JPS60145744A - Two-line bidirectional burst transmission control system - Google Patents

Abstract

PURPOSE:To prevent effect due to noise generated at intermission of frame signals by setting a transmission delay time when a frame signal from a slave station is received normally as a reception guard time in receiving the next frame signal. CONSTITUTION:If any transmission error is detected in the received frame signal, a synchronism error detection signal SERR is outputted to a delay measuring section 5 from a synchronism error detection section 9. A delay measuring section 5 clears the reception guard time used for the reception of the present frame by using the synchronism error detection signal SERR and uses the signal as the initial value, the signal is outputted when the transmission window is reset so as to set the reception window and the transmission delay is measured again.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a transmission control system for performing two-wire bidirectional burst transmission between a master station and a slave station, such as an exchange and a terminal connected thereto. Regarding.

[Technical background of the invention and its problems J] With the development of digital IT technology, the digitization of switching equipment is progressing. jft>"X, the digitization of not only the exchange itself but also terminal equipment such as telephones connected to it is being promoted.

As a result, digitization of signal transmission between switchboards and terminal equipment is being considered, and among them, two-wire bidirectional burst transmission method, Kokore, and Bing Bong transmission use existing analog two-wire telephone lines as is. It is attracting attention because it allows simultaneous two-way transmission of voice and data.

As one method for establishing transmission synchronization between transmitter and receiver in ping-pong transmission, a method similar to an asynchronous transmission method such as start-stop signal transmission can be considered. Generally, in the asynchronous transmission method, the data to be transmitted is divided into several bits, and start, stop, and parity bits are added to each data before transmission.The receiving side first detects the start bit. Then, synchronization between transmission and reception is established by placing a nominal speed clock at the center of the start bit or the data bit following the start bit, and zumbling each bit. By the way, in a noisy transmission path, noise may be mistakenly detected as a start bit and received as data. In this case, as a result of receiving data, it is possible to detect errors using transmission error detection means using parity bits, etc.; If noise is generated, the data reception tends to switch from the noise to the original frame, and there is a high possibility that the original frame signal will also be lost.

[Two purposes of invention]

The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to transmit signals between the main station and the slave station by two-way bidirectional burst transmission in the building between the exchange and the terminal equipment. In this case, the purpose is to provide a two-way burst transmission control system that minimizes the loss of frame signals due to the influence of transmission line noise, especially during reception on the main station side.

[Summary of the invention]

The present invention provides a method for two-wire bidirectional burst transmission of frame signals in a predetermined format between a master station such as an exchange and a slave station such as a terminal device. The master station determines different transmission delay times depending on the transmission distance between slave stations, and automatically adjusts the reception guard time until it is possible to receive frame 1N from the slave station according to this transmission delay time. , when an abnormality is detected in frame No. 46 from the slave station, set the reception guard time to the initial value,
When synchronization is established again with the frame signal from the slave station, the reception guard time is adjusted.

〔Effect of the invention〕

Thus, according to the present invention, two-wire bidirectional burst transmission is performed between the exchange and the terminal equipment (between the main station and the main station, it+3 songs). If noise in the transmission path occurs during frame invasion or waiting, reception often starts erroneously, but with the present invention,
Since the optimum reception window control is set according to the transmission distance between the master station and the slave station, the effect of suppressing the accumulation of .k frames of frame No. 46 due to V noise such as noise on the transmission path is achieved.

[Embodiments of the invention]

The following is an example of non-invention by taking a moment to explain the details.
Between the lines.・1't Figure 1 is a system configuration diagram when the present invention is applied between an exchange (main station) and a terminal device (1Jf station).

In Figure 1, switch 1 has PCM switch system 1.
a, a plurality of digital interface cards (Rishita IJ) that control two-wire bidirectional burst transmission (hereinafter abbreviated as Binhong transmission) to which Honkakumei is applied (abbreviated as c) H+
, lc, ... 1n are connected, and the terminal device (hereinafter referred to as 1) TI! ; (abbreviated)) Performs refiring between 2a, 2b, . . . 2n.

1) 'I'E 2a, 2b, 2n are, for example, digital packing machines, data terminal equipment, etc., IJIClb, lc, -
1n and 11", which can transmit frame signals in a predetermined format, is especially dangerous for the controller.

By the way, the transmission distance between exchange 1 and each DTE 1ijJ (
r, J-.

1 each. ) There are various 54 depending on the TE installation location I9T.

Transmission delay time 'l'' of general V transmission line d, i, Td-1
3,33''7 (μ East) l: Transmission distance (Km) εr: It can be calculated as a ratio of the transmission path.

