Synchronization accuracy evaluation device and program

Abstract

To simply evaluate synchronization precision in an IP broadcast system using the PTP.SOLUTION: A synchronization precision evaluation device 2 comprises: a sending device PTP off-set calculation unit 24 that takes a sending switch 5 as a master and a sending device 6 as a slave and calculates a PTP off-set variation amount ΔO of the sending device 6 by a predetermined expression using time information included in a Delay Request message, reception time of the message, time information included in a Delay Response message, and reception time of the message; and a sending switch PTP off-set calculation unit 25 that takes a gland master apparatus 4 as a master and the sending switch 5 as a slave and calculates a PTP off-set variation amount ΔO of the sending switch 5 by a predetermined expression using the time information and the reception time.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a synchronization accuracy evaluation device and program for evaluating time synchronization in an IP (Internet Protocol) system that realizes time synchronization by PTP (Precision Time Protocol), particularly for program production, transmission, and the like. [Background technology]

[0002] Conventionally, PTP has been known as a standard for performing precise time synchronization on an IP system (see, for example, Non-Patent Document 1). In addition, IP-based broadcasting systems such as program production systems and transmission systems (hereinafter referred to as "IP broadcasting systems") use PTP to establish synchronization between devices in the system.

[0003] In order to stably operate this IP broadcasting system, it is recommended that the time difference (synchronization accuracy) of any device in the system be 1 μs or less (for example, see Non-Patent Document 2). In particular, in an IP broadcasting system, it is desirable that the synchronization accuracy of the slave clock provided in the end device with respect to the master clock for any two end devices selected from a group of end devices that generate video, audio, etc., converge to 1 μs or less.

[0004] A known method for measuring synchronization accuracy is to use a measuring device such as an oscilloscope, which measures the phase difference of the high-precision time pulse (1PPS) output between the master clock in the IP broadcasting system and the slave clock that is attempting to establish synchronization based on the master clock.

[0005] There is also a known method of calculating and correcting the synchronization accuracy between a master device equipped with a master clock and a slave device equipped with a slave clock by using messages transmitted between these devices (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6869447 [Patent Document 2] JP 2018-78351 A [Non-patent literature]

[0007] [Non-Patent Document 1] IEEE Std,1588-2008 [Non-Patent Document 2] SMPTE ST 2059-2:2015 Summary of the Invention [Problem to be solved by the invention]

[0008] In the method using the measuring equipment mentioned above, it is necessary to reconstruct the measurement system for measuring the high-precision time pulse (1PPS) every time the equipment constituting the IP broadcasting system is changed, which makes the measurement time-consuming. Also, when the IP broadcasting system is composed of many devices, it is difficult to measure the synchronization accuracy on a daily basis and easily.

[0009] In contrast, in the methods of Patent Documents 1 and 2 mentioned above, it is only necessary to acquire messages transmitted and received between the master device and the slave device, and therefore it is possible to easily measure synchronization accuracy.

[0010] However, in order to measure and evaluate the synchronization accuracy of all devices constituting an IP broadcasting system, all devices must be equipped with the functions described in the above-mentioned Patent Documents 1 and 2. This means that existing devices cannot support this, and there is a problem in that it is difficult to easily evaluate the synchronization accuracy of the entire IP broadcasting system.

[0011] Therefore, the present invention has been made to solve the above-mentioned problems, and its object is to provide a synchronization accuracy evaluation device and program that can easily evaluate synchronization accuracy in an IP broadcasting system using PTP. [Means for solving the problem]

[0012] In order to solve the above problem, the synchronization accuracy evaluation device of claim 1 is composed of a grandmaster device, and a switch and a plurality of devices that transmit and receive video, audio, and auxiliary data, and transmits and receives PTP (Precision Time Protocol) messages between the grandmaster device functioning as a master and the switch functioning as a slave, and transmits and receives the PTP messages between the switch functioning as the master and the plurality of devices functioning as the slaves. In this synchronization accuracy evaluation device, under an IP broadcasting system in which the PTP messages are transmitted and received between the switch functioning as the master and the plurality of devices functioning as the slaves, the synchronization accuracy evaluation device evaluates the accuracy of time synchronization of the IP broadcasting system, and includes a receiving unit that receives the PTP message copied by the switch from the switch and specifies the reception time of the PTP message, and determines whether the PTP message received by the receiving unit is a Sync message, a Delay Request message, or a Delay Response message, specifies source information and destination information of the PTP message, and evaluates the accuracy of time synchronization of the Delay Request message based on time information included in the Delay Request message (DReq time information that is the transmission time of the Delay Request message by the slave), the reception time of the Delay Request message specified by the receiving unit (DReq reception time), the source information (DReq source information) and destination information of the Delay Request message, and the Delay Response message. time information included in the Delay Response message (DRes time information which is the reception time of the Delay Request message by the master), the reception time of the Delay Response message specified by the receiving unit (DRes reception time), andand a device PTP offset calculation unit which, when the switch is the master and each of the plurality of devices is the slave, reads from the memory, for each of the plurality of devices, the DReq time information and the DReq reception time corresponding to the device identified as the DReq source information, and reads the DRes time information and the DRes reception time corresponding to the device identified as the DRes destination information, and calculates the amount of time offset fluctuation between the switch and the device as a PTP offset fluctuation amount ΔO of the device based on the DReq time information, the DReq reception time, the DRes time information, and the DRes reception time.

[0013] The synchronization accuracy evaluation device of claim 2 is composed of a grandmaster device, a switch and a plurality of devices that transmit and receive video, audio and auxiliary data, and transmits and receives PTP (Precision Time Protocol) messages between the grandmaster device functioning as a master and the switch functioning as a slave, and transmits and receives the PTP messages between the switch functioning as the master and the plurality of devices functioning as the slaves. In this synchronization accuracy evaluation device, the synchronization accuracy evaluation device evaluates the accuracy of time synchronization in an IP broadcasting system, and includes a receiving unit that receives the PTP message copied by the switch from the switch and specifies the reception time of the PTP message, and determines whether the PTP message received by the receiving unit is a Sync message, a Delay Request message or a Delay Response message, specifies source information and destination information of the PTP message, and evaluates the accuracy of time synchronization in the IP broadcasting system based on time information included in the Delay Request message (DReq time information that is the transmission time of the Delay Request message by the slave), the reception time of the Delay Request message specified by the receiving unit (DReq reception time), the source information (DReq source information) and destination information of the Delay Request message, and the Delay Response message. time information included in the Delay Response message (DRes time information which is the reception time of the Delay Request message by the master), the reception time of the Delay Response message specified by the receiving unit (DRes reception time), andand a switch PTP offset calculation unit that, when the grandmaster device is the master and the switch is the slave, reads from the memory the DReq time information and the DReq reception time corresponding to the switch identified as the DReq source information, and reads the DReq time information and the DRes reception time corresponding to the switch identified as the DRes destination information, and calculates the amount of time offset fluctuation between the grandmaster device and the switch as a PTP offset fluctuation amount ΔO of the switch based on the DReq time information, the DReq reception time, the DRes time information, and the DRes reception time.

[0014] The synchronization accuracy evaluation device of claim 3 is the synchronization accuracy evaluation device of claim 1, further comprising: a device PTP offset calculation unit that calculates the DReq time information, which is the transmission time of the Delay Request message by the device, by calculating Td k,3 The DReq reception time, which is the reception time of the Delay Request message specified by the receiving unit, is set to Ts k,4 The DRes time information, which is the reception time of the Delay Request message by the switch, is stored in TMb k,4 The DRes reception time, which is the reception time of the Delay Response message specified by the receiving unit, is set to Ts k,5 The preset parameter is n (an integer of 1 or more), and the following formula is used: The PTP offset fluctuation amount ΔO of the device is calculated using TIFF0007651435000001.tif37170.

[0015] The synchronization accuracy evaluation device of claim 4 is the synchronization accuracy evaluation device according to claim 2, further comprising: a synchronization accuracy evaluation unit for evaluating the synchronization accuracy of the Sync message, the Delay Request message, and the Delay Response message; a sequence number of the sequence when the sequence is continuously performed is k; and the switch PTP offset calculation unit calculates the DReq time information, which is the transmission time of the Delay Request message by the switch, from TSb k,3 The DReq reception time, which is the reception time of the Delay Request message specified by the receiving unit, is set to Ts k,3 The DRes time information, which is the reception time of the Delay Request message by the grandmaster device, is Tg k,4 The DRes reception time, which is the reception time of the Delay Response message specified by the receiving unit, is set to Ts k,6 The preset parameter is n (an integer of 1 or more), and the following formula is used: The present invention is characterized in that the PTP offset fluctuation amount ΔO of the switch is calculated using TIFF0007651435000002.tif37170.

[0016] In addition, the synchronization accuracy evaluation device of claim 5 is characterized in that, in the synchronization accuracy evaluation device of claim 1 or 3, it further includes a device synchronization monitoring unit that outputs a device synchronization abnormality when it is determined that the PTP offset fluctuation amount ΔO calculated by the device PTP offset calculation unit exceeds a preset threshold value for one or more of the multiple devices.

[0017] In addition, the synchronization accuracy evaluation device of claim 6 is characterized in that, in the synchronization accuracy evaluation device according to claim 2 or 4, it further comprises a switch synchronization monitoring unit which outputs a switch synchronization abnormality when it is determined that the PTP offset fluctuation amount ΔO calculated by the switch PTP offset calculation unit exceeds a preset threshold value for the switch.

