JPS62239632A - Time division multiplex communication system - Google Patents

Abstract

PURPOSE:To send properly a reception state display signal at the reception side at the transmission preparation period just before data transmission by utilizing a terminal device ready signal, a transmission request signal and a transmission enable signal at the transmission side even in the time division multiplex system. CONSTITUTION:Pattern detectors 51, 52 detect the 1st and 2nd patterns respectively at the receiver side. At first, the 1st pattern is detected by the pattern detector 51, a flip-flop 53 is reset in response to the detection and the 2nd pattern is detected succeedingly by the pattern detector 52 and the flip-flop 53 is set in response to the detection. The set state of the flip-flop 53 is continued even during the data transmission period after the 2nd pattern is lost and a carrier is detected by a carrier detector 46 during this period. Thus, the gate 54 is opened and a reception state display signal CD is generated just before the start of the transmission data.

Description

DETAILED DESCRIPTION OF THE INVENTION 1.1 The present invention relates to a time division multiplex communication system, and particularly to a time division multiplex communication system in which information is transmitted in a time division manner between a plurality of transmitting and receiving terminals on a common information transmission path. Regarding communication methods.

BACKGROUND ART Conventionally, a method has been widely used in which an analog transmission path is frequency-division multiplexed, and information on a plurality of channels is modulated onto individual carrier waves having different frequencies for transmission. In this method, before starting data signal transmission for each channel on the transmitting side, the carrier wave of that channel is transmitted, and after the data signal transmission of that channel is finished, the carrier wave is stopped, and then the receiving side By detecting the carrier wave of each channel, it is possible to know the start and end of the data signal. Thereby, it is possible to appropriately send to the receiving device a reception display signal that rises before data transmission for each channel and falls after data transmission is completed. However, in state frequency division multiplexing, the signal deteriorates significantly due to level fluctuations and noise in the transmission path, so time division multiplexing has come to be used. In this case, since there is no carrier wave for each channel, generation of the reception status indicating signal is not simple.

Although there is a method of transmitting an indication bit indicating the presence or absence of a valid signal of each digital channel, transmitting the indication bit limits the number of data signals that can be transmitted, resulting in poor transmission efficiency.

Purpose of the Invention The present invention has been made to solve the above-mentioned drawbacks of the conventional ones, and its purpose is to receive data signals without limiting the capacity of data signals or causing malfunctions. An object of the present invention is to provide a time division multiplex communication system capable of generating a reception status display signal indicating the status.

According to the present invention, a plurality of transmitting terminals, a plurality of receiving terminals provided corresponding to each of these transmitting terminals, and a common information transmission path connecting these transmitting and receiving terminals. A time division multiplex communication system in which information is transmitted using a time division multiplex system on this common information transmission path, wherein each of the transmitting terminals has a data transmission preparation period immediately before entering a data transmission state. and a pattern sending means for sending out terminal-specific pattern information assigned in advance to each of the sending terminals during a period immediately after data transmission ends, and in each of the receiving terminals, a sending terminal corresponding to each receiving terminal is provided. is provided with a pattern detection means for detecting the terminal-specific pattern information transmitted by the terminal, and generates a reception status signal in response to detection of the pattern information in the data transmission preparation period, and generates a reception status signal in response to the detection of the pattern information in the data transmission preparation period. A time division multiplex communication system is obtained, characterized in that the generation of the reception status indicating signal is cut off in response to the detection of pattern information.

K-3 Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, and is an example in which two channels of data are transmitted and received, but it is clear that the same applies to systems with three or more channels. In the figure, transmitting terminals IA and 1B are provided corresponding to channels A and B, respectively, and both transmitting terminals IA.

Each 1B transmission output is supplied to a transmission circuit 2, time-division combined, modulated, and sent to a common analog transmission path 3. The transmitted data is subjected to II tuning in the receiving circuit 4, separated and received by each channel.

The signals are supplied to terminals 5A and 5B, respectively.

