JPH03940B2 - - Google Patents

Description

[Detailed description of the invention] Technical field to which the invention pertains The present invention relates to a two-wire transmission system that is inserted into a two-wire line of a time-division two-wire bidirectional transmission system that transmits bidirectional signals through a two-wire transmission line in a time-division system. Regarding repeaters for

Prior Art FIG. 3 is a block diagram showing an example of a conventional two-wire bidirectional transmission system. In other words, the main station and the slave station are connected by a two-wire line L of a non-repeater, and the master station sends a downlink burst signal at a constant cycle, and the slave station sends a downlink burst signal to the gap between the downlink burst signals. Sends an uplink burst signal. The main station includes a buffer memory 1 for storing transmission data;
A frame generation circuit 5 that generates a frame synchronization signal of a constant period, a transmission circuit 3, a reception circuit 4, a frame synchronization circuit 6, a buffer memory 2 for storing received data, a reception switch 7, and a line transformer 8. It consists of The slave station side has almost the same configuration.

Then, on the main station side, following the frame synchronization signal of a constant period generated by the frame generation circuit 5,
Transmission data is read out in bursts from the buffer memory 1, converted into a waveform code (for example, bipolar code) suitable for transmission on a line by a transmission circuit 3, and converted into a downlink burst signal by a line transformer 8. Send to wire line L. The downlink burst signals are sent out at a constant period (frame period), and there is an appropriate gap between each burst signal.

On the slave station side, the received signal input to the receiving circuit 12 via the line transformer 16 and the receiving switch 15 is equalized and amplified by the receiving circuit 12, and the bit timing is extracted to identify and reproduce the received signal. The frame synchronization circuit 14 detects the output of the reception circuit 12 or a frame synchronization signal to establish frame synchronization, and the output data of the reception circuit 12 is stored in the buffer memory 10. On the other hand, the frame generation circuit 13 generates a frame signal with a certain time delay (eg, half a cycle) behind the frame synchronization signal output from the frame synchronization circuit 14 and sends it to the transmission circuit 11 .
Following the frame signal, transmission data is read out from the buffer memory 9 in a burst manner, and a burst signal is transmitted from the transmission circuit 11 to the two-wire line L via the line transformer 16. While the upstream burst signal is being sent, the receiving switch 15 is closed to prevent the output of the transmitting circuit 11 from being input to the receiving circuit 12. Incidentally, since the upstream burst signal is transmitted during the interval between the downstream burst signals, the reception of the downstream burst signal is not hindered by closing the reception switch 15.

The uplink burst signal sent from the slave side is 2
It is transmitted through the wire line L, is received by the receiving circuit 4 via the receiving switch 7 of the main station, and is received by the frame synchronization circuit 6.
The frames are synchronized and stored in the buffer memory 2.

The conventional method described above has the disadvantage that since no repeater is inserted in the two-wire line L, the level of the received signal decreases as the length of the two-wire line increases, making it impossible to transmit accurate data. . Furthermore, when the transmission speed is increased, the frequency band of the transmission signal is expanded and line loss increases, so the transmission distance becomes shorter. Furthermore, if crosstalk noise or impulse noise from other devices is mixed, the transmission distance and transmission speed will be further limited.

OBJECT OF THE INVENTION The object of the invention is to solve the above-mentioned conventional drawbacks and
The object of the present invention is to provide a repeater that can be inserted into a two-wire line, thereby eliminating restrictions on line length, transmission speed, etc. of the time-division two-wire bidirectional transmission system.

Structure of the Invention The repeater of the present invention is inserted into a two-wire line connecting a main station that sends out a down burst signal at a constant cycle and a slave station that send out an up burst signal in the gap between the down burst signals. A downlink relay circuit that receives and reproduces a downlink burst signal transmitted from a station to a slave station, a frame synchronization circuit that detects a frame synchronization signal from a received signal of the downlink relay circuit, and a frame synchronization circuit that is inserted into the downlink relay circuit and from the frame synchronization circuit. a delay circuit that delays and outputs the received signal by half a cycle using the frame synchronization signal supplied; an uplink relay circuit that regenerates and relays the uplink burst signal; The present invention is characterized by comprising a delay circuit that outputs the burst signal with a half-cycle delay.

