JPH0813021B2 - Time division multiplex transmission system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of use) The present invention relates to a time division multiplex transmission system for digitally transmitting a signal whose speed is synchronized and a signal whose speed is asynchronous with respect to a transmission path.

(Prior Art) In recent years, a system for time-division-multiplexing a plurality of signals and transmitting the signals via a high-speed digital line has been put into practical use. Some transmit signals and asynchronous signals respectively.
For example, a video transmission system transmits an audio signal that is generally synchronized with the speed of a transmission path and a video signal that is asynchronous with the speed of a general-purpose transmission path.

By the way, in this type of conventional transmission system, for example, a multiplexer for an asynchronous signal and a multiplexer for a synchronous signal are provided on the transmitting side, and a separator for an asynchronous signal and a synchronous signal are provided on the receiving side. And a separation device for each of them are connected to each other by a spatially independent transmission line for each of the asynchronous system side and the synchronous system side. Then, of these, in the transmission system on the asynchronous system side, the multiplexing device on the transmission side first inserts extra bits in the asynchronous system signal according to the difference from the transmission rate to synchronize with the speed of the transmission line, and then similarly. By time-division-multiplexing with other stuff-synchronized signals and sending them to the transmission line, and separating these stuff-synchronized signals with a demultiplexing device on the receiving side, de-stuffing each to remove excess bits. Reproducing an asynchronous signal. That is, in the asynchronous signal transmission system, stuff synchronization is performed for transmission. On the other hand, in the synchronization signal transmission system, the multiplexing device on the transmitting side performs time-division multiplexing on the synchronization signals as they are, and then sends them to the transmission line, and the demultiplexing device on the receiving side demultiplexes the time-division multiplexed signals as they are. Are playing multiple sync signals. Therefore, with such a configuration, it is possible to reliably time-division-multiplex and transmit a signal that is asynchronous with respect to the transmission rate, such as a video signal, and a signal that is synchronized with the transmission rate, such as an audio signal. it can.

However, such a conventional system is provided with a multiplexing device and a demultiplexing device for each of the synchronous system signal and the asynchronous system signal, and time-division multiplex of the signals through spatially independent transmission lines between these devices. It is transmitting. For this reason, two multiplexers and demultiplexers and a transmission line are required for each of the asynchronous signals and the synchronous signals, which causes a problem that the system configuration becomes complicated and large and the system becomes expensive.

(Problems to be Solved by the Invention) As described above, the conventional system is spatially independent.
The present invention has a problem in that the system configuration is complicated and large due to the need for a pair of transmission types, which increases the system price. The present invention pays attention to this point, and the synchronous system signal and the asynchronous system It is an object of the present invention to provide a time division multiplex transmission system that enables signals and signals to be transmitted by one set of transmission systems, thereby simplifying the system and reducing the system cost.

[Structure of the Invention] (Means for Solving Problems) The present invention relates to a stuff synchronization unit that performs stuffing processing on a signal whose speed is asynchronous with respect to a transmission line and converts it into a signal synchronized with the speed of the transmission line. And a multiplexing unit, the multiplexing unit time-division-multiplexes the stuff synchronization signal output from the stuff synchronization unit and a synchronization signal separately input according to a predetermined multiplexing order set in advance. And transmitting the data to the transmission path, and further comprising a demultiplexing section and a destuff reproducing section, and setting the time division multiplexed signal arriving via the transmission path to the transmission side multiplexing section by the demultiplexing section. According to the multiple addition order, the sync signal and the stuff synchronization signal are separated, and the stuff synchronization signal among the signals separated by this separation part is subjected to the destuffing process by the destuffing reproducing part to perform the asynchronous signal. In which it was to play.

(Operation) As a result, the synchronous signal and the asynchronous signal are transmitted by one set of transmission system, whereby the system configuration can be simplified and miniaturized, and the system price can be reduced. You can

(Embodiment) FIG. 1 shows the configuration of a time division multiplex transmission system according to an embodiment of the present invention. This system includes a multiplexer 1 provided on a transmitting side and a demultiplexer provided on a receiving side. 2 is connected via a transmission line 3 using an optical fiber.

