JP2011049640A - Facsimile reception device, facsimile reception method, and facsimile reception program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a facsimile reception device, a method, and a program which can secure the quality of facsimile communication using the Internet network while keeping the tolerance of the fluctuation of a reception signal. <P>SOLUTION: A facsimile reception device 10 includes a threshold setting means 13 which sets a plurality of kinds of thresholds as a time in which a received packet signal can be stored in a buffer memory 11 in accordance with the length of a time to time-out of the received packet signal. For the reception of image data, a threshold longer than that for a control signal can be set. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a facsimile reception apparatus, a facsimile reception method, and a facsimile reception program, and more particularly to a facsimile reception apparatus, a facsimile reception method, and a facsimile reception program that receive a packet signal from a transmission side.

  By converting a facsimile signal into a packet signal and transmitting it, facsimile communication using the Internet network becomes possible. By using the Internet network, the communication cost required for facsimile communication can be greatly reduced, but various failures such as packet delay, fluctuation, loss, and bit error may occur. Among such communication failures, for example, when a failure occurs in which a packet is partially delayed, the arrival order of the images is out of order, and if this is reproduced as it is, a correct image cannot be formed. .

  Therefore, a first related technique has been proposed that absorbs fluctuations among various factors that cause communication failures that occur on the Internet (see, for example, Patent Document 1). In the first related technique, a fluctuation absorbing buffer is provided as a buffer memory for absorbing fluctuation on the network. The received voice packet is temporarily stored in the fluctuation absorbing buffer, and when a predetermined threshold value is reached, data transfer to a codec unit (not shown) is started.

  FIG. 18 is a diagram for explaining data transfer from the fluctuation absorbing buffer to the codec unit according to the first related technique of the present invention. FIG. 4A shows the state of the fluctuation absorbing buffer before starting facsimile communication. The fluctuation absorbing buffer 101 stores packets in units of 20 ms (milliseconds), for example. In this example, a threshold value 102 for transferring data to the codec unit is set at a position in the fluctuation absorbing buffer 101 that accommodates packets up to 140 ms.

FIG. 2B shows a relatively initial state in which a packet is received by the fluctuation absorbing buffer after facsimile communication is started. The fluctuation absorbing buffer 101 receives the first to eighth packets 103 _{1 to} 103 ₈ indicated by circled numbers in order. To the seventh packet 103 ₇ is a reception amount of the threshold value 102 or less, when a packet 103 ₈ eighth is received exceeds a threshold value 102. Therefore, shifts packet 103 _{2-103 8} of the second to eighth the fluctuation absorbing buffer 101 to the left in FIG one compartment, as shown in FIG. (C), ₁ is the first packet 103 It is passed to the codec unit 104 in an extruded form. Hereafter, the ninth packet 103 ₉ is received, the second packet 103 ₂ is to be passed to the CODEC unit 104 in the same manner.

  As described above, in the first related technique, the packet is stored in the fluctuation absorbing buffer 101 until the threshold value 102 is reached. For this reason, in the facsimile apparatus including the fluctuation absorbing buffer 101 and a jitter buffer having the same function (hereinafter simply referred to as a jitter buffer), processing of received data is sequentially delayed. Further, as the threshold value 102 of the jitter buffer is set larger, the tolerance to fluctuation increases, but the delay generated in the facsimile apparatus also increases.

  When the signal delay increases in this way, the transmission side facsimile apparatus increases the waiting time until the response signal is received from the reception side after the signal is transmitted. As a result, the response signal cannot be received within the specified time, causing a timeout, resulting in an increased risk of causing a communication error.

  Therefore, it is proposed in the second related technology of the present invention to check the delay state of the Internet network before the start of facsimile communication (see, for example, Patent Document 2). In the second related technique, communication of an echo request and an echo response in ICMP (Internet Control Message Protocol) is periodically performed between IP communication apparatuses. Then, the time from when one IP communication device sends an echo request to the other IP communication device until the echo response arrives at one IP communication device is measured. Depending on the measurement result, the corresponding line between the IP communication devices is controlled to be blocked and released, and notification to that effect is given to the appropriate device, and an error may occur after link establishment. Is reduced.

  Further, when the delay state of the Internet network exceeds a predetermined time, switching from facsimile communication on the Internet network to facsimile communication on the public network has been proposed as a third related technique of the present invention (for example, a patent) Reference 3). In the third related technique, when the delay state of the Internet network exceeds a predetermined time, the communication is switched to the facsimile communication on the public line network regardless of whether or not a communication error has actually occurred in the facsimile communication on the Internet network.

Japanese Patent Laying-Open No. 2006-121176 (paragraph 0041, FIG. 2) JP2003-258902A (paragraph 0006) JP 2006-033258 (paragraph 0024, FIG. 3)

  However, when the second related technique is adopted, the line is blocked for control, and there is a problem that facsimile communication itself cannot be performed.

  In addition, when the third related technology is adopted, there is a problem that communication on the public line network costs more than communication on the Internet network.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a facsimile receiving apparatus, a facsimile receiving method, and a facsimile receiving program capable of ensuring the quality of facsimile communication using the Internet network while maintaining the tolerance of fluctuation of received signals.

  In the present invention, (a) a buffer memory for storing packet signals received from a transmission source in facsimile communication using the Internet network in the order of reception; and (b) a packet signal stored in the buffer memory with a predetermined threshold from storage. Received signal decoding means for sequentially taking out and decoding the signals exceeding the indicated time, and (c) according to the length of time until timeout as a time limit for responding to the received packet signal. The facsimile receiving apparatus includes threshold setting means for setting a plurality of threshold values.

