JPS6352533A - Method and apparatus for multi-channel data coummunication using two-way catv network - Google Patents

Abstract

PURPOSE:To execute a multiplex data communication between terminal equipments using an idle channel by eliminating a wiring work for an exclusive line for data communication through the utilization of a coaxial line of a CATV and bringing a broad frequency band into multi-channel use. CONSTITUTION:An incoming signal sent from a terminal equipment 1a is converted into an outgoing signal by a converter 3 and sent to terminal equipments 1a, 1b, 1c-. In case of the communication between a computer 8a of the terminal equipment 1a and a computer 8b of the terminal equipment 1b, a central processing unit (CPU) of the terminal equipment 1a varies the frequency of a variable oscillator 10a to searches an idle line not in use for the communication. When an idle channel is found out, the frequency of a variable oscillator 10b is matched with an incoming channel in pairs with the idle channel, an RF switch 12 is turned on to send a carrier. Data communication is applied without giving hindrance to TV reception in the CATV network because of the adoption of the multi-channel communication system in this way.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a multi-channel data communication method using a two-way CATV network, in which the frequency band used for communication is multi-channeled and an empty channel is selected from among the frequency bands. using C
This enables full-duplex or half-duplex frequency-multiplexed data communication between terminals of an ATV network.

(Prior Art) There have been various data communication methods. One of these is the stand-alone system, in which a center where an exchange is installed and a number of terminals are each connected with separate wiring, and the terminals are connected to each other by switching the connections at the center's exchange. be.

Another method is the bus method, in which many coded terminals are connected to a single communication line, and communication is performed between the terminals.Another method is the CATV network. In some cases, a converter is installed at the center to convert upstream signals to downstream signals, and a number of coded terminals are connected to the terminals, allowing packet communication to take place between the terminals.

Furthermore, in some of the above systems, the frequencies used are switched for each group at the time of system installation.

(Problems with the prior art) The conventional system described above had the following problems: (a) In the one-way system, the wiring is separate for each terminal, so a lot of wiring is required near the exchange. are concentrated, making construction and maintenance troublesome.

(b) In packet communication, a single communication line is shared by many terminals, so when sending long data, other terminals are unable to use the communication line, resulting in poor system usage efficiency.

(c) In the frequency switching method, the frequency is determined for each group, so data communication is not possible even between terminals installed on the same coax if they are in different frequency groups.

(Objective of the Invention) The object of the present invention is to eliminate the need for wiring work for a dedicated line for data communication by using CAT'V coaxial, and to make the wide frequency band, which is a characteristic of coaxial, multi-channel.
The system is designed to allow multiplex data communication between terminals using the empty channels, and to avoid complicating the structure of the center of the CATV system even if multiplexing is performed.

(Means for Solving the Problems) The data communication method according to claim 1 of the present invention includes uplink signal channels A, B, as shown in FIGS.
C---・- and downlink signal channels A+α, B+α, C
A large number of +αΦ dedicated channels are prepared, and at least a predetermined uplink signal channel and a predetermined downlink signal channel are made into a set of upper and lower pair channels, for example, A and A+α,
B and B+α), some of these upper and lower pair channels (for example, A and A+α) are used as shared pair channels, and empty channels that are not used among the many upper and lower channels are used to connect CATV system terminals. 1a, 1b***eln In a data communication method that allows data communication between each other, the terminal (for example, la) that wants to communicate uses downlink signal channels B+α, C+α
Select an unused empty channel (for example, B+α) from @Φ..., and when an empty channel is selected, send an uplink signal for calling from the FI terminal 1a to the center 2 of the CATV system, and then send the uplink signal to the CATV system center 2. is converted into a down signal by the converter 3 of the same center 2, and sent to the terminal 1a and lbs building 1n to call the desired terminal (for example, lb), and the calling terminal 1a sends a message to the called terminal 1b. Terminal 1b receives notification that it will perform data communication on the selected empty channel B+α, and the terminal 1b that receives the notification sets its receiving channel to the notified empty channel B+α, and its transmitting channel is set to the upstream channel B paired with the empty channel B+α.
In this state, data communication between the calling terminal and the called terminal is possible using those channels (B+α and B), and during communication, the shared channel (A and A+α) is ) is communicating using the terminal (1a.

lb), it is possible to transmit an interrupt.

