JPH03127550A - Group 3 facsimile modem device and control method therefor - Google Patents

Abstract

PURPOSE:To attain MODEM training of high speed MODEM function by provid ing a means detecting the start of a synchronizing signal of the high speed MODEM function. CONSTITUTION:In a transmission energy spectrum of a segment SG2 of a V.29 MODEM (at 9600bps), there are peaks at a carrier frequency 1700Hz of the V.29 MODEM and at frequencies 500 and 2900Hz apart from the carrier fre quency 1700Hz by a frequency of 1200Hz corresponding to a modulation speed 2400baud. Then a synchronizing signal detection circuit 26 discriminates it that the segment SG2 of a synchronizing signal is detected when the transmis sion of signal energy at the frequencies of 500 and 2900Hz is larger than a prescribed value. When the synchronizing signal detection circuit 26 detects the segment SG2 of the synchronizing signal, a MODEM control section 23 switches a demodulation section 21 and a modulation section 24 to the V.29 MODEM function (at 9600bps), a switching end signal is outputted to the group 3 facsimile MODEM 9 and a CPU 1 transfers to the picture information recep tion processing by the V. 29 MODEM function(at 9600bps). Thus, the training of the high speed MODEM function is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of controlling a Group 3 facsimile modem device having a low speed modem function and a high speed modem function.

[Prior Art] Group 3 facsimile equipment uses a method for transmitting transmission procedure signals exchanged for its transmission procedure.

The low-speed modem function specified in CCITT Recommendation V, 21 (300bps) is used to transmit image information.

CCITT Recommendation V, 29 (9600, 7200 bps)
Or recommendation■.

The high-speed modem function specified in 27ter (4800, 2400 bps) is used.

An example of the transmission procedure of the Group 3 facsimile device is shown in FIG. In this case, the image information is one page.

The receiving device RX, which is called by the transmitter 3A station TX, sends the called station identification 81 signal C, which warns that the own terminal is a non-voice terminal.
In addition to responding with ED, the terminal also responds with a digital identification signal DNS for notifying the standard transmission function of its own terminal.

Transmission lA11'ffitX is a digital identification signal DIS
When receiving the message, it selects the transmission function to be used at that time based on the content, notifies the receiving device RX of the selection using the digital command signal DC5, and selects the Group 3 facsimile modem of its own terminal at that time. 1 to training check signal tHcF is transmitted with the transmission speed set to the specified transmission speed.

When receiving the digital command signal DC3, the receiving device Rx sets the group 3 facsimile modem of its own terminal to the transmission speed set at that time.

The training check signal TCP is received and the number of reception errors is counted. Then, when the reception of the training check signal TCF is finished, the total number of reception errors is checked, and if it is less than a certain value, the reception preparation confirmation signal C
Send the FR and move on to preparing to receive image information.

When the transmitter TX receives the reception preparation confirmation signal CFR, it transmits the one-picture information PIX, and when it finishes transmitting the picture information PIX, it transmits a procedure end signal EOP to notify the end of the picture information transmission.

The receiving device RX receives the image information PIX, decodes it into the original image signal, records and outputs it from the plotter of its own terminal, and detects the transmission error included in the image information based on the decoding result. Determine whether or not is less than a certain value. Then, when the reception of the one-picture information PIX is completed and the transmission error is less than a certain one, it responds with a message confirmation signal MCF congratulating that the received picture information is normal.

When the transmitting device TX receives the message confirmation signal MCFa, it sends out a disconnection command signal DCN to restore the line.
The series of image information transmission operations ends.

Further, upon receiving the disconnection command signal DCN, the receiving device Rx restores the line and ends the series of image information receiving operations.

Here, 5 digital identification signal DIS, digital command signal D
C3, reception preparation confirmation signal CFR1 procedure end signal EO)]
, message confirmation signal MCF, and command disconnection signal D
The CN transmits and receives the transmitting device 71Tx and the receiving device RX with the group 3 facsimile modem of its own terminal set to the low-speed modem function, and the training check signal TCP and image information PIX are sent and received by the transmitting device @Tx and the receiving device RX. The device RX transmits and receives data while setting the group 3 facsimile modem of its own terminal to the high-speed modem function of the transmission speed specified by the transmitting device Tx by the digital command signal DC5.

