Time information management device and time information management method

Abstract

To detect an abnormality of a time packet in a stream.SOLUTION: A time information management device comprises: a first reception part that receives a target signal containing a first stream; a second reception part that receives a broadcasting wave containing a second stream; a first acquisition part that acquires a first time packet as a time packet containing time information from the first stream; a second acquisition part that acquires a second time packet containing second time information from the second stream; and a detection part that detects an abnormality of the first time packet on the basis of a comparison result of the first time information as the time information contained in the first time packet with the second time information contained in the second time packet.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a time information management device and a time information management method.

Background Art

[0002] Conventionally, a system for transmitting a broadcast signal including content has been proposed. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2008-211587) discloses the following IP / RF conversion device as a device used in such a system. That is, the IP / RF conversion device includes an IP packet receiving device (32-1 to 32-n) that receives an IP packet carrying a broadcast TS packet, a broadcast TS packet processing device (34-1 to 34-n) that extracts the broadcast TS packet from the IP packet received by the IP packet receiving device and outputs it in order of time on the transmission side, a clock extraction device (36-1 to 36-n) that extracts a synchronization clock necessary for OFDM modulation from the broadcast TS packet supplied from the broadcast TS packet processing device and synchronously outputs the synchronization clock and the broadcast TS packet, and an OFDM modulation device (38-1 to 38-n) that OFDM-modulates the broadcast TS packet from the clock extraction device in synchronization with the synchronization clock from the clock extraction device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A stream including content includes a time packet for correcting an internal time in a receiver of the stream. If an abnormality occurs in the time packet, the operations such as viewing reservations in the receiver may be hindered.

[0005] The present disclosure has been made to solve the above-described problems, and an object thereof is to provide a time information management device and a time information management method capable of detecting an abnormality in a time packet in a stream.

Means for Solving the Problems

[0006] The time information management device of the present disclosure includes a first receiving unit that receives a target signal including a first stream, a second receiving unit that receives a broadcast wave including a second stream, and a first receiving unit that receives the target signal received by the first receiving unit. A first acquisition unit that acquires a first time packet that is a time packet including time information from the first stream included in the target signal, and a second time packet that includes second time information from the second stream included in the broadcast wave received by the second receiving unit. And a detection unit that detects an abnormality in the first time packet based on a comparison result between the first time information that is the time information included in the first time packet acquired by the first acquisition unit and the second time information that is the second time information included in the second time packet acquired by the second acquisition unit.

[0007] One aspect of the present disclosure can be realized not only as a time information management device including such a characteristic processing unit, but also as a program for causing a computer to execute steps of such characteristic processing. Further, one aspect of the present disclosure can be realized as a semiconductor integrated circuit that realizes part or all of the time information management device, or can be realized as a system including the time information management device.

Effects of the Invention

[0008] According to the present disclosure, an abnormality in a time packet in a stream can be detected.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

[0010] First, the contents of the embodiments of the present disclosure will be listed and described.

[0011] (1) The time information management device according to an embodiment of the present disclosure includes a first receiving unit that receives a target signal including a first stream, a second receiving unit that receives a broadcast wave including a second stream, a first obtaining unit that obtains a first time packet, which is a time packet including time information, from the first stream included in the target signal received by the first receiving unit, a second obtaining unit that obtains a second time packet including second time information from the second stream included in the broadcast wave received by the second receiving unit, and a detecting unit that detects an abnormality of the first time packet based on a comparison result between first time information included in the first time packet obtained by the first obtaining unit and second time information included in the second time packet obtained by the second obtaining unit.

[0012] In this way, based on the comparison result between the first time information included in the first time packet obtained from the first stream and the second time information included in the second time packet obtained from the second stream included in the broadcast wave, it is possible to detect a deviation in the time indicated by the first time information with reference to the time indicated by the second time information. Therefore, for example, it can be detected as an abnormality of the first time packet that a deviation has occurred in the time indicated by the first time information due to the interruption of communication between the device that is the source of the target signal and an NTP (Network Time Protocol) server. Accordingly, it is possible to detect an abnormality of the time packet in the stream.

[0013] (2) In the above (1), the detecting unit may detect an abnormality of the first time packet based further on a difference in processing time based on a difference in format between the target signal and the broadcast wave.

[0014] With such a configuration, for example, when demodulation processing is not required to obtain the first stream from the target signal, the abnormality of the first time packet can be detected more accurately in consideration of the time required for the demodulation processing to obtain the second stream from the broadcast wave.

[0015] (3) In the above (1) or (2), the time packet may include a sequence value, and the time information management device further includes a generation unit that generates a third time packet that is a time packet including time information based on the second time information, a stream transmission unit that transmits the first stream included in the target signal, and when an abnormality of the first time packet is detected by the detection unit, a switching unit that switches the time packet included in the first stream transmitted by the stream transmission unit from the first time packet to the third time packet including the sequence value adjusted based on the first time packet.

[0016] With such a configuration, when a deviation occurs in the time indicated by the first time information, a first stream including a third time packet generated based on the second time information and having its sequence number adjusted based on the first time packet can be transmitted instead of the first time packet.

[0017] (4) In the above (3), when the abnormality of the first time packet is resolved, the switching unit may switch the time packet included in the first stream transmitted by the stream transmission unit back from the third time packet to the first time packet.

[0018] With such a configuration, when the deviation of the time indicated by the first time information is resolved, a first stream including the first time packet that should originally be transmitted can be transmitted.

[0019] (5) In the above (3) or (4), the switching unit may include a removing unit that removes the first time packet from the first stream included in the target signal, a selecting unit that selects either the first time packet or the third time packet, and a multiplexing unit that multiplexes the time packet selected by the selecting unit onto the first stream from which the first time packet has been removed by the removing unit.