  In the present invention, (a) facsimile communication using the Internet network by measuring the time required to request a response from the facsimile transmission apparatus at the start of facsimile communication using the Internet network and return the response. (B) a reception step for storing packet signals received from a transmission source in the above-described facsimile communication in a buffer memory in the order of reception; and (c) a reception step described above in this reception step. A received signal decoding step for sequentially extracting and decoding the signals exceeding the time indicated by the predetermined threshold from the stored packet signals stored in the buffer memory, and (d) the communication determined in the delay status determining step described above Delay time and time as a time limit for responding to the received packet signal Facsimile receiving method and threshold setting step of setting a threshold above the plurality of types are provided according to the length of time until the out.

  Further, according to the present invention, as a facsimile reception program, the computer requests (a) a response time from the facsimile transmission apparatus at the start of facsimile communication using the Internet network and measures the time until the response is returned. (B) a reception process for storing packet signals received from a transmission source in the above-described facsimile communication in the buffer memory in the order of reception; A reception signal decoding process for sequentially extracting and decoding the signals that have exceeded the time indicated by the predetermined threshold from the stored packet signals stored in the buffer memory in the reception process; and (d) the delay situation described above It responds to the communication delay status determined in the determination processing and the received packet signal. Executing the threshold value setting processing for setting a threshold value and in response to said length of time until the timeout as temporal limit to a plurality of kinds.

  As described above, according to the present invention, the signal storage time in the buffer memory that stores the packet signals in the order of reception is determined according to the length of time until timeout as a time limit for responding to the received packet signal. A plurality of threshold values representing the upper limit are set. Thereby, the quality of the received signal can be improved while avoiding timeout.

It is a claim corresponding | compatible figure of the facsimile receiver of this invention. It is a claim corresponding | compatible figure of the facsimile receiving method of this invention. It is a claim corresponding | compatible figure of the facsimile reception program of this invention. 1 is a system configuration diagram showing an overview of a facsimile communication system according to a first embodiment of the present invention. It is explanatory drawing which showed the relationship between the jitter buffer threshold value in this Embodiment, a temporary threshold value, and a timeout value. It is a flowchart showing the mode of the determination process of the jitter buffer threshold value performed at the time of the start of the reception operation | movement of the facsimile receiving terminal in this Embodiment. It is explanatory drawing which showed an example in which the jitter buffer threshold value A, B, C was set according to the delay amount of IP network in this Embodiment. It is a flowchart showing the situation of the reception process of the facsimile receiving terminal after storing the jitter buffer threshold value in the jitter buffer in the present embodiment. FIG. 9 is a flowchart specifically showing the image data reception process shown in step S336 of FIG. 8. FIG. 10 is a flowchart specifically showing a modification of the image data reception process shown in FIG. 9 as a first modification of the present invention. It is a block diagram showing the outline | summary of the structure of the facsimile receiving terminal in the 2nd modification of this invention. It is explanatory drawing which showed the relationship between the jitter buffer threshold value and timeout value at the time of taking Taro in a 2nd modification as an example. It is a flow chart showing the situation of calculation and registration processing of jitter buffer threshold AA after average delay value I calculation in the 2nd modification. It is a flowchart showing the mode of the storing process of new jitter buffer threshold value AA, BB, and CC in the 2nd modification. It is explanatory drawing which showed the relationship between a jitter buffer threshold value and a timeout value in case a sender is not registered in the threshold value memory | storage part in the 2nd modification. It is a block diagram showing the outline | summary of the structure of the facsimile receiving terminal in the 3rd modification of this invention. It is a flowchart showing the mode of the rewriting control of the jitter buffer threshold value in the 3rd modification. It is explanatory drawing which showed the delivery of the data from the fluctuation absorption buffer by the 1st related technique of this invention to a codec part.

  FIG. 1 is a diagram corresponding to the claims of the facsimile receiving apparatus of the present invention. The facsimile receiving apparatus 10 according to the present invention includes a buffer memory 11, a received signal decoding unit 12, and a threshold setting unit 13. Here, the buffer memory 11 stores packet signals received from a transmission source in facsimile communication using the Internet network in the order of reception. The received signal decoding means 12 sequentially extracts signals that have exceeded the time indicated by the predetermined threshold from the stored packet signals stored in the buffer memory 11 and decodes them. The threshold setting unit 13 sets the above-described thresholds to a plurality of types according to the length of time until timeout as a time limit for responding to the received packet signal.

  FIG. 2 is a diagram corresponding to claims of the facsimile receiving method of the present invention. The facsimile reception method 20 of the present invention includes a delay state determination step 21, a reception step 22, a reception signal decoding step 23, and a threshold setting step 24. Here, in the delay state determination step 21, a facsimile using the Internet network is measured by measuring the time until a response is returned to the facsimile transmission apparatus at the start of facsimile communication using the Internet network. A communication delay state in communication is determined. In the reception step 22, the packet signal received from the transmission source by facsimile communication is stored in the buffer memory in the order of reception. In the reception signal decoding step 23, the packet signals stored in the buffer memory in the reception step 22 are sequentially extracted from the stored signals exceeding the time indicated by the predetermined threshold value and decoded. In the threshold setting step 24, a plurality of types of the above-described thresholds are selected according to the communication delay status determined in the delay status determination step 21 and the length of time until timeout as a time limit for responding to the received packet signal. Set to.

