JPS613534A - Data transmission system - Google Patents

Abstract

PURPOSE:To reduce remarkably a time of transmission pre-procesure by transmitting a non-standard device signal and terminal control information in sucession to an equalizer adjusting pattern. CONSTITUTION:When a transmission station calls a reception station and a non- standard device signal NSF, its information field and a digital identification signal DIS are transmitted, the transmission station brings a digital signal processor DSP2 into a low speed mode, receives an HDLC frame of a transmission control signal and an HDLC controller 3 discriminates a terminal function of the reception station. Then the transmission station transmits a training signal TRN comprising three segments. The reception station receiving a TRN signal responds to the transmission station by using s speed set signal SPD representing 4,800bps when the residual phase error is smaller than a prescribed value at the training end point of time and responds thereto by using the SPD representing fall-back speed when the error is larger than a prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a data transmission method that can reduce the time required for transmission control procedures before information transmission.

[Prior Art] In a data communication device such as a facsimile machine, modem training is performed to match the modem prior to information transmission.

For example, in a GnI facsimile machine, it is specified that modem training is to be performed in the procedure before transmitting image information, and an example of this procedure is shown in FIG. Note that the figure shows a non-standard protocol.

When the transmitting station TX calls the receiving station RX, the receiving station RX sends the called station identification signal CED and then sends the non-standard equipment signal NSF.
and transmits the digital identification signal DIS
I Declare to the transmitting station TX that it has standard and non-standard functions. Note that the information field of the signal NSF includes information indicating the content of the non-standard function.

The transmitting station TX selects the non-standard function and sends the non-standard equipment signal NS.
S and its functional contents are transmitted to the receiving station RX, and immediately after that, modem training is performed and a training check signal TCP is sent.

The format of this signal TCP is 1.5 seconds of data I.
After receiving the signal TCP, the receiving station RX determines whether data transmission is possible by checking for data errors, and if possible, sends the reception preparation confirmation signal CFR to the transmitting station TX. respond.

As a result, image information PIX is transmitted from the transmitting station TX to the receiving station RX.
This is done according to the communication speed set by modem training.

In such a pre-transmission procedure, the data output status of the transmitting station TX from signals NSS to TCF is shown in FIG.

CCITY (International Telegraph and Telephone Consultative Committee) Recommendation T, which stipulates transmission control procedures (protocols) for Gm facsimile equipment.
According to 30, the transmission frame of the signal NSS is v, 21
After being sent by the modem (low speed modem) at a communication speed of 300 bps, modem training (defined by the modem used) takes place after an interval IT of 75 ms, immediately after which the signal TCP is sent.

The information field of the signal NSS is 80 bits (10 octets), the frame of the signal NSS is 17 octets,
Modem is V, communication speed is 4800 with 27ter modem
bps.

For ■, 21 modem and V, 27ter modem,
Each modem complies with CCITT recommendations.

In this case, in the transmission frame of the signal NSS, the first preamble is 1 second (T1), and the transmission frame of the field signal is 453 seconds.
It takes a total of 1.453 seconds in milliseconds (T2). Also, modem training takes 0.923 seconds (T3), and as mentioned above, the format of the signal TCP is a ``107+ continuous signal of 1.5 seconds (T4).

Therefore, the transmission time of signal N5S-TCP is 3.95
It will be 1 second.

In recent years, various efforts have been made to shorten the data transmission time, such as increasing the communication speed, but as mentioned above, the pre-transmission procedure requires a lot of time, so this is not enough to shorten the data transmission time. It was a hindrance.

[Objective] The present invention has been made in order to eliminate the drawbacks of the prior art described above, and the present invention has been made to solve the above-mentioned drawbacks of the prior art.
The purpose of the present invention is to provide a data transmission method that can significantly reduce the time required for pre-transmission procedures by transmitting user data.

[Configuration] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 shows a facsimile machine according to an embodiment of the present invention.

