JP2005223412A - IP network facsimile machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent fluctuations in communication quality by absorbing fluctuations in the arrival interval of IP packets with a relatively simple configuration in facsimile communication via an IP network.
A VoIP processing unit (12) that generates a data signal by decoding a voice frame in which facsimile data is stored, and a FAX processing unit that receives and demodulates a data signal transmitted from the VoIP processing unit ( 13), and the reception operation of the FAX processing unit is a synchronization signal (BITCLK) for synchronizing with the VoIP processing unit, and a start signal (SPCLK) for signaling the start of transmission of the bit string of the target data in the data signal In the IP network facsimile apparatus (1) adjusted by the above, the VoIP processing unit adds a bit string of the indicator data for identifying the presence / absence of the bit string of the target data in the data signal according to the start signal, and performs the FAX processing. The section is configured to determine whether the data signal is valid or invalid based on the sign information.
[Selection] Figure 1

Description

  The present invention relates to an IP network facsimile apparatus capable of communicating via an IP network by VoIP (Voice over Internet Protocol).

  In recent years, VoIP technology for realizing voice calls on IP networks has been rapidly developed, and facsimile devices can communicate on IP networks by transmitting and receiving IP packets by regarding facsimile signals as voice signals. Existed.

With regard to this type of technology, for example, transmission / reception means for performing transmission / reception of information, IP network interface means capable of setting a communication connection to the counterpart device, decoding means for decoding received IP packets, and transmission 2. Description of the Related Art An IP network communication facsimile apparatus that includes an encoding unit that encodes information to be packetized and the like and enables communication with a counterpart apparatus via an IP network is known (see, for example, Patent Document 1). ).
JP 2002-101256 A

  By the way, in the conventional facsimile communication via the PSTN (Public Switched Telephone Network), once communication between facsimile apparatuses is established, the facsimile data transmitted by the transmission side apparatus is not interrupted at the same speed. Usually received by the device.

  On the other hand, in facsimile communication via an IP network based on VoIP, facsimile data is divided into IP packets at the transmission side device, and each is sent with a label including IP address information as a destination. In this case, even if the IP packet is transmitted from the transmission side device at a constant cycle, the IP packet is received irregularly by the counterpart device due to fluctuations in the arrival interval of the IP packet due to transmission delay or the like. A change in the order of transmission may also occur.

  However, the technique as described in Patent Document 1 cannot appropriately cope with the fluctuation in the arrival interval of the IP packet as described above. Here, it is conceivable to provide a buffer for absorbing such fluctuations in the arrival interval of IP packets in the receiving unit of the counterpart device. However, if an overflow or underflow occurs in the buffer, it is necessary to discard or interpolate the data, which obstructs faithful reproduction of facsimile data and degrades communication quality. . Furthermore, even at the present time when the IP network has been developed, the need for facsimile communication via the PSTN that has been used conventionally is still high, and a facsimile apparatus that can use both the PSTN and the IP network with a simple configuration is desired.

  The present invention has been made on the basis of such knowledge. In facsimile communication via an IP network, a relatively simple configuration absorbs fluctuations in the arrival interval of IP packets and prevents deterioration in communication quality. An object of the present invention is to provide a facsimile apparatus for IP network that can be used.

  In order to solve the above-mentioned problems, a facsimile apparatus for IP network according to the present invention comprises a VoIP processing unit for decoding a voice frame storing facsimile data to generate a data signal, and a VoIP A FAX processing unit that receives and demodulates a data signal transmitted from the unit, and the reception operation of the FAX processing unit is a synchronization signal for synchronizing with the VoIP processing unit, and target data in the data signal An IP network facsimile apparatus that is adjusted by a start signal for signaling the start of transmission of a bit string, wherein the VoIP processing unit is an indicator for identifying the presence or absence of the bit string of the target data in the data signal according to the start signal A bit string of data is added, and the FAX processing unit determines whether the data signal is valid or invalid based on the sign information.

  According to this, even when an invalid data signal that does not include the bit string of the target data is generated in the facsimile communication via the IP network due to fluctuations in the arrival interval of the IP packet, the FAX processing unit determines whether the data signal is valid or invalid. Since it is possible to determine and obtain only a valid data signal including a bit string of the target data while ignoring the invalid data signal, it is possible to prevent a reduction in communication quality.

  Further, since the FAX processing unit can always receive a data signal without interruption in a predetermined cycle regardless of the generation of an invalid data signal that does not include a bit string of the target data, a facsimile via a conventional public switched telephone network Data processing similar to communication can be performed.

