JPS5888948A - Regenerative repeater - Google Patents

Abstract

PURPOSE:To completely perform the processing of regenerative relaying and processing of collision for information signals among >=3 coaxial cables, by transmitting a collision signal to all the transmission lines, at the detection of collision corresponding to some transmission lines. CONSTITUTION:An information signal is transmitted from a work station connected to a coaxial cable 14A, a carrier detection circuit CSA detects it and contacts SA1, SB2 and SC2 are closed. With a little time delay, when a work station connected to a coaxial cable 14B makes transmission, collision tales place on the cable 14B, and this collision is detected at a detection circuit CDB and fad to a control section CTL. The control section CTL operates a prescribed contact, starts a collision signal generating circuit CSG and transmits the collision signal to cables 14A-14C via regnerating devices 310A-310C and prescribed contacts.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a regenerative repeater, and particularly to a regenerative repeater in a local communication network.

As a local communication network installed in the user's premises, communication terminal devices (workstations) are commonly connected through multiple intermediate taps of coaxial cables via transmitting/receiving devices (transceivers), and each communication terminal device is connected independently. The so-called C8MA/CD method is known, in which information signals are transmitted to other communication terminal devices, and in the event of a transmission collision between terminal devices, each terminal device stops transmitting and retransmits after a random waiting time. It is being This coaxial cable has a cable length of, for example, about 500 m to 2 km, and a transmission band of about 20 MHz, and baseband and baseband signals are transmitted.

The information to be transmitted includes images, sounds, and data, and is assembled into message blocks such as no and kerat, and control codes such as destination addresses and check codes are added.

Such a coaxial cable is, for example, 10 megabits/
Transmitting baseband signals at transmission speeds of seconds limits the KFi cable length to at most 1 km to 2 km to keep signal degradation within acceptable limits. If a longer cable length is required, two or more coaxial cables must be connected by a regenerative repeater to regenerate the pulse signal.

In a regenerative repeater that connects two coaxial cables to each other, a workstation connected to the other coaxial cable attempts to start transmitting information almost simultaneously with the information signal from one coaxial cable, with a slight time delay. The collision problem is solved by a collision detection circuit in the regenerative repeater detecting the collision, aborting one transmission of both rotary cable signals, and retransmitting it after a random waiting period.

However, when connecting three or more coaxial cables, it is possible to simply connect three or more coaxial cables in cascade by using the same regeneration repeater used to interconnect two coaxial cables. The collision detection circuit included in the relay device cannot solve this collision problem. For example, information signals transmitted from a workstation connected to the middle coaxial cable of three or more cascaded coaxial cables are transmitted in both directions, so collisions occur during transmission in one direction. Even if no collision occurs, a collision may occur in transmission in the other direction. In this case, it is difficult for the collision detection circuit that has detected the collision to send out a collision signal to all the workstations included in the network to notify them of the occurrence of a collision and to temporarily stop transmission.

For example, if a predetermined i+turn code is used for this collision signal, each regenerative repeater is independent from the other, so the transmission of this code itself will be detected by the collision detection circuit of any other regenerative repeater and other transmissions. There is a possibility that it will be judged as a collision. Additionally, when a collision signal that changes the impedance of a coaxial cable is used, a regenerative repeater amplifier is used to connect the coaxial cables, so this impedance change is transmitted to the subsequent coaxial cables through the regenerative repeater amplifier. It is not possible.

Therefore, an object of the present invention is to provide a regenerative repeater that eliminates the drawbacks of the prior art and can completely perform regenerative repeating and collision processing of information signals between three or more coaxial cables. shall be.

Another object of the present invention is to provide a regenerative relay device which performs regenerative relay by interconnecting an arbitrary number of three or more coaxial cables and is flexible for expansion of a communication network and network system. There is a particular thing.

According to the present invention, these objects are achieved by the following regenerative repeater. In other words, this regenerative repeater interconnects at least three transmission lines, each of which is connected to a plurality of communication terminals in common, and regenerates and relays information signals between each transmission line. A regenerative relay circuit is provided corresponding to each transmission path and performs regenerative relay of information signals bidirectionally between that transmission path and a single common communication path, and a regenerative relay circuit is provided corresponding to each transmission path and performs regenerative relay of information signals in both directions between that transmission path and a single common communication path. transmission detection means for detecting transmission of an information signal; collision detection means provided corresponding to each transmission path for detecting a collision on the transmission path; connected to a common communication path and generating a collision signal on the common communication path. comprising a single collision signal generating means and a control means,
When the transmission detecting means corresponding to one of the transmission paths detects transmission, the control means energizes a regenerative relay circuit from that transmission path to the other transmission path through the common communication path, and When the collision detection means corresponding to a transmission line detects a collision, the collision signal generation means is activated to send a collision signal to all transmission lines.

