JPS60201750A - Repeater - Google Patents

Abstract

PURPOSE:To attain the signal amplification in a semidouble communication mode without using any special control signal line, control data, etc., by inhibiting the output of an amplifier which is opposite in the direction, if a carrier signal at one side is detected. CONSTITUTION:A carrier signal sent from a communication medium 5b is amplified by an amplifier C13 and supplied to a carrier detecting part b15. Then a carrier-detected output signal 21 is outputted through the part b15. The output of an amplifier D14 is permitted by the signal 21 and at the same time the output of an amplifier A10 is inhibited. As a result, the carrier signal if outputted later from a communication medium 5a is not sent to a stage further than the amplifier A10 of a repeater 3, and therefore not to the side of the medium 5b. The same way of control is executed even in an adverse case.

Description

[Detailed Description of the Invention] [Technical Field J] The present invention relates to a repeater that connects transmission devices using a communication medium and amplifies signals on the communication medium when transmitting data, and particularly relates to a repeater that connects transmission devices using a communication medium and amplifies signals on the communication medium when transmitting data. This is related to a repeater.

[Prior Art] Conventionally, when transmitting devices are connected via a communication medium to transmit data, when the distance between the transmitting devices is long, the transmitted signal is attenuated and reception errors occur in the receiving device. I end up. For this reason, a repeater is placed in the middle of the communication medium to amplify the transmitted signal to prevent reception errors. If the communication medium is unidirectional, it is sufficient to simply insert an amplifier circuit between the communication media and simply amplify the received signal and output it, but if the transmission device performs half-duplex communication, the communication medium When the repeater has bidirectionality, the direction of signal amplification by the repeater must be switched. For this reason, a signal line for controlling switching of the direction of signal amplification by the repeater is provided outside the communication medium for data transmission, and the repeater is controlled by this signal line.

In another example, special control data for switching the signal amplification direction of a repeater other than data transmission is sent to the communication medium, and the repeater analyzes this control data and switches the amplification direction. Therefore, switching control of the transmission device is also complicated.

[Objective] The present invention has been made in view of the above-mentioned drawbacks of the prior art, and provides a repeater that does not require a special control or configuration for switching the amplification direction of the repeater in a transmission device and can reliably switch the amplification direction. The purpose is to

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an example of the configuration of a data transmission system in which a repeater according to an embodiment of the present invention is arranged, and 1.2 is a transmission device;
3 is a repeater, and 5a and 5b are communication media.

Details of this repeater 3 are shown in FIG.

In the figure, 5a and 5b are the communication media shown in FIG.
0 to 14 are amplifiers, and 12.15 is a carrier detection unit. The carrier detection unit a12 detects the carrier sent from the communication medium 5a side, and uses the output signal 20 to decode the output of the amplifier 811. , the output of amplifier C13 is prohibited. The carrier detection unit b15 is the communication medium 5
It detects the carrier sent from the b side,
Output signal 21 inhibits amplifier AIO output, amplifier D
14 outputs are permitted. Since the carrier detection circuit of the carrier detection section is well known, a description thereof will be omitted.

Next, the control when the transmission device 1 transmits data via the communication medium connected to the repeater of this embodiment will be explained with reference to the flowchart of FIG.

First, in step 100, the transmission device l checks whether a carrier is detected from the communication medium 5a, and if no carrier is detected, the process proceeds to step 102, and
Send the carrier to a. Then, the process proceeds to step 104, where it is determined whether or not a collision has occurred in the carrier sent out by the own device.

If no collision has occurred, data is sent in step 106.

If a collision has occurred in step 104, the process proceeds to step 108, where the transmission is stopped, and in step 110, the reception mode is set, and the process proceeds to step 112, which is a reception process. Also, if a carrier is detected in step 100, step 11
0 and executes reception processing. For example, communication medium 5
When a carrier signal is sent from side b, this carrier signal is amplified by amplifier C13 and carrier detection 19 is performed.
Carrier detection unit b15 is manually operated by rxIlb l5.
The carrier is detected and an output signal 21 is output. This output signal 21 enables the output of the amplifier 014, and the amplification 1
Alo output is prohibited. Therefore, even if carriers 4 and 1 are output from the transmission device 1 after this, they will not be sent beyond the amplifier AIO of the repeater 3 and will not be sent to the communication medium 5b side. Therefore, the transmission device 1 is placed in a reception mode in preparation for receiving data sent from the transmission device 2.

By controlling in this way, very efficient data transmission can be performed without causing data collisions that disrupt the transmission control procedure or providing wait time.

[Effect] As explained above, according to the present invention, it is possible to prevent the attenuation of zero signal on the communication medium that connects the transmission devices, and also to reliably transmit the signal on the communication medium without using any special control signal line or control data. A repeater that can amplify signals during half-duplex communication can be provided.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an applied system according to an embodiment of the present invention. FIG. 2 is a configuration diagram of a repeater device according to an embodiment of the present invention.

Claims (1)

[Claims] a first amplifying means for amplifying a signal on the communication medium disposed at a predetermined location of a communication medium connecting between transmission devices, or for amplifying a signal from one communication medium;
a first carrier detection means for detecting a carrier signal from the one communication medium; a first control means for controlling the output of the first amplification means; and a first carrier detection means for detecting a carrier signal from the one communication medium; a second amplification means for amplifying a signal from the communication medium; a second carrier detection means for detecting a carrier signal from the other communication medium; and a second control means for controlling the output of the second amplification means. The first control means disables the output of the first amplification means when the second carrier detection means detects the carrier, and the second control means disables the output of the first amplification means when the first carrier detection means detects the carrier. A repeater characterized in that the output of the second amplifying means is disabled when the output of the second amplifying means is disabled.