For example, when the dielectric constant of the transmission line is 4.6, the transmission delay time rt'f, and the transmission distance IKm are expressed as 714μ. For example, as shown in Fig. 2, when transmit frame 1 is transmitted from each DIC of the exchange to D'rE, receive frame 1 is received at DTE with a transmission delay of tl depending on the transmission distance. Frame 1 sent from 1) CE K
When transmitted, a transmission delay of tz (t+ = t2) occurs, and reception frame 1 is received by the DIC. That is, e:L with 1 IC, I) Frame transmission to TE 1g
After passing the transmission delay t3 (tJ-tl+t2>%1.), the frame from 'l'E can be transmitted.

On the main side, C determines the transmission delay line between the slave stations and sets the reception guard time of j3 after 4g from the frame as shown in Figure 42. Setting-9
'F, the frame/ψ signal from the station, the reception window in front of l? i1<1lrll 1141.

・i! Figure 3 shows an example of 1) IC production to which the present invention is applied.
Antibody 1 (, not yet)) It is connected to CM Highway PT
Controls Binhong transmission between E and E.

Fig. 3 Output of the PCM highway of the father exchanger (1
) CIVIUUT ) to the transmitter IK-: The PCM signal is input as transmission data. This transmission data is framed in the transmission 1H section 1 as shown in frame No. 16 of a predetermined formant, 1>Suell-1: Figure 4.

Here, frame synchronization partner ■l pit, 641GIz
data (C) Io) 8 hits, 8 Kl (z data (CHI), control 1I414n (c) 1 bit,
Varite ((p) A total of 112 hits of 1 pit is transmitted as one frame signal. In the transmitter 1, the transmitting window signal (TXW) supplied from the window controller 2, which will be described later, is turned on. time, frame signal (T)G
IVlRZ), this TXNRZ signal is
The RZ-die phase signal converter 3 converts the die phase signal (
TXDP) and transmitted to L7rE through the hybrid circuit 4.

The window control unit 2 controls the timing of 1) frame transmission from the IC to the DTE and frame reception from the DTE to the DIC, and uses a transmission window signal (TXW).
, outputs a reception window signal (RXW). This Tx
Only when the w and ff signals are on, the frame from the transmitter 1 is read out, and the received frame signal is written into the receiver 7.

From the main station, DIC, the synchronization signal (PHFS) of the PCJvI highway shown in Figure 4a is sent using the -period 125μ formula (
8 KHz), the transmission window is turned on as shown in the figure, and frame 1g is transmitted to the slave station DTE. The time that this transmission window is on is determined by the bit length of the frame signal and the transmission speed, but the transmission speed is set to 256 KHz (1
Bit = 4 μ9! c), one frame has a 12-bit configuration, and it becomes approximately 48 μ east.

When the frame from the DEC is transmitted, at the rising edge of the TXW signal, the delay controller 5 transmits the I)T from the end of frame transmission.
The time required to detect the frame from E is determined 6i11. Now, if Lyl''C has just been turned on, the iJ
'l'E,! : Since frame synchronization has not been established, the delay time is set to 0" as an initial value.
Immediately after the T and XW multiplication signals are turned off, as shown in FIG.

On the other hand, the window control unit 2 turns off the transmission window signal TXW, waits for the reception window timing signal (listening) from the delay measurement unit 5, and turns on the reception window signal (RXW) as shown in Figure 44C. shall be.

Now, as shown in figure f, frame 11 from DCE
When No. 1'1'X1 is sent, DIC-()Ill;
with a delay of td' time depending on the transmission distance between
As shown in g in the figure, a frame signal is received by JTE as RXI'.

I) TE receives a frame signal from I) CU, and conversely sends a frame signal TXI from J'rE to I) IC.
'Send.

This frame signal 'l'X1' is similarly received by the DIC with a transmission delay of td time. This frame signal passes through the hybrid circuit 4, is converted into an RXNRZ signal by a diphase-NRZ converter 6, and is input to the receiving section. On the other hand, when the ff signal from the window control circuit 2 is turned on, the synchronization detection section 7 starts detecting the frame synchronization bit in the loss/P signal. Detection of this frame synchronization signal is performed by detecting the rising edge of the frame synchronization bit of the tie phase signal shown in the fourth diagram and confirming a predetermined pulse width (here, 4μ5ec). In this way, when a frame synchronization bit is detected, a synchronization clock SC of a nominal speed capable of sampling the center of each bit of the frame signal from the following data bits to the parity bit is supplied to the reception section 8, and the reception section 8 After writing the RXNRZ signal and outputting a high signal in synchronization with the clock PHCLK from the PCM highway, measure the transmission delay time TD as shown in d. This transmission delay time TIJ is calculated when all 12 bits of this frame are received normally.
It is stored internally as the father-uncle guard time when the time passes. L
) In parallel with detecting the frame 1M, 1st period signal from TE and placing frame 4b in reception error 8, the synchronization error detection unit 9 detects the reception diphase signal (branch) ■P
is monitored to detect abnormalities in the frame signal.Here, the die phase (g) shown in Figure 4 is shifted by half a bit between the frame synchronization bit η and the parity (P), and the valley bit is 2 times "00" Anomaly detection is performed using the character that does not appear.

