JPS63123239A - Recovery repeater for incoming data signal in two-way catv system - Google Patents

Abstract

PURPOSE:To eliminate the noise of an incoming frequency band giving effect on the incoming line of the entire system caused by the transmission from the subscriber's equipment to the line by providing a recovery repeater for an incoming data signal to a distribution line and a drawing line to which subscriber's equipments are connected. CONSTITUTION:A recovery repeater 5 is connected between a subscriber's equipment 4 and a transmission line 2. The incoming data signal modulated to an incoming frequency band and the noise of the incoming frequency band are given to the demodulator 8 through a branching filter 6 and a band pass filter 7. The demodulator 8 detects the incoming data carrier to demodulate it into the base band and informs the carrier detection information 12 to the modulator 9. The modulator 9 is operated only when the carrier exists and modulates the demodulated signal again into the incoming frequency band and outputs the modulation signal to the transmission line 2 via a branching filter 10. Thus, the transmission of noise generated from the subscriber's equipment 4 to the transmission line 2 is prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a two-way CATV system that performs two-way data communication between a center and each subscriber terminal, and particularly relates to a regenerative relay system that regenerates and relays uplink data signals. It is related to the device.

[Conventional technology]

An example of a conventional two-way CATV system is shown in FIG. 4 and will be described.

In the figure, 1st+1ms...1□Two and oneb,1
c is each subscriber terminal, and these subscriber terminals 11111 to 1a
The uplink data signals modulated in the uplink frequency band transmitted from n, 1b, and 1c are sent to the transmission path 2 and transmitted to the center 3. This uplink data signal is transmitted from the center 3 to each subscriber terminal 1. , ~1□
The response is transmitted from 1b11c in a time-division manner. In addition,
4 indicates an apartment complex consisting of subscriber terminals 11□, 1.2, . . . 1an.

[Problem that the invention seeks to solve]

In the conventional two-way CATV system as mentioned above, CA
Since the TV system is a dendritic distribution network, there is a problem in that when noise in the upstream frequency band flows into the transmission path from a certain subscriber's home, the uplink of the entire system is affected. Particularly in existing apartment complexes where indoor wiring has been routed in advance, subscribers and non-subscribers coexist, so devices other than subscriber terminals can be connected to the output terminals in the house, and upstream frequency bands can be transmitted from there. There is a risk that noise will flow into the transmission path.

The above problems will be explained with reference to FIG. 5, which shows signals in the upstream frequency band at each point A to D in FIG. 4.

When noise in the upstream frequency band flows into the transmission line 2 from the housing complex 4 in FIG. 4, the signal at point A becomes as shown in (-) in FIG. Also, assuming that no noise is generated from the subscriber's home connected to points B and C, Fig. 5(b),
The signals shown in (a) will be generated, but when these signals are transmitted toward the center 3, they will be interfered with by the noise flowing from the apartment complex 4 (point D in Fig. 5 (d)). reference).

[Means for solving problems]

The uplink data signal regeneration repeater in the two-way CATV system of the present invention is installed in distribution lines and drop-in lines to which subscriber homes that tend to generate noise in the upstream frequency band, such as apartment complexes, are connected. a separating means for separating the modulated uplink data signal from a signal in the lower frequency band; a demodulator for demodulating the uplink data signal separated from the signal in the lower frequency band by the separating means to baseband;
The transmitter is provided with a modulator that re-modulates the uplink data signal demodulated into the baseband by the demodulator into the uplink frequency band.

[Effect]

In the present invention, a regenerative relay device that regenerates and relays uplink data signals removes noise in the uplink frequency band that flows from the subscriber's home to the transmission path and affects the uplink of the entire system.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing a configuration example of a bidirectional CATV system to which the present invention is applied.

In FIG. 1, corresponding parts are denoted by the same reference numerals as in FIG.

Now, each subscriber terminal 1al11111 of apartment complex 4
The uplink data signal modulated in the uplink frequency band transmitted from '1□ and the noise in the uplink frequency band flowing from the housing complex 4 to the transmission path 2 are input to the regenerative repeater 5. Then, the data signal is changed again to the upstream frequency band by the regenerative repeater 5 and is transmitted to the p center 3 through the transmission line 2.