[0018] Further, a program according to a seventh aspect of the present invention is characterized in that it causes a computer to function as the synchronization accuracy evaluation device according to any one of the first to sixth aspects of the present invention. Effect of the Invention

[0019] As described above, according to the present invention, it is possible to easily evaluate synchronization accuracy in an IP broadcasting system using PTP. [Brief description of the drawings]

[0020] [Figure 1] 1 is a schematic diagram showing an example of the overall configuration of an IP broadcasting system including a synchronization accuracy evaluation device according to an embodiment of the present invention. [Diagram 2] 1 is a block diagram showing an example of the configuration of a synchronization accuracy evaluation device; [Diagram 3] 4 is a diagram for explaining details of S information, DReq information, and DRes information stored in a memory. FIG. [Figure 4] 13 is a flowchart showing an example of processing by a transmitting device PTP offset calculation unit. [Diagram 5] A diagram showing the sequence of PTP messages between a sending switch acting as a master and a sending device acting as a slave. [Figure 6] FIG. 6 is a diagram for explaining time parameters in the sequence of FIG. 5. [Figure 7] FIG. 13 is a diagram showing a time transition between a sending switch functioning as a master and a sending device functioning as a slave. [Figure 8] 13 is a flowchart showing an example of processing by a sending switch PTP offset calculation unit. [Figure 9] A diagram showing the sequence of PTP messages between a grandmaster device acting as a master and an egress switch acting as a slave. [Figure 10] FIG. 10 is a diagram for explaining time parameters in the sequence of FIG. [Figure 11]FIG. 13 is a diagram showing a time transition between a grandmaster device functioning as a master and a transmission switch functioning as a slave. [Figure 12] 1 is a schematic diagram showing an example of the overall configuration of another IP broadcasting system including a synchronization accuracy evaluation device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The following describes in detail the embodiment of the present invention with reference to the drawings. The present invention is characterized in that, in an IP broadcasting system, a PTP message transmitted between devices is intercepted, and a PTP offset fluctuation amount ΔO is calculated based on the time information included in a Delay Request message and the reception time of the Delay Request message, and the time information included in a Delay Response message and the reception time of the Delay Response message, using a predetermined formula to calculate the amount of offset fluctuation of the time of a device functioning as a slave relative to the time of a device functioning as a master.

[0022] In an IP broadcasting system using PTP, since there is no need to implement new functions in each device to implement the present invention, the synchronization accuracy of the entire system can be easily evaluated.

[0023] [Overall structure] First, an example of the overall configuration of an IP broadcasting system using PTP will be described. Fig. 1 is a schematic diagram showing an example of the overall configuration of an IP broadcasting system including a synchronization accuracy evaluation device according to an embodiment of the present invention. This IP broadcasting system is a minimum basic system equipped with one facility, for example a program transmission system, and multicast packets including video, audio, and auxiliary data are transmitted within the facility.

[0024] This IP broadcasting system 1A is configured with a grandmaster equipment 4, a transmission switch 5, and transmission devices 6-1,...,6-N, and further includes a synchronization accuracy evaluation device 2 and a time monitoring terminal 3. N is an integer equal to or greater than 2. Network equipment is omitted. Hereinafter, the transmission devices 6-1,...,6-N are collectively referred to as transmission device 6. The IP broadcasting system 1A refers to any broadcasting system that transmits video and audio data defined in SMPTE ST 2110 over an IP network.

[0025] The IP broadcasting system 1A corresponds to a minimum system including one facility among a large-scale system in which facilities that produce video and audio such as production studios (hereinafter referred to as "transmission resources") and facilities that receive video and audio from the transmission resources, switch them, and transmit them (hereinafter referred to as "transmission masters") are connected. Here, one facility is a transmission resource or a transmission master, and is composed of a transmission switch 5 and transmission devices 6-1,...,6-N (the area indicated by the dotted line in Fig. 1).

[0026] A large-scale system in which a plurality of transmission resources and various facilities of transmission masters are connected will be described later with reference to FIG.

[0027] The transmission staff who operates the time monitoring terminal 3 is an engineer who performs maintenance work such as health checks of the transmission switch 5 and each of the transmission devices 6-1,...,6-N in the facility and monitoring of broadcast video and audio. This transmission staff quantitatively observes the PTP offset fluctuation amount ΔO for each of the transmission switch 5 and each of the transmission devices 6-1,...,6-N calculated by the synchronization accuracy evaluation device 2.

[0028] The synchronization accuracy evaluation device 2 receives a PTP message including time information from the transmission switch 5, stores the PTP message in a memory, and analyzes it. Then, the synchronization accuracy evaluation device 2 generates measurement data by calculating the PTP offset fluctuation amount ΔO of each device of the transmission switch 5 and the transmission devices 6-1, . . . , 6-N based on the time information included in the PTP message and the reception time of the PTP message (the time when the synchronization accuracy evaluation device 2 received the PTP message) and by performing threshold processing on the PTP offset fluctuation amount ΔO to determine synchronization abnormality.

[0029] The synchronization accuracy evaluation device 2 also processes the PTP offset variation amount ΔO into visualized data (hereinafter referred to as "time synchronization information") that is easy for humans to visually recognize, such as a time series graph, and transmits the time synchronization information to the time monitoring terminal 3. Furthermore, the synchronization accuracy evaluation device 2 receives a request from the time monitoring terminal 3, searches for or refers to measurement data in response to the request, and transmits the result to the time monitoring terminal 3 as a response to the request. Details of the synchronization accuracy evaluation device 2 will be described later.

[0030] The time monitoring terminal 3 receives time synchronization information from the synchronization accuracy evaluation device 2, and displays the time synchronization information on a screen in a WEB browser, etc. In addition, the time monitoring terminal 3 transmits a request to the synchronization accuracy evaluation device 2 in accordance with a search or reference operation by the person in charge of sending, receives a response corresponding to the request from the synchronization accuracy evaluation device 2, and displays the response on a screen in a WEB browser, etc.

[0031] The grandmaster device 4 generates international atomic time and a clock frequency and has a grandmaster clock that operates based on these. The grandmaster device 4 performs messaging according to PTP v2 according to the time of the grandmaster clock.

[0032] The grandmaster device 4 functions as a master and transmits and receives PTP messages to and from the transmission switch 5 which functions as a slave.

[0033] The sending switch 5 is a PTP-compatible network switch. Note that, since the IP broadcasting system 1A constituting the program sending system is taken as an example here, the sending switch 5 is named "sending", but this switch is also applicable to other broadcasting systems such as a program production system. In other words, this switch is a network switch used for broadcasting systems such as a program sending system and a program production system.

[0034] The transmission switch 5 receives multicast packets including video, audio, and auxiliary data from a transmission device 6 within the facility (indicated by a dotted line) and forwards the multicast packets to other transmission devices 6 within the facility. The transmission switch 5 also exchanges multicast route information with an adjacent multicast router (not shown) using PIM-SSM (Protocol Independent Multicast Source Specific Multicast), and updates the multicast route information.

[0035] The transmission switch 5 is equipped with a boundary clock (BC) and performs messaging according to PTP v2 according to the time of the boundary clock. The transmission switch 5 functions as a slave to the grandmaster device 4, which is the master, and also functions as a master to the transmission device 6, which is the slave.

[0036] When the transmission switch 5 functions as a slave, it transmits and receives PTP messages to and from the grandmaster device 4 functioning as a master. The transmission switch 5 then corrects the boundary clock time (PTP time) to synchronize the boundary clock time with the grandmaster clock time provided in the grandmaster device 4.

[0037] On the other hand, when the transmission switch 5 functions as a master, it transmits and receives PTP messages to and from the transmission device 6 which functions as a slave.

[0038] In addition, the transmission switch 5 copies the PTP messages transmitted and received between the grandmaster equipment 4 and the transmission device 6 by port mirroring, and transmits the copied PTP messages to the synchronization accuracy evaluation device 2.

[0039] That is, the sending switch 5 copies a PTP message received from the grandmaster device 4 and transmits it to the synchronization accuracy evaluation device 2, and also copies a PTP message sent to the grandmaster device 4 and transmits it to the synchronization accuracy evaluation device 2. In addition, the sending switch 5 copies a PTP message sent to the sending device 6 and transmits it to the synchronization accuracy evaluation device 2, and also copies a PTP message received from the sending device 6 and transmits it to the synchronization accuracy evaluation device 2.

[0040] The transmission device 6 is a broadcasting device used in a PTP-compatible network. Note that, since the IP broadcasting system 1A constituting the program transmission system is taken as an example here, the name "transmission" is used for the transmission device 6, but this device is also applicable to other broadcasting systems such as a program production system. In other words, this device is a broadcasting device constituting a broadcasting system such as a program transmission system or a program production system.

[0041] The sending device 6 generates video, audio, and auxiliary data in the SMPTE ST 2110 format, and transmits a multicast packet including the video, audio, and auxiliary data to the sending switch 5. The sending device 6 also receives a multicast packet from the sending switch 5 by IGMP (Internet Group Management Protocol) v3, and extracts and processes the video, audio, and auxiliary data from the multicast packet.

[0042] The sending device 6 functions as a slave, has a slave clock, and operates according to the time of the slave clock. The sending device 6 transmits and receives PTP messages with the sending switch 5 functioning as a master. The sending device 6 corrects the time of the slave clock (PTP time) to synchronize the time of the slave clock with the time of the boundary clock provided in the sending switch 5.

[0043] [Synchronization accuracy evaluation device 2] Next, a detailed description will be given of the synchronization accuracy evaluation device 2 shown in Fig. 1. Fig. 2 is a block diagram showing an example of the configuration of the synchronization accuracy evaluation device 2.

[0044] This synchronization accuracy evaluation device 2 includes a receiving unit 20, memories 21, 23, 26, an analysis unit 22, a sending device PTP offset calculation unit 24, a sending switch PTP offset calculation unit 25, a sending device synchronization monitoring unit 27, a sending switch synchronization monitoring unit 28, a processing unit 29, a request processing unit 30, and a sending / receiving unit 31.

[0045] The receiving unit 20 receives a PTP message including time information from the transmission switch 5, identifies the time at which the receiving unit 20 received the PTP message (reception time), and stores the PTP message in the memory 21 together with the reception time.

[0046] PTP messages include a PTP message for Sync (hereinafter referred to as a "Sync message"), a PTP message for Delay Request (hereinafter referred to as a "Delay Request message"), and a PTP message for Delay Response (hereinafter referred to as a "Delay Response message").