  FIG. 3 is a diagram corresponding to the claims of the facsimile reception program of the present invention. The facsimile reception program 30 of the present invention causes a computer to execute a delay state determination process 31, a reception process 32, a received signal decoding process 33, and a threshold setting process 34. Here, in the delay status determination processing 31, a facsimile using the Internet network is measured by requesting a response from the facsimile transmission apparatus at the start of facsimile communication using the Internet network and measuring the time until the response is returned. A communication delay state in communication is determined. In the reception process 32, packet signals received from the transmission source by facsimile communication are stored in the buffer memory in the order of reception. In the received signal decoding process 33, signals that have exceeded the time indicated by the predetermined threshold from the stored packet signals stored in the buffer memory in the receiving process 32 are sequentially extracted and decoded. In the threshold value setting process 34, a plurality of types of threshold values described above are used according to the communication delay state determined in the delay state determination process 31 and the length of time until timeout as a time limit for responding to the received packet signal. Set to.

  <First Embodiment of the Invention>

  Next, a first embodiment of the present invention will be described.

  FIG. 4 shows an outline of the facsimile communication system according to the first embodiment of the present invention. The facsimile communication system 200 has a configuration in which a facsimile transmission terminal 201 and a facsimile reception terminal 202 are connected via an IP (Internet Protocol) network 203 as a voice communication path.

  The facsimile receiving terminal 202 includes a communication interface unit 211, a control unit 212, a jitter buffer 213, a jitter buffer control unit 214, a codec unit 215, a threshold value calculation unit 216, a threshold value storage unit 217, and a reception common function unit 218. Here, the communication interface unit 211 communicates with the facsimile transmission terminal 201 via the IP network 203. The control unit 212 includes a CPU (Central Processing Unit) 221 and a memory 222 such as a ROM (Read Only Memory) storing a control program executed by the CPU 221, and controls the entire facsimile receiving terminal 202. The jitter buffer control unit 214 performs processing of the jitter buffer 213. The codec unit 215 decompresses the encoded image data. The threshold calculation unit 216 calculates the threshold of the jitter buffer 213. The threshold storage unit 217 stores a threshold of the jitter buffer 213 used in facsimile communication. The common reception function unit 218 is a circuit component that is commonly provided in the facsimile reception terminal 202, such as an operation unit (not shown), a display unit, or a printer unit that performs printing.

  The facsimile transmission terminal 201 has a general configuration as a transmission-side facsimile apparatus. Therefore, description of the configuration of the facsimile transmission terminal 201 is omitted.

  FIG. 5 shows the relationship between the jitter buffer threshold, the temporary threshold, and the timeout value in the present embodiment. This will be described with reference to FIG.

In this embodiment, it is assumed that there are three types of timeout values as the time until timeout of a signal exchanged between the facsimile transmission terminal 201 and the facsimile reception terminal 202. Of these, there are two types of timeout values T ₁ and T ₂ for signals not related to the reception of the image data itself, and one timeout value T ₁ is relatively long 35 ± 5 seconds. It is assumed that the other timeout value T ₂ is relatively short 6 ± 1 seconds. The timeout value for “image data reception” is not particularly defined here, but is generally longer than the timeout value T ₁ .

  The longer the timeout value, the lower the possibility of a communication error due to timeout even if the threshold value of the jitter buffer 213 is large. If the threshold value of the jitter buffer 213 is set to a large value, not only the tolerance to the temporal fluctuation of the arrival of the packet is increased, but also the possibility of relieving the delay of the packet described above becomes high, and the bit error is increased. There is also a high possibility of correcting. However, when the threshold value of the jitter buffer 213 increases, the signal processing is delayed inside the facsimile receiving terminal 202 as described above, and the probability of occurrence of timeout increases.

  Therefore, in the present embodiment, an ICMP (Internet Control Message Protocol) packet is transmitted at an initial stage when the facsimile receiving terminal 202 starts communication with the facsimile transmitting terminal 201. The ICMP packet is also called an ICMP echo request packet, and the facsimile transmission terminal 201 that receives the ICMP packet returns an ICMP echo response packet to the facsimile reception terminal 202.

The facsimile receiving terminal 202 can grasp the delay state of the IP network 203 by grasping the time when the ICMP echo request packet is transmitted and the time when the ICMP echo response packet is received and obtaining the time difference therebetween. . Thus, it is desirable to reduce the risk of timeout as much as possible by setting the threshold value of the jitter buffer 213 as small as possible when the delay of the IP network 203 is small. On the other hand, in a state where the delay of the IP network 203 is large, unless the threshold value of the jitter buffer 213 is set to a certain large value, it is difficult to absorb the temporal fluctuation of arrival of the packet. Further, the possibility of relieving packet delay and the possibility of correcting bit errors are reduced. For this reason, in the latter case, it is necessary to increase the threshold value of the jitter buffer 213 to the limit where no timeout occurs. Accordingly, when the delay amount of the IP network 203 is obtained using the ICMP echo request packet, the timeout values T ₁ and T ₂ and the timeout value for receiving image data can be adjusted accordingly.

For this reason, in this embodiment, the jitter buffer temporary thresholds a, b, and c are determined for the timeout values T ₁ and T ₂ and the timeout value for receiving image data, respectively. Then, the delay state of the IP network 203 is checked a plurality of times with an ICMP packet (ICMP echo request packet), and the average delay value I is obtained. The threshold calculation unit 216 corrects the jitter buffer temporary thresholds a, b, and c indicated by the arrow 231 according to the average delay value I indicated by the arrow 232, and the optimum jitter buffer threshold A, indicated by the arrow 233, B and C are calculated.

  However, the method of obtaining the delay amount of the IP network 203 using the ICMP echo request packet cannot be realized when the facsimile transmission terminal 201 does not support the ICMP response. Therefore, in such a case, the jitter buffer temporary thresholds a, b, and c as the thresholds serving as the reference for the jitter buffer 213 corresponding to the three types of signals or data are directly adopted as the threshold values of the jitter buffer. This is shown as arrow 234.