The data communication device according to claim 4 of the present invention, as shown in FIG. A terminal 1a of the system is provided with a converter 3 for transmitting data.

A number of terminals 4a, 4b, . One modem 6 is capable of detecting an empty channel and transmitting an uplink signal using the empty channel, and the other modem 7 is designed to allow interrupt communication from a terminal other than the terminal currently communicating.

(Operation of the Invention) In the present invention, an upstream signal sent from the terminal 1a in FIG. 1 is converted into a downstream signal by the converter 3 and sent to each terminal 1a, lb, lc, . . . . The frequency of the converter 3 is divided into multiple channels for both upstream and downstream channels as shown in FIGS. 2 and 3. A, B, C--- in Fig. 2 are upstream signal channels, A+α, B+α, C+α in Fig. 3
Φ...- are downlink signal channels frequency-converted by the converter 3.

Among these channels, A and A+α are used as a pair as a shared channel.

For other channels, adjacent channels are arranged in pairs as shown below.

A pair of upstream channels B and C A pair of D and E A pair of F and G A pair of downlink channels B+α and C+α A pair of D+α and E+α A pair of F+α and G+α These upstream paired channels and downlink paired channels are further combined as follows. It is also possible to match the upper and lower pairs.

The pair (D and E) of (B and C) and (B+α and C+α) and (
D+α and E+α) of the pair (F and G) (F+α and G+α
) computer 8a of terminal 1a in Figure 1 is terminal 1.
When communicating with the computer 8b of the terminal 1a, the central processing unit (CPU) of the terminal 1a changes the frequency of the variable excavator 10a, sequentially receives channels other than A+α among the down channels shown in FIG. 3, and demodulates @lla. A carrier detection device detects the carrier of the receiving channel while searching for an empty channel that is not used for communication.

When an empty channel (for example B1α) is found, variable oscillation occurs.
The frequency of 510b is tuned to channel B of upstream channels B and C, which are a pair of empty channels B + α,
The RF switch 12 is turned on and the carrier is sent out. This declares to other terminals other than terminals 1a and lb that the paired channels of channels B and B+α and C and C+α are in use. At the same time, the modem 6 of the terminal 1a calls the terminal lb using channels A/A+α and informs it that communication will be performed on channels B and B+α and C and C+α.

On the other hand, when the terminal 1b is not communicating with any other terminal other than the terminal 1a, the variable oscillation of the terminal 1b @13a
and 13b are operated to switch the transmission channel to C and the reception channel to B+α, and the modem 6 of the terminal 1b notifies the terminal 1a that it is ready for communication using channels A and A+α.

This allows the terminals 1a and 1b to use the selected pair of channels in full duplex mode for a desired period of time.

Further, when the third terminal IC calls the terminal 1a which is in communication, the modem 6 of the terminal 1a which is in communication uses channels A and A+α to notify the calling terminal IC that it is in communication.

(Example) FIG. 1 shows an example of the present invention. In FIG. 1, 1 is the center of the CATV system network, 3 is a converter, 20 is a low band pass filter, 21 is a high band pass filter, 22 is a mixer, and O20 is a local oscillator.

In FIG. 1, 30 is a low band pass filter in the modem 6 of the terminal 1b, 31 is a high band pass filter, 32.33
is a mixer, 34 is a modulator, and 11a is a demodulator.

1, 40 is a low band pass filter in the modem 6, 41 is a high band filter, and 42.43 is a mixer. Note that a portion of the interior of the modem 6 of the terminal 1b in FIG. 1 is omitted.