[0047] A Sync message is sent from a master to a slave and includes the time when the master sends the Sync message (transmission time). A Delay Request message is sent from a slave to a master and includes the time when the slave sends the Delay Request message (transmission time). A Delay Response message is sent from a master to a slave and includes the time when the master receives the Delay Request message from the slave (reception time).

[0048] 5, which will be described later, it is assumed that the sending switch 5 functions as a master and the sending device 6 functions as a slave. In this case, for example, a Sync message (1) is sent from the sending switch 5 to the sending device 6, and the time when the sending switch 5 sends the Sync message (1) (time information TMb 0,1 (α0(k=0))). This Sync message (1) is copied by the transmission switch 5 and transmitted to the synchronization accuracy evaluation device 2.

[0049] The Delay Request message (2) is transmitted from the transmission device 6 to the transmission switch 5, and the time at which the transmission device 6 transmits the Delay Request message (2) (time information Td 0,3 (α1(k=0))). This Delay Request message (2) is copied by the transmission switch 5 and transmitted to the synchronization accuracy evaluation device 2.

[0050] The Delay Response message (3) is sent from the sending switch 5 to the sending device 6, and the time at which the sending switch 5 receives the Delay Request message from the sending device 6 (time information TMb 0,4 (α2(k=0))). This Delay Response message (3) is copied by the transmission switch 5 and transmitted to the synchronization accuracy evaluation device 2.

[0051] Returning to FIG. 2, the memory 21 stores the Sync message, the Delay Request message, and the Delay Response message together with the reception time.

[0052] Specifically, referring to FIG. 5 described later, when the sending switch 5 functions as a master and the sending device 6 functions as a slave, the memory 21 stores the Sync message sent from the master sending switch 5 to the slave sending device 6, the Delay Request message sent from the slave sending device 6 to the master sending switch 5, and the Delay Response message sent from the master sending switch 5 to the slave sending device 6, each together with the reception time.

[0053] Also, referring to FIG. 9 described later, when the grandmaster device 4 functions as a master and the transmission switch 5 functions as a slave, the memory 21 stores a Sync message transmitted from the master grandmaster device 4 to the slave transmission switch 5, a Delay Request message transmitted from the slave transmission switch 5 to the master grandmaster device 4, and a Delay Response message transmitted from the master grandmaster device 4 to the slave transmission switch 5, together with the reception time of each message.

[0054] 2, the analysis unit 22 reads the PTP message and the reception time from the memory 21, and extracts the value of messageType from the header of the PTP message (PTP message header). Then, the analysis unit 22 determines the type of the PTP message (Sync message, Delay Request message, or Delay Response message) based on the value of messageType.

[0055] When the analysis unit 22 determines that the PTP message is a Sync message, it extracts the value of originTimestamp (time information: transmission time of the master) from the Sync message and identifies the source information and destination information (IP address and MAC address) of the Sync message. In practice, the source information and destination information are extracted and identified from the header of an Ethernet frame that includes the PTP message.

[0056] The analysis unit 22 generates Sync information (hereinafter referred to as “S information”) for the Sync message, which includes time information, a reception time (the reception time when the Sync message is received by the synchronization accuracy evaluation device 2), as well as source information and destination information. Then, the analysis unit 22 stores the S information in the memory 23.

[0057] When the analysis unit 22 determines that the PTP message is a Delay Request message, it extracts the value of originTimestamp (time information: transmission time of the slave) from the Delay Request message and identifies the source information and destination information of the Delay Request message.

[0058] The analysis unit 22 generates Delay Request information (hereinafter referred to as “DReq information”) for the Delay Request message, the Delay Request information including time information, a reception time (the reception time when the Delay Request message is received by the synchronization accuracy evaluation device 2), source information, and destination information. Then, the analysis unit 22 stores the DReq information in the memory 23.

[0059] When the analysis unit 22 determines that the PTP message is a Delay Response message, it extracts the value of receiveTimestamp (time information: the time when the Delay Request message is received by the master) from the Delay Response message. In addition, the analysis unit 22 identifies the source information and destination information of the Delay Response message.

[0060] The analysis unit 22 generates Delay Response information (hereinafter referred to as “DRes information”) for the Delay Response message, the Delay Response information including time information, a reception time (the reception time when the Delay Response message is received by the synchronization accuracy evaluation device 2), source information, and destination information. Then, the analysis unit 22 stores the DRes information in the memory 23.

[0061] The S information, DReq information, and DRes information are stored in the memory 23. Fig. 3 is a diagram for explaining the details of the S information, DReq information, and DRes information stored in the memory 23.

[0062] The S information is composed of time information (the value of originTimestamp) included in the Sync message, the reception time of the Sync message by the synchronization accuracy evaluation device 2, and source and destination information. For example, referring to FIG. 5, the time information is TMb 0,1 (α0(k=0)), the corresponding reception time is Ts 0,1 Also, referring to FIG. 9, the time information is Tg 0,1 (β0(k=0)), the corresponding reception time is Ts 0,2 It is.

[0063] The DReq information is composed of time information (value of originTimestamp) (DReq time information) included in the Delay Request message, the reception time of the Delay Request message by the synchronization accuracy evaluation device 2 (DReq reception time), source information (DReq source information) and destination information. For example, referring to FIG. 5, the time information is Td 0,3 (α1(k=0)), the corresponding reception time (for the same sequence (k=0)) is Ts 0,4 (α3(k=0)). Also, referring to FIG. 9, the time information is TSb 0,3 (β1(k=0)), the corresponding reception time is Ts 0,3 (β3(k=0)).

[0064] The DRes information is composed of time information (value of receiveTimestamp) (DRes time information) included in the Delay Response message, the reception time of the Delay Response message by the synchronization accuracy evaluation device 2 (DRes reception time), and source information and destination information (DRes destination information). For example, referring to FIG. 5, the time information is TMb 0,4 (α2(k=0)), the corresponding reception time is Ts 0,5 (α4(k=0)). Also, referring to FIG. 9, the time information is Tg 0,4 (β2(k=0)), the corresponding reception time is Ts 0,6 (β4(k=0)).

[0065] Returning to FIG. 2, the sending device PTP offset calculation unit 24 calculates, for each of all sending devices 6, the amount of change in the PTP offset accumulated over a certain period of time as the PTP offset fluctuation amount ΔO.

[0066] Specifically, the sending device PTP offset calculation unit 24 reads out the DReq information and the DRes information from the memory 23. Then, the sending device PTP offset calculation unit 24 calculates the PTP offset fluctuation amount ΔO for each sending device 6 functioning as a slave, based on the time information included in the DReq information and the DRes information and the reception time of the PTP message by the synchronization accuracy evaluation device 2.

[0067] The sending device PTP offset calculation unit 24 stores the PTP offset fluctuation amount ΔO for each sending device 6 in the memory 26, and also outputs it to the sending device synchronization monitoring unit 27. The sending device PTP offset calculation unit 24 will be described in detail later.

[0068] The transmission switch PTP offset calculation unit 25 calculates, for the transmission switch 5, the amount of change in the PTP offset accumulated over a certain period of time as a PTP offset fluctuation amount ΔO.

[0069] Specifically, the sending switch PTP offset calculation unit 25 reads out the DReq information and the DRes information from the memory 23. Then, the sending switch PTP offset calculation unit 25 calculates the PTP offset fluctuation amount ΔO of the sending switch 5 functioning as a slave based on the time information included in the DReq information and the DRes information and the reception time of the PTP message by the synchronization accuracy evaluation device 2.

[0070] The send-out switch PTP offset calculation unit 25 stores the PTP offset fluctuation amount ΔO of the send-out switch 5 in the memory 26, and also outputs it to the send-out switch synchronization monitoring unit 28. The send-out switch PTP offset calculation unit 25 will be described in detail later.

[0071] In the memory 26, the PTP offset fluctuation amount ΔO for each of the sending devices 6 (sending devices 6-1, . . . , 6-N) and the PTP offset fluctuation amount ΔO for the sending switch 5 are stored.

[0072] The sending device synchronization monitoring unit 27 monitors whether the PTP offset fluctuation amount ΔO of all sending devices 6 connected to the sending switch 5 to be synchronized converges within a certain range.

[0073] In general, when the master clock and slave clock maintain a normal synchronized state, the PTP offset falls within a certain range over time, and ideally converges to 0. That is, ideally, the PTP offset (S(t)-M(t)) satisfies the following equation for any time t. [Number 1] TIFF0007651435000003.tif15170S(t) indicates the time transition of the sending device 6 functioning as a slave, and M(t) indicates the time transition of the sending switch 5 functioning as a master (see FIG. 7 described later).

[0074] In the embodiment of the present invention, the PTP offset fluctuation amount ΔO is judged based on a threshold value so that the person in charge of sending can grasp the tendency of the PTP offset of the sending device 6 to increase or decrease.

[0075] Specifically, the sending device synchronization monitoring unit 27 inputs the PTP offset fluctuation amount ΔO for each sending device 6 from the sending device PTP offset calculation unit 24. Then, for each sending device 6, the sending device synchronization monitoring unit 27 determines whether the PTP offset fluctuation amount ΔO is equal to or less than a preset threshold value A, as shown in the following formula, for each preset time a (e.g., a=1) seconds. [Number 2] TIFF0007651435000004.tif15170

[0076] When the sending device synchronization monitoring unit 27 determines that the formula (2) is not satisfied for one or more of all sending devices 6 (when the sending device synchronization monitoring unit 27 determines that the PTP offset fluctuation amount ΔO exceeds the threshold value A), it generates a sending device synchronization abnormality. Then, the sending device synchronization monitoring unit 27 outputs the sending device synchronization abnormality to the transmitting / receiving unit 31. The sending device synchronization abnormality is transmitted from the transmitting / receiving unit 31 to the time monitoring terminal 3.

[0077] This allows the person in charge of sending to determine that a sending device synchronization abnormality has occurred and thereby determine that the PTP offset fluctuation amount ΔO in one or more of all sending devices 6 within the same facility has not converged within a certain range.