  FIG. 6 shows how the jitter buffer threshold is determined at the start of the reception operation of the facsimile receiving terminal. This will be described with reference to FIGS.

  When facsimile communication starts with the facsimile transmission terminal 201, the communication interface unit 211 of the facsimile reception terminal 202 receives a CNG (Calling tone) signal (step S301). When determining that the CNG signal has been received, the control unit 212 transmits an ICMP packet to the facsimile transmission terminal 201 using the communication interface unit 211 (step S302). The facsimile receiving terminal 202 waits for an ICMP echo response from the facsimile transmitting terminal 201.

  When an ICMP echo response is returned from the facsimile transmission terminal 201, the control unit 212 temporarily stores this time interval in the memory 222 (step S303). Then, it is determined whether the ICMP echo request packet has been transmitted a preset number of times (step S304). The preset number of times is an arbitrary integer value of 1 or more. If the ICMP echo request packet has not been sent a preset number of times (N), it is checked whether the time interval measurement process can be continued (step S305). If it is possible to continue (Y), the process returns to step S302, and the ICMP echo request packet is transmitted again.

  When the transmission of the ICMP echo request packet is executed a predetermined number of times as described above (step S304: Y), the threshold value calculation unit 216 averages the time intervals until each ICMP echo response packet is obtained. A value is obtained and set as an average delay value I (step S306). Next, the threshold value calculation unit 216 calculates and determines the jitter buffer threshold values A, B, and C using the average delay value I and the temporary threshold values a, b, and c (step S307). The jitter buffer threshold values A, B, and C obtained in this way are stored in the threshold value storage unit 217 (step S308), and a series of processes until the jitter buffer threshold value is stored ends (END).

  On the other hand, even if the ICMP echo request packet is transmitted, the time interval measurement may not be continued as in the case where the ICMP echo response packet is not returned from the facsimile transmission terminal 201. In such a case (step S305: N), the threshold value calculation unit 216 cannot calculate the jitter buffer threshold values A, B, and C. Therefore, in this case, the temporary threshold values a, b, and c are stored in the threshold storage unit 217 as temporary threshold values (step S309), and the process ends (END). However, for example, when the setting is made such that the ICMP echo response packet is acquired three times and the average value of these is obtained, partial continuation in which the ICMP echo response packet can be acquired only twice of these is continued. Unacceptable processing may occur. In such a case, the jitter buffer thresholds A, B, and C may be determined using time intervals at which measurement was successful.

FIG. 7 shows an example in which the jitter buffer thresholds A, B, and C are set according to the delay amount of the IP network. FIG. 6A shows a jitter buffer threshold A set in the jitter buffer 213 corresponding to the timeout value T ₁ . In this example, the jitter buffer threshold A is a value increased by ΔA from the provisional threshold a. This is because the average delay value I is slightly larger than the reference value.

FIG (B) is the jitter buffer threshold B is set in the jitter buffer 213 in response to a timeout value T _2. FIG. 6C shows a case where a jitter buffer threshold C in the jitter buffer 213 is set in correspondence with the reception of image data. A value increased by ΔB from the provisional threshold b is the jitter buffer threshold B, and a value increased by ΔC from the provisional threshold c is the jitter buffer threshold C.

  The three types of jitter buffer thresholds A, B, and C shown in FIG. 6 are switched depending on the type of signal or data received by the facsimile receiving terminal 202 shown in FIG. This will be described next as processing subsequent to FIG. 6 in the facsimile receiving terminal 202.

  FIG. 8 shows the reception process of the facsimile receiving terminal after the jitter buffer threshold value is stored in the jitter buffer. This will be described with reference to FIGS.

  The facsimile receiving terminal 202 transmits a CED (Called Station Identification) signal as a response to the reception of the CNG signal in Step S301 of FIG. 6 from the facsimile transmitting terminal 201 in the line establishment sequence stage (Step S321). At this timing, the control unit 212 reads the threshold value A of the jitter buffer from the threshold value storage unit 217, and changes the threshold value of the jitter buffer 213 to the threshold value A (step S322). Then, DIS (digital identification signal) is transmitted from the communication interface unit 211 (step S323).

Next, the control unit 212 determines whether a response is received from the facsimile transmission terminal 201 within the time indicated by the timeout value T ₁ with respect to the DIS (steps S324 and S325). If there is no response within the time indicated by the timeout value T ₁ (step S324: N, step S325: Y), it is checked whether the DIS transmission at step S323 exceeds the preset maximum number of trials. (Step S326). If the maximum number of trials has not been exceeded (N), the process returns to step S323, and DIS is transmitted from the communication interface unit 211. On the other hand, if the maximum number of trials is exceeded if the DIS is sent next (step S326: Y), the line is disconnected because a communication error has occurred (step S327), and the process is terminated (step S327). End).

  On the other hand, when there is a response to the DIS from the facsimile transmission terminal 201 in step S324 (Y), DCS (digital command signal) reception is performed (step S328). Then, after receiving a TCF (Training check) signal (step S329), the communication interface unit 211 sends a CFR (confirmation to receive) signal (step S330).

  Next, using the transmission of the CFR signal as a trigger, the control unit 212 reads the threshold value B of the jitter buffer 213 from the threshold value storage unit 217, and changes the jitter buffer threshold value A to the jitter buffer threshold value B (step S331). As shown in FIG. 7, the value of the jitter buffer threshold A is larger than the value of the jitter buffer threshold B. For this reason, the jitter buffer 213 is in a state where packets are accumulated up to an area exceeding the jitter buffer threshold B. Therefore, the jitter buffer control unit 214 deletes the silent packet among these packets (step S332). A silence packet is received from the reception of the TCF signal in step S329 to the start of reception of image data described later. Therefore, even if the threshold value of the jitter buffer 213 is changed at the time of step S331, the facsimile communication is not affected.