Next, embodiments of a regenerative repeater according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram showing an example of a local communication network to which a regenerative repeater according to the present invention is applied. In the same figure, a plurality (n+1) of transmitting and receiving devices (transceivers) 100-0 to 100-n are connected as intermediate tags to a coaxial cable 14 whose both ends 10a and lob are terminated with terminating resistors 12a and 12b with matching impedance, respectively.
is provided. Each transceiver is a communication terminal device (workstation W S ) 200-0 to 200-2.
They are connected by 00-nK cables 16-0 to 16-nVc.

The coaxial cable 14 has a cable length of, for example, 500 m.
It has a transmission band of approximately 20 MHz at 2 km and is installed within the premises of users of this local communication network. The information transferred within the cape 14 is composed of message clock units such as packets, and includes image signals,
Includes voice and data signals. Of course, this message block includes control codes such as destination addresses and check codes. Message block transfer FiI
It is done in baseband at a speed of O megabits/second.

The transceivers 100-0 to 100-n are branch-connected to the coaxial cable 14 with matching impedance at the intermediate tap point of the coaxial cable 14, and transmit and receive signals between the coaxial cable 14 and the workstations 200-0 to 200-n, Performs transmission collision detection and power supply. The details are omitted because they are not directly relevant to understanding the present invention.

The workstations 200-0 to 200-n are information sources and information sinks, such as image terminals, audio terminals, data terminals or computers, and transceivers 1 and 200-n.
It includes an interface section with 00-0 to 100-n.

When transmitting from workstations 200-0 to 200-n, a message clock containing the destination address is sent to the coaxial cable 14, and each workstation transmits a message when the destination address of the message clock matches its own address. Get that block. Since there is no coordination between the workstations, so-called collisions can occur in which one workstation starts transmitting at about the same time as another tries to start transmitting immediately after.

When a collision occurs, each workstation detects this and stops transmitting, and each workstation resumes transmitting after a random waiting time. This method is known as the i1'j C8MA/CD method.

By the way, since such a coaxial cable 14 transmits a baseband signal at a transmission rate of 10 megabits/second, for example, the cable length must be limited to at most 1 km or 2 kmK in order to keep signal deterioration within the permissible limit. be done. If a longer cable length is required, two or more coaxial cables must be connected by a regenerative repeater to regenerate the pulse signal.

FIG. 2 is a block diagram showing an embodiment of a regenerative repeater according to the present invention. In the figure, as an example, three coaxial cables 14A, 14B, and 14C are connected to the regenerative repeater 3oo.
A local communication network interconnected by is shown. Coaxial cable 14 A, 1 in the same figure
4 B and 14C are coaxial cables 14 in FIG.
, and many workstations are
Although the transceivers and workstations are connected to each coaxial cable, their illustrations are omitted to avoid complicating the diagram.

One coaxial cable, eg, 14A core 20A, is connected by lead 302AK to the input of regenerator 804A and to common communication path 808 via its output 806AFi, normally open (make) contact SAI. As can be seen from the figure, the communication signal path in the regenerative repeater 300 is shown by a solid line, and the control signal path is shown by a dotted line. Furthermore, elements in the device corresponding to the coaxial cables 14A, 14B, and 14C have A, B, and C added to the end of their reference numerals, respectively, to indicate that they have similar functions.

Common communication path 308 is also connected to the input of a similar regenerator 310A connected in the opposite direction to regenerator 304A, whose output 312A is connected to lead 30 via make contact SA2.
It is connected to 28. These contacts SAI and SA
2 Fi is a contact point of high-speed operation relay, and as symbolically shown by the control line 314A from the control unit CTL, the control unit C
Operates under control from TL. This will be explained later.

The core wire 20A of the coaxial cable 14A is also connected to the lead 302.
It is also connected to each input of the carrier detection circuit C8A and the collision detection circuit CDA via A. When an information signal is transmitted from the workstations 200-0 to 200-n connected to the carrier detection circuit C8A Fi and the coaxial cable 14A, a change in the DC level of the /'P pulse train included in the information signal is detected. This circuit detects the presence or absence of carriers by detecting the presence or absence of carriers, and transmits the information to the control unit CTLK through the lead 316A. Collision detection circuit CDA ID, coaxial cable 14A from other coaxial 'y-f le 14B or 14C
When transmitting the K information signal, a collision caused by the start of transmission from one of the workstations connected to the coaxial cable 14A is detected by a change in the DC level of the coaxial cable 14A, and is sent to the control unit CTL through the lead 318A. It is a circuit that conveys information.

The control unit CTL is a circuit that performs overall control of the entire apparatus as described later, and a collision signal generation circuit C8G is connected to this via a lead 320. The collision signal generation circuit C8G is a circuit whose output is connected to the common communication path 308, and outputs a collision signal to the common communication path 308 under control of the control unit CTL. The collision signal may be, for example, a code having a predetermined number of turns that would not logically be included in a normal information signal transmitted over coaxial i-pulls 14A, 14B, and 14C. Or, alternatively, the signals may present each coaxial cable with an unusually high or low impedance. Note that these control units CT
L and the collision signal generation circuit C8G are the regenerative repeater 300.
It is provided in a single location.