The multiplexer 1 time-division-multiplexes a stuff circuit section 11 that performs a stuffing process on the asynchronous signal AS, a stuff-synchronized signal by the stuff circuit section 11 and a synchronous signal BS, and sends them to the transmission line 3. And a clock generator 13 for generating a transmission clock CLK for the transmission line 3. First, the stuff circuit section 11 has a buffer memory 14 for speed conversion, and writes the asynchronous signal AS into the write control section.
Under the control of 16, the buffer memory 14 is written in synchronization with the asynchronous clock extracted by the clock extraction circuit 15, and the written asynchronous signal AS is read by the read controller 17 in accordance with the transmission clock CLK. Further, at this time, the comparison unit 18 compares the phases of the asynchronous clock and the transmission clock CLK, and according to the difference, the reading of the signal from the buffer memory 14 is stopped to insert an extra bit in the asynchronous signal. . That is, the stuffing process of the asynchronous signal is performed. On the other hand, the multiplexing unit 12 multiplexes the stuff synchronization signal output from the stuff circuit unit 11 and the synchronization system signal BS by a predetermined length in a predetermined multiplexing order, for example, as shown in FIG. A frame synchronization signal is added to the beginning of one frame, and a stuff control signal is inserted in the middle of the frame and sent to the transmission line 3.

On the other hand, the demultiplexing device 2 arranged on the receiving side includes a demultiplexing unit 21 that demultiplexes the time-division multiplexed signal sent via the transmission line 3 into a stuff-synchronized signal and a synchronous signal, and the time-division unit. The clock extraction unit 22 extracts the transmission clock CLK from the multiplex signal, and the destuff circuit unit 23 destuff-processes the stuff-synchronized signal. Of these, first the separation section
21 has a memory table that stores the multiplexing order used in the multiplexing unit 12 on the transmission side, and converts the time division multiplexed signal into a stuff-synchronized signal and a synchronization system signal according to the contents of this memory table. To separate. Then, the synchronization signal BS
Is sent to the signal processing circuit in the subsequent stage as it is. On the other hand, the de-stuff circuit section 23 has a buffer memory 24 for speed conversion.
The write control unit 25 writes the stuff synchronization signal output from the separation unit 21 in the buffer memory 24 according to the transmission clock CLK. At this time, the surplus signal of the stuff synchronization signal is not written. In addition, the destuff circuit section 22 is the buffer memory
The signal written in 24 is read by the read control unit 26 according to the asynchronous system clock reproduced by the clock reproduction unit 27 based on the transmission clock CLK. That is, the asynchronous signal AS is reproduced by the destuff processing.

With such a configuration, when a video signal AS asynchronous with the transmission speed and an audio signal BS in synchronization with the transmission speed are input to the multiplexing device 1 on the transmission side, the video of these signals AS and BS is input. The signal AS is stuffed by the stuffing circuit section 11 and synchronized with the transmission speed, and then introduced into the multiplexing section 12. Then, in the multiplexing unit 12, the audio signal BS, which is a synchronizing signal, and the second signal
As shown in the figure, they are alternately time-division multiplexed and sent to the transmission line 3.

On the other hand, in the receiving-side demultiplexing device 2, when a time division multiplexed signal arrives via the transmission line 3, the time division multiplexed signal is first a stuff-synchronized video signal in the demultiplexing unit 21 and an audio signal which is a synchronous system signal. And separated. Then, the audio signal BS among these is output as it is to the signal processing circuit in the subsequent stage, but the video signal is output in synchronization with the asynchronous clock while the surplus bit is deleted by the destuff circuit unit 23. That is, the video signal which is an asynchronous signal is reproduced by this.