When the packets accumulated in the jitter buffer 213 are deleted in this way, the process proceeds to step S333 and subsequent steps. In the process of step S333, it is checked whether an instruction is received from the facsimile transmission terminal 201. When the command is not received from the facsimile transmission terminal 201 (N), it is checked whether image data is received (step S334). If neither the command nor the image data is received within the time indicated by the timeout value T ₂ (step S334: N, step S335: Y), the process proceeds to step S327, where it is determined as a communication error, the line is disconnected, and the processing is performed. End (end).

In the usual case, image data within a time indicated by the timeout value T ₂ is sent. In this case (step S334: Y), an image data reception process described in detail below is performed (step S336), and a series of processes is ended (end) by the end of this process.

Such image without reception of data is performed (step S334: N), if the other instructions from the facsimile transmitting terminal 201 is sent within the time indicated by the time-out value T ₂ (step S333: Y), The process after step S328 is performed.

  FIG. 9 specifically shows the image data reception process shown in step S336 of FIG. This will be described with reference to FIGS.

  When image data is received in step S334 of FIG. 8, the control unit 212 uses this as a trigger to read the threshold value C of the jitter buffer 213 from the threshold value storage unit 217, and to set the jitter buffer threshold value B to the jitter buffer threshold value. Change to C (step S351). Then, image data packets sequentially transmitted from the facsimile transmission terminal 201 via the communication interface unit 211 are stored in the jitter buffer 213 (step S352). At this time, as described with reference to FIG. 18, in a state where packets exceeding the jitter buffer threshold C are received, the packets sent out the oldest from the facsimile transmission terminal 201 are moved to the codec unit 215 one by one. . Therefore, a plurality of packets stored in an area that does not exceed the threshold value C in FIG. 7C are output in a time-aligned manner even if the order of reception is out of order before being sent to the codec unit 215. The

  The storage of the image data in the jitter buffer 213 is continued until an EOP (End Of Procedure Signal) indicating the end of the last one page is received from the facsimile transmission terminal 201 (step S353: N). When the EOP is received (Y), the control unit 212 returns an MCF (Message Confirmation) signal (step S354). When a DCN (Disconnect) signal is received from the facsimile transmission terminal 201 (step S355: Y), the line is disconnected (step S356), and the facsimile communication is ended (end).

  In the above description, the jitter buffer threshold values A, B, and C are set in the jitter buffer 213. However, when the jitter buffer threshold values A, B, and C cannot be calculated, the jitter buffer temporary threshold values a, b , C are naturally set instead.

  According to the embodiment described above, in the facsimile communication procedure, the timeout value of the response signal with respect to the transmitted signal is taken into consideration, and the jitter buffer 213 has a value corresponding to the timeout value of the response signal at a predetermined signal transmission timing. The threshold value is varied. This is because the timeout time of facsimile communication differs for each signal to be transmitted. As a result, in this embodiment, the jitter buffer threshold is increased during image data reception that is unlikely to cause a time-out error, and the number of packets stored in the buffer memory is increased, thereby enhancing resistance to fluctuations. On the other hand, in the section of the procedure signal that is likely to cause a timeout error, the jitter buffer threshold is made smaller than that during the reception of the image data to suppress the delay occurring in the terminal.

  ITU-T (International Telecommunication Union Telecommunication Standardization Sector) recommendation 30 defines timeout values as T0, T1, T2, T3, and T5. The timeout T0 defines the time for the called terminal to wait for a call to be answered in an automatic call. The timeout T1 defines the time during which the two terminals are trying to identify each other. In the timeout T2, a time for detecting a loss of command and response synchronization is determined. The timeout T3 defines the time during which the terminal is trying to alert the local operator in response to a procedure interruption. The timeout T5 is defined for TTC (Telecommunication Technology Committee) standard JT-T4 Error Correction Mode (ECM) and defines a waiting time for releasing the busy state of the receiving terminal.

  ITU-T recommendation In 30 standard facsimile communications, the values of T1 and T2 are mainly used as timeout values, and there are many cases of communication errors due to timeouts at T2. For this reason, in the present embodiment, the timeout values of T1 and T2 are dealt with, but the present invention is not limited to this. The same applies to a modified example of the present invention described later.

  ITU-T recommendation 30, the values of T1 and T2 are defined as 35 ± 5 seconds and 6 ± 1 seconds, respectively. In this embodiment, the threshold value for receiving image data is newly set in order to increase the jitter buffer threshold value during image data reception and increase the tolerance against fluctuation. In this embodiment, the threshold value of the jitter buffer 213 is changed to a value commensurate with the “timeout value of the response signal for signal transmission”. As a result, in the section of the procedure signal, it is possible to save from an error due to time-out. On the other hand, during image data reception, control that is resistant to fluctuations is possible. In this embodiment, the delay state on the network immediately before the facsimile communication is checked, and the threshold value of the jitter buffer 213 is set accordingly. Therefore, the facsimile considering the delay value of the network used in the facsimile communication is used. Communication is possible.

  <First Modification of Invention>

  In the embodiment described above, when reception of image data is started, the jitter buffer threshold B is changed to the jitter buffer threshold C in step S351 of FIG. 9, and the jitter buffer threshold C is held until the end of facsimile communication. I made it. The present invention is not limited to this. For example, when there are two or more pages of image data, the jitter buffer threshold value may be switched between the image data reception interval and other signal reception intervals.

  FIG. 10 specifically shows a modification of the image data reception process shown in FIG. 9 as a first modification of the present invention. This will be described with reference to FIGS. 4, 7 and 8. In FIG. 10, the same parts as those in FIGS. 8 and 9 are denoted by the same step numbers, and description thereof will be omitted as appropriate.