[0078] It should be noted that the preset time a and threshold value A can be changed by the operation of the time monitoring terminal 3 by the person in charge of transmission.

[0079] The send switch synchronization monitoring unit 28 monitors whether the PTP offset fluctuation amount ΔO of the send switch 5 converges to a certain range. In the embodiment of the present invention, the PTP offset fluctuation amount ΔO is subjected to a threshold judgment so that the sender can grasp the increase or decrease trend of the PTP offset of the send switch 5.

[0080] Specifically, the send-out switch synchronization monitoring unit 28 inputs the PTP offset fluctuation amount ΔO of the send-out switch 5 from the send-out switch PTP offset calculation unit 25. Then, the send-out switch synchronization monitoring unit 28 judges, for the send-out switch 5, every preset time b (e.g., b=1) seconds, whether or not the PTP offset fluctuation amount ΔO is equal to or less than a preset threshold value B, as shown in the following formula. [Number 3] TIFF0007651435000005.tif15170

[0081] When the send switch synchronization monitoring unit 28 determines that the send switch 5 does not satisfy the formula (3) (when the send switch 5 determines that the PTP offset fluctuation amount ΔO exceeds the threshold value B), the send switch synchronization monitoring unit 28 generates a send switch synchronization abnormality. Then, the send switch synchronization monitoring unit 28 outputs the send switch synchronization abnormality to the transmitting / receiving unit 31.

[0082] It should be noted that the preset time b and threshold value B can be changed by the operation of the time monitoring terminal 3 by the person in charge of transmission.

[0083] The processing unit 29 reads out the PTP offset fluctuation amount ΔO for each of the sending devices 6 and the PTP offset fluctuation amount ΔO of the sending switch 5 from the memory 26. Then, the processing unit 29 processes the PTP offset fluctuation amount ΔO of the sending device 6 and the PTP offset fluctuation amount ΔO of the sending switch 5 into a format that is easily visible to the person in charge of sending, and outputs it to the transmitting / receiving unit 31 as time synchronization information.

[0084] The request processing unit 30 receives a request from the transmitting / receiving unit 31, searches or references data corresponding to the request from the memories 21, 23, 26, generates the result as a response to the request, and outputs the response to the transmitting / receiving unit 31.

[0085] The transmitting / receiving unit 31 receives a request associated with an operation by the person in charge of sending from the time monitoring terminal 3, and outputs the request to the request processing unit 30. The transmitting / receiving unit 31 inputs sending device synchronization anomalies from the sending device synchronization monitoring unit 27, sending switch synchronization anomalies from the sending switch synchronization monitoring unit 28, time synchronization information from the processing unit 29, and a response from the request processing unit 30, and transmits these data to the time monitoring terminal 3.

[0086] (Transmission device PTP offset calculation unit 24) Next, the sending device PTP offset calculation unit 24 shown in Fig. 2 will be described in detail. Fig. 4 is a flow chart showing an example of processing by the sending device PTP offset calculation unit 24, and Fig. 5 is a diagram showing a sequence of PTP messages between the sending switch 5 functioning as a master and the sending device 6 functioning as a slave. Fig. 6 is a diagram explaining time parameters in the sequence of Fig. 5.

[0087] 5, the vertical axis is the time axis, and indicates the time of the synchronization accuracy evaluation device 2, the transmission switch 5, and the transmission device 6. Also, the parameter k indicates the sequence number when the transmission and reception of a Sync message, a Delay Request message, and a Delay Response message are regarded as one sequence in the sequence of transmission and reception of PTP messages and the sequence is performed continuously.

[0088] 6 shows parameters corresponding to the time of the sending switch 5 functioning as a master, the time of the sending device 6 functioning as a slave, and the time of the synchronization accuracy evaluation device 2. The parameters show the case where the n-th Sync message, Delay Request message, and Delay Response message are transmitted and received, and the contents of the parameters are as described in the definitions, so that the description will be omitted here.

[0089] Among these parameters, the parameters used to calculate the PTP offset fluctuation amount ΔO of the transmission device 6 are Td n,3(α1) (the time when the sending device 6 sent the Delay Request message), TMb n,4 (α2) (the time when the transmission switch 5 receives the Delay Request message), Ts n,4 (α3) (the time when the synchronization accuracy evaluation device 2 receives the Delay Request message received by the transmission switch 5), and Ts n,5 This is (α4) (the time when the synchronization accuracy evaluation device 2 receives the Delay Response message transmitted by the transmission switch 5).

[0090] The sending device PTP offset calculation unit 24 selects one sending device 6 from all sending devices 6 (step S401). The sending device PTP offset calculation unit 24 reads out the DReq information of the sending device 6 selected in step S401 from the memory 23 (step S402). That is, the sending device PTP offset calculation unit 24 identifies the sending device information that matches the sending device 6 from the DReq information, and reads out the DReq information corresponding to the sending device information. The sending device PTP offset calculation unit 24 also reads out the DRes information of the sending device 6 selected in step S401 from the DRes information (step S403). That is, the sending device PTP offset calculation unit 24 identifies the destination information that matches the sending device 6 from the DRes information, and reads out the DRes information corresponding to the destination information.

[0091] The sending device PTP offset calculation unit 24 calculates the time information Td k,3 (α1(k)), the time Ts k,4 (α3(k)) is extracted (step S404).

[0092] As a result, by referring to the time axis of the transmission device 6 in FIG. 5, the time information Td 0,3 (α1(k=0)), Td 1,3(α1(k=1)),···,Td n,3 (α1(k=n)) is extracted. Also, referring to the time axis of the synchronization accuracy evaluation device 2 in FIG. 0,4 (α3(k=0)),Ts 1,4 (α3(k=1)),···,Ts n,4 (α3(k=n)) is extracted.

[0093] The sending device PTP offset calculation unit 24 calculates time information TMb k,4 (α2(k)), the time Ts when the Delay Response message is received by the synchronization accuracy evaluation device 2 k,5 (α4(k)) is extracted (step S405).

[0094] As a result, by referring to the time axis of the transmission switch 5 in FIG. 0,4 (α2(k=0)),TMb 1,4 (α2(k=1)),···,TMb n,4 (α2(k=n)) is extracted. Also, referring to the time axis of the synchronization accuracy evaluation device 2 in FIG. 0,5 (α4(k=0)),Ts 1,5 (α4(k=1)),···,Ts n,5 (α4(k=n)) is extracted.

[0095] The sending device PTP offset calculation unit 24 calculates the time information Td k,3 (α1(k)), reception time Ts k,4 (α3(k)), time information TMb k,4 (α2(k)) and reception time Ts k,5 Based on (α4(k)), the PTP offset fluctuation amount ΔO of the selected sending device 6 is calculated using equation (12) described later, and this is stored in the memory 26 and output to the sending device synchronization monitoring unit 27 (step S406).

[0096] The sending device PTP offset calculation unit 24 determines whether or not the processes of steps S402 to S406 have been completed for all sending devices 6 (step S407).

[0097] If the sending device PTP offset calculation unit 24 determines in step S407 that the above-mentioned process has not been completed for all sending devices 6 (step S407: N), the sending device PTP offset calculation unit 24 selects the next sending device 6 (step S408) and proceeds to step S402. As a result, the processes of steps S402 to S406 are performed for the next sending device 6.

[0098] When the sending device PTP offset calculation unit 24 determines in step S407 that the above-mentioned process is completed for all sending devices 6 (step S407: Y), the sending device PTP offset calculation unit 24 ends the process. Then, the sending device PTP offset calculation unit 24 performs the process of steps S401 to S407 for the following k=0 to n, thereby calculating the PTP offset fluctuation amount ΔO for each of all sending devices 6 for k=0 to n.

[0099] In this manner, the PTP offset fluctuation amount ΔO is calculated for each of all the sending devices 6 in units of k=0 to n.

[0100] (PTP offset fluctuation amount ΔO of sending device 6) Next, the PTP offset fluctuation amount ΔO of the sending device 6 will be described. Fig. 7 is a diagram showing the time transition between the sending switch 5 functioning as a master and the sending device 6 functioning as a slave. The horizontal axis indicates the time of the synchronization accuracy evaluation device 2, and the vertical axis indicates the time of the sending switch 5 and the sending device 6. Fig. 7 shows the time transition S(t) of the sending device 6 functioning as a slave, and the time transition M(t) of the sending switch 5 functioning as a master. The time transition S(t) of the sending device 6 is the transition of the transmission time of the Delay Request message by the sending device 6, and the time transition M(t) of the sending switch 5 is the transition of the reception time of the Delay Request message by the sending switch 5.

[0101] The PTP offset is the difference in time (PTP time difference) between the time axes of the transmission switch 5 and the transmission device 6 at the same time on the time axis (horizontal axis) of the synchronization accuracy evaluation device 2. For example, when the time t of the synchronization accuracy evaluation device 2 is t=TMb' 0,4 At this time, the PTP offset of the transmission switch 5 and the transmission device 6 is Td 0,4 -TMb 0,4 (A'0, B0, see the arrow).

[0102] The transmitting device PTP offset calculation unit 24 calculates a PTP offset fluctuation amount ΔO, which is an integral value of the PTP offset for a certain elapsed time of the synchronization accuracy evaluation device 2, as an index for evaluating the tendency of the PTP offset to increase or decrease.

[0103] The transitions of the PTP times of the transmission switch 5 and the transmission device 6 with respect to time t of the synchronization accuracy evaluation device 2 are M(t) and S(t), respectively, and the amount of PTP offset fluctuation of the synchronization accuracy evaluation device 2 in the time span [t1, t2] is ΔO(t1, t2). In general, the following equation holds: [Number 4] TIFF0007651435000006.tif20170

[0104] When a series of PTP messaging consisting of a Sync message, a Delay Request message, and a Delay Response message is repeated n times between the sending switch 5 and the sending device 6, the time span [TMb' 0,4 ,Td' n,3 ] (γ in FIG. 7) with respect to the PTP offset fluctuation amount ΔO(TMb' 0,4 ,Td' n,3 ) is calculated using the following formula: [Number 5] TIFF0007651435000007.tif22170

[0105] In addition, when n=3, the PTP offset fluctuation amount ΔO(TMb' 0,4 ,Td' 3,3 ) corresponds to the signed area shown by the diagonal lines in FIG.