The channels in Figures 2 and 3 are upstream signal channels,
Each of the downlink signal channels is paired, and the paired upper and lower channels are further paired to enable full-duplex communication, but the present invention may also enable half-duplex communication. is between upstream signal channels,
Downlink signal channels are not paired, but a predetermined uplink signal channel and a predetermined downlink signal channel (for example, B and B
+α, C and C+α) should be paired.

The data transmitted and received in the present invention is not limited to general data, and may be moving images, still images, audio, etc. (Effects of the Invention) The data communication method of the present invention has the following effects.

(1) Since it uses a CATV network, there is no need to prepare equipment exclusively for data communication, making it economical.

(2) Since it is a multi-channel communication method, the T of the CATV network
Data communication can be performed without any problem.

(3) Since it selects and uses an empty channel from among multiple channels, communication between other terminals is hardly affected even if it is used for a long time. Data communication becomes possible, and the efficiency of system usage does not decrease even if this is done.

(4) Since there is no equivalent to a controller or exchange at the center of the CATV system, the configuration at the center is simple, the system is highly reliable, and maintenance is easy.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of the communication method of the present invention, FIG. 2 is an explanatory diagram of uplink signals in the communication method of the present invention, and FIG. 3 is an explanatory diagram of downlink signals in the communication method of the present invention. la, 1b*5asln is the terminal 2 is the center 3 is the converter 4 is the central processing unit 6.7 is the modem A, B, C@... is the upstream signal channel A+α, B+α
, C+α... is the downlink signal channel

Claims (5)

[Claims] (1) A large number of uplink signal channels and downlink signal channels are prepared for communication, and at least a predetermined uplink signal channel and a predetermined downlink signal channel are set as upper and lower paired channels, and among these upper and lower paired channels, Some of the upper and lower paired channels are shared paired channels,
In a data communication method that enables data communication between terminals of a CATV system by using an unused empty channel among a large number of paired upper and lower channels, the terminal that wants to communicate uses an unused empty channel from among the downlink signal channels. When a channel is selected and an empty channel is selected, the terminal sends an uplink signal for calling to the center of the CATV system, and the converter at the center converts the uplink signal into a downlink signal and sends it to the terminal. The calling terminal notifies the called terminal that it will perform data communication on the previously selected empty channel, and the receiving terminal sets its reception channel to the notified empty channel and transmits. The channel is set as the uplink channel paired with the empty channel, and in this state, data communication is possible between the calling terminal and the called terminal using the set channel, and the shared channel is not transmitted from other terminals during communication. 1. A multi-channel data communication method using a CATV network, characterized in that interrupt transmission can be performed to a terminal communicating using the CATV network. (2) Out of the uplink signal channels, predetermined channels are paired in pairs to form uplink pair channels, and out of the downlink signal channels, predetermined channels are made into pairs in pairs to become downlink pair channels; A patent that also pairs a predetermined uplink pair channel and a predetermined downlink pair channel to form a set of upper and lower pair channels, and enables full-duplex communication between terminals using this pair of upper and lower channels. CATV according to claim 1
A multi-channel data communication method using a network. (3) Using the CATV network set forth in claim 1, which allows the terminal in communication to notify the interrupting terminal that communication is in progress when there is an interruption from another terminal. multi-channel data communication method. (4) A converter is installed at the center of the CATV system to convert the upstream signal from the terminal into a downstream signal and send it to the terminal.Many terminals are connected to the terminal of the system, and each terminal has a central processing unit. A processing device and at least two modems are provided, one of which is capable of selecting an empty channel for a downstream signal and transmitting an upstream signal using the selected empty channel, and the other modem is capable of transmitting an upstream signal using the selected empty channel. A multi-channel data communication device using a CATV network, characterized in that it is capable of receiving interrupts sent from terminals. (5) A modem that can select an empty channel and send an uplink signal using the selected empty channel must at least have a variable oscillator and demodulator for detecting the empty channel, and change the frequency of the transmitted signal to the frequency of the empty channel. 5. A multi-channel data communication device using a CATV network according to claim 4, which is provided with a variable oscillator and a modulator adapted to the above.