In this way, according to the present embodiment, the asynchronous signal AS and the synchronous signal BS are time-division multiplexed with each other for transmission, and as a result, only one transmission system is required. For this reason, compared to a conventional system in which a multiplexing device and a demultiplexing device are provided for each of the asynchronous system signal and the synchronous system signal, and transmission is performed between these devices via a spatially independent transmission path. Can be greatly simplified and miniaturized, and thereby the system price can be reduced.

The present invention is not limited to the above embodiment.
For example, in the above embodiment, the case where the signal transmission in one direction is performed from the transmission side to the reception side has been described. However, in the case of performing bidirectional transmission, the multiplexing devices are arranged in the opposite devices as shown in 5 of FIG. 1 and the separation device 2 may be provided, and the system may be configured such that these devices are connected by different transmission lines 31 and 32, respectively. Even in such a system, conventionally, two transmission lines for each of the upper and lower lines are required, but one system for each of the upper and lower lines is required, which makes it possible to simplify the system configuration. Other,
The configurations of the stuff synchronization unit and the destuffing reproduction unit, the means for multiplexing and demultiplexing the asynchronous signal and the synchronous signal, the types of the asynchronous signal and the synchronous signal, etc. are also various within the scope of the present invention. It can be modified and implemented.

[Effects of the Invention] As described in detail above, according to the present invention, a stuff synchronization unit that performs a stuffing process on a signal whose speed is asynchronous with respect to a transmission line and converts it into a signal synchronized with the speed of the transmission line, And a stuffing synchronization signal output from the stuffing synchronization unit and a synchronization signal separately input, which are time-division multiplexed according to a preset predetermined multiplexing order. The time-division multiplexed signal arriving via the transmission line is set in the transmission side multiplexing unit by the demultiplexing unit, and the demultiplexing unit is provided with the demultiplexing unit and the destuff reproducing unit. Separate the sync signal and the stuff synchronization signal according to the multiplexing order, and perform the destuffing process on the stuff synchronization signal among the signals separated by this demultiplexing unit to reproduce the asynchronous signal. By doing so, it is possible to transmit the synchronous system signal and the asynchronous system signal by one set of the transmission system, whereby the system can be simplified and downsized and the system price can be reduced. Can be provided.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing a configuration of a time division multiplex transmission system in an embodiment of the present invention, FIG. 2 is a schematic diagram showing a signal transmission format used in the same system, and FIG. 3 is another example of the present invention. It is a circuit block diagram which shows the structure of one transmission apparatus of the time division multiplex transmission system in an Example. 1 ... Multiplexer, 2 ... Separator, 3 ... Transmission line, 11 ...
... Stuff circuit part, 12 ... multiplex part, 13 ... transmission clock generation part, 14,24 ... buffer memory, 15,22 ... clock extraction part, 16,25 ... write control part, 17,26 ... ... Read control unit, 18
…… Comparison section, 21 …… Separation section, 23 …… Destuff circuit section, 27
…… Clock regeneration unit, AS …… Asynchronous signal (video signal), BS …… Synchronous signal (audio signal), CLK …… Transmission clock.

Claims (1)

[Claims] 1. A time division multiplex transmission system for transmitting a signal having a speed asynchronous with a speed of a transmission line and a signal having a speed synchronous with a speed of a transmission line, respectively, by performing a stuffing process on the asynchronous signal. A stuff synchronization unit for converting into a signal synchronized with the speed of the transmission line, and a stuff synchronization signal output from the stuff synchronization unit and the synchronization signal separately input according to a predetermined multiplexing order set in advance. A multiplexing unit that time-division-multiplexes and sends out to the transmission line, and a synchronization signal and a stuff synchronization signal according to a multiplexing order set in the transmission-side multiplexing unit for the time-division multiplexed signal that has arrived through the transmission line. And a destuff reproducing section for performing a destuff process on the stuff-synchronized signal among the signals separated by the demultiplexing section to reproduce an asynchronous signal. Division multiplex transmission system when said and.