JP2906823B2 - Optical subscriber transmission system and subscriber time division two-way communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for performing two-way communication of time-division multiplexed data using a single transmission line, and more particularly to an optical subscriber transmission system in which a plurality of communicating subscribers are connected. The present invention relates to a subscriber time division two-way communication system.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional optical subscriber transmission system. In FIG. 2, a plurality of subscriber units 1 to n are connected to subscriber lines 51, 52,.
0, and the 1: n optical branching device 100
Is connected to the subscriber line termination device 61. This subscriber line termination device 61 has a directional optical coupler 201 connected to the transmission line 101. The directional optical coupler 201 has an electro-optical converter for converting an electric signal of the transmission circuit 203 into an optical signal. The module 202 is connected by an optical signal line 501. Then, the optically converted signal of the transmission circuit 203 is expressed as:
The signal is transmitted to the n optical branching device 100. The optical output terminal of the directional optical coupler 201 is connected to an optical-electrical conversion module 204 via an optical signal line 503.
, 22n are connected in parallel. Further, each of the synchronization circuits 221, 222,.
, 21n are signal lines 541, 542,.
n.

In the above configuration, the transmission circuit 203 generates data to be transmitted to the subscriber units 1 to n as electric signals, and the electric-optical conversion module 202 converts the electric signals into optical signals. Electric-optical conversion module 20
2 outputs the optically converted signal to the 1: n optical branching device 100 via the directional optical coupler 201 and the transmission path 101. The 1: n optical branching device 100 converts the received optical signal into n
.. 5n and output to the respective subscriber units 1 to n.

The subscriber units 1 to n generate data to be transmitted to the subscriber line terminating unit 61 based on transmission timing information included in the data in the received optical signal. The subscriber units 1 to n each transmit data at different timings,
The signals are combined by the 1: n optical branching device 100 and output to the directional optical coupler 201 of the subscriber line termination device 61. The optical signal input to the directional optical coupler 201 is converted into an electric signal by the optical-electrical conversion module 204,
22,... 22n. Synchronous circuits 221 and 22
, 22n have synchronization patterns corresponding to the subscriber units 1 to n, and establish synchronization with the respective transmission frames according to the respective synchronization patterns. , 21n for signal processing.

[0005]

In the conventional optical subscriber transmission system described above, the same number of synchronous circuits as the number of subscriber units to be connected are required, and a large number of synchronous circuits having substantially the same configuration are provided in the subscriber line terminating device. Is within. For this reason, there are disadvantages that the circuit scale of the subscriber line terminating device becomes large and power consumption increases.

Accordingly, an object of the present invention is to eliminate such a conventional problem and reduce the circuit scale of the subscriber line terminating device by reducing the number of synchronous circuits as compared with the number of subscriber devices. It is an object of the present invention to provide an optical subscriber transmission system and a subscriber time division two-way communication system which are reduced in size and consume less power.

[0007]

A first solution of the present invention for solving the above-mentioned problems is to provide a 1: n optical branch which is connected to n subscriber units via a subscriber line. 1: Directional light connected to the transmission line in an optical subscriber transmission system for performing time-division bidirectional communication by providing n receiving circuits in a subscriber line termination device connected to the n optical branches and the transmission line. An optical-electrical conversion module for converting the output optical signal of the coupler into reception data of an electric signal, a synchronization circuit for synchronizing each frame of the reception data, and a synchronization frame output from the synchronization circuit, A stop bit detection circuit that detects a stop bit added in the subscriber device and outputs a stop bit detection signal, and synchronizes a frame of data to be received next by the synchronization circuit according to the stop bit detection signal. A synchronizing pattern generating circuit for generating a synchronizing pattern, a selector control circuit for generating a select signal according to the stop bit detection signal, and synchronizing frame data output from the synchronizing circuit based on the select signal to each of the receiving circuits. And a selector for sorting and outputting.