Embodiments of the Invention Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. That is, it is inserted into a two-wire line connecting a main station that sends down burst signals at a constant cycle and a slave station that sends out up burst signals in the gap between the down burst signals, and from the two-wire line L1 on the main station side. A receiving circuit 21 that receives and reproduces a downlink burst signal inputted via a line transformer 28, a frame synchronization circuit 27 that detects a frame synchronization signal from a received and reproduced signal of the downlink reception circuit 21, and a receiving circuit 2.
1 and stores the output data of frame synchronization circuit 2.
a delay circuit 22 which delays the output by a half period according to a frame synchronization signal supplied from 7; and a delay circuit 2
2 into a line signal and sends it to the slave side 2-wire line L2 via a line transformer 29, and a similar receiving circuit 24 and transmitting circuit 26 for reproducing and repeating the upstream burst signal. and a delay circuit 25 which stores the output data of the receiving circuit 24 and outputs the data after a half cycle delay according to the frame synchronization signal outputted from the frame synchronization circuit 27. The receiving circuit 21 and the transmitting circuit 23 constitute a down relay circuit, and the receiving circuit 24 and the transmitting circuit 26 constitute an up relay circuit.

FIG. 2A shows the signal on the main station side line L1,
B in the same figure is a time chart showing the signal on the slave side line L2. . That is, a low-level down burst signal inputted from the line L1 is received and reproduced by the receiving circuit 21 and stored in the delay circuit 22.
It is read out with a half-cycle delay due to the output of the frame synchronization circuit 27, and is sent from the transmitting circuit 23 to the line L2. On line L2, as shown in FIG. 25
The signal is stored on the line L1 with a delay of half a cycle (A in the same figure). The frame synchronization circuit 27 continuously maintains frame synchronization by detecting the frame synchronization signal of the downlink burst signal, and the above operation is repeated for each frame period. Therefore, in this embodiment, since the uplink burst signal and the downlink burst signal are received at the same timing and sent out at the same timing, the uplink and downlink relay circuits go into reception mode at the same time, and go into transmission mode at the same time. Therefore, it is possible to regenerate and relay the upper and lower burst signals without generating near-end crosstalk even without using a changeover switch or the like. Therefore, there is an effect that restrictions on line distance and data transmission speed between the master station and slave stations can be eliminated.

Effects of the Invention As described above, the present invention includes a frame synchronization circuit that extracts a frame signal from a downlink burst signal reproduced and outputted by a downlink relay circuit to establish frame synchronization, and a frame synchronization circuit that is inserted into the upper and lower relay circuits to It is equipped with a delay circuit that delays each received burst signal by half a cycle under the control of a synchronization circuit and outputs it, so that the upper and lower burst signals are received at the same timing and sent out at the same timing. It is possible to regenerate and relay each of the upper and lower burst signals without causing near-end crosstalk.
Therefore, it is possible to eliminate limitations on the line distance and data transmission speed between the main station and the slave station in the time-division two-wire bidirectional transmission system.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
Fig. 2 is a time chart showing signals on the two-wire lines on the main station side and slave side in the above embodiment, and Fig. 3 is a block diagram showing an example of a conventional time-division two-wire bidirectional transmission system using no repeaters. It is a diagram. In the figure, 1, 2, 9, 10: buffer memory, 3, 11: transmitting circuit, 4, 12: receiving circuit,
5, 13: Frame generation circuit, 6, 14: Frame synchronization circuit, 7, 15: Reception switch, 8, 1
6: Line transformer, 21, 24: Receiving circuit, 22,
25: Delay circuit, 23, 26: Transmission circuit, 27:
Frame synchronization circuit, 28, 29: line transformer,
L, L1, L2: 2-wire line.

Claims (1)

[Claims] 1 A downlink burst that is inserted into a two-wire line that connects a main station that sends downlink burst signals at a fixed period and a slave station that sends uplink burst signals in the gaps between the downlink burst signals, and is transmitted from the main station to the slave station. A downlink relay circuit that receives and reproduces a signal, a frame synchronization circuit that detects a frame synchronization signal from a received signal of the downlink relay circuit, and a frame synchronization signal inserted into the downlink relay circuit and supplied from the frame synchronization circuit. a delay circuit that delays and outputs the received signal by half a period; an uplink relay circuit that regenerates and relays the uplink burst signal; and a delay circuit that delays and outputs the uplink burst signal by a half period based on the frame synchronization signal supplied from the frame synchronization circuit. A repeater characterized by comprising a circuit.