The sending terminal 1A has a sending signal selection circuit 11,
At the input of this circuit 11, data input SD and pattern signals generated by pattern generators 12 and 13 are connected to gates 14 and 14, respectively.
．． 15 and 16. Gate 14.
The gate signals 15 and 16 include a terminal ready signal ER, a data set ready signal @DR, and a transmission request signal R.
3 are used respectively. Data set ready signal DR
is the delayed output of the delay circuit 17 which delays the previous terminal ready signal ER by a predetermined time, and the transmission request signal @R3 is delayed by the delay circuit 18 by a predetermined time to become the send ready signal C8. The terminal ready signal ER and the transmission ready signal C8 are used as control signals for the transmission signal selection circuit 11.

The pattern generators 12 and 13 each divide the clock signal output from the system clock generator 6 at a predetermined division ratio to generate first and second clock signals having different frequencies II.
It is assumed that the transmitting terminal 1A of channel A is assigned a frequency division ratio of 115 and 1/13, respectively. Other channels 8
, it is assumed that a frequency division ratio specific to the channel is similarly assigned.

The transmitting circuit 2 includes a multiplexing circuit 21 that time-division multiplexes input signals of two channels, and a D/A that converts the output into analog.
It has a (digital/analog) converter 22, a modulation circuit 23 that modulates a transmission carrier wave 24 with its output, and an amplifier 25 that amplifies the modulated output.

The receiving circuit 4 includes an amplifier 41 that filters and amplifies the transmission signal from the analog transmission line 3, a carrier wave regeneration circuit 42 that separates a carrier wave from the output thereof, and a demodulation circuit 43 that performs demodulation using the regenerated carrier wave. An A/D (analog/digital) converter 44 that converts this demodulated output into a baseband signal, a separation circuit 45 that separates the time division multiplexed signal necessary for the output for each channel, and a carrier wave from the output of the amplifier 41. It has a carrier wave detection circuit 46 that detects.

The receiving terminal bag f15A outputs the data of channel A from the separation circuit 45 as a received data signal RD. Detectors 51 and 52 are provided to detect the first and second clock patterns from the received data signal RD, respectively, and an RS flip-flop 53 which uses the outputs of the rain detectors 51 and 52 as set and reset inputs; The output of this flip-flop 53 is output by one person, and the carrier wave detector 46
AND gate 5 which uses the detection output by as another gate input
4 is provided. The output of this AND gate 54 becomes the reception display signal CD.

Channel B also has the same configuration, but the clock patterns of pattern generators 12 and 13 on the transmitting terminal side are different from channel A, and as a result,
It is assumed that the detection patterns of the pattern detectors 51 and 52 on the receiving terminal side are also configured in advance so as to detect only the pattern corresponding to the transmission pattern.

Vt! in such a configuration! The operation of i will be explained with reference to the timing chart of FIG. Note that the signal waveforms in FIG. 2 indicate the waveforms of the various signals shown in FIG. 1 with the same corresponding symbols, and D in the second row from the bottom indicates transmission information.

First, when the pattern generators 12 and 13 are started, the first pattern generators 12 and 13 are generated by dividing the system clock by 115 and 1/13.
and a second clock pattern are generated, respectively. Here, when the terminal ready signal ER arrives, the data set ready signal DR is generated by the delay circuit 17 after a predetermined time delay from the arrival of the terminal ready signal ER. The gate 14 is opened in response to the arrival of the terminal ready signal ER, but the transmission data S is still
D is not being sent out at all and selection circuit 11 operates to select the output of gate 15 which gates the pattern of pattern generator 12. In response to subsequent generation of the data set ready signal DR, the first pattern signal of the pattern generator 12 is selected by the selection circuit 11 via the gate 15 and sent to the analog transmission line via the transmission circuit 2.

When the transmission request signal R8 arrives in response to the generation of the data set ready signal OR, the second pattern signal of the pattern generator 13 is selected by the selection circuit 11 and transmitted. After a predetermined time delay from the arrival of the transmission request signal R3, the delay circuit 18 generates the transmission enable signal C8, and in response, the selection circuit 11 selectively transmits the transmission data SD.