In the figure, the CPU (central processing bag 1) controls the entire device w5, such as mode setting of the DSP (digital signal processing unit) 2 that realizes the modem function, segment sequence processing during modem traying, transmission control processing, HD
Access processing of LC controller 3, scanner 4. Performs driving processing of the printer 5, etc. The control program executed by this CPU is ROM (read only memory)
The work area of the CPU 1 and the storage area for control data are RAM (random access memory) 7.
is formed.

The DSP2 has two modes: a low-speed modem (V, 21 modem) mode for exchanging transmission control signals, and a high-speed modem (V, 27ter modem or V, 29 modem) mode for exchanging image information. and is connected to a telephone line via a signal converter 8.

The signal converter 8 converts the transmitted digital signal of the DSP 2 into a transmitted analog signal and sends it to the telephone line, and also converts the received analog signal sent from the other party via the telephone line to a received digital signal and transmits it to the DSP 2. give.

) The IDLC controller 3 performs a framing process to form an HDLC frame having a transmission control signal in the information field applied from the CPU 1, a deframing process to decompose an HDLC frame from a partner station applied to the DSP 2 to extract a transmission control signal, and Performs processing such as zero insursicon and zero illusion on the frame data.

Further, image signals from the scanner 4 and recording data to the printer 5 are exchanged with the cPUl via the interface 7.

Now, in this embodiment, when the transmitting station TX executes a training sequence to the receiving station RX, the terminal control information, that is, the signal NSS and the contents of its information field are transmitted in the final segment, so that the pre-transmission procedure is performed. This significantly reduces the time required to complete the process.

゛Figure 4 shows an example of the transmission procedure.

When the transmitting station TX calls the receiving station RXt-, the receiving station RX notifies the non-voice terminal with the called station identification signal CHD, and then
The o'Lc framed signal NSF and its information field and the HDLC framed signal DIS are transmitted by a low speed modem (V, 21 modem; 300 baud).

At the transmitting station TX, the DSP2 is set to low-speed modem mode, receives the HDLC frame of the transmission control signal, and converts it into HDL.
C controller 3 separates it into only signals. This results in
The terminal function of the receiving station RX is determined.

From the transmitting station TX, three segments SGI, SG2 . A training signal TRN consisting of SG3 is transmitted to the receiving station RX.

Currently, the high-speed modem is a V, 27ter modem with a modulation rate of 1600 baud and an 8-phase differential phase modulation method (communication speed 480 baud).
0 bps). This V, 27t, er modem has a modulation rate of 1200 baud and a function that can fall back to a four-phase differential phase modulation communication rate of 2400 bps.

In this case, segment SGI is 180″ of 50 symbols
The segment SG2 consists of 1074 symbols of 09 to 180° two-phase equalizer adjustment random buttons. Segment SG3 consists of a 544-symbol (bit) signal obtained by repeating a 136-bit frame consisting of the signal NSS and its information field four times, and then randomizing this frame using the CPUI. In addition, +-CPLII is
The signal NSS etc. is randomized by a predetermined generating polynomial (for example, 1+X-"+X-"), and the segment SG3 is
form a signal.

Therefore, the transmission time Tll of segment SGI is 31
milliseconds, the transmission time T12 of segment SG2 is 671 milliseconds, the transmission time T13 of segment SG3 is 340 milliseconds, and the total time of this training signal TRN is 1.
It will be 042 seconds.

Receiving station RX receiving such training signal TRN
Then, AGC, timing synchronization, etc. are performed in segment SGI, convergence of the adaptive automatic equalizer in the modem is performed in segment SG2, and in this state, the signal of segment SG3 is demodulated to restore the signal NSS and its information field. do.

If the residual phase error at the end of training is smaller than a predetermined value, it is determined that transmission at 4800 bps is possible, and a speed setting signal SPD for transmitting 4 BOO bps is sent to the transmitting station TX, If the residual phase error is larger than a predetermined value, it is determined that transmission at 4800 bps is impossible, and a speed setting signal SPD for setting a fallback speed is sent to the transmitting station TX. Note that this signal SPD has a communication speed set in its information field.

Therefore, the transmitting station TX transmits the image information PIX to the receiving station RX at the communication speed indicated by this signal SPD.