[0106] Here, when n is sufficiently large, the following formula holds: [Number 6] TIFF0007651435000008.tif35170

[0107] Therefore, the PTP offset fluctuation amount ΔO(TMb' 0,4 ,Td' n,3 ) is expressed by the following formula: [Number 7] TIFF0007651435000009.tif80170

[0108] Also, the time Td' of the synchronization accuracy evaluation device 2 when the sending device 6 sends the Delay Request message k,3 , and the time TMb' of the synchronization accuracy evaluation device 2 when the transmission switch 5 receives the Delay Request message. k,4 are expressed by the following formulas, respectively. [Number 8] TIFF0007651435000010.tif29170

[0109] That is, the transmission interval and reception interval of the Delay Request message in the synchronization accuracy evaluation device 2 are respectively expressed by the following equations. [Number 9] TIFF0007651435000011.tif91170

[0110] Here, when the transmission interval of the Delay Request message is sufficiently large, the following formula holds: [Number 10] TIFF0007651435000012.tif55170

[0111] Therefore, the transmission interval and reception interval of the Delay Request message in the synchronization accuracy evaluation device 2 are respectively expressed by the following equations. [Number 11] TIFF0007651435000013.tif28170

[0112] From the above, the PTP offset fluctuation amount ΔO(TMb' 0,4 ,Td' n,3 ) is represented by the following formula, where n is an integer of 1 or more. [Number 12] TIFF0007651435000014.tif48170

[0113] In this manner, the transmitting device PTP offset calculation unit 24 calculates the PTP offset fluctuation amount ΔO using the above-mentioned equation (12).

[0114] In the actual operation of the IP broadcasting system 1A shown in Fig. 1, the standard value of the transmission rate of the Sync message, the Delay Request message, and the Delay Response message is 8 Hz. In this case, the memory 23 shown in Figs. 2 and 3 stores S information, DReq information, and DRes information corresponding to eight sets of Sync messages, Delay Request messages, and Delay Response messages every second. For example, n=8, and the process of calculating the PTP offset fluctuation amount ΔO using the eight sets of DReq information and DRes information stored in the memory 23 according to the above formula (12) is repeated every second. Such a process is performed for each transmission device 6.

[0115] It is assumed that the parameter n is preset and can be changed by the operation of the time monitoring terminal 3 by the person in charge of transmission.

[0116] (Sending switch PTP offset calculation unit 25) Next, the sending switch PTP offset calculation unit 25 shown in Fig. 2 will be described in detail. Fig. 8 is a flow chart showing an example of processing of the sending switch PTP offset calculation unit 25, and Fig. 9 is a diagram showing a sequence of PTP messages between the grandmaster device 4 functioning as a master and the sending switch 5 functioning as a slave. Fig. 10 is a diagram explaining time parameters in the sequence of Fig. 9.

[0117] 9, the vertical axis is the time axis, and indicates the time of the grandmaster device 4, the transmission switch 5, and the synchronization accuracy evaluation device 2. Also, the parameter k indicates the sequence number when the transmission and reception of a Sync message, a Delay Request message, and a Delay Response message is regarded as one sequence in the sequence of transmission and reception of PTP messages and the sequence is performed continuously.

[0118] 10 shows parameters corresponding to the time of the grandmaster device 4 functioning as a master, the time of the transmission switch 5 functioning as a slave, and the time of the synchronization accuracy evaluation device 2. The parameters show the case of transmitting and receiving the n-th Sync message, Delay Request message, and Delay Response message, and the contents are as described in the definitions, so the explanation will be omitted here.

[0119] Among these parameters, the parameters used to calculate the PTP offset fluctuation amount ΔO of the transmission switch 5 are TSb n,3 (β1) (the time when the transmission switch 5 sends the Delay Request message), Tg n,4 (β2) (The time when Grandmaster device 4 receives the Delay Request message), Ts n,3 (β3) (the time when the synchronization accuracy evaluation device 2 receives the Delay Request message transmitted by the transmission switch 5), and Ts n,6 This is (β4) (the time when the synchronization accuracy evaluation device 2 receives the Delay Response message received by the transmission switch 5).

[0120] 8, the sending switch PTP offset calculation unit 25 reads out, from the memory 23, DReq information whose source information is the sending switch 5 (step S801). Also, the sending switch PTP offset calculation unit 25 reads out, from the memory 23, DRes information whose destination information is the sending switch 5 (step S802).

[0121] The sending switch PTP offset calculation unit 25 calculates the time information TSb k,3 (β1(k)), the time Ts k,3 (β3(k)) is extracted (step S803).

[0122] 9. In this way, by referring to the time axis of the transmission switch 5 in FIG. 0,3 (β1(k=0)),TSb 1,3 (β1(k=1)),···,TSb n,3 (β1(k=n)) is extracted. Also, with reference to the time axis of the synchronization accuracy evaluation device 2 in FIG. 0,3 (β3(k=0)),Ts 1,3 (β3(k=1)),···,Ts n,3 (β3(k=n)) is extracted.

[0123] The sending switch PTP offset calculation unit 25 calculates the time information Tg for k=0 to n from the read DRes information. k,4 (β2(k)), the time Ts when the Delay Response message is received by the synchronization accuracy evaluation device 2 k,6 (β4(k)) is extracted (step S804).

[0124] As a result, the time information Tg 0,4 (β2(k=0)),Tg 1,4 (β2(k=1)),···,Tg n,4 (β2(k=n)) is extracted. Also, with reference to the time axis of the synchronization accuracy evaluation device 2 in FIG. 0,6 (β4(k=0)),Ts 1,6 (β4(k=1)),···,Ts n,6 (β4(k=n)) is extracted.

[0125] The sending switch PTP offset calculation unit 25 calculates the time information TSb k,3 (β1(k)), reception time Ts k,3 (β3(k)), time information Tg k,4 (β2(k)) and reception time Ts k,6 Based on (β4(k)), the PTP offset fluctuation amount ΔO of the transmission switch 5 is calculated by equation (19) described later, and this is stored in the memory 26 and output to the transmission switch synchronization monitoring unit 28 (step S805).

[0126] In this manner, the PTP offset fluctuation amount ΔO of the transmission switch 5 is calculated in units of k=0 to n.

[0127] (PTP offset fluctuation amount ΔO of transmission switch 5) Next, the PTP offset fluctuation amount ΔO of the sending switch 5 will be described. Fig. 11 is a diagram showing the time transition between the grandmaster device 4 functioning as a master and the sending switch 5 functioning as a slave. Fig. 11 shows the time transition S(t) of the sending switch 5 functioning as a slave, and the time transition M(t) of the grandmaster device 4 functioning as a master. The time transition S(t) of the sending switch 5 is the transition of the transmission time of the Delay Request message by the sending switch 5, and the time transition M(t) of the grandmaster device 4 is the transition of the reception time of the Delay Request message by the grandmaster device 4.

[0128] As in the case of calculating the PTP offset fluctuation amount ΔO of the transmission device 6, when a series of PTP messaging consisting of a Sync message, a Delay Request message, and a Delay Response message is repeated n times between the grandmaster device 4 and the transmission switch 5, the time width [Tg' 0,4 ,TSb' n,3 ] (γ in FIG. 11) with respect to the PTP offset fluctuation amount ΔO(Tg' 0,4 ,TSb' n,3 ) is calculated using the following formula: [Number 13] TIFF0007651435000015.tif22170

[0129] Here, when n is sufficiently large, the following formula holds: [Number 14] TIFF0007651435000016.tif81170

[0130] Also, the time TSb' of the synchronization accuracy evaluation device 2 when the transmission switch 5 transmits the Delay Request messagek,3 , and the time Tg′ of the synchronization accuracy evaluation device 2 when the grandmaster device 4 receives the Delay Request message. k,4 are expressed by the following formulas, respectively. [Number 15] TIFF0007651435000017.tif43170

[0131] That is, the transmission interval and reception interval of the Delay Request message in the synchronization accuracy evaluation device 2 are respectively expressed by the following equations. [Number 16] TIFF0007651435000018.tif93170

[0132] Here, when the transmission interval of the Delay Request message is sufficiently large, the following formula holds: It is. [Number 17] TIFF0007651435000019.tif54170

[0133] Therefore, the transmission interval and reception interval of the Delay Request message in the synchronization accuracy evaluation device 2 are respectively expressed by the following equations. [Number 18] TIFF0007651435000020.tif29170

[0134] From the above, the PTP offset fluctuation amount ΔO(Tg' 0,4 ,TSb' n,3 ) is represented by the following formula, where n is an integer of 1 or more. [Number 19] TIFF0007651435000021.tif47170

[0135] In this way, the sending switch PTP offset calculation unit 25 calculates the PTP offset fluctuation amount ΔO using the above equation (19).

[0136] As in the case of the transmitting device PTP offset calculation unit 24, for example, n=8, and the process of calculating the PTP offset fluctuation amount ΔO using the eight pairs of DReq information and DRes information stored in the memory 23 according to the above equation (19) is repeated every second.

[0137] It is assumed that the parameter n is preset and can be changed by the operation of the time monitoring terminal 3 by the person in charge of transmission.

[0138] As described above, according to the synchronization accuracy evaluation device 2 of the embodiment of the present invention provided in the IP broadcasting system 1A of FIG. 1, when the transmission switch 5 functions as a master and the transmission device 6 functions as a slave, the transmission device PTP offset calculation unit 24 calculates the time information Td k,3 (α1(k)) (the transmission time of the Delay Request message by the sending device 6), the reception time Ts of the Delay Request message by the synchronization accuracy evaluation device 2 k,4 (α3(k)), time information TMb included in the Delay Response message k,4 (α2(k)) (the reception time of the Delay Request message by the transmission switch 5) and the reception time Ts of the Delay Response message by the synchronization accuracy evaluation device 2 k,5 Using (α4(k)), the PTP offset fluctuation amount ΔO is calculated for each of all sending devices 6 according to the above formula (12).