Here, the transmission procedure signal is as shown in FIG.
It is exchanged in a frame format compliant with LC (High Level Data Link Control Procedure).

This frame has a head flag F and an address field A.
, Control field C5 Information field in which identification information of the transmission procedure signal, parameters of the transmission procedure signal, etc. are set, CR for error detection of this frame data
It consists of a frame check sequence FC5 consisting of a C code and a termination flag F. Furthermore, a redundancy flag FR may be added following the termination flag F so that the other device can reliably detect the termination flag F.

Figure 8 shows the high-speed modem function of CCITT Recommendation v, 29 (
1 transmitted at 9600 bps; 16-level QAM)
Six types of signal elements are shown.

Transmission data is scrambled and then divided into groups (quad bits) of 4 consecutive bits, and the signal element to be transmitted is determined by the first pin 1 in each quad bit. The relative amplitude of is set, and the second to fourth bit patterns set the phase change with respect to the phase of the immediately preceding signal element.

In this way, the signal elements corresponding to the quad bits of the transmission data string are determined.

Also, prior to data transmission by the V.29 modem,
The transmitting terminal sends a synchronization signal (a) for phase synchronization of transmission data, amplitude adjustment, and initialization of the descrambler.
do.

As shown in FIG. 9, this synchronization signal is transmitted from segment SG1. Signal element PA and signal element l-PB
Segment 5G2 in which the symbol interval number TS2 is 128, which alternately repeats (at 9600 bps; see Figure
(timing detection), segment SG3.V, where the symbol interval number TS3 is 384 and consists of an equalizer adjustment pattern for adjusting the continuous type automatic equalizer built in the V.29 modem. and scrambled data rlJ
The symbol interval number TS4 consists of 48 segments SG4 (descrambler reset).

Following this synchronization signal, user data is transmitted.

[Problems to be Solved by the Invention] However, such group 3 facsimile devices sometimes have the following disadvantages.

That is, for example, the receiving device RX receives the reception preparation confirmation 4i.
When transmitting No. CF'R, set the function of the group 3 facsimile modem of the own terminal to V, 21 modem, and receive I'l! When the transmission of the readiness confirmation signal CFH is completed, the receiving bag WRx starts the high-speed modem function of the transmission speed notified by the digital command signal DO3 (for example, V of 9600 bps).
, 29 modem) to switch the Group 3 fax modem.

On the other hand, the transmitting (4 device TX receives k('! fil M
L': 2 When receiving the signal CFR1r, set the function of the group 3 facsimile modem of the own terminal to v, 21 modem, and confirm reception 1 < 0 (when it is determined that frame reception of No. a CFH is completed, Switch the group 3 facsimile modem of the terminal to the 9600 bps V, 29 modem function and start transmitting the image information PIX.

Here, in order to ensure that the transmitter TX can detect the end of the signal frame of the reception preparation confirmation signal CFR, the receiver R
In the case where X has added a redundancy flag FR to the termination flag F of the signal frame of the reception preparation confirmation signal CFH, the transmitting device child X recognizes the termination flag F and receives the 4M preparation confirmation signal CF.
The end of the H signal frame is detected, and immediately after that, ■, 2
When the 9th modem starts sending synchronization signals, the 10th modem
As shown in the figure, the receiving device JRX is transmitting the redundancy flag FR with the v,21 modem at 7v.

The transmission of the synchronization signal of the V.29 modem is started.

For this reason, the receiving device RX cannot sufficiently receive the segment SG2 of the synchronization signal of the modem ①, 29, and therefore cannot properly perform modem training of the modem Ⅰ, 29 in the receiving device RX. This may cause an inconvenience in that the image information PIX cannot be received normally.

The present invention was conceived in view of the above circumstances, and an object of the present invention is to provide a group 3 facsimile modem apparatus and a control method thereof, which enable reliable modem training of high-speed modem functions.

