JPH07193575A - Communication system for bi-directional catv system - Google Patents

Abstract

PURPOSE:To realize communication by N to N between terminals with a simple device by converting an up-telegram transmitted from the terminal by means of polling into a down-telegram so as to turn it back and conducting communication between the terminals by a ping-pong system on a center-side. CONSTITUTION:When HT3a transmits data to a general-purpose terminal 5b, it returns the up-telegram including a specified control code, an opposite address and transmission data in response to basic polling from HTC1 on the center-side. When HTC1 receives it, it converts the control code and transmits it to a down direction in return. Since address information is included in the telegram, the general-purpose terminal 5b can receive it. Up/down communication channels in a bi-directional CATV transmission line 9 use the same frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system of a bidirectional CATV system, and more particularly to a communication system of a bidirectional CATV system for performing bidirectional data communication using a lower band of a broadcasting channel.

[0002]

2. Description of the Related Art Conventionally, the communication system of this type of bidirectional CATV system uses a lower band of a broadcast channel to provide a transmission / reception dedicated frequency for the bidirectional communication channel, and one-to-one between specific terminals. A method is used in which communication is performed or one dedicated center device sequentially polls a plurality of terminals to collect data on the terminal side. In this case, the terminal means a general-purpose terminal including a home terminal and a personal computer. In addition, the data for bidirectional communication is general data such as personal computer communication in the one-to-one communication, and in the case of the polling method, billing information on the terminal side that does not require immediacy, data in the area mail or circulation board system etc. Is.

[0003]

As described above, in the conventional example, the communication is performed between specific one-to-one terminals, or the polling method centered on the center is used. Frequency is needed. Therefore, communication between arbitrary terminals, that is, N to N communication cannot be performed,
Further, there is a problem that the device becomes complicated due to multiplexing of upstream and downstream dedicated frequencies.

[0004]

Bidirectional CATV of the present invention.
The communication method of the system is a communication of a bidirectional CATV system in which a home terminal control device and a plurality of home terminals are connected by a bus-shaped or tree-shaped network and bidirectional data communication is performed using a lower band of a broadcasting channel. In the method, the home terminal has a control code indicating that it is an upstream signal for two-way communication when polled by the home terminal control device, a destination code indicating a communication partner, and a caller indicating its own station. Means for sending an upstream information telegram including a code in the upstream direction, the control code when receiving a downstream information telegram including a control code indicating a downlink signal of bidirectional communication, a destination code and a calling source code And means for identifying the own station addressed from the destination code and fetching the downlink information telegram addressed to the own station. For example, also, the home terminal controller comprises means for transmitting said converted it receives the uplink information message on the downlink information message downstream from said home terminal.

The upstream information message and the downstream information message are each composed of a packet having the same format, and are transmitted in a ping-pong method using the lower band of the broadcast channel.

[0006]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the system configuration of this embodiment. FIG. 2 is a block diagram showing the electronic message format in FIG. In FIG. 1, the system is one home terminal control device (hereinafter referred to as HTC) on the center side.
1 and two home terminals (hereinafter HT) 3 on the terminal side
a, 3b and two general-purpose terminals 6a, 6b. The general-purpose terminals 6a and 6b each have an RF- that performs signal conversion.
Bidirectional CATV transmission line 9 via MODEMs 5a and 5b
It is connected to and data is input from the keyboards KB7a, 7b. Further, the HTs 3a and 3b have a T for receiving a program.
V4a, 4b and remote controllers 8a, 8b for HT control are connected. The HTs 3a, 3b and the general-purpose terminals 6a, 6b are each assigned an address for selecting their own station.

The HTC 1 refers to the subscriber master 13 via the data communication section 12 and the RF-MODEM 21 of the headend 2 from the control section 11 and refers to the viewing control data as H level.
Basic polling master 1 while transmitting to T3a, 3b
4, the HTs 3a and 3b and the general-purpose terminals 5a and 5b are polled at regular intervals.

When performing data communication, the HT or general-purpose terminal has remote controllers 8a, 8b or keyboard 7 at hand.
The transmission data including the other party's address is input using the input device of a and 7b, and this data is STX (signal indicating the data read position) on the HT and the general-purpose terminal side as shown in the message format of FIG. 2 (a). , Control code,
After the control information such as ETX (signal indicating the end of data position) and BCC (horizontal parity) is added, it is sent to the HTC by basic polling from the HTC side. In this case, the subscriber master 13 and the basic polling master 14 do not have to match, and data can be transmitted from a general-purpose terminal other than HT. When receiving the upstream information telegram from the HT or the general-purpose terminal by basic polling, the control unit 11 of the HTC examines the control code, and if the two-way communication data is upstream (= 0001h),
Control code for bidirectional communication data downlink (= 000
Change to 2h) and horizontal parity BC for error checking
After C is recalculated, it is returned in the downlink direction as a downlink information message in the format shown in FIG.

Since the other party's address information is included in the message, the terminal having the matching address can receive this. FIG. 1 shows the state of data transmission from the HT 3a with address = 0001h to the general-purpose terminal 5b with address = 0004h, and FIG. 2 shows the data format of the upstream and downstream information telegrams at that time. Bidirectional CATV transmission line 9
The upstream and downstream information telegrams in 1) use the same frequency band arranged in the lower band of the broadcast channel.

Although this system is limited in terms of the immediacy of communication and the amount of data that can be handled at one time, in addition to data collection on the HT side in the conventional HTC, regional immunity and circulation board system, etc. It can be applied to an N-to-N communication application that exchanges a relatively small amount of data without needing it.

[0012]

As described above, according to the present invention, in the home terminal control unit on the center side, since the upstream information telegram to which each home terminal responds by polling is converted into the downstream information telegram and returned, it is addressed. You can receive this at your home terminal. In addition, the transmission of the upstream and downstream information telegrams is a ping-pong transmission method by packets using the same transmission band. Therefore, there is an effect that N-to-N communication with versatility can be performed with a simple device configuration.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 shows (a) an upstream message, showing a message format in FIG.
(B) It is a block diagram of a downlink message.

[Explanation of symbols]

 1 Home Terminal Control Device (HTC) 11 Control Unit 12 Data Communication Unit 13 Subscriber Master 14 Basic Polling Master 2 Headend 21 RF-MODEM 3a, 3b Home Terminal (HT) 4a, 4b Television (TV) 5a, 5b RF- MODEM 6a, 6b General-purpose terminal 7a, 7b Keyboard (KB) 8a, 8b Remote control

Claims (2)

[Claims] 1. A communication system of a bidirectional CATV system in which a home terminal control device and a plurality of home terminals are connected by a bus-shaped or tree-shaped network and bidirectional data communication is performed using a lower band of a broadcasting channel. In the home terminal, when the home terminal receives a polling from the home terminal control device, a control code indicating that it is an upstream signal for two-way communication, a destination code indicating a communication partner, and a calling source code indicating its own station. Means for sending an upstream information telegram including an upstream direction, the control code and the control code when receiving a downstream information telegram including a control code indicating a downlink signal of bidirectional communication, a destination code, and a calling source code. A destination code and a means for identifying the own station addressed to take in the downlink information telegram addressed to the own station, The communication system of a two-way CATV system, wherein the home terminal control device comprises means for receiving the uplink information telegram from the home terminal, converting the uplink information telegram to the downlink information telegram, and sending back the downlink information telegram. 2. The uplink information telegram and the downlink information telegram are each composed of a packet of the same format, and are transmitted in a ping-pong method by using a lower band of the broadcast channel. Bidirectional CAT
V system communication method.