  According to a second aspect of the present invention, an analog front end connected to the FAX processing unit for performing facsimile communication via the public switched telephone network is further provided, and the receiving operation of the FAX processing unit is synchronized with the analog front end. And a start signal for signaling the start of transmission of the bit string of the target data in the data signal from the analog front end.

  Thereby, by sharing the FAX processing unit, it becomes possible to cope with facsimile communication via the IP network and the public switched telephone network with a relatively simple configuration.

  Further, as shown in claim 3, the frequency of the synchronization signal for the FAX processing unit to synchronize with the VoIP processing unit is the frequency of the synchronization signal for the FAX processing unit to synchronize with the analog front end. It can be set as the structure which is 2 times the magnitude | size.

  This ensures the flexibility of the timing of receiving the target data in the facsimile communication via the IP network, and even if an invalid data signal that does not include the bit string of the target data is generated due to fluctuation of the arrival interval of the IP packet, the communication can be performed. The deterioration of quality can be prevented more effectively.

  Further, as shown in claim 4, the data signal transmitted from the VoIP processing unit includes a bit string of the target data having an 8-bit length and a bit string of the indicator information having an 8-bit length, and the data signal transmitted from the analog front end is It can be configured to include a bit string of target data having a length of 8 bits.

  As described above, according to the present invention, even when an invalid data signal that does not include target data is generated due to fluctuations in the arrival interval of IP packets in facsimile communication via an IP network, it is determined whether the data signal is valid or invalid. Since only valid data signals including target data can be acquired, it is possible to prevent deterioration in communication quality.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a schematic configuration of an IP network facsimile apparatus according to the present invention. The IP network facsimile apparatus 1 performs facsimile communication via the conventional PSTN 3 with the facsimile apparatus 2 as a counterpart apparatus, and is connected to the facsimile apparatus 4 and VoIP-TA 5 with built-in VoIP-TA (VoIP Telephony Adapter). Facsimile communication via the IP network 7 is made possible by using the facsimile apparatus 6 as a partner apparatus, and includes a transmission / reception unit 11, a VoIP processing unit 12, a FAX processing unit 13, a control unit 14, and an AFE (analog front end) 15; have.

  The transmission / reception unit 11 constitutes an interface with the IP network, converts an IP packet storing facsimile data received from the counterpart device into a voice frame and outputs the voice frame to the VoIP processing unit. Voice frames are converted into IP packets and transmitted to the destination via the IP network.

  The VoIP processing unit 12 performs conversion between a voice frame and voice data. The decoder 21 that generates a data signal including target data (image data or the like) by decoding the audio frame input from the transmission / reception unit 11 in accordance with H.711, the decoder memory 22 that functions as a frame buffer, and the modem 31 A bit clock (BITCLK; for synchronizing operations of the encoder 23, the encoder memory 24, the VoIP processing unit 12, and the modem 31). A clock generator 25 for generating a sampling clock (SPCLK; start signal) for signaling the start of transmission and a modem interface (I for transmitting and receiving data to and from the modem 31). / F) part 26.

  The FAX processing unit 13 modulates and demodulates facsimile data and records and reads an image. The FAX processing unit 13 converts voice data from the counterpart device into facsimile data in accordance with the G3 facsimile communication procedure. A modem 31 that converts facsimile data from the facsimile apparatus 1 into voice data, a recording unit 32 that records a facsimile image on a recording medium, a reading unit 33 that reads a document image and generates image data, and a FAX processing unit 31 are provided. And a central processing unit (CPU) 34 for overall control.

  The control unit 14 comprehensively controls the transmission / reception unit 11, the VoIP processing unit 12, and the like.

  The AFE 15 is an interface connected to the modem 31 to perform facsimile communication via the PSTN 3, and D / A converts a transmission signal from the IP network facsimile apparatus 1, while converting a reception signal from the counterpart apparatus into an A / It has a function of D conversion.

  When the facsimile apparatus 1 for IP network configured as described above receives facsimile data via the IP network, first, the transmission / reception unit 11 receives the IP packet storing the facsimile data, and converts the IP packet into a voice frame. At the same time, the data information is analyzed to determine whether IP packets are replaced. When the audio frame is output from the transmission / reception unit 11, the audio data is generated by being decoded by the decoder 21 of the VoIP processing unit 12.

  This audio data is sent as a predetermined data signal to the modem 31 of the FAX processing unit 13 via the modem I / F unit 26. Here, the transmission / reception operation of the modem I / F unit 26 and the modem 31 is synchronized by the bit clock (BITCLK) generated by the clock generation unit 25, and sampling generated at a constant cycle with respect to the bit clock. The start of transmission of the target data is signaled by the clock (SPCLK), and the data (RXD) is sent from the AFE 15 or the VoIP processing unit 12 to the modem 31. The voice data is demodulated by the modem 31, and recording processing is performed in the recording unit 32 based on the facsimile data acquired here.