[Means for Solving the Problem] The present invention includes a detection means for detecting the start of a synchronization signal of a high-speed modem function, and detects a redundant flag of a termination flag of a transmission procedure signal that responds immediately before receiving image information during transmission. When the means detects a synchronizing signal for the high-speed modem function, the modem function is switched from the low-speed modem function to the high-speed modem function at that point.

[Operation] Therefore, immediately after the synchronization signal Z of the high-speed modem function is started from the partner device, the synchronization signal (No. 3) can be received, so training of the high-speed modem function can be reliably performed, and the image information will be able to receive it properly.

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

FIG. 1 shows a Group 3 facsimile machine according to one embodiment of the present invention.

In the figure, the CPU (Central Processing Unit) l is for controlling the operation of each part of this Group 3 facsimile machine and processing the transmission procedure, and the ROM (Read Only Memory) 2 is for the CPU to execute. It stores control programs and data such as various constants necessary for executing the control programs, and uses RAM (random memory).
The access memory 3 constitutes the work area of the CPUI.

The scanner 4 is for reading a document image at a predetermined resolution, and the plotter 5 is for reading an image at a predetermined resolution.
This is for recording and outputting.

The operation display section 6 is made up of various keys and displays necessary for operating this Group 3 facsimile device.

The percussion decoding unit 7 encodes and compresses both signals obtained by reading with the scanner 4, and also restores the percussively compressed image information to the original image information. .

The image storage device 8 is for storing a large amount of image information in a percussively compressed state, and the image storage device 8 is for storing a large amount of image information in a percussively compressed state.
Consists of etc.

The group 3 facsimile modem 9 performs processing to modulate and demodulate digital data, and has a low-speed modem function for exchanging transmission procedure signals and a high-speed modem function for transmitting two-picture information. The low-speed modem functions include CCITT Recommendation V and Recommendation Dem functions (300bps), and the high-speed modem functions include:
CCITT Recommendation v, Recommendation Dem function (9600bps
, 7200bps) and V, 27ter modem function (4800bps, 2'1OObps).

The network control device 1o is for connecting this Group 3 facsimile device to the public telephone line network, and is equipped with an automatic call origination/reception function.

These CPU1. ROM2, RAM3. scanner 4,
Plotter 5, operation display section 6, encoding de-encoding section 7, image?
The B product device 8, group 3 facsimile modem 9, and network control device 10 are connected to a system bus 11, and data exchange between these elements is performed by opening this system bus 11. . .

Furthermore, the transmission signal Brxd is output from the group 3 facsimile modem 9 to the network control device 10, and the network control 'nr+
The received signal RXd is output from the terminal o to the group 3 facsimile modem 9.

FIG. 2 shows an example of the group 3 facsimile modem 9.

This group 3 facsimile modem 9 receives the received signal qRx.
An analog/digital converter 20 for converting the digital received signal DD into a corresponding digital received signal DD, a predetermined demodulator 11! ! a demodulation section 21 for forming g data RD; an interface circuit 22 for exchanging data via the system bus II; a modem control section 23 for controlling the operation of this group 3 facsimile model 1.9; .A modulator 24 performs predetermined modulation processing on the transmission data TD transferred via the system bus 11 to form a digital transmission signal (TDI); A digital/analog converter 25 for converting the transmission signal TXd into a transmission signal TXd. V.

29 modem (at 9600 bps) modem 1 to modem 26 for detecting the segment SG2 of the synchronizing signal sent for training.

Further, the demodulation unit 21 has a demodulation processing function for a low-speed modem function and a high-speed modem function, and the modulation unit 24 has a modulation processing function for a low-speed modem function and a high-speed modem function.

Here, the transmission energy spectrum of segment l-5G2 of the 29 modem (at 9600 bps) is the third
As shown in UiJ, the carrier frequency of the modem 29 is 1700Hz, and the carrier frequency 1700117.
The frequency corresponding to the modulation rate of 2400 baud (12
50011z and 29001 separated by 001(z)
Each has a peak at 1z.