Also, the receiving station RX receives at least two (or three) of the four frames of the signal NSS and its information field.
The information that matches the frames can be determined as valid information.

By the way, in the above-mentioned training sequence (training signal TRN), since the segment SG2 is set to be very large at 1074 symbols, it is considered that the adaptive automatic equalizer in the modem has sufficiently converged. Therefore, if the reception error is considered to be sufficiently small, segment SG3 may be transmitted at the modem's lowest communication speed, that is, the fallback speed of 2400 bps. In this case, segment SG3 becomes a four-phase modulation signal.

Further, the training sequence when the high-speed modem is a v.2ii modem is as follows. Furthermore, this v, 29
The modem uses 16-level quadrature amplitude modulation (
Communication speed is 9600bpg) and 7200bps
, with a fallback function to 4800 bps.

Segment SGI is a bang in which signal points A and 83 shown in FIG. 6 are alternately repeated for 128 symbols. Segment SG2 consists of a 384-symbol random button for adjusting the isoconductor, and each symbol of this button takes signal point A at value II OII, and signal point D3 at value 11''. This is a randomization of data of 544 symbols for 4 frames of NSS and its information field using a predetermined generating polynomial (for example, 1+X-" 1X-23), and its value II O" is The value rr 1 rr takes the signal point D3.

Since the modulation speed of this v,29 modem is 240 robo,
The time Tll of segment SGI is 53 milliseconds, the time T12 of segment SG2 is 160 milliseconds, and the time T13 of segment SG3 is 226 milliseconds, and the time required for this training sequence is 0.439 seconds.

The receiving station RX determines the maximum transmission speed based on the residual phase error at the end of segment SG2, and transmits the signal S
It sets the information in the PD and responds to the transmitting station TX.

In addition, the minimum communication speed of segment SG3 is 4800 bps.
In that case, the communication speed of segment SG3 is set higher than the modulation speed, so modem training can be performed more reliably.

In this way, the transmission and training sequence of the signal NSS and its information field, which took the longest time in the pre-transmission procedure, can be shortened to about 0.5 to 1 second, so the time required for the transmission control procedure can be significantly reduced. . Further, since the receiving station RX notifies the transmitting station TX of the possible transmission speed in response to the speed setting signal SPD, modem training at the fall pack speed is not required, which is further advantageous. In addition.

The training sequence time is not limited to that shown in the embodiment described above, and the training sequence time is not limited to that shown in the above embodiment.

SG2. The combination of time lengths of SG3 may be set to an optimal combination according to the characteristics (variation range) of the line on which the device is used. For example, if segment SG2 is set to a longer symbol interval, the residual phase error when receiving segment sG3 will be smaller, so that terminal control information, that is, signal NSS and the contents of its information field can be reliably transmitted.

[Effects] As explained above, according to the present invention, terminal control information is transmitted following the random pattern for iso-signal adjustment.
The advantage is that the time required for transmission control procedures is shortened, resulting in increased transmission speed.

[Brief explanation of the drawing]

FIG. 1 is a timing diagram showing an example of a transmission control procedure of a Gm facsimile machine, FIG. 2 is a timing diagram showing a conventional example of a signal NSS and a training signal, and FIG. 3 is a facsimile according to an embodiment of the present invention. 4 is a timing diagram showing an example of a transmission control procedure by the device shown in FIG. 3, FIG. 5 is a timing diagram showing an example of a training sequence, and FIG. 6 is a timing diagram showing an example of a training sequence. , 29 is a signal arrangement diagram showing signal points in the .29 modem. 1...CPLI (central processing bag W), 2...DSP
(digital signal processing device), 3...HDLC (high level data link procedure) controller, 6...RO
M (read-only memory), 7...RAM (random access memory). Figure 7 Figure 2 I Figure 3

Claims (2)

[Claims] (1) A data transmission method characterized in that, prior to information transmission, terminal control information is transmitted at the same modulation rate following a random pattern for equalizer adjustment transmitted during a modem training period. (2) A data transmission method characterized in that, prior to information transmission, terminal control information is transmitted at the modem's lowest communication speed following a random pattern for equalizer adjustment transmitted during a modem training period.