  When image data is received in step S334 of FIG. 8, the control unit 212 uses this as a trigger to read the threshold value C of the jitter buffer 213 from the threshold value storage unit 217, and to set the jitter buffer threshold value B to the jitter buffer threshold value. Change to C (step S351). Then, image data packets sequentially transmitted from the facsimile transmission terminal 201 via the communication interface unit 211 are stored in the jitter buffer 213 (step S352).

  The image data is stored in the jitter buffer 213 until EOP (End Of Procedure Signal) indicating the end of the last one page is received from the facsimile transmission terminal 201 (step S353) or MPS (Multi Page Signal) is received. Continue (step S401). MPS is a signal indicating that the next page is received.

  When the EOP is received (step S353: Y), since the reception of the last page is completed, the processing after step S354 is performed as described above, the line is disconnected in step S356, and the facsimile communication is performed. End (end).

  On the other hand, when MPS is received (step S353: N, step S401: Y), using this as a trigger, the threshold value B of the jitter buffer 213 is read from the threshold value storage unit 217, and the jitter buffer threshold value C is set to the jitter buffer. The threshold value is changed to B (step S402). Then, the process proceeds to the standby loop of steps S333 to S335 as described with reference to FIG. Here, when the command is received from the facsimile transmission terminal 201 (step S333: Y), the processing of step S328 to step S332 is performed, and the process returns to the standby loop of step S333 to step S335 again.

  If image data is received in step S334 (Y), the process returns to step S351, and the change from the jitter buffer threshold B to the jitter buffer threshold C is executed again. Then, processing for storing the image data of the corresponding page in the jitter buffer 213 is performed (step S352).

If the time indicated by the timeout value T ₂ has passed without receiving the above command or image data (step S333: N, step S334: N, step S335: Y), a communication error Is disconnected (step S403). Then, the image data reception process ends (END).

According to the first modification of the present invention described above, when a plurality of pages of image data are sent, the jitter buffer threshold is different between the interval in which the image data is received and the interval in which the control signal is received. did. Thus, while reducing the occurrence of a communication error due to a timeout value T _2, at the time of image data reception, it is possible to control resistant to fluctuations.

  <Second Modification of Invention>

  FIG. 11 shows an outline of the configuration of the facsimile receiving terminal according to the second modification of the present invention. In the facsimile receiving terminal 202A of the second modification, the same parts as those of the facsimile receiving terminal 202 shown in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  The facsimile receiving terminal 202A has a sender identification unit 501 newly. The sender identification unit 501 identifies a sender or a sender terminal from address information such as a telephone number of the facsimile transmission terminal 201 shown in FIG. The threshold calculation unit 216A calculates a jitter buffer threshold for each sender identified by the sender identification unit 501. The threshold storage unit 217A stores a jitter buffer threshold for each sender. In the threshold storage unit 217A, a Taro storage area 502 and a Hanako storage area 503 are shown as an example. The control unit 212A is provided with a memory 222A that stores a control program for controlling the facsimile receiving terminal 202A in the second modification. By executing this control program, the CPU 221 controls the facsimile receiving terminal 202A in the second modification.

  FIG. 12 shows the relationship between the jitter buffer threshold and the timeout value when Taro as a sender is taken as an example. This will be described with reference to FIGS. 4 and 11.

For Taro as a sender, three types of jitter buffer threshold values used in the previous facsimile communication are stored in the Taro storage area 502 of the threshold storage unit 217A. These are the jitter buffer threshold A ′ for the timeout value T ₁ , the jitter buffer threshold B ′ for the timeout value T ₂ , and the jitter buffer threshold C ′ for receiving image data.

  The threshold value calculation unit 216A checks the delay state of the IP network 203 a plurality of times with an ICMP packet at the start of communication this time, and calculates jitter buffer threshold values A, B, and C indicated by arrows 511. Then, learning is performed using the previously obtained jitter buffer threshold values A ′, B ′, and C ′ indicated by an arrow 512, and a new jitter buffer threshold value for Taro (new threshold value using a learning function) is indicated by an arrow 513. AA, BB, and CC are calculated. Facsimile communication is largely due to the current network conditions. For this reason, the newly calculated jitter buffer threshold values AA, BB, and CC have a weight of the jitter buffer threshold values A, B, and C calculated this time rather than the previously obtained jitter buffer threshold values A ′, B ′, and C ′. It is preferable to calculate so that it may become large.

  In the second modification, the jitter buffer threshold values AA, BB, and CC for Taro obtained in this way are used as three types of threshold values when receiving a facsimile from Taro. When the facsimile communication is completed, as indicated by an arrow 514, these jitter buffer threshold values AA, BB, CC are set as jitter buffer threshold values A ′, B ′, C ′ in the Taro storage area 502 of the threshold storage unit 217A. Overwrite.

  FIG. 13 shows how the jitter buffer threshold AA is calculated and registered after the average delay value I is calculated in the second modification described above. This will be described with reference to FIGS. 6, 11 and 12. The process shown in FIG. 13 corresponds to the process after step S306 in FIG. The same steps as those in FIG. 6 are denoted by the same step numbers, and description thereof will be omitted as appropriate.

  When the average delay value I is calculated in step S306 of FIG. 13, jitter buffer thresholds A, B, and C are calculated (step S307). Next, the control unit 212A identifies the sender by specifying the telephone number or address information of the facsimile transmission terminal 201 (FIG. 4) from the communication interface unit 211 (step S601). Then, it is checked whether or not the sender is registered in the threshold storage unit 217A (step S602).