Therefore, the synchronization signal detection circuit 26 detects this 500 t(z
and 290011z is larger than a predetermined value, it is determined that the segment SG2 of the synchronization signal has been detected.

In the synchronization signal detection circuit 26, the bandpass filter 3
0.31 is 29001tz of digital received signal RDD
and 50011z signal components,
Multipliers 32 and 33 square the outputs of the bandpass filters 30 and 31, respectively, to obtain a digital received signal R.
DD's 2900) IZ and 500Hz power signal EP
I, EP2 are calculated, and their electric power bond%
[E P 1 and E P 2 are added to the adder 34.

Adder 34 receives power signal EP1. EP2 is added, and the addition result is added to the low-pass filter 35 as a power sum signal EP3, and its envelope is extracted via the low-pass filter 35, and the envelope PE is added to the positive side of the comparator 36. It is added to the input end.

The negative input terminal of the comparator 36 receives the base value /j:.

A reference signal ST outputted from a device 37 is added.

Comparator 36 raises its output signal to logic 11 level when envelope signal PE becomes larger than reference signal ST. The output signal of this comparator 36 is divided into segments 1 to SG2.
The detection signal OR is applied to one input terminal of the AND circuit 38 as a hail detection signal OR.

The other input terminal of the AND circuit 38 has CP (,, J
A switching permission signal EN output from l is added,
The output signal of this AND circuit 138 is the output signal of the flip-flop 3
9 is added to the Glock input end.

At the data input end of the flip-flop 39, the data “
1'' is added, and the signal at the output terminal Q of the flip-flop 39 is applied to the modem control section 23 as a switching request signal Sa, and is also applied to one input terminal of the AND circuit 40.

The modem control unit 23 is connected to the other input terminal of the AND circuit 40.
The output signal from the AND circuit 40 is applied to the clock input terminal of the flip-flop.

Data "1" is applied to the data input terminal 1 of the clip-flop 41, and the signal at the output terminal Q of the flip-flop 41 is the modem disconnection J! 2! Completed 4￥'j
It is added to the modem control section 23 as SC, and is also sent to CPIJI via the interface circuit 22.

Also, flip-flop 4I clear human power g5c1. R
(Z'L logic) has a switching permission signal pasted,
The negative logic output terminal 0 of the flip-flop 41 (?r3
．． ≦1 is the clear input terminal CI of the flip-flop 39
R(j'lΔ) principle).

Furthermore, the modem control unit 23 controls the PJ? A part 21 top 211;
'j -r3-RR is exchanged to control the function of the demodulator 21 □ Both monitor the state of the demodulator 21 and exchange (1) control signal TR with the modulator 24 to control the function of the modulator 24. The state of the modulation section 24 is also monitored by the person controlling the function.

With the above configuration, the CPUI receives image information )) 1x, 1
When transmitting the immediately preceding transmission method (1) (1) (14), for example, the reception error confirmation signal CFR or multi-page signal (PS), when the transmission up to the frame check sequence FC5 of the signal frame is completed (see Fig. 4). (see (a)),
At the same time, the transmission of the termination flag F is started, and the switching permission I3 is
The signal EN is raised to the logic H level (turned on; see FIG. 4(g)). Thereby, the AND circuit 38 becomes operable.

Immediately after completing the sending of the termination flag F, the transmitting device detects the termination flag F and sends out a synchronization signal of the v, 29 modem (9600 bps). (see FIG. 4(b)), and the received signal RXd is converted into a corresponding digital received signal RDD by the analog/digital converter 20 and applied to the synchronization signal detection circuit 26.

On the other hand, following the termination flag F, the CPU 1 starts sending out the redundancy flag FR.

Now, when segment SGI of the synchronization signal ends and segment SG2 begins, bandpass filter 30.3
1, the signal components of 2900.5001+z are extracted, and the respective power signals EPI and EP2 are obtained (FIG. 4(C)).

(d)) are output from the multipliers 32 and 33, and the sum of these power signals EPI and EP2 is formed by the adder .

Thereby, the formed power summation signal EP3 is converted into an envelope m-line signal PIE (see FIG. 4(e)) via the low-pass filter 35, and compared with r? ! Added to 36.