In a silent state where no information signal is transmitted on the coaxial cables 14A, 14B and 14C, the system remains in the initial state shown in FIG. 2, and each carrier detection circuit C8A
, C8B and C8C are their respective coaxial cables”
The signal states of 14A, 14B and 14C are monitored.

For example, when a certain workstation connected to the coaxial cable 14AK starts transmitting an information signal, the carrier detection circuit C8A detects this and transmits it to the control unit CTL. Control unit CTL Fi In response to this, lead 314
A: (energizes 14B and 314C, contacts SAI
, SB2 and SC2 are activated to close their contacts. As a result, information signals are regenerated and relayed from coaxial cable 14A to coaxial cables 14B and 14C through regenerator 304A, common communication channel 308, and regenerators 310B and 310C, respectively. When the workstation on the coaxial cable 14A finishes transmitting, the carrier detection circuit 14
A detects a carrier loss and notifies the controller CTL through the lead 316A that the transmission has ended. Control unit CTL
deenergizes the relays corresponding to contacts SAI, SB2 and SC2 through leads 814A, :(-14B and 314C, restoring these contacts. The system thus returns to its initial state. From other coaxial cables 14B or 140 When transmitting, the information signal is regenerated and relayed to the remaining coaxial cables by the same operation.The relationship between the transmission from the coaxial cables 14A, 14B, and 14C and the open/closed states of each contact is shown in the table below. show.

○...Open, ×...Closed By the way, for example, an information signal is transmitted from one of the workstations connected to the coaxial cable 14AK, and the carrier detection circuit C8A detects this and closes the contact SA.
Assume that I, 5Bjf and SC2 are closed. If, for example, any workstation connected to the coaxial cable 14BK makes a call almost at the same time with a slight time delay, a collision will occur on the coaxial cable 14B. This collision is detected by the collision detection circuit CDB and transmitted to the control section CTL through the lead 318B't-. Therefore, the control unit CTL board: (14A,
314B and 314C to restore contacts SAI, SBI, and SCI, and then activate collision signal generating circuit C8G via lead 320 and regenerators 310A, 310.
B and 310C1 and closed contacts SA2, S
Coaxial cable 14A through B2 and SC2 respectively
.

14B and 14CK send out the aforementioned collision signals. The workstation connected to the coaxial cable 14A and 1ASVC, which has started transmission and caused the collision, detects this collision signal and immediately stops transmitting the information signal.

The controller CTL deenergizes the collision signal generation circuit C8G with a time delay sufficient for each workstation to detect the collision signal and stop transmission, and restores each contact to return the system to its initial state.

Note that the workstation 7 that has stopped transmitting will start transmitting again after a random waiting time has elapsed. The same applies to the collision with the coaxial cable 14C and the collision between the coaxial cables 14B and 14C.

Although the embodiment of the regenerative repeater according to the present invention in which three coaxial cables are connected to each other has been described, when an arbitrary number of coaxial cables of four or more are connected to each other, a corresponding number of regenerators may be used. 304 and 310, carrier detection circuit C8 DEG collision detection circuit CD, and associated fast acting relays may be provided.

By configuring the regenerative repeater according to the present invention in this manner, three or more coaxial cables can be connected to each other, and information signal regenerative repeating and collision processing can be completely performed between them. Additionally, for the expansion of coaxial cables after the local communication network is launched, regenerators 304 and 310, carrier detection circuit C8, collision detection circuit CD, and related high-speed operation relays may be added accordingly. Therefore, there is flexibility when adding coaxial cables, that is, system expandability.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a local communication network, and FIG. 2 is a block diagram showing an embodiment of a regenerative repeater according to the present invention. Explanation of symbols of main parts 14A...Coaxial cables 304A, 310A...Regenerator 308...Common communication channel CDA...Collision detection circuit C8A...Carrier detection circuit C8G...Collision signal generation circuit CTL ...Control unit patent applicant Ricoh Co., Ltd.

Claims (1)

[Scope of Claims] A regenerative relay device that interconnects at least three transmission lines, each of which has a plurality of communication terminals commonly connected thereto, and regenerates and relays information signals between the respective transmission lines. The device includes a regenerative relay circuit, which is provided corresponding to each transmission path, and which regenerates and relays information signals in both directions between the transmission path and a single common communication path; h, a transmission detection means for detecting transmission of an information signal from the transmission path; a collision detection means provided corresponding to each transmission path for detecting a collision on the transmission path; and a transmission detection means connected to the common communication path. , a single collision signal generating means that generates a collision signal on the common communication channel, and a control means, and when the transmission detection means corresponding to any transmission channel detects transmission, the control means: A regenerative repeater circuit in the direction from the transmission path to another transmission path through the common communication path is energized, and when the collision detection means corresponding to any transmission path detects a collision, the collision signal is generated. A regenerative repeater characterized in that a means is activated to detect collision signals on all transmission paths.