[0008] A second solution of the present invention for solving the above problems is a concentrator connected to n subscriber units via a subscriber line, and connected to the concentrator by a transmission line. In a subscriber time-division two-way communication system for performing time-division two-way communication by providing n receiving circuits in a subscriber line terminating device, a synchronization circuit for taking frame synchronization of a time-division multiplexed signal received from the transmission line; A stop bit detection circuit that detects a stop bit added in the subscriber device and outputs a stop bit detection signal during a synchronization frame output from the synchronization circuit; A synchronization pattern generating circuit for generating a synchronization pattern for synchronizing frames of data to be received, and a select signal in accordance with the stop bit detection signal. A selector control circuit, characterized in that it comprises a selector for outputting the synchronous frame data output of the synchronization circuit distributes to each of the reception circuits on the basis of the select signal.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block circuit diagram showing one embodiment of the present invention. In FIG. 1, the same devices and the like as those of the conventional example are denoted by the same reference numerals. In FIG. 1, subscriber units 1 to n are 1: n on subscriber lines 51, 52... 5n which are optical signal cables.
The 1: n optical branching device 100 is connected to the directional optical coupler 201 of the subscriber line termination device 61 via a transmission line 101 which is also an optical cable. The directional optical coupler 201 includes a transmission circuit 203
An electric-optical conversion module 202 that converts an electric signal, which is data generated in step (1), into an optical signal is connected by an optical signal line 501. The optical signal output from the directional optical coupler 201 is converted into an electrical signal by the optical-electrical conversion module 204 and connected to the synchronization circuit 205 via the signal line 504. The synchronization circuit 205 is connected to a synchronization pattern generation circuit 206 for generating a synchronization pattern. Further, an output signal of the synchronization circuit 205 is connected and input to a stop bit detection circuit 207 and a selector 209. The output signal of the stop bit detection circuit 207 is connected and input to the selector control circuit 208 and the synchronous pattern generation circuit 206. The output signal of the selector control circuit 208 is connected and input to the selector terminal of the selector 209, and
09 are output from signal lines 511 and 51, respectively.
, 51n, the receiving circuits 211, 212,.
n.

The operation of the above configuration will be described below. The transmission circuit 203 of the subscriber line termination device 61
A signal to be transmitted to each of the subscriber units 1 to n is generated. An electric signal output from the transmission circuit 203 is converted into an optical signal by an electro-optical conversion module 202, and the directional optical coupler 201 and the transmission path 101 To the 1: n optical branching device 100 via In the 1: n optical branching device 100, an optical signal is branched into n subscriber lines 51, 52,..., 5n and transmitted to the respective subscriber devices 1 to n. The subscriber units 1 to n
Then, data to be transmitted to the subscriber line termination device 61 is generated based on the transmission timing information included in the data in the received optical signal. The generated data is generated at different timings in each subscriber unit, and the data at the different timings is time-division multiplexed by the 1: n optical branching unit 100 and transmitted to the transmission line 101. Is done. The transmission line 101 and the subscriber lines 51, 52,.
Performs time-division multiplex bidirectional communication, so that the transmitted signal and the received signal do not collide.

The signals transmitted from the subscriber units 1 to n have a format as shown in FIG. 3, and one frame 603, which is a unit transmission amount per subscriber, has a frame synchronization pattern 600 consisting of preamble bits and frame bits.
And a main signal 601 having a stop bit 602. Each frame 603 is transmitted with a guard time 604 interposed between the frames. Signals of such a format are combined by the 1: n optical branching device 100 and transmitted to the subscriber line termination device 61.

The transmitted signal is input to the optical-electrical conversion module 204 via the directional optical coupler 201, converted into an electric signal, and output to the synchronization circuit 205. In the synchronization circuit 205, the frame pattern of the subscriber unit 1 is set as an initial value of the frame synchronization pattern. First, frame synchronization with a transmission signal from the subscriber unit 1 is established. The signal synchronized and output by the synchronization circuit 205 is output to the stop bit detection circuit 2
07 and the selector 209. The stop bit detection circuit 207 detects the stop bit 602 added to the frame 603 from the subscriber unit 1 whose frame has been synchronized by the synchronization circuit 205. This gives 1
The tail of the frame 603 is detected. The detection signal of the stop bit 602 in the stop bit detection circuit 207 is transmitted to the synchronization pattern generation circuit 206 and the selector control circuit 20.
8 is output. When the detection signal of the stop bit 602 is input, the synchronization pattern generation circuit 206 generates a synchronization pattern for synchronizing with the next frame of the subscriber unit 2 and outputs the synchronization pattern to the synchronization circuit 205. The stop bit detection circuit 207 detects the stop bit 602 as described above and identifies the end of one frame 603 for each of the subscriber units 1 to n.
On the basis of the detection signal 02, the synchronization pattern generation circuit 206 sequentially generates a frame synchronization pattern for synchronizing with the next transmission frame from the subscriber unit n. As described above, the synchronization circuit 205 establishes synchronization with the transmission frame from each subscriber device according to the synchronization pattern set by the synchronization pattern generation circuit 206. Since this synchronization pattern is set within the guard time 604 as shown in FIG.
The processing on the main signal 601 and the frame synchronization pattern 600 is not affected.