  In the example shown in FIG. 11, the sender is “Taro”, and the Taro storage area 502 has been registered in the threshold storage unit 217A. As described above, when the sender is registered in the threshold storage unit 217A (step S602: Y), the jitter buffer threshold values A ′, B ′, and C ′ previously stored for the person are read from the threshold storage unit 217A. (Step S603). In the case where the sender is “Taro”, the jitter buffer thresholds A ′, B ′, and C ′ stored in the Taro storage area 502 are read.

  The threshold calculation unit 216A performs threshold calculation using the jitter buffer thresholds A, B, and C calculated in step S307 and the jitter buffer thresholds A ′, B ′, and C ′ read this time (step S604). Then, a new jitter buffer threshold value AA, BB, CC specialized for the sender “Taro” and the current average delay value I is determined (step S605), and the threshold value for the control signal and image data reception processing is determined. End the registration process (END). The control signal and image data reception processing after registration of the new jitter buffer threshold values AA, BB, and CC has already been described with reference to FIG.

  If it is determined in step S602 that the sender of the facsimile is not registered in the threshold storage unit 217A (N), the previous jitter buffer thresholds A ′, B ′, and C ′ for that person exist. Not done. Therefore, in this case, the process proceeds to step S604 as it is, and the jitter buffer threshold is calculated in a general human environment, and new jitter buffer thresholds AA, BB, and CC are determined (step S605).

  FIG. 14 shows how the new jitter buffer threshold values AA, BB, and CC are stored. This will be described with reference to FIGS. 4 and 11.

  When the facsimile reception terminal 202A completes the facsimile communication with the facsimile transmission terminal 201 and the line is disconnected (step S621: Y), the sender's jitter buffer threshold is registered in the threshold storage unit 217A as a trigger. It is determined whether it has been completed (step S622). For example, if the sender is “Taro”, since there is a Taro storage area 502 in the threshold storage unit 217A, it is already registered (Y). In this case, new jitter buffer threshold values AA, BB, and CC are overwritten in the Taro storage area 502 as jitter buffer threshold values A ′, B ′, and C ′ (step S623), and the new threshold value storing process is terminated (step S623). End).

  On the other hand, when the sender is not registered in the threshold storage unit 217A (step S622: N), the storage area of the person is newly installed in the threshold storage unit 217A. For example, if “Hanako” is not registered, a Hanako storage area 503 is newly provided in the threshold storage unit 217A. Then, the jitter buffer threshold values A ′, B ′, and C ′ are stored in the Hanako storage area 503 (step S624), and the new threshold value storing process is terminated (END).

  FIG. 15 shows the relationship between the jitter buffer threshold and the timeout value when the sender is not registered in the threshold storage unit. This will be described with reference to FIGS. 4 and 11.

Because the data for the telephone number of Hanako as the sender does not exist, the threshold value calculation unit 216A includes a jitter buffer threshold A for the timeout value T ₁ to the current at the start of communication, the jitter buffer threshold B and field for the timeout value T ₂ A jitter buffer threshold C for data reception is calculated. These values are adopted as values after learning (new threshold values using a learning function) by the threshold value calculation unit 216A as indicated by arrows 521 and 522. The jitter buffer control unit 214 controls the jitter buffer 213 using these jitter buffer threshold values A, B, and C.

  When facsimile communication related to Hanako as a sender is completed, a Hanako storage area 503 is created corresponding to the telephone number “0123-34-5678” of the current facsimile transmission terminal 201 as indicated by an arrow 523. Then, the jitter buffer thresholds A, B, and C are registered in this new area where data is not yet registered, as indicated by an arrow 524.

  According to the second modification of the present invention described above, the tendency of delay for each communication path to which the communication partner facsimile transmission terminal 201 is connected is reflected each time the facsimile communication is repeated. Therefore, it is possible to perform facsimile communication in which the threshold value of the jitter buffer 213 suitable for the communication partner is set.

  Further, in the second modification of the present invention, when the counterpart jitter buffer threshold values A ′, B ′, and C ′ are not registered in the threshold value storage unit 217A, these can be newly registered. Thereby, whenever the facsimile communication is repeated, the facsimile communication suitable for more communication partners can be performed.

  <Third Modification of the Invention>

  FIG. 16 shows an outline of the configuration of the facsimile receiving terminal according to the third modification of the present invention. In the facsimile receiving terminal 202B of the third modification, the same parts as those of the facsimile receiving terminal 202 shown in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  The facsimile receiving terminal 202B newly has a communication error analysis unit 701. The communication error analysis unit 701 newly analyzes and classifies the contents when there is a communication error due to timeout in facsimile communication. The threshold value calculation unit 216B calculates jitter buffer threshold values A, B, and C for the next communication according to the contents of the classified errors. The control unit 212B is provided with a memory 222B that stores a control program for controlling the facsimile receiving terminal 202B in the third modification. By executing this control program, the CPU 221 controls the facsimile receiving terminal 202B in the third modification.

  FIG. 17 shows the state of the rewrite control of the jitter buffer threshold in the third modification. This will be described with reference to FIG.

  When a communication error due to a timeout occurs while the facsimile communication reception process is being performed (step S801: Y), the control unit 212B causes the communication error analysis unit 701 to analyze the content of the communication error (step S802). At this time, the delay state at the start of communication may be taken into consideration. Depending on the analysis result of the communication error, the threshold value calculation unit 216B keeps the jitter buffer threshold values A, B, and C at their current values or corrects these values, and corrects the corrected jitter buffer threshold values A ′, B ′, Hold C 'temporarily. When the line is disconnected (step S804: Y), the stored jitter buffer threshold values A ′, B ′, and C ′ are overwritten in the threshold storage unit 217 as new jitter buffer threshold values A, B, and C (step S805). Then, the threshold value changing process ends (END).