Ru.

When the reception (ii) state of segment SG2 becomes stable and the envelope signal PE becomes larger than the reference signal ST, the comparator 36
The detection signal DH output from the circuit changes by a logical H level (see FIG. 4(f)).

As a result, the output signal of the AND circuit g38 rises to the logic 11 level, and at the rising edge, the state of the flip-flop 39 changes to "1", and the switching request signal Sa output from the output terminal Q becomes the logic 11 level. Stand up (Figure 4)
h)). As a result, the amplifier circuit 40 becomes operable.

As a result, the modem control section 23 changes the functions of the demodulation section 21 and the modulation section 24 from V,21 modem function to v,2 modem function.
9 modem function (9600 bps) and when the switching operation is completed, the V and 21 modem transmission abort completion signal sb goes to logic H level (4th
(see figure (j)).

As a result, the output signal of the AND circuit 40 rises to the logic 11 level, the state of the flip-flop 41 changes to rlJ at the rising edge, and the modem switching completion signal Sc output from the output terminal Q rises to the logic H level. - Next (see FIG. 4(j)), the CPU 1 is notified that the function of the group 3 facsimino modem 9 has been switched to the v.29 modem function (9600 bps).

Also, since the signals i3 and 5d output from the output terminal Q of the flip-flop 41 fall to the logic L level (see FIG. 4(k)), the flip-flop 39 is cleared and its state changes to "0". However, switching request No. 43 Sa is logic 1.
．． Get down to the level.

At the same time, when the completion of switching to the 29 modem function is notified, the CPIJ1 lowers the switching permission signal EN to the logic L level (turns off). This clears the flip-flop 41 and changes its state to "0".

Further, at the time when the modulation section 24 switches to the v,29 modem function, the output of the redundancy flag FR is stopped.

Due to this, the demodulator 21 can start receiving the segment SG2 of the synchronization signal immediately after the segment SG2 starts, and can appropriately perform the modem training operation using the synchronization signal.

Therefore, the group 3 facsimile modem 9 is ■,
The reception operation of the X.29 modem function can be performed properly, thereby preventing data errors when receiving image information.

FIG. 5 shows 1, for example, reception preparation confirmation signal CFR or multi-page signal MPS? , A, and immediately after completing the transmission of the signal frame of the transmission procedure signal up to the frame check sequence FC3 immediately before receiving the image information PIX, an example of the processing executed by the CPU is shown.

First, the CPU 1 starts sending the termination flag F (processing 101), and the group 3 facsimile modem 9
The process 102) instructs the modem control unit 23 to perform an automatic switching operation from the V, 21 modem function to the V, 29 modem function (9600 bps), and the redundancy flag FR.
A counter CA for managing the number of transmissions is cleared to 0 (process 103), and a switching permission signal EN is turned on (process 104).

In this state, either the switching completion signal Sc is input manually from the group 3 facsimile modem 9, or the counter CA is set to the specified value FN.
b, or waits until the next redundancy flag FR can be sent (decisions 105 and 106).
．． 107 No loop).

As described above, the synchronization detection circuit 26 detects the segment SG2 of the synchronization signal of v, 29 modem function (9600 bps).
, the modem control section 23 switches the demodulation section 21 and the modulation section 24 to the V,29 modem function (9600 bps), and as a result, the group 3 facsimile modem 9 outputs the switching completion signal Sc, and the result of judgment 105 is When becomes YES, CPUI turns off the switching permission signal EN (process 108), and turns off the V, 29 modem function (9600
The process moves on to image information reception processing based on (bps).

In addition, the fifth-order redundancy flag FR is now ready to be sent.
When the result of judgment 107 is YES, CPU 1 starts sending one redundancy flag FR (process 109), increments counter CA (process 110), and returns to judgment 105.