[0139] In addition, when the grandmaster device 4 functions as a master and the transmission switch 5 functions as a slave, the transmission switch PTP offset calculation unit 25 calculates the time information TSb k,3 (β1(k)) (the transmission time of the Delay Request message by the transmission switch 5), the reception time Ts of the Delay Request message by the synchronization accuracy evaluation device 2 k,3 (β3(k)), the time information Tg included in the Delay Response message k,4(β2(k)) (the reception time of the Delay Request message by the grandmaster device 4) and the reception time Ts of the Delay Response message by the synchronization accuracy evaluation device 2 k,6 Using (β4(k)), the PTP offset fluctuation amount ΔO of the transmission switch 5 is calculated according to the above equation (19).

[0140] This makes it possible to calculate the PTP offset variation amount ΔO from only the time information included in the PTP message and the reception time of the PTP message, eliminating the need to implement a new function in the transmission switch 5 and the transmission device 6. Therefore, by providing the synchronization accuracy evaluation device 2 in the IP broadcasting system 1A including the existing transmission switch 5 and transmission device 6, it is possible to easily evaluate the synchronization accuracy of the entire system regardless of the model and manufacturing vendor of the transmission switch 5 and the transmission device 6.

[0141] In addition, the person in charge of transmission can evaluate the synchronization accuracy between two transmission devices 6 selected arbitrarily from all the transmission devices 6 in the same facility by referring to the PTP offset variation amount ΔO. For example, it can be evaluated whether the synchronization accuracy of the slave clocks provided in the two transmission devices 6 with respect to the master clock has converged to 1 μs or less.

[0142] [Other overall configuration] Next, an example of the overall configuration of another IP broadcasting system using PTP will be described. Fig. 12 is a schematic diagram showing an example of the overall configuration of another IP broadcasting system including a synchronization accuracy evaluation device according to an embodiment of the present invention. This IP broadcasting system is a program production and transmission system to which various facilities of a plurality of transmission resources and one transmission master are connected, and multicast packets including video, audio, and auxiliary data are transmitted from the plurality of transmission resources to the transmission master.

[0143] This IP broadcasting system 1B is configured with grandmaster equipment 4, transmission resource switches 5A-1, . . . 5A-M, transmission resource devices 6A-1-1, . . . 6A-1-L1, . . . 6A-M-1, . . . 6A-M-LM, transmission master switch 5B, transmission master devices 6B-1, . . . 6B-N, time distribution switch 7, core switch 8 and time collection switch 9, and further includes a synchronization accuracy evaluation device 2 and a time monitoring terminal 3. N, M, L1 and LM are integers equal to or greater than 2. Network equipment is omitted.

[0144] The IP broadcasting system 1B, like the IP broadcasting system 1A shown in FIG. 1, refers to a general broadcasting system that transmits video and audio data defined in SMPTE ST 2110 over an IP network.

[0145] The IP broadcasting system 1B is a large-scale system connected to transmission resources 10-1, ..., 10-M, which are facilities such as production studios that produce video and audio, and a transmission master 11, which is a facility that receives video and audio from the transmission resources, switches them, and transmits them.

[0146] The number of facilities of the transmission resources 10-1,...,10-M is M, and the first transmission resource 10-1 is composed of a transmission resource switch 5A-1 and L1 transmission resource devices 6A-1-1,...,6A-1-L1. Similarly, the Mth transmission resource 10-M is composed of a transmission resource switch 5A-M and LM transmission resource devices 6A-M-1,...,6A-M-LM.

[0147] The number of facilities of the sending master 11 is one, and the sending master 11 is made up of a sending master switch 5B and N sending master devices 6B-1, . . . , 6B-N.

[0148] Comparing the IP broadcasting system 1A shown in FIG. 1 with this IP broadcasting system 1B, both IP broadcasting systems 1A and 1B have in common the point that they are provided with a synchronization accuracy evaluation device 2, a time monitoring terminal 3, and a grandmaster device 4.

[0149] On the other hand, the IP broadcasting system 1B differs from the IP broadcasting system 1A having one facility in that it has facilities for M transmission resources 10-1,...,10-M and one transmission master 11, as well as a time distribution switch 7, a core switch 8 and a time collection switch 9.

[0150] Hereinafter, the sending resource switches 5A-1,...,5A-M are collectively referred to as sending resource switches 5A, the sending resource devices 6A-1-1,...,6A-1-L1,...,6A-M-1,...,6A-M-LM are collectively referred to as sending resource devices 6A, the sending master devices 6B-1,...,6B-N are collectively referred to as sending master device 6B, and the sending resources 10-1,...,10-M are collectively referred to as sending resources 10.

[0151] Incidentally, a sending resource switch 5A and a sending master switch 5B provided in the IP broadcasting system 1B correspond to the sending switch 5 of the IP broadcasting system 1A shown in FIG.

[0152] The sending staff who operates the time monitoring terminal 3 is an engineer who performs maintenance work such as health checks and broadcast video and audio monitoring for each of the devices, the sending resource switch 5A and the sending resource device 6A in the sending resource 10, and the sending master switch 5B and the sending master device 6B in the sending master 11. This sending staff quantitatively observes the PTP offset fluctuation amount ΔO calculated by the synchronization accuracy evaluation device 2 for each of the devices, the sending resource switch 5A, the sending master switch 5B, the sending resource device 6A, and the sending master device 6B.

[0153] The synchronization accuracy evaluation device 2 performs processing corresponding to the synchronization accuracy evaluation device 2 shown in Fig. 1. Specifically, the synchronization accuracy evaluation device 2 receives a PTP message including time information from the time collection switch 9, stores the PTP message in a memory, and analyzes it. Then, similar to the synchronization accuracy evaluation device 2 of Fig. 1, the synchronization accuracy evaluation device 2 generates measurement data by calculating the PTP offset fluctuation amount ΔO of each device of the sending resource switch 5A, the sending master switch 5B, the sending resource device 6A, and the sending master device 6B based on the time information included in the PTP message and the receiving time of the PTP message, or by performing threshold processing on the PTP offset fluctuation amount ΔO to determine a synchronization abnormality.

[0154] 1, the synchronization accuracy evaluation device 2 processes the PTP offset fluctuation amount ΔO to generate time synchronization information that is easily visible to humans, such as a time series graph, and searches for or refers to measurement data in response to a request received from the time monitoring terminal 3. Then, the synchronization accuracy evaluation device 2 transmits the time synchronization information and a response to the request to the time monitoring terminal 3. The synchronization accuracy evaluation device 2 will be described in detail later.

[0155] The time monitoring terminal 3 and the grandmaster device 4 perform the same processes as those of the time monitoring terminal 3 and the grandmaster device 4 shown in FIG.

[0156] The sending resource switch 5A performs processing corresponding to the sending switch 5 shown in Fig. 1. Specifically, the sending resource switch 5A receives multicast packets including video, audio, and auxiliary data from all sending resource devices 6A in the sending resources 10. The sending resource switch 5A then transfers the multicast packets to the backbone switch 8 and other sending resource devices 6A in the sending resources 10. The sending resource switch 5A also exchanges multicast route information with an adjacent multicast router (not shown) by PIM-SSM, and updates multicast route information.

[0157] The sending resource switch 5A includes a boundary clock (BC) and performs messaging according to PTP v2 according to the time of the boundary clock. The sending resource switch 5A functions as a slave to the grandmaster device 4, which is the master, and also functions as a master to the sending resource device 6A, which is the slave.

[0158] When the transmission resource switch 5A functions as a slave, it transmits and receives PTP messages to and from the grandmaster device 4 functioning as a master via the time distribution switch 7. The transmission resource switch 5A then corrects the boundary clock time (PTP time) to synchronize the boundary clock time with the grandmaster clock time provided in the grandmaster device 4.

[0159] On the other hand, when the sending resource switch 5A functions as a master, it transmits and receives PTP messages to and from the sending resource device 6A functioning as a slave.

[0160] In addition, the sending resource switch 5A copies the PTP messages transmitted and received between the grandmaster equipment 4 and the sending resource device 6A by port mirroring, and transfers the copied PTP messages to the time collection switch 9.

[0161] The sending resource device 6A performs processing corresponding to the sending device 6 shown in Fig. 1. Specifically, the sending resource device 6A generates video, audio, and auxiliary data in the SMPTE ST 2110 format, and transmits a multicast packet including the video, audio, and auxiliary data to the sending resource switch 5A. In addition, the sending resource device 6A receives a multicast packet from the sending resource switch 5A by IGMP v3, and extracts and processes the video, audio, and auxiliary data from the multicast packet.

[0162] The sending resource device 6A functions as a slave, has a slave clock, and operates according to the time of the slave clock. The sending resource device 6A transmits and receives PTP messages with the sending resource switch 5A functioning as a master. The sending resource device 6A corrects the time of the slave clock (PTP time) to synchronize the time of the slave clock with the time of the boundary clock provided in the sending resource switch 5A.

[0163] The sending master switch 5B performs processing corresponding to the sending switch 5 shown in Fig. 1. Specifically, the sending master switch 5B receives multicast packets including video, audio, and auxiliary data from the backbone switch 8 and all sending master devices 6B in the sending master 11, and transfers the multicast packets to other sending master devices 6B in the sending master 11. In addition, the sending master switch 5B exchanges multicast route information with adjacent multicast routers (not shown) by PIM-SSM, and updates the multicast route information.

[0164] The sending master switch 5B is equipped with a boundary clock (BC) and performs messaging by PTP v2 according to the time of the boundary clock. The sending master switch 5B functions as a slave to the grandmaster device 4, which is the master, and also functions as a master to the sending master device 6B, which is the slave.