  On the other hand, when the facsimile communication is completed without causing a communication error (step S801: N, step S806: Y), the normal processing for the jitter buffer threshold as described above is performed ( Step S807), the processing relating to the threshold value is ended (END).

  According to the third modified example of the present invention described above, when a communication error due to timeout occurs even under normal control of the jitter buffer threshold, it is possible to take a countermeasure that the timeout is unlikely to recur, and to improve communication durability. Can be increased.

  Although the embodiment and each modification mainly described the relief of fluctuations during packet transmission, it is natural that the jitter buffer 213 may be used to rescue other obstacles such as packet delay. .

DESCRIPTION OF SYMBOLS 10 Facsimile receiver 11 Buffer memory 12 Received signal decoding means 13 Threshold setting means 20 Facsimile reception method 21 Delay situation determination step 22 Reception step 23 Reception signal decoding step 24 Threshold setting step 30 Facsimile reception program 31 Delay situation determination process 32 Reception process 33 Received signal decoding process 34 Threshold setting process 200 Facsimile communication system 201 Facsimile transmission terminal (facsimile transmission apparatus)
202, 202A, 202B Facsimile receiving terminal (facsimile receiving device)
203 IP network 211 Communication interface unit 212, 212A, 212B Control unit 213 Jitter buffer (buffer memory)
214 Jitter buffer control unit 215 Codec unit 216, 216A, 216B Threshold calculation unit 217, 217A Threshold storage unit 221 CPU
222, 222A, 222B Memory 501 Sender identification unit 502 Taro storage area 503 Hanako storage area 701 Communication error analysis section I Average delay value A, B, C Jitter buffer threshold

Claims (10)

A buffer memory for storing packet signals received from a sender in facsimile communication using the Internet network in the order of reception;
Received signal decoding means for sequentially taking out and decoding the signals exceeding the time indicated by the predetermined threshold from the stored packet signals stored in the buffer memory;
A facsimile receiving apparatus comprising: threshold setting means for setting a plurality of thresholds according to a length of time until timeout as a time limit for responding to the received packet signal. Delay state measuring means for measuring a delay state of a signal using the Internet network with a transmission source at the start of facsimile communication;
2. The facsimile receiving apparatus according to claim 1, further comprising delay state reference means for calculating the threshold value at the time of the current communication according to the measurement result of the delay state measuring means.   2. The facsimile receiving apparatus according to claim 1, wherein the threshold value at the time of receiving image data is set longer than any of a plurality of types set by the threshold value setting means. Image data reception start detection means for detecting the start of image data reception;
MPS detection means for detecting timing for receiving MPS (Multi Page Signal);
EOP detection means for detecting timing for receiving EOP (End Of Procedure Signal);
When the MPS detection means detects the MPS, the image data reception start detection means returns to the threshold immediately before detecting the start of reception of the image data, and thereafter the image data reception start detection means starts the reception of the image data. 2. The facsimile receiving apparatus according to claim 1, further comprising threshold switching means for returning the threshold to the threshold at the time of receiving the image data upon detection. A transmission source discrimination means for discriminating a transmission source of the facsimile signal;
A previous communication threshold storage means for storing the threshold in the previous facsimile communication for each transmission source determined by the transmission source determination means;
A history of reading the threshold value of the same transmission source from the previous communication threshold storage unit when receiving a facsimile signal from the transmission source determined by the transmission source determination unit, and calculating the threshold value of the current communication with reference to this 2. The facsimile receiving apparatus according to claim 1, further comprising a data reference means. A communication error analysis means for analyzing a communication error during facsimile communication;
2. The facsimile receiving apparatus according to claim 1, further comprising an error occurrence threshold correcting means for correcting the threshold after the next communication according to an analysis result of the communication error analyzing means. Delay that determines the delay status of communication in facsimile communication using the Internet network by measuring the time required for a response to the facsimile transmission device at the start of facsimile communication using the Internet network and returning the response. A status determination step;
A reception step of storing packet signals received from a transmission source in the facsimile communication in a buffer memory in the order of reception;
A reception signal decoding step for sequentially taking out and decoding the signals that have exceeded the time indicated by the predetermined threshold value from the packet signal stored in the buffer memory in the reception step;
A threshold setting step for setting the threshold to a plurality of types according to the communication delay status determined in the delay status determination step and the length of time until timeout as a time limit for responding to the received packet signal; A facsimile receiving method comprising: An image data reception start detection step for detecting the start of image data reception;
An image data reception threshold setting step for setting the threshold value of the buffer memory longer than any of the threshold values set in the threshold value setting step when the reception start of the image data is detected in the image data reception start detection step. The facsimile receiving method according to claim 7. On the computer,
Delay that determines the delay status of communication in facsimile communication using the Internet network by measuring the time required for a response to the facsimile transmission device at the start of facsimile communication using the Internet network and returning the response. Status determination processing;
A reception process for storing packet signals received from a transmission source in the facsimile communication in a buffer memory in the order of reception;
A reception signal decoding process for sequentially taking out and decoding the signals exceeding the time indicated by the predetermined threshold from the stored packet signals stored in the buffer memory in the reception process;
Threshold setting processing for setting a plurality of types of the threshold according to the delay status of communication determined in the delay status determination processing and the length of time until timeout as a time limit for responding to the received packet signal; A facsimile reception program to be executed. Image data reception start detection processing for detecting the start of image data reception;
The image data reception threshold setting process for setting the threshold value of the buffer memory longer than any of the threshold values set in the threshold value setting step when the image data reception start detection process is detected in the image data reception start detection process. The facsimile reception program according to claim 9, further executed.

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