JPS59190735A - Repeater - Google Patents

Abstract

PURPOSE:To obtain a repeater to be used effectively in a time-division two- wire both-way transmission system by performing control so that the amplification factor of the automatic gain amplifier in the repeater follows up speedily the loss of a transmission line even when an input signal intermitted. CONSTITUTION:When a signal is sent from a transmission line 11 while there is a signal in neither direction of the transmission line, the signal is inputted to a repeating circuit 21 and outputted to a transmission line 12 immediately when switch circuits 26-29 are placed at sides of switching contacts (a), or within a maximum and shorter than half period until the circuits are changed over to contacts (a) and stop when connected to the contacts (b). At this time, the signal is passed through a peak detecting circuit 22 from the circuit 21 and amplified 23 to control the automatic gain control circuit in the circuit 21 through an integration circuit 24, holding the level of equalized waveform amplitude constant. When the signal from the transmission line 11 is ceased, the circuits 26- 29 are changed over at some period and stop while connected to the contacts (b), and when a signal is sent from the transmission line 22, the output of the circuit 22 is held by an integration circuit 25 to control automatically the gain of the circuit 21.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a repeater for performing time-division relay transmission in a time-division two-wire bidirectional transmission system.

Since conventional repeaters have the function of amplifying signals in only one direction, it has been impossible to use repeaters for time-division two-wire bidirectional transmission.

For this reason, traditionally cable loss increases with distance;
It was not possible to perform long-distance communication using the time-division two-wire bidirectional transmission method.

An object of the present invention is to control the amplification degree of the automatic gain amplifier in the repeater so that it quickly follows the cable loss of the transmission line even if the input signal is intermittent. The object of the present invention is to provide a repeater that can be used effectively.

The repeater of the present invention includes a relay circuit having an input disconnection detection means and a means for automatically controlling the gain according to the control input to obtain a constant level output, and a first switch circuit in which the connections between the input and output terminals of the circuit and the two transmission lines are switched; a peak detection circuit that detects the peak of the output of the relay circuit; and an amplifier circuit that amplifies the output of the peak detection circuit; a second switch circuit that receives the output of the amplifier circuit as an input, switches in synchronization with the first switch circuit, and outputs the output to either one of two output terminals;
A first integrating circuit that receives one output of the second switch circuit as an input, a second integrating circuit that receives the other output of the second switch circuit as an input, and is synchronized with the first switch circuit. and a third switch circuit that selects and outputs either one of the outputs of the first and second integrating circuits and uses this as the control input.

The present invention will be explained in detail below using the embodiment shown in FIG. In FIG. 1, 10 is a repeater, and 11 and 12 are transmission lines separated by the repeater. To explain the configuration of the repeater 10 here, the repeater circuit 21 is substantially the same as a conventional repeater, but the difference is that the signal input to the repeater circuit 21 is interrupted for a certain period of time. It has a function of simultaneously switching the switch circuits 26, 27, 28, and 29 by detecting this. The peak detection circuit 22 detects the level of the equalized waveform amplitude produced by the relay circuit 21, and the amplifier circuit 23 amplifies the level and outputs it to an integration circuit 24 or 25 having a holding function. The output of the switch circuit 26 is configured to be connected to a terminal for controlling the amplification degree of an automatic gain amplification circuit in the relay circuit 21.

If we now consider a state in which there is no signal in either direction on the transmission line, the circuit for detecting input disconnection in the relay circuit Zl is working and the switch circuits 26, 27, 28 and 29 are switched at a certain period. When a signal is sent from the transmission line 11 in this state, at that point the switch circuits 26, 27, 2
If 8 and 29 are connected at switching contact a as shown in Figure 1, they will switch immediately, and if they are connected to the other switching contact, they will switch to contact a and remain in that state for the maximum time. Within half the period, it enters the relay circuit 21 and transfers to the transmission line 12.
Output to. At this time, the repeater IO is constituted by a feedback circuit that starts from the repeater circuit 21, passes through the peak detection circuit 22, is amplified by the amplifier circuit 23, and enters the control terminal of the automatic gain amplification circuit in the repeater circuit 21 via the integrating circuit 24 having a holding function. As a result, the level of the equalized waveform amplitude produced by the relay circuit 21 is kept constant. Here, the output voltage of the integrating circuit 24 having a holding function is maintained at a value sufficient for the relay circuit 21 to correct cable loss caused by relay transmission on the transmission line 11 side.

When the signal from the transmission line 11 ends, the switch circuit 26.
27, 28 and 29 are switched at a certain period. Next, when a signal is sent from the transmission line 12, the switch circuit 2
6, 27, 28, and 29 are connected to the switching contacts and stopped, contrary to FIG. A feedback circuit is constructed which enters the relay circuit 21 through the relay circuit 25, and the level of the equalized waveform amplitude produced by the relay circuit 21 is held constant. At this time, the output voltage of the integrating circuit 25 having a holding function is maintained at a value sufficient for the relay circuit 21 to correct the relay distance cable loss on the transmission line 12 side.

When the input signal from the transmission line 12 is interrupted again and a signal comes from the transmission line 11, the switch circuits 26, 27, 2.8, and 29 stop being connected to the switching contact a, and the input signal is transferred to the transmission line 11. from the switch circuit 28 to the relay circuit 21
At the same time, the switch circuits 26 and 27 are connected to the switching terminal a, and the output voltage of the integrating circuit 24 is amplified and transmitted to the transmission line 12 via the switch circuit 29. , the repeater 10 quickly stabilizes and can relay the signal from the transmission line 11 to the transmission line 12.

Conversely, when the input signal from the transmission line 11 is interrupted and a signal comes from the transmission line 12, the output voltage of the integrating circuit 25 changes to the relay circuit 2.
1, the repeater lO quickly stabilizes and sends the signal to transmission line 1.
It becomes possible to relay from 2 to 11.

As is clear from the above explanation, if the repeater of the present invention is used, it can be installed at different locations with different repeating intervals in the time division transmission system, which has hitherto been subject to distance limitations due to non-repeater transmission. Even if the repeater is activated quickly, effective time-division two-wire bidirectional relay transmission becomes possible.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. 10...Repeater, 11.12...Transmission line, 21...Relay circuit, 22...Peak detection circuit, 23... Amplification circuit, 24.25・
...Integrator circuit, 26.27°28.29...
...Switch circuit.

Claims (1)

[Claims] a relay circuit having input disconnection detection means and means to automatically control gain to obtain a constant level output according to a control input; and an input/output terminal of the relay circuit according to the output of the input disconnection detection means; a first switch circuit in which the connection of the transmission line is switched; a peak detection circuit that detects the peak of the output of the relay circuit; an amplifier circuit that amplifies the output of the peak detection circuit; , a second switch circuit that switches in synchronization with the first switch circuit and outputs to one of the two output terminals, and a first integration circuit that receives the output of one of the second switch circuits as an input. and a second integrating circuit which receives the other of the outputs of the second switch circuit as an input, and one of the outputs of the first and second integrating circuits which is switched in synchronization with the first switch circuit. and a third switch circuit that selects and outputs the selected signal as the control input.