[0165] When the transmission master switch 5B functions as a slave, it transmits and receives PTP messages to and from the grandmaster device 4 functioning as a master via the time distribution switch 7. The transmission master switch 5B then corrects the boundary clock time (PTP time) to synchronize the boundary clock time with the grandmaster clock time provided in the grandmaster device 4.

[0166] On the other hand, when the sending master switch 5B functions as a master, it transmits and receives PTP messages to and from the sending master device 6B which functions as a slave.

[0167] In addition, the sending master switch 5B copies the PTP messages transmitted and received between the grandmaster equipment 4 and the sending master device 6B by port mirroring, and transfers the copied PTP messages to the time collection switch 9.

[0168] The sending master device 6B performs processing corresponding to the sending device 6 shown in Fig. 1. Specifically, the sending master device 6B generates video, audio, and auxiliary data in the SMPTE ST 2110 format, and transmits a multicast packet including the video, audio, and auxiliary data to the sending master switch 5B. The sending master device 6B also receives a multicast packet from the sending master switch 5B by IGMP v3, and extracts and processes the video, audio, and auxiliary data from the multicast packet.

[0169] The sending master device 6B functions as a slave, has a slave clock, and operates according to the time of the slave clock. The sending master device 6B transmits and receives PTP messages with the sending master switch 5B, which functions as a master. The sending master device 6B corrects the time of the slave clock (PTP time) to synchronize the time of the slave clock with the time of the boundary clock provided in the sending master switch 5B.

[0170] The time distribution switch 7 is equipped with a transparent clock (TC) and operates according to the time of the transparent clock. The time distribution switch 7 transfers PTP messages transmitted and received between the grandmaster device 4 and the sending resource switch 5A and sending master switch 5B that are synchronized with the grandmaster clock provided in the grandmaster device 4.

[0171] The backbone switch 8 receives the multicast packet from the sending resource switch 5A, and transfers the multicast packet to the sending master switch 5B.

[0172] The time collection switch 9 receives PTP messages from the sending resource switch 5A and the sending master switch 5B, and transfers the PTP messages to the synchronization accuracy evaluation device 2.

[0173] [Synchronization accuracy evaluation device 2 installed in IP broadcasting system 1B] Next, the synchronization accuracy evaluation device 2 shown in Fig. 12 will be described in detail. This synchronization accuracy evaluation device 2 has the same components as those in Fig. 2. The receiving unit 20, memories 21, 23, 26, analyzing unit 22, processing unit 29, request processing unit 30 and transmitting / receiving unit 31 are the same as those in Fig. 2, so their description will be omitted.

[0174] The sending device PTP offset calculation unit 24 calculates the PTP offset fluctuation amount ΔO, which is the amount of change in the PTP offset accumulated over a certain period of time, for each of all the sending resource devices 6A and the sending master device 6B, using the above-mentioned formula (12).

[0175] Specifically, the sending device PTP offset calculation unit 24 corresponds to the sending switch 5 in Figure 1 in which the sending resource switch 5A functioning as a master and the sending master switch 5B function as a master, and corresponds to the sending device 6 in Figure 1 in which the sending resource device 6A functioning as a slave and the sending master device 6B function as a slave, and performs processing similar to the processing described in Figures 4 to 7.

[0176] The sending switch PTP offset calculation unit 25 calculates the PTP offset fluctuation amount ΔO, which is the amount of change in the PTP offset accumulated over a certain period of time, for each of all the sending resource switches 5A and the sending master switch 5B, using the above formula (19).

[0177] Specifically, the sending switch PTP offset calculation unit 25 corresponds to the sending switch 5 in Figure 1 in which the grandmaster device 4 functions as the master and the sending resource switch 5A and the sending master switch 5B function as slaves, and performs processing similar to the processing described in Figures 8 to 11.

[0178] The sending device synchronization monitoring unit 27 performs processing corresponding to the sending device synchronization monitoring unit 27 shown in Fig. 2. Specifically, when monitoring the synchronization of the sending resource device 6A, the sending device synchronization monitoring unit 27 monitors whether the master clock to be synchronized is the same and whether the PTP offset fluctuation amount ΔO of all sending resource devices 6A connected to the sending resource switch 5A having the master clock converges within a certain range. For example, for the sending resource 10-1, the PTP offset fluctuation amount ΔO of all sending resource devices 6A-1-1, ..., 6A-1-L1 is monitored.

[0179] If the sending device synchronization monitoring unit 27 determines that the above formula (2) is not satisfied for one or more of all sending resource devices 6A in the sending resource 10 (if it determines that the PTP offset fluctuation amount ΔO exceeds the threshold value A), it outputs a sending resource device synchronization abnormality for that sending resource 10.

[0180] Furthermore, when monitoring the synchronization of the sending master device 6B, the sending device synchronization monitoring unit 27 monitors whether the PTP offset fluctuation amount ΔO of all sending master devices 6B connected to the sending master switch 5B having the same master clock to be synchronized converges within a certain range. For example, for the sending master 11, the PTP offset fluctuation amount ΔO of the sending master devices 6B-1, . . . , 6B-N is monitored.

[0181] If the sending device synchronization monitoring unit 27 determines that the formula (2) is not satisfied for one or more of all the sending master devices 6B in the sending master 11 (if it determines that the PTP offset fluctuation amount ΔO exceeds the threshold value A), it outputs a sending master device synchronization abnormality for that sending master 11.

[0182] As a result, the sending person in charge of sending can determine that the PTP offset fluctuation amount ΔO in one or more sending resource devices 6A among all sending resource devices 6A in the same sending resource 10 has not converged to a certain range by determining the occurrence of a sending resource device synchronization abnormality in units of sending resources 10. Similarly, the sending person in charge of sending can determine that the PTP offset fluctuation amount ΔO in one or more sending master devices 6B among all sending master devices 6B in the same sending master 11 has not converged to a certain range by determining the occurrence of a sending master device synchronization abnormality in units of sending masters 11.

[0183] The sending switch synchronization monitoring unit 28 performs processing corresponding to the sending switch synchronization monitoring unit 28 shown in Fig. 2. Specifically, when monitoring the synchronization of the sending resource switch 5A, the sending switch synchronization monitoring unit 28 monitors whether the grandmaster clock to be synchronized is the same and whether the PTP offset fluctuation amount ΔO of all the sending resource switches 5A connected to the grandmaster device 4 having the grandmaster clock converges within a certain range. For example, the PTP offset fluctuation amount ΔO of all the sending resource switches 5A-1, ..., 5A-M is monitored.

[0184] If the transmission switch synchronization monitoring unit 28 determines that the above formula (3) is not satisfied for one or more of all the transmission resource switches 5A (if it determines that the PTP offset fluctuation amount ΔO exceeds the threshold value B), it outputs a transmission resource switch synchronization abnormality.

[0185] In addition, when the transmission switch synchronization monitoring unit 28 monitors the synchronization of the transmission master switch 5B, it monitors whether the grand master clock to be synchronized is the same and whether the PTP offset fluctuation amount ΔO of the transmission master switch 5B connected to the grand master device 4 equipped with that grand master clock converges within a certain range.

[0186] When the sending switch synchronization monitoring unit 28 determines that the sending master switch 5B does not satisfy the formula (3) (when the sending switch synchronization monitoring unit 28 determines that the PTP offset fluctuation amount ΔO exceeds the threshold value B), it outputs a sending master switch synchronization abnormality.

[0187] As a result, by determining the occurrence of a sending resource switch synchronization abnormality, the sending person can determine that the PTP offset fluctuation amount ΔO in one or more sending resource switches 5A among all sending resource switches 5A in units of the grandmaster device 4 has not converged to a certain range. Similarly, by determining the occurrence of a sending master switch synchronization abnormality, the sending person can determine that the PTP offset fluctuation amount ΔO in the sending master switch 5B in units of the grandmaster device 4 has not converged to a certain range.

[0188] As described above, according to the synchronization accuracy evaluation device 2 of an embodiment of the present invention provided in the IP broadcasting system 1B of Figure 12, the PTP offset fluctuation amount ΔO can be calculated for each of all the transmitting resource switches 5A, the transmitting master switch 5B, the transmitting resource device 6A and the transmitting master device 6B from only the time information contained in the PTP message and the receiving time of the PTP message.

[0189] As a result, there is no need to implement new functions in the transmission resource switch 5A, the transmission master switch 5B, the transmission resource device 6A, and the transmission master device 6B, as in the case of the IP broadcasting system 1A in Fig. 1. Therefore, by providing the synchronization accuracy evaluation device 2 in the IP broadcasting system 1B including the existing transmission resource switch 5A, the transmission master switch 5B, the transmission resource device 6A, and the transmission master device 6B, it is possible to easily evaluate the synchronization accuracy of the entire system regardless of the models and manufacturing vendors of the transmission resource switch 5A, the transmission master switch 5B, the transmission resource device 6A, and the transmission master device 6B.

[0190] In addition, the person in charge of transmission can evaluate whether or not the synchronization accuracy between the two transmission resource devices 6A has converged to 1 μs or less, which is required for the IP broadcasting system 1B, by referring to the PTP offset fluctuation amount ΔO for two transmission resource devices 6A arbitrarily selected from all the transmission resource devices 6A in the same transmission resource 10. The same applies to the transmission master 11.

[0191] Furthermore, even if the IP broadcasting system 1B is a large-scale remote production system equipped with multiple grandmaster devices 4, it is possible to quickly grasp synchronization errors and abnormalities, thereby enabling rapid detection of faults and recovery.

[0192] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the technical concept thereof.

[0193] For example, the IP broadcasting system 1B shown in FIG. 12 includes a plurality of transmission resources 10 and one transmission master 11 under one grandmaster device 4.

[0194] The present invention is also applicable to an IP broadcasting system having multiple transmission resources 10 and multiple transmission masters 11 under a single grandmaster device 4, and also to an IP broadcasting system having a single transmission resource 10 and one or multiple transmission masters 11.