When an abnormality is detected in the actual frame signal, a frame synchronization error signal (SERR) is output to the delay measuring section 5.

Next, the DIC sends the second frame, and the transmission window (
When the H 'l' row turns from on to off, the reception window timing is determined as shown in FIG. Send signal t2 Wind signal TXW
Output is delayed by IW time from the time when is turned off. This delay time is set to be several microns smaller than the transmission delay time TD, and as a result, the reception window signal W is turned on immediately before receiving the second frame number 2 from the DTE. becomes possible. In this way, as shown in FIG. 4(d), the receiver (i-wind timing upper 2) is output, and the window control unit 2 turns on the receiving window 4M RXW.

Next, an explanation will be given of the operation when noise on the transmission path is mixed into the received 4G signal from the DTE. Transmission line noise N1 in Fig. 4 f
If it occurs during the reception guard time, 1r, t, D
Even if the IC waits for a frame signal from the DTE, it will not receive it in error.

However, if noise on the transmission path is mixed in during frame signal reception from the DTE, such as N2 in Figure (f), it is impossible to prevent reception errors, so if necessary, the DIC - DTE may take measures such as error retransmission. When a transmission error is detected in the received frame signal, the synchronization error detection unit 7 outputs a synchronization error detection signal (SERR).
) is output to the delay measuring section 5 as shown in FIG. 4e. The delay measurement unit 5 determines the reception guard time IW used for reception of the current frame based on the synchronization error detection signal (SERR).
Clear the initial value, and as shown in t4 in Figure d of 5r44, the fourth frame is transmitted (Tx4), which is output when the transmit window is turned off, turns on the receive window, and then returns it again. Measure transmission delay.

The meaning of resetting the transmission delay when this synchronization error is detected is as follows. For example, when establishing frame synchronization for the first time, such as when power is turned on, if the frame signal from IJTE is mistakenly output +4 in the middle of the frame and synchronization is established, synchronization errors may not be detected. If the reception guard time is fixed based on the transmission delay time, all subsequent frames from the DTE will be erroneous.

In addition, after the power is turned on, even if the normally installed I) TE is replaced with a different 1) TE on the IJTE side, depending on the characteristics of the DTE, the 1) frame from the IC may be
114B, there may be slight variations in transmission from the DTE to the DIC.

As explained above, according to the present invention, when performing two-wire bidirectional burst transmission between a master station and a slave station, such as between an exchange and terminal equipment, the master station side has to set the installation location J9r (distance ), and the transmission delay time when the frame signal from the slave station is correctly received is set as the reception guard time when receiving the next frame No. 16, so the frame between the master station and the slave station is The effect of suppressing the reception 1a error due to transmission line noise generated in the No. 16 gap and the influence on subsequent frame signal reception is significant and is extremely practical.

Note that the present invention is not limited to the above embodiments. For example, the reception guard time is set when multiple frames (number m) are consecutively received without errors, and the reception guard time is reset when multiple frames are consecutively received in error. It's okay.

However, the method for establishing synchronization with love frames, the method for detecting frame synchronization errors, the frame structure, etc. are not limited to the actual 1fi5 example.

[Brief explanation of the drawing]

・Figure 1 is a configuration diagram of the master station and slave station, and Figure 2 is the configuration diagram of the master station and slave station.
Tight switch for two-wire bidirectional burst transmission between slave stations, 1a...PCM switch system, lb, lc,...In...DIC (digital interface card) 2a, 21+, -2n -DTE ( Terminal equipment) 1.
...Includes part 1a. 2...Window control unit, :U...Nk-2-diphase converter, 4...Hybrid circuit, 5...Delay measurement unit, 6...Diphase-Nu (Z converter). 7... 11J detection section, 8... Receiving section, 9... Synchronization error detection section. Fig. 1 Fig. 2 Fig. 3 Fig. 6 Cb)

Claims (1)

[Claims] In a method of transmitting P9T frame signals in a 2611-style burst between a master station and a slave station. The slave station establishes synchronization with frame No. 46 from the master station,
The frame signal is received, and after the reception is completed, the frame signal is transmitted to the master station, and the master station has a means for transmitting the frame signal to the slave station every short period, and a means for synchronizing the frame signal from the slave station. and the transmission delay time from when the frame signal is sent to the slave station until the frame signal is received from the slave station is lI + li
57 and means for detecting an abnormality in the frame signal from the slave station, and when the frame signal from the slave station is normally received, the reception guard time is set according to the measured transmission delay time. d, receiver 4 when an abnormality is detected in the frame signal from the slave station.
= A two-wire bidirectional burst transmission control method characterized by setting the guard time to an initial value.