[0020] With such a configuration, it is possible to selectively include a time packet containing more accurate time information in the first stream and transmit it.

[0021] (6) In any of the above (1) to (5), the time information management device may further include a time information transmission unit that transmits time information based on the second time information to an external device that synchronizes time with an NTP server and that is the external device that is the transmission source of the target signal.

[0022] With such a configuration, it is possible to make the time information transmitted to the external device redundant, so that it is possible to suppress the occurrence of an abnormality in the first time packet in the target signal transmitted by the external device.

[0023] (7) The time information management method according to an embodiment of the present disclosure is a time information management method in a time information management device, and includes steps of receiving a target signal including a first stream, receiving a broadcast wave including a second stream, obtaining a first time packet that is a time packet including time information from the first stream included in the received target signal, obtaining a second time packet including second time information from the second stream included in the received broadcast wave, and detecting an abnormality in the first time packet based on a comparison result between the first time information that is the time information included in the obtained first time packet and the second time information that is the second time information included in the obtained second time packet.

[0024] Thus, based on the comparison result between the first time information included in the first time packet obtained from the first stream and the second time information included in the second time packet obtained from the second stream included in the broadcast wave, the deviation of the time indicated by the first time information can be detected with reference to the time indicated by the second time information. Therefore, for example, it is possible to detect that a deviation has occurred in the time indicated by the first time information due to the interruption of communication between the device that is the source of the target signal and the NTP server as an abnormality of the first time packet. Accordingly, it is possible to detect an abnormality of the time packet in the stream.

[0025] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated. Also, at least a part of the embodiments described below may be arbitrarily combined.

[0026] <First Embodiment> [Configuration and Basic Operation] FIG. 1 is a diagram showing the configuration of a broadcast system according to the first embodiment of the present disclosure. Referring to FIG. 1, the broadcast system 501 includes an encoding device 211 and a modulation device 221. The encoding device 211 is an example of an external device. The encoding device 211 and the modulation device 221 can communicate with an NTP server 321 and a control server 322 via a switch 311. The modulation device 221 and the encoding device 211 can communicate with each other via the switch 311. Note that the encoding device 211 and the modulation device 221 may be integrated and provided in one housing.

[0027] The broadcast system 501 transmits content to an STB (Set Top Box) 401 provided in a user's home via a cable television network 411. The content includes, for example, audio information, video information, PSI (Program Specific Information) information, and SI (Service Information) information.

[0028] The NTP server 321 transmits NTP information indicating the current time to the encoding device 211 via the switch 311, for example, periodically.

[0029] The control server 322 transmits control information regarding the transmission of content to the encoding device 211 and the modulation device 221 via the switch 311.

[0030] The encoding device 211 generates a stream S1 including content and transmits the generated stream S1 to the modulation device 221.

[0031] FIG. 2 is a diagram showing the configuration of an encoding device according to the first embodiment of the present disclosure. Referring to FIG. 2, the encoding device 211 includes a TS (Transport Stream) generation unit 21, a multiplexing unit 22, an output unit 23, a management unit 24, and a counter 25. The TS generation unit 21 includes an encoding unit 21A, a PSI generation unit 21B, and an SI generation unit 21C.

[0032] The counter 25 counts clock pulses generated by, for example, an oscillation circuit using a crystal oscillator and holds a count value indicating the counted value. The count value indicates, for example, the current time.

[0033] The management unit 24 can communicate with the modulation device 221, the NTP server 321, and the control server 322 via the switch 311.

[0034] The management unit 24 receives NTP information from the NTP server 321 via the switch 311 and performs a process of synchronizing the counter 25 with the NTP server 321 based on the received NTP information. More specifically, the management unit 24 updates the count value of the counter 25 based on the NTP information. Further, the management unit 24 receives control information from the control server 322 via the switch 311 and outputs the received control information to the TS generation unit 21 and the multiplexing unit 22.

[0035] The encoding unit 21A outputs a plurality of TS packets P1 including information in which audio information and video information are divided into a plurality of parts to the multiplexing unit 22. More specifically, the encoding unit 21A receives control information indicating the content to be transmitted by the broadcast system 501 from the management unit 24, and according to the received control information, acquires one or a plurality of contents of the independent broadcast from a storage unit inside or outside the encoding device 211. The encoding unit 21A generates a plurality of TS packets P1 including information in which audio information and video information are divided into a plurality of parts by encoding the audio information and video information included in the acquired content. The encoding unit 21A outputs the generated TS packets P1 to the multiplexing unit 22.

[0036] The PSI generation unit 21B outputs a TS packet P1 including PSI information to the multiplexing unit 22. In the TS packet P1 output to the multiplexing unit 22 by the PSI generation unit 21B, as the PSI information, a PAT (Program Association Table), a PMT (Program Map Table), a TOT (Time Offset Table), etc. are stored. The TOT includes a TOT time indicating the Japanese standard time and a continuity index CC indicating the sequence value of the TOT. Hereinafter, the TS packet in which the TOT is stored is also referred to as a "TS packet tot", and the TS packet P1 in which the TOT is stored is also referred to as a "TS packet P1_tot". The TS packet P1_tot is an example of a first time packet. The TOT stored in the TS packet P1_tot is an example of first time information.

[0037] The PSI generation unit 21B outputs the TS packet P1_tot to the multiplexing unit 22 at a transmission timing according to a predetermined transmission period Ct. More specifically, the PSI generation unit 21B acquires the count value of the counter 25 at the transmission timing, converts it into a TOT time, and generates a TOT including the converted TOT time and the continuity index CC. Then, the PSI generation unit 21B outputs the TS packet P1