  FIG. 2 is a conceptual diagram showing the timing of data transmission / reception between the VoIP processing unit and the modem in the IP network facsimile apparatus shown in FIG. 2A shows the timing of data received by the modem 31 from the VoIP processing unit 12 in facsimile communication via the IP network 7, and FIG. 2B shows the modem 31 in facsimile communication via the PSTN 3. Shows the timing of data received from the AFE 15, and the respective timings are shown on substantially the same time axis.

  In facsimile communication via PSTN3, devices are generally connected point-to-point each time, so that a single dedicated line is realized, so that facsimile data sent from the partner device is It is received by AFE without interruption at the same speed. Therefore, as shown in FIG. 2B, all the bit strings D0 to D7 of the 8-bit target data sent from the AFE 15 according to the sampling clock are received by the modem 31 as valid data signals.

  On the other hand, in the facsimile communication via the IP network 7, the arrival interval of the IP packet fluctuates due to transmission delay or the like. Therefore, as shown in FIG. 2A, in order to provide flexibility in the timing of data transmission / reception, the bit clock frequency is set to twice that of AFE15 and 16 bits including the target data according to the sampling clock. A bit string of long indicator data is transmitted.

  The first 8 bits of this 16-bit bit string are a flag (label data) for identifying the presence or absence of the bit string of the target data. When this flag is ON (F = 1), it indicates that the 8-bit bit string D0 to D7 following the flag is the target data (valid data signal), while the flag is OFF (F = 0). In this case, the bit string following the flag indicates an invalid data signal that does not include the target data. As a result, the modem 31 can determine whether the data signal is valid or invalid, discard the invalid data signal, and acquire only the valid data signal.

  In addition, the sampling clock generated at a constant period with respect to the bit clock is generated twice in the case of the VoIP processing unit 12 as compared with one generation in the case of the AFE 15, and as a result, the transmission timing of the target data is also increased. Doubled.

  Here, as a preferred example, the frequency of the bit clock is twice as large as that of the frequency in the case of AFE15. However, in some cases, the frequency of the bit clock is an arbitrary integral multiple of the reference frequency. It is also possible to set to. Also, the bit lengths of the target data and the indicator data can be changed.

  The facsimile apparatus for an IP network according to the present invention enables a valid data signal including target data even when an invalid data signal not including target data is generated due to fluctuations in an IP packet arrival interval in facsimile communication via the IP network. Therefore, it is possible to prevent the communication quality from being deteriorated, and it is useful as a facsimile apparatus capable of communicating via the IP network by VoIP.

1 is a block diagram showing a schematic configuration of an IP network facsimile apparatus according to the present invention. Schematic diagram showing timing of data transmission / reception between VoIP processing unit and modem

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Facsimile apparatus for IP networks 7 IP network 11 Transmission / reception part 12 VoIP processing part 13 FAX processing part 14 Control part 15 AFE (analog front end)

Claims (4)

A VoIP processing unit for decoding a voice frame storing facsimile data to generate a data signal; and a FAX processing unit for receiving and demodulating a data signal transmitted from the VoIP processing unit. The receiving operation is an IP network facsimile apparatus adjusted by a synchronization signal for synchronizing with the VoIP processing unit and a start signal for signaling the start of transmission of a bit string of the target data in the data signal. ,
In accordance with the start signal, the VoIP processing unit adds a bit string of marker data for identifying the presence or absence of a bit string of target data in the data signal, and the FAX processing unit uses the marker information to identify the data signal. An IP network facsimile apparatus characterized by determining validity or invalidity.   An analog front end connected to the FAX processing unit to perform facsimile communication via a public switched telephone network, and the reception operation of the FAX processing unit is a synchronization signal for synchronizing with the analog front end. 2. The IP network facsimile apparatus according to claim 1, wherein the IP network facsimile apparatus is adjusted by a start signal for signaling the start of transmission of a bit string of target data in a data signal from the analog front end.   The frequency of the synchronization signal for the FAX processing unit to synchronize with the VoIP processing unit is twice the frequency of the synchronization signal for the FAX processing unit to synchronize with the analog front end. 3. The facsimile apparatus for an IP network according to claim 2, wherein: The data signal transmitted from the VoIP processing unit includes a bit string of 8-bit target data and a bit string of 8-bit indicator information, and the data signal transmitted from the analog front end is 8-bit target data. 4. The facsimile apparatus for an IP network according to claim 2, further comprising:

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