FIG. 2 is a block diagram showing an embodiment of the uplink data signal regenerative repeater shown in FIG.

In the figure, 6 is a branching filter, and this branching filter 6
It is installed on distribution lines and drop-in lines (not shown) to which subscriber homes that tend to generate noise in the upstream frequency band, such as apartment complex 4, are connected, and the upstream data signal changed to the upper frequency band is sent down. It constitutes a separation means for separating signals in a frequency band. 7 is a band pass filter which inputs the output of the separation filter 6, which is this separation means, and 8 is a band pass filter that separates signals in the 919 frequency band by the separation filter 6. A demodulator 8 demodulates the above-mentioned upstream data signal separated into baseband.
A modulator 10 is a demultiplexing filter that modulates the upstream data signal demodulated into the baseband again into the upstream frequency band. Note that 11 indicates data, 12 indicates carrier detection information, and 13 indicates a downlink signal.

Next, the operation of the embodiment shown in FIG. 2 will be explained with reference to FIG. 3.

First, the upstream data signal modulated in the upstream frequency band and the noise in the upstream frequency band are separated from the downstream frequency band signal by the demultiplexing filter 6, and then passed through the band pass filter 7 for the upstream data signal band to the demodulator. 8. The demodulator 8 detects the uplink data signal carrier, demodulates it to the baseband, and notifies the modulator 9 of the presence or absence of the uplink data signal carrier as carrier detection information 12.

Next, the modulator 9 receives the carrier detection information 1 from the demodulator 8.
2, it operates only when the carrier is present, and the demodulator 8
The uplink data signal demodulated into the baseband is modulated into the uplink frequency band. The uplink data signal modulated again into the uplink frequency band by the modulator 9 is outputted through the demultiplexing filter 10.

FIG. 3 is an operation explanatory diagram showing signals in the upstream frequency band at each point A-E in FIG. 1, where (a) shows the signal at point A, (b) shows the signal at point E, (C)
is the signal at point B, (d) is the signal at point 0, (e
) indicates the signal at the 0 point.

When noise in the upstream frequency band flows into the transmission line 2 from the housing complex 4 shown in FIG. 1, the signal at point A becomes as shown in FIG. 3 (&). This signal passes through the regenerative relay device 5, and the regeneratively relayed signal at point E is as shown in FIG. 3(b).
The noise generated from Apartment House 4 will be removed.

Therefore, as shown in FIG. 3(e) as a 0-point signal, upstream data signals transmitted from other subscriber terminals are not interfered with by noise in the upstream frequency band generated from the apartment complex 4.

〔Effect of the invention〕

As explained above, according to the present invention, in a two-way CATV that performs two-way data communication between a center and each subscriber terminal, subscriber homes that tend to generate noise in the upstream frequency band, such as apartment buildings, are connected. By installing a regenerative relay device for upstream data signals on the distribution and lead-in gauze, the noise generated therefrom can be removed and does not affect the transmission of upstream data signals from other subscriber terminals. There are some effects that can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a configuration example of a bidirectional CATV system to which the present invention is applied, FIG.
The figure is an operational explanatory diagram showing signals in the upstream frequency band to provide an explanation of the operation in Fig. 1, Fig. 4 is a block diagram showing an example of the configuration of a conventional two-way CATV system, and Fig. 5 is an explanation of the operation in Fig. 4. FIG. 3 is an operation explanatory diagram showing a signal in an upstream frequency band provided for use in the uplink frequency band; 5...uplink data signal regeneration relay device, 6...
Branching filter, 8... demodulator, 9... modulator.

Claims (1)

[Claims] In a two-way CATV system that performs two-way data communication between the center and each subscriber terminal, upstream a separation means for separating an uplink data signal modulated into a frequency band from a signal in a downlink frequency band; a demodulator for demodulating the uplink data signal separated from a signal in the downlink frequency band by the separation means to a baseband; 1. An uplink data signal regeneration repeater in a two-way CATV system, comprising: a modulator that re-modulates an uplink data signal demodulated to baseband by a demodulator into an uplink frequency band.