[0195] Furthermore, the present invention may be configured to configure a redundant system by providing multiple grandmaster devices 4. In this case, the IP broadcasting system is configured to include one or multiple transmission resources 10 and one or multiple transmission masters 11 under each grandmaster device 4.

[0196] In the embodiment, the synchronization accuracy evaluation device 2 shown in FIG. 2 includes a sending device PTP offset calculation unit 24, a sending switch PTP offset calculation unit 25, a sending device synchronization monitoring unit 27, a sending switch synchronization monitoring unit 28, and the like.

[0197] In contrast, in order to calculate only the PTP offset fluctuation amount ΔO of the sending device 6, the synchronization accuracy evaluation device 2 may be provided with a sending device PTP offset calculation unit 24, etc. in the configuration shown in Figure 2, but may not be provided with the sending switch PTP offset calculation unit 25, the sending device synchronization monitoring unit 27, and the sending switch synchronization monitoring unit 28.

[0198] In addition, the synchronization accuracy evaluation device 2 calculates the PTP offset fluctuation amount ΔO of the sending device 6 and is equipped with a sending device PTP offset calculation unit 24 and a sending device synchronization monitoring unit 27, etc., in order to generate a sending device synchronization anomaly, and may not be equipped with a sending switch PTP offset calculation unit 25 and a sending switch synchronization monitoring unit 28.

[0199] Furthermore, in order to calculate only the PTP offset fluctuation amount ΔO of the send switch 5, the synchronization accuracy evaluation device 2 may be provided with a send switch PTP offset calculation unit 25 and the like in the configuration shown in FIG. 2, and may not be provided with the send device PTP offset calculation unit 24, the send device synchronization monitoring unit 27, and the send switch synchronization monitoring unit 28.

[0200] In addition, the synchronization accuracy evaluation device 2 calculates the PTP offset fluctuation amount ΔO of the send switch 5 and is equipped with a send switch PTP offset calculation unit 25 and a send switch synchronization monitoring unit 28, etc., in order to generate a send switch synchronization anomaly, and may not be equipped with a send device PTP offset calculation unit 24 and a send device synchronization monitoring unit 27.

[0201] The synchronization accuracy evaluation device 2 shown in FIG. 2 is used in the IP broadcasting system 1A constituting a program transmission system, and therefore uses the name "transmission" in the transmission device PTP offset calculation unit 24, the transmission switch PTP offset calculation unit 25, the transmission device synchronization monitoring unit 27, and the transmission switch synchronization monitoring unit 28, but these components can also be applied to other broadcasting systems such as program production systems.

[0202] A normal computer can be used as the hardware configuration of the synchronization accuracy evaluation device 2 according to the embodiment of the present invention. The synchronization accuracy evaluation device 2 is configured by a computer including a CPU, a volatile storage medium such as a RAM, a non-volatile storage medium such as a ROM, and an interface.

[0203] The functions of the receiving unit 20, memories 21, 23, 26, analysis unit 22, sending device PTP offset calculation unit 24, sending switch PTP offset calculation unit 25, sending device synchronization monitoring unit 27, sending switch synchronization monitoring unit 28, processing unit 29, request processing unit 30 and sending / receiving unit 31 provided in the synchronization accuracy evaluation device 2 are each realized by having a CPU execute a program that describes these functions.

[0204] These programs are stored in the storage medium and are read and executed by the CPU. These programs can also be distributed by storing them in a storage medium such as a magnetic disk (floppy disk, hard disk, etc.), an optical disk (CD-ROM, DVD, etc.), or a semiconductor memory, and can also be transmitted and received via a network. [Explanation of symbols]

[0205] 1A,1B IP Broadcasting System 2. Synchronization accuracy evaluation device 3. Time monitoring terminal 4. Grandmaster Equipment 5 Sending switch 5A sending resource switch 5B Output master switch 6. Output Device 6A Sending resource device 6B Sending master device 7 Time distribution switch 8. Core Switch 9 Time collection switch 10. Sending Resources 11 Sending Master 20 Receiving section 21,23,26 Memory 22 Analysis Department 24 Transmission device PTP offset calculation unit 25 Transmission switch PTP offset calculation unit 27 Transmission device synchronization monitoring section 28 Transmission switch synchronization monitor 29 Processing Department 30 Request Processing Unit 31 Transmitter / receiver

Claims

1. A synchronization accuracy evaluation device for evaluating the accuracy of time synchronization in an IP broadcasting system, the IP broadcasting system being composed of a grandmaster device, and a switch and a plurality of devices that transmit and receive video, audio, and auxiliary data, and transmitting and receiving a Precision Time Protocol (PTP) message between the grandmaster device functioning as a master and the switch functioning as a slave, and transmitting and receiving the PTP message between the switch functioning as the master and the plurality of devices functioning as slaves, comprising: a receiving unit that receives the PTP message copied by the switch from the switch and identifies a receiving time of the PTP message; Determine whether the PTP message received by the receiving unit is a Sync message, a Delay Request message, or a Delay Response message, and identify source information and destination information of the PTP message; an analysis unit that stores in a memory time information included in the Delay Request message (DReq time information which is the transmission time of the Delay Request message by the slave), the reception time of the Delay Request message specified by the receiving unit (DReq reception time), the source information of the Delay Request message (DReq source information) and the destination information, as well as time information included in the Delay Response message (DRes time information which is the reception time of the Delay Request message by the master), the reception time of the Delay Response message specified by the receiving unit (DRes reception time), and the source information and destination information of the Delay Response message (DRes destination information); When the switch is the master and each of the plurality of devices is the slave, For each of the plurality of devices, read from the memory the DReq time information and the DReq reception time corresponding to the device identified as the DReq source information, and read the DRes time information and the DRes reception time corresponding to the device identified as the DRes destination information; a device PTP offset calculation unit that calculates a fluctuation amount of a time offset between the switch and the device based on the DReq time information, the DReq reception time, the DRes time information, and the DRes reception time as a PTP offset fluctuation amount ΔO of the device; A synchronization accuracy evaluation device comprising:

2. A synchronization accuracy evaluation device for evaluating the accuracy of time synchronization in an IP broadcasting system, the IP broadcasting system being composed of a grandmaster device, and a switch and a plurality of devices that transmit and receive video, audio, and auxiliary data, and transmitting and receiving a Precision Time Protocol (PTP) message between the grandmaster device functioning as a master and the switch functioning as a slave, and transmitting and receiving the PTP message between the switch functioning as the master and the plurality of devices functioning as slaves, comprising: a receiving unit that receives the PTP message copied by the switch from the switch and identifies a receiving time of the PTP message; Determine whether the PTP message received by the receiving unit is a Sync message, a Delay Request message, or a Delay Response message, and identify source information and destination information of the PTP message; an analysis unit that stores in a memory time information included in the Delay Request message (DReq time information which is the transmission time of the Delay Request message by the slave), the reception time of the Delay Request message specified by the receiving unit (DReq reception time), the source information of the Delay Request message (DReq source information) and the destination information, as well as time information included in the Delay Response message (DRes time information which is the reception time of the Delay Request message by the master), the reception time of the Delay Response message specified by the receiving unit (DRes reception time), and the source information and destination information of the Delay Response message (DRes destination information); When the grandmaster device is the master and the switch is the slave, reading, from the memory, the DReq time information and the DReq reception time corresponding to the switch identified as the DReq source information, and reading, from the memory, the DRes time information and the DRes reception time corresponding to the switch identified as the DRes destination information; a switch PTP offset calculation unit that calculates a time offset fluctuation amount between the grandmaster device and the switch based on the DReq time information, the DReq reception time, the DRes time information, and the DRes reception time as a PTP offset fluctuation amount ΔO of the switch; A synchronization accuracy evaluation device comprising:

3. 2. The synchronization accuracy evaluation device according to claim 1, The transmission and reception of the Sync message, the Delay Request message, and the Delay Response message are regarded as one sequence, and the sequence number when the sequence is continuously performed is denoted by k, The device PTP offset calculation unit The DReq time information, which is the transmission time of the Delay Request message by the device, is Td k,3 The DReq reception time, which is the reception time of the Delay Request message specified by the receiving unit, is set to Ts k,4 The DRes time information, which is the reception time of the Delay Request message by the switch, is stored in TMb k,4 The DRes reception time, which is the reception time of the Delay Response message specified by the receiving unit, is set to Ts k,5 , where n is a preset parameter (an integer equal to or greater than 1), The formula: and calculating the PTP offset fluctuation amount ΔO of the device by the above-mentioned method.

4. 3. The synchronization accuracy evaluation device according to claim 2, The transmission and reception of the Sync message, the Delay Request message, and the Delay Response message are regarded as one sequence, and the sequence number when the sequence is continuously performed is denoted by k, The switch PTP offset calculation unit The DReq time information, which is the transmission time of the Delay Request message by the switch, is stored in TSb k,3 The DReq reception time, which is the reception time of the Delay Request message specified by the receiving unit, is set to Ts k,3 The DRes time information, which is the reception time of the Delay Request message by the grandmaster device, is Tg k,4 The DRes reception time, which is the reception time of the Delay Response message specified by the receiving unit, is set to Ts k,6 , where n is a preset parameter (an integer equal to or greater than 1), The following formula: and calculating the PTP offset fluctuation amount ΔO of the switch by the above-mentioned.

5. 4. The synchronization accuracy evaluation device according to claim 1, The synchronization accuracy evaluation device further comprises a device synchronization monitoring unit that outputs a device synchronization abnormality when it is determined that the PTP offset fluctuation amount ΔO calculated by the device PTP offset calculation unit exceeds a predetermined threshold value for one or more of the multiple devices.

6. 5. The synchronization accuracy evaluation device according to claim 2, The synchronization accuracy evaluation device further comprises a switch synchronization monitoring unit that outputs a switch synchronization abnormality when it is determined that the PTP offset fluctuation amount ΔO calculated by the switch PTP offset calculation unit exceeds a predetermined threshold value for the switch.

7. A program for causing a computer to function as the synchronization accuracy evaluation device according to any one of claims 1 to 6.

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