dedicated control channel different from that for service.

Hereinafter, the operation of the present invention will be explained in detail together with examples.

(Embodiment) FIG. 1 is a block diagram showing the configuration of a cable television system according to an embodiment of the present invention, in which 10 is a center station, 20 is a cable transmission line, 30a, 30b...30
n... is a terminal device, 40a, 4Qb...40n...
・ is a television receiver.

The center station 10 includes a plurality of television signal transmitting devices 1
1a, llb...11m, and modulation devices 12a, 12b
=12m and the control device 13a.

It includes a pseudo control device 13b, modulation devices 14a and 14b, and a multiplexing device 15.

The terminal devices 30a, '30b, . . . 30n, . The ink face portion 34 is also provided.

Wired transmission line 20 via multiplexer 15 in center station 10
As illustrated in the spectrum diagram of FIG.
lb...ILm to modulators 12a, 12b...1
Frequencies Fa, Fb, which are transmitted through 2m respectively.
- Each channel of the Fm television signal and the frequency Fs sent from the control device 13a via the modulation device 14a
regular control signal channel and the pseudo control device 13b.
and a channel for a test control signal of frequency Ft sent from the modulator 14b through the modulator 14b.

In the example shown in FIG. 1, it is assumed that a new subscriber's terminal device 30n is connected to the wired transmission line 20, and a control signal function confirmation test is performed with the center station 10. First, from the control device 13a of the center station 10 to the terminal device 3. On, a test start command is sent using the regular control signal channel of frequency Fs. In the terminal device 30n,
By initialization performed immediately after power-on, the control signal tuner 32 is in a state where it selects a regular control signal channel of frequency Fs. Therefore, a test start command from the center station 10 is received by the control section 33 through the control signal tuner 32. When the control section 33 receives this test start command, it changes the tuning frequency of the control signal tuner 32 from the frequency Fs of the regular control section channel to the frequency Ft of the test control signal channel.

After that, from the pseudo control unit 13b and the modulation device 14b of the center station 10, using the test channel of frequency Ft, individual control signals destined for the terminal device 30n and retransmission characteristics destined for all terminal devices are transmitted. The control signal is transmitted through the wired transmission line 20
By sending the signal to the terminal device 30n, a function confirmation test of the control signal in the terminal device 30n is performed. In the existing terminal devices 30a, 30b, . . ., which are connected to the batting line transmission line 20 and are in the state of receiving regular service, the part corresponding to the control signal tuner 32 of the terminal device 30n is initialized immediately after power is turned on, so that the terminal device 30a, 30b, etc. It is in a state of tuning to the channel frequency Fs of the control signal. Therefore, the broadcast control signal appearing on the wired transmission line 20 is not received by the existing terminal devices, so that their operations are not disturbed.

When the control signal function confirmation test is completed, the pseudo control unit 13b sends a test end command to the terminal device 30n. When the control unit 33 of the terminal device 30n receives the test end command via the control signal tuner 32, the control unit 33 changes the tuning frequency of the control signal tuner 32 from the test control signal channel frequency Ft to the regular control signal channel. By changing the frequency to Fs,
Shift to a state where you can enjoy regular services.

The configuration above has been exemplified in which one test control signal channel is added to the regular control signal channel. However, a configuration may also be adopted in which a plurality of test channels are added and a function confirmation test is performed simultaneously on a plurality of terminal devices grouped into groups for each additional channel.

Further, although a configuration in which unidirectional transmission is performed from the center station to the terminal device is illustrated, the present invention can also be applied to a bidirectional transmission system in which data transmission is also performed from the terminal device to the center station.

(Effects of the Invention) As explained in detail above, in the wired television system of the present invention, the center station sends control signals for multiple channels including a channel change command onto the wired transmission path during a control signal function confirmation test. Since the configuration includes the means, it is possible to perform a confirmation test of the control function on a wired transmission line where the service is being provided using a dedicated control channel different from that for the service.

As a result, it is possible to sufficiently confirm the actual control function on the wired transmission path during service provision, and there is no need to wait for a free time slot for the service, thereby eliminating constraints on work time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of a cable television system according to an embodiment of the present invention, and FIG. 2 is a signal spectrum diagram in the cable television system of FIG. 1. 10... Center station, 112-11m... Television signal transmission device, 12a-12b... Modulation device, 1
3a...Control device, 13b...Pseudo control device, 14
a, 14b... Modulation device, 15... Multiplexing device, 2
0...Wired transmission line, 30a-30n...Terminal device,
31... Television signal tuner, 32... Control signal tuner, 33... Control section, 34... Input interface section, 40a-40n... Television receiver, FO-Fm... Television John signal channel, F
s... regular control signal channel, Ft... control signal channel for testing.

Claims (1)

[Claims] A wired transmission path, a center station that sends television video signals and control signals to the wired transmission path, and a plurality of terminal devices that receive television video signals and control signals from the wired transmission path. A wired television system comprising: the center station having means for transmitting control signals of multiple channels including a channel change command onto a wired transmission line during a function confirmation test of control signals in a terminal device; A cable television system characterized by: