JP2009267611A - Facsimile machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that it is necessary to be normally terminated without terminating communication by an error even in an IP line. <P>SOLUTION: Channel transition control between a PrimaryChanel (PC) and ControlChanel (CC) is changed as described below: (a) "PC→CC automatic transition" is permitted, which has been conventionally prohibited in starting the PC; (b) CC retraining processing is performed by each fixed interval when the following conditions are detected during PC reception, i.e., a carrier interruption for fixed time or more during the PC reception, the divergence of a MODEM (it is determined when an EQM value reaches a fixed value or more), and the PC→CC transition of a transmission side MODEM (an error code from the MODEM); and (c) the prevention of a collision in CC retraining. When an AC signal is received from a transmission side in a case where a self device (a reception side) tries to perform the CC retraining under the above conditions, the CC retraining processing is stopped or a CC retraining start timer is extended. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to data communication, ITU-T (International Telecommunication Union-Telecommunication Standardization Sector) The present invention relates to a control method for continuing communication even when a line failure or the like occurs when a facsimile apparatus conforming to the 34th recommendation communicates and a modem loses synchronization and it is difficult to continue communication. In particular, the present invention relates to processing when an instantaneous interruption occurs in the primary channel and the control channel.

(1) "Dissemination of IP network / IP phone"
In recent years, Internet connection services using ADSL / FTTH have become widespread in homes and small and medium-sized offices, and in companies with a certain scale, sharing of information equipment by LAN within a base and communication between bases are conventional. The IP network has become widespread due to a shift from a dedicated line to VPN (Virtual Private Network: technology for creating a dedicated line on the Internet).

  In addition, IP telephones using these IP networks have also become widespread. An IP phone is a communication means that uses a technology to send voice as an IP packet (VoIP: Voice over Internet Protocol) and allows voice calls to be made through an inexpensive IP network / router without using expensive equipment such as an exchange. Yes. In terms of communication costs, users with a lot of long-distance calls bring a great cost advantage.

(2) “Increase in facsimile communication via IP network”
With the development and popularization of these IP networks / IP telephones, the number of facsimile terminals connected to the IP network is increasing in businesses and homes, and facsimile communication via the IP network is increasing (FIG. 1).

  From a conventional facsimile communication via only the public telephone network (communication path (1) in FIG. 1), a VoIP router connects to an ISP (Internet Service Provider) and a facsimile communication via the Internet (communication path (2) in FIG. 1). ) And VoIP routers are connected to corporate private lines and VPNs such as VPN networks and are connected to the public telephone network via VoIP gateways (communication path (3) in Fig. 1), and also connected to IP networks. Communication between facsimiles (communication path (4) in FIG. 1) and the like and facsimile communication via an IP network in various connection forms are increasing.

(3) “Problems of facsimile communication via IP network”
In conventional facsimile communication on the public telephone network, the necessary bandwidth on the transmission path is guaranteed, so that communication failure does not occur much. However, as the IP network becomes widespread, facsimile communication via the IP network increases. Communication failures caused by IP networks are gradually increasing.

  In facsimile communication via an IP network, a facsimile signal is divided into packets as voice signals and transmitted, and the receiver assembles the packets and decodes the voice signals for communication. In the IP network, there is no guarantee of signal transmission time, and when the IP network is congested, the voice signal band and other data communication bands cannot be taken sufficiently. / Line failure due to loss may occur.

  These failures are likely to occur in a corporate network with a large amount of communication, and are concentrated in a time zone where data communication is concentrated.

(4) “Factors of voice quality degradation in IP networks”
The voice signal on the transmitter side is transmitted after being analog-to-digital converted, encoded, and packet-divided by the VoIP router (or VoIP gateway between the public network and the IP network) before reaching the receiver side. The Routing relaying / forwarding is performed by a router in the IP network, and a voice signal is restored by packet assembly, decoding, and digital-analog conversion by a VoIP router (or VoIP gateway) on the receiver side.

  In an IP network, the transmission speed of the transferred packet is not constant, and the transferred packet has a difference in the arrival timing to the VoIP router on the receiver side (fluctuation) due to network congestion or failure in the IP network on the way. ) Occurs (FIG. 2). If this degree of fluctuation is large or packet loss (packet loss) occurs in the IP network, the VoIP router may not be able to recover the signal waveform sampled on the transmitter side, and the reproduced audio signal will be momentarily interrupted. Will occur.

(5) "Effect of voice quality deterioration on facsimile communication"
Signal interruption caused by fluctuations in IP network or packet loss affects facsimile communication.

  Facsimile communication is a communication method that repeats procedure signal / image data transfer while synchronizing between the modem on the transmitter side and the modem on the receiver side. In such a communication method that requires synchronization between the transmitter and receiver, the loss of the communication signal due to a momentary interruption causes the modem to lose synchronization. It will be difficult to maintain procedures and continue receiving image data. In particular, ITU-T recommendation V.I. When facsimile communication is performed with a modem conforming to 34, this instantaneous interruption is strongly affected.

  FIG. This figure shows the process of ending facsimile error on the receiver side in time series from the state of transmission / reception signal when instantaneous interruption occurs due to the influence of the IP network during communication with 34 modem.

  V. 34 communication image data consists of consecutive frames. For this reason, if an interruption occurs during image signal reception, the frame image data cannot be received for the time from the loss of frame communication synchronization to resynchronization. Also, the process for resynchronization is complex, and if a line signal interruption occurs for a certain period of time or longer, resynchronization cannot be performed, and the modem diverges after the occurrence of the interruption. The image data cannot be received normally.

V. Patent Document 1 discloses a conventional example in which communication can be continued properly even when an instantaneous interruption of a line signal occurs due to a line failure during data communication such as image data using a 34 modem. This prohibits a mode that automatically shifts to the control channel when a training signal pattern is detected during data reception, thereby improving the resistance against instantaneous signal interruption in the primary channel.
Japanese Patent Laid-Open No. 10-308863

  As described above, the facsimile communication via the IP network is more likely to cause a line failure such as a momentary interruption than the conventional facsimile communication via the public line network, and therefore, there are many cases of communication errors. .

  Therefore, the object of the present invention is the above-described V.V. In facsimile communication using a 34 modem, Even when an interruption of the line signal occurs during reception of the 34 primary channels, the transition from the primary channel to the control channel can be appropriately performed, and communication can be continued even if the interruption occurs. It is to provide a facsimile apparatus that can be used.

In order to solve the problems / problems described above,
In the present invention, when control channel resynchronization cannot be performed in the transition from the primary channel to the control channel, control channel retraining is actively performed to perform resynchronization and communication is continued.

The facsimile apparatus of the present invention
(1) ITU-T recommendation V. V. performs communication according to the 34 standard. 34 communication means. 34. Carrier loss detection means for detecting carrier loss during reception of the primary channel 34, reception signal quality determination means for determining the quality of the data signal being received, 34, a facsimile apparatus having a reception signal monitoring means for monitoring a reception signal at the time of communication and an RCP detection means for detecting a signal (RCP) indicating the rear end of image data received by a primary channel;
After detecting the carrier interruption in the primary channel by the carrier interruption detecting means, after detecting the divergence of the modem in the primary channel by the received signal quality judging means, or from the primary channel on the transmitter side by the received signal monitoring means If the control channel is not resynchronized after detecting the transition to the channel or within a certain time after detecting the trailing edge of the image data received by the RCP detection means on the primary channel, the control channel retrain is performed. The control channel is resynchronized.

  (2) In the facsimile apparatus of (1), if the control channel is not re-synchronized within a certain time after the control channel / retrain is performed, the control is performed at regular intervals until the control channel is re-synchronized. The control channel retrain is repeatedly performed.

  (3) Also, in the facsimile apparatus of (2), if an error is detected in the modem connection state between the transmitter side and the receiver side within a predetermined time after the control channel / retrain is performed, the control channel resynchronization is performed. The control channel / retrain is repeatedly performed at regular intervals until the operation is performed.

  (4) In the facsimile apparatus of (2), when the control channel retrain (AC signal) on the transmitting side is detected at the timing when the receiver side performs control channel retraining, control is performed from the receiver side. A timer for starting the control channel retrain is extended at the predetermined intervals without starting the channel retrain.

According to the present invention, V.I. Even if a sudden line failure occurs in the 34 communication, communication errors due to modem divergence / carrier disconnection in the primary channel or control channel can be avoided, and communication can be continued without ending the error. The details are as follows.
-Even if the rear end of the primary channel (RCP signal) cannot be detected due to a momentary interruption, it is possible to reliably shift to control.

  -Even if a line failure occurs in the control channel, there is an effect of increasing the chance of recovery and continuing communication.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

  Hereinafter, the present invention will be described in detail based on the embodiments shown in FIGS.

  FIG. 4 is a block diagram showing a configuration of a communication apparatus according to an embodiment of the present invention.

In FIG.
101: The CPU is a system control unit and controls the entire apparatus.

  102: The ROM stores a control program for the CPU.

  103: The RAM is composed of SRAM or the like, and is used for storing image data.

  104: The image memory is constituted by a DRAM or the like, and is used for storing image data.

  105: The resolution conversion processing unit performs resolution conversion control such as milli-inch resolution conversion of raster data.

  106: A reading / recording coding / decoding processing unit (reading / recording codec) performs coding / decoding processing of image data handled by the communication apparatus.

  107: The clock unit measures an operation interval and the like and is configured by an IC or the like.

  108: The modem demodulates the modulated signal from the line, or conversely modulates the signal from the apparatus and sends it to the line.

  109: The line i / f unit is a control unit configured by an NCU or the like. When the telephone has two connection terminals, each connection terminal has a hook detection circuit in order to detect off-hook / on-hook at each terminal.

  110: The telephone is a handset (telephone having no dialer) or an external telephone (such as an answering machine) connected to the telephone line through a line i / f unit (NCU).

  111: A VoIP router that connects an IP network and a terminal. The VoIP router connects an IP network and a communication device with an analog port.

  112: An IP network such as VPN.

  113: The image processing unit performs correction processing on the image data read by the scanner and outputs high-definition image data.

  114, 115: A sheet scanner and a book scanner are composed of a CS image sensor, a document transport mechanism, and the like, and optically read a document and convert it into electrical image data. Scan double-sided originals.

  116: The operation unit includes a keyboard, a display unit, and the like, and is used by the operator to perform various input operations. Indicates that immediate dialing is possible when the handset is off-hook. When the external telephone is off-hook, it displays that communication is in progress and that communication reservations can be accepted.

  117: The line buffer is. This is a line buffer used when image data transfer control is performed.

  118: The print buffer is a buffer memory for one page for storing the character code for printing.

  119: The printer is a printer such as an LBP that records received images and file data on plain paper, and can perform double-sided recording.

  FIG. 5 is a sequence diagram showing how a line failure is avoided in the embodiment of the present invention.

  (1) shows a normal communication sequence when there is no line failure shown for comparison. When the training signal pattern is detected during reception of the primary channel at the beginning of the primary channel, the mode is set to automatically shift to the control channel (PC → CC automatic transition is allowed), and the transmitter side finishes sending the image data When turn-off is started, the transmitter side receiver side performs resynchronization at the beginning of the control channel, and communication on the control channel is continued.

  (2) shows a state in which an error is recovered by a sequence diagram on the transmission side and the reception side when a line failure occurs during reception of a primary channel and an instantaneous interruption occurs.

  Even if a momentary interruption due to a line failure occurs, if the momentary interruption itself is short and does not affect the synchronization of the modem, the modem will not diverge and be the same as during normal reception in (1). Transition from the primary channel to the control channel takes place. However, since the data is in error, the receiver side returns a PPR signal and requests retransmission of the error frame.

  In the case where a momentary interruption occurs at the time of a line failure and the modem is diverged by affecting the synchronization of the modem, the receiver side starts the retraining process of the control channel with a carrier interruption for a certain time or more. If re-synchronization of the control channel cannot be confirmed within a predetermined time after the start of the control channel / retrain, the receiver side repeats the control channel / retrain at regular intervals until the control channel re-synchronization is performed.

  FIG. 6 is a flowchart showing the reception process of the primary channel in the embodiment of the present invention.

  V. After 8 procedures / probing / training (S1), the control channel is entered and the T.T. 30 handshakes are performed (S2). Move to the primary channel and retrain (S3). After retraining, it is determined whether or not VoIP compatible processing that is resistant to instantaneous interruption is performed (S4). If VoIP processing is performed, the control register RTDIS of the modem is turned off and retraining is permitted (S5). If not, the modem control register RTDIS is turned on in the same way as in the conventional processing to prohibit retraining of the modem (S6). Thereafter, while receiving the image data (S7), the processing from (S8 to S11, S13) is repeated to monitor the end condition of the primary channel.

  The control channel is monitored by the received signal monitoring means (S8). If the control channel is started (S14), the control channel is not started. If the control channel is not started, 40 before the Turn-off indicating the end of the primary channel. The reception of the continuous transmission of 1 bit is monitored (S9), and if the continuous transmission of 1 is detected, the process proceeds to (S14). If one continuous transmission is not detected, carrier disconnection monitoring is performed by the carrier disconnection detection means (S10). If the carrier interruption is detected (S12), if the carrier interruption is not detected, the reception signal quality determination means determines whether the EQM value is a normal value (S11). If the EQM value is not a normal value, the process proceeds to (S12), and if the EQM value is a normal value, the monitor judgment of the RCP signal attached after the image data is performed (S13). If no RCP has been received, the process returns to (S7) and the primary channel reception process is continued. If the RCP is received, the primary channel is terminated, so the modem control register RTDIS is turned off (S14), retraining is permitted, and control channel resynchronization can be performed, and the process proceeds to (A).

  FIG. 7 is a flowchart showing a transition process from the primary channel to the control channel in the embodiment of the present invention. Continuing from FIG. 6A, the end of the primary channel is detected and the control channel is waited for resynchronization.

  The control channel resynchronization waiting Tx timer is started (S15). It is a timer that ends in error when resynchronization is not possible. The control channel is resynchronized to determine whether the control channel is in communication (S16). If the control channel has started, the process proceeds to (C) and T. 30 procedure processes are performed.

  If the control channel is not started, it is determined whether or not the VoIP compatible process is to be performed (S17). If the VoIP compatible process is not to be performed, the process returns to S16 and waits for the start of the control channel. When performing VoIP-compatible processing, it is monitored in S18 whether or not the transmitter side has started control channel retraining (AC signal detection) (S18). When an AC signal is detected, since the control channel / retrain is started from the transmitter side, the retrain timer for starting the control channel / retrain next is started without starting the retrain from the receiver side ( S19). Next, it is monitored whether there is an error in the connection state of the modem on the transmitter side and the receiver side (S20). If there is an error, control channel retrain is started (S22), and the control channel is resynchronized. If not, a retrain timer for starting retraining is started again (S23). If there is no error in the modem connection state in S20, if the retrain timer is monitored in S21 and timed out, the control channel / retrain is started (S22), and the control channel is not re-synchronized. A retrain timer for starting retraining again is started (S23). In S24, the control channel resynchronization town timer Tx is confirmed, and if it has timed out, the process proceeds to (B) and ends in error.

  FIG. 8 is a flowchart showing reception processing on the control channel in the embodiment of the present invention. Continuing from FIG. 7C, the control channel state is determined, and if resynchronization is required, the control channel is resynchronized.

  T.A. The T2 timer and the retrain timer at 30 are started (S27), and the control channel state and the retrain timer value are determined (S28). When the control channel cannot communicate or when the retrain timer is up, the control channel state details are determined (S29). When the transmitter AC signal is detected, the control channel retrain is started from the transmitter, so the abort in the modem is canceled (S30), and the retrain starts again if the control channel is not resynchronized. To start the retrain timer (S31) and return to D (S28). If there is an error in the modem connection state on the transmitter side and the receiver side, the abort of the modem is canceled (S32), control channel retrain is started (S33), and the process proceeds to S31. When the retrain timer expires, control channel retrain is started (S34), and the process proceeds to S31.

  If the control channel can communicate without the retrain timer being timed out in S28, T.S. The command reception process at 30 is performed (S35). If no command has been received, a T2 timeout decision is made (S36). If no timeout has occurred, the process returns to S28 to continue the control channel reception process. If T2 has timed out in S36, the line is opened and the communication is terminated with an error (S37). If an instruction is received in S35, it is determined whether or not there is a next page (S38). If there is a next page, the process proceeds to (E) and the process proceeds to a training sequence reception process. If there is no next page in S38, the line is opened and the communication is normally terminated (S39).

The network relationship figure which shows the increase in facsimile communication via an IP network. FIG. 3 is a mechanism diagram showing the occurrence of voice quality degradation in an IP network. The sequence diagram which showed the process in which a line failure generate | occur | produces in the conventional process and an error end. It is a block diagram which shows the structure of the communication apparatus concerning Example 1 of this invention. The sequence diagram which showed a mode that the line failure in Example 1 of this invention was avoided. The flowchart which shows the reception process of the primary channel in Example 1 of this invention. The flowchart which shows the transition process from the primary channel in Example 1 of this invention to a control channel. 5 is a flowchart showing reception processing on a control channel in Embodiment 1 of the present invention.

Explanation of symbols

101 CPU
102 ROM
103 RAM
104 Storage memory (image memory)
105 Resolution conversion processor
106 Coding decoding processing unit for reading and recording
107 Clock
108 modem
109 NCU (line if section)
110 telephone
111 VoIP router
112 IP network
113 Image processor
114 Sheet scanner
115 book scanner
116 Control panel
117 line buffer
118 Print buffer
119 Printer

Claims (4)

ITU-T Recommendation V. V. performs communication according to the 34 standard. 34 communication means. 34. Carrier loss detection means for detecting carrier loss during reception of the primary channel 34, reception signal quality determination means for determining the quality of the data signal being received, 34, a facsimile apparatus having a reception signal monitoring means for monitoring a reception signal at the time of communication and an RCP detection means for detecting a signal (RCP) indicating the rear end of image data received by a primary channel;
After detecting the carrier interruption in the primary channel by the carrier interruption detecting means, after detecting the divergence of the modem in the primary channel by the received signal quality judging means, or from the primary channel on the transmitter side by the received signal monitoring means If the control channel is not resynchronized after detecting the transition to the channel or within a certain time after detecting the trailing edge of the image data received by the RCP detection means on the primary channel, the control channel retrain is performed. A facsimile apparatus characterized by resynchronizing the control channel.   The control channel retrain is repeatedly performed at regular intervals until the control channel resynchronization is performed when the control channel resynchronization is not performed within a certain time after the control channel retrain is performed. 1. The facsimile apparatus according to 1.   If an error is detected in the connection status of the transmitter and receiver modems within a certain period of time after the control channel retrain is performed, the control channel retrain is repeated at regular intervals until control channel resynchronization is performed. The facsimile apparatus according to claim 2, wherein the facsimile apparatus is performed.   If the control channel retrain (AC signal) on the transmitting side is detected at the timing when the receiver side performs control channel retraining, the receiver side does not start the control channel retraining at regular intervals. 3. The facsimile apparatus according to claim 2, wherein a timer for starting the control channel retrain is extended.

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