Also, even if the redundancy flag FR is sent by the specified number FNb,
If group 3 facsimile modem 9 does not switch to v,29 modem function (9600bps), judgment 1
The result of step 06 is YES, and in this case, the CPU 1 turns off the switching permission signal EN (111), stops the V and 21 modem functions of the group 3 facsimile modem 9, and receives the V and 29 modem functions (9600 bps). Command to start operation (processing 1.12, 113)
, (2) Shifts to image information reception processing using the 29 modem function (9600 bps).

In this way, after finishing sending the termination flag F,
If the transmitting device starts transmitting with the v,29 modem function (9600 bps) before it finishes sending the first redundancy flag FR, at that point the group 3 facsimile modem 9 starts transmitting with the v,29 modem function (9600bps). 9600 bps)
Then, the CPUI transitions to reception operation.

In addition, between the time when the transmission of the first redundancy flag FR is completed and the time when the transmission of the specified number FNb of redundancy flags FR is completed, the transmission device has a v, 29 modem function (9600bps).
If the transmission operation of group 3 is started, at that point
Fax modem 9 v, 29 modem function (9600
bρS), the CPUI shifts to reception operation.

Furthermore, when the transmission of the specified number FNb of redundancy flags FR is completed, the transmitting device
If the transmission operation of S) has not started, the transmission operation of the v, 29 modem function ('1600bps) of the transmitting device will start after that, so in preparation for this, the transmission operation of group 3
Fax modem 9 v, 29 modem function (9600
bps), the CPUI shifts to reception operation.

In this way, the sending device's v, 29 modem function (96
00 bps) to start the transmission operation.

CPUI is V of group 3 facsimile modem 9.

29 modem function (9600bρS), and ■.

29 modem function (9600bρS).

By the way, in the embodiment described above, the group 3 facsimile modem 9 has a v, 29 modem function (!l) 600 bps
), but the present invention can be applied in the same manner to cases where the modem 1 is switched to other functions.

[Effects of the Invention] As explained above, according to the present invention, when the synchronization signal Z of the high-speed modem function is detected while transmitting the redundancy flag of the termination flag of the transmission procedure signal that responds immediately before receiving image information, at that point Since we have changed the modem function from low-speed modem function to high-speed modem function, we can receive the synchronization transmission from the other device immediately after the high-speed modem function synchronization (it! 'r' is started). To obtain the effect that training of a high-speed modem music section can be reliably performed and one-way information can be properly received.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a Group 3 facsimile device according to an embodiment of the present invention, FIG. 2 is a block diagram showing an example of a Group 3 facsimile modem, and FIG. 3 illustrates the distribution of transmission spectrum energy of a synchronization signal. 4 is a waveform diagram for explaining the operation of a group 3 facsimile modem, FIG. 5 is a flowchart showing an example of processing executed by the CPU, and FIG. 6 is an example of a transmission procedure of a group 3 facsimile machine. Fig. 7 is a schematic diagram showing an example of a frame of a transmission procedure signal, Fig. 8 is a signal space diagram showing signal elements of V, 29 modem function (9600 bps), and Fig. 9 is an example of a synchronization signal. FIG. 10 is a time chart 1 for explaining the disadvantages of the conventional device. 1...CPU (central processing unit), 2...ROM, (
3...RAM (random access memory), 9...Group 3 facsimile modem. 23...Modem control section, 26...Synchronization signal detection circuit. Figure 3 Figure R (k) Sd Figure 5 Figure R Figure 0

Claims (2)

[Claims] (1) In a group 3 facsimile modem device equipped with a low-speed modem function for transmitting transmission procedure signals and a high-speed modem function for transmitting image information signals, a detection means for detecting the start of a synchronization signal of the high-speed modem function is provided. A group 3 facsimile modem device comprising: (2) In a method for controlling a Group 3 facsimile modem device equipped with a low-speed modem function for transmitting a transmission procedure signal and a high-speed modem function for transmitting an image information signal, the start of a synchronization signal of the high-speed modem function is detected. If the detection means detects a high-speed modem function synchronization signal while transmitting the redundant flag of the termination flag of the transmission procedure signal frame that responds immediately before receiving image information, the low-speed modem function changes to the high-speed modem function at that point. A method for controlling a group 3 facsimile modem device, characterized by switching modem functions.