The selector control circuit 208 to which the detection signal of the stop bit 602 is input generates a switching signal for selecting the output of the selector 209 based on the detection signal, and outputs the switching signal to the selector 209. By this switching signal, the selector 209 causes the synchronous circuit 20
The output of the main signal 601 inputted from 5 is switched to the respective signal lines 511, 512,... 51n, and supplied to the corresponding receiving circuits 211, 212,. This main signal 6
01 is input to each of the receiving circuits 211, 21
2, 21n perform predetermined data processing.

As described above, the synchronization pattern for synchronizing with the frame from each subscriber unit is sequentially changed by the synchronization pattern generation circuit 206 for each frame in the synchronization circuit 205 for establishing synchronization with the received signal. By setting them, those which conventionally had to be provided with the same number of synchronous circuits as the number of subscriber units can be consolidated into one, thereby reducing the circuit scale of the subscriber line termination unit 61.

In the above example, an example of a transmission system using an optical signal is shown. However, in a conventional time division multiplex transmission system using an electric signal using a metallic cable, a stop bit is added to each frame. Frame synchronization may be performed by the synchronization circuit.

[0016]

As described above, in the optical subscriber transmission system and the subscriber time division two-way communication system of the present invention, a stop bit is provided in the data transmitted from each subscriber unit, and this is transmitted to the subscriber line. The stop bit detection circuit provided in the termination device detects the signal, and based on the detection signal, generates a synchronization pattern for synchronizing with the next transmitted frame in the synchronization pattern generation circuit and sets the synchronization pattern in the synchronization circuit. Thus, the frame synchronization circuits can be integrated into one. As a result, the circuit scale of the subscriber line termination device can be reduced, and the power consumption can be suppressed.

[Brief description of the drawings]

FIG. 1 relates to one embodiment of the present invention and is a block circuit configuration diagram showing the configuration thereof.

FIG. 2 is a block circuit configuration diagram of a conventional optical subscriber transmission system.

FIG. 3 is a transmission format diagram used in an embodiment of the present invention.

[Explanation of symbols]

1, 2,... N subscriber units 51, 52,... 5n subscriber line 61 subscriber line termination device 100 1: n optical branching device 101 transmission line 201 directional optical coupler 202 electric-optical conversion module 203 transmission circuit 204 Optical-to-electrical conversion module 205 Synchronous circuit 206 Synchronous pattern generation circuit 207 Stop bit detection circuit 208 Selector control circuit 209 Selector 211, 212,... 21n Receiving circuit 221, 222,. 505, 506, 507, 508, 5
61 signal lines 511, 512, ... 51n signal lines

Claims (2)

(57) [Claims] 1. A 1: n optical branch connected to n subscriber units via a subscriber line, and n subscriber lines connected to the 1: n optical branch via a transmission line have n subscriber lines. An optical subscriber transmission system including a receiving circuit and performing time-division bidirectional communication, wherein an optical-to-electrical conversion module for converting an output optical signal of a directional optical coupler connected to the transmission line into reception data of an electrical signal. A synchronization circuit for synchronizing with each frame of the received data; and a stop bit for detecting a stop bit added in the subscriber unit and outputting a stop bit detection signal during a synchronization frame output from the synchronization circuit. A synchronization circuit for generating a synchronization pattern for synchronizing with a frame of data to be received next by the synchronization circuit according to the stop bit detection signal; A selector control circuit for generating a select signal according to a bit detection signal; and a selector for allocating and outputting synchronous frame data output from the synchronous circuit to each of the receiving circuits based on the select signal. Person transmission system. 2. A concentrator connected to n subscriber units via a subscriber line, and a subscriber line termination unit connected to the concentrator and a transmission line, comprising n receiving circuits. In a subscriber time-division two-way communication system that performs divided two-way communication, a synchronization circuit that synchronizes a frame of a time-division multiplexed signal received from the transmission line, and a synchronization frame output from the synchronization circuit, A stop bit detection circuit for detecting a stop bit added by the user device and outputting a stop bit detection signal, and generating a synchronization pattern for synchronizing a frame of data to be received next by the synchronization circuit according to the stop bit detection signal. A synchronizing pattern generation circuit, a selector control circuit for generating a select signal in accordance with the stop bit detection signal, When subscriber division duplex communication system, comprising a selector which have a synchronous frame data output of the synchronization circuit distributes to each of the receiving circuit output.