While this series of operations is being performed, the pattern detectors 51 and 52 of the receiving device detect the first and second patterns, respectively. First, the first pattern is detected by the pattern detector 51, and in response to this detection, the flip-flop 53 is reset, and the subsequent second pattern is detected by the pattern detector 52, and in response to this detection, the flip-flop 53 is reset. The knob 53 is set. This set state of the flip-flop 53 continues even during the data transmission period after the second pattern is no longer present. In this case, since the carrier wave is detected by the carrier wave detector 46, the gate 54 is in the open state, and therefore the reception status indication signal CD is generated immediately before the start of the transmission data.

When the transmission data signal SD is input to the transmission terminal 1A of channel A, it is transmitted from the transmission circuit 2 to the reception circuit 4 via the transmission path 3, and after demodulation in the reception circuit 4, it is transmitted to the transmission terminal 1A of channel A.
is derived as the received data signal RD. During this time, the reception status display signal CD continues to be generated.

When the transmission of all data signals is completed and the transmission request signal R8 disappears, the output of the selection circuit 11 is the pattern generation i! !
:12, and this first pattern will be transmitted until the data set ready signal OR is no longer present.

The first pattern at this time is detected by the pattern detector 51, and in response to this detection, the flip-flop 53 transitions from the set state to the reset state. Therefore, the receiving state display signal CD is cut off and disappears in response to the transition timing of the flip-flop 53.

In this way, by making good use of the preparation period at the start of transmission on the sending side and the response period at the end of transmission, specific pattern information for each channel is transmitted, and in response to the detection of these specific patterns on the receiving side. This controls the generation and disappearance of the reception state display signal, and it is possible to reliably control the generation of the reception state display signal without reducing the quality of the equivalent data signal.

It should be noted that the form of the specific pattern information allocated in advance to each channel is not limited to the above embodiment.
In short, it is sufficient if a specific pattern (channel identification pattern) different from the data is transmitted for each channel immediately before and immediately after the data is transmitted, and the receiving side can detect this pattern to distinguish it from other channels.

Further, although two combination patterns, the first and second patterns, are used, the present invention is not limited to this, and a combination of three or more patterns may be used, or a configuration may be made using only one pattern. Furthermore, the pattern sent during the transmission preparation period immediately before data transmission may be sent out at the same time as the terminal ready signal ER rises. Furthermore, although an analog transmission line is used as the transmission line 3, the same disadvantages will not arise even if the transmission line 3 is a digital transmission line for transmitting at baseband.

Effects of the Invention As described above, according to the present invention, even in a time-division multiplexing system, the terminal device ready signal, the transmission request signal, and the transmission clear signal on the transmitting side are effectively used to transmit data on the receiving side during the transmission preparation period immediately before data transmission. This has the effect that the reception status display signal can be appropriately transmitted.

Furthermore, the circuit of the present invention is extremely simple and has the advantage of fewer malfunctions. By implementing the present invention, the terminal device is not started up in vain, or the receiving terminal device does not continue to operate because the receiving status display signal does not disappear immediately after communication ends.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram explaining the operation of the blocks in FIG. 1. - It is. Explanation of symbols of main parts IA, 1B...Transmission terminal 3...Transmission path

Claims (1)

[Claims] A plurality of transmitting terminals, a plurality of receiving terminals provided corresponding to each of these transmitting terminals, and a common information transmission path connecting these transmitting and receiving terminals are provided, and on this common information transmission path, A time division multiplex communication system in which information is transmitted using a time division multiplex system, wherein each of the transmitting terminals transmits data during a data transmission preparation period immediately before entering a data transmission state and during a period immediately after data transmission ends. A pattern transmitting means is provided for transmitting terminal-specific pattern information assigned in advance to each of the terminals, and each of the receiving terminals detects the terminal-specific pattern information transmitted by the transmitting terminal corresponding to each receiving terminal. A pattern detection means is provided, and generates a reception status display signal in response to the detection of the pattern information in the data transmission preparation period, and displays the reception status in response to the detection of the pattern information in the period immediately after the end of the data transmission. A time division multiplex communication system characterized by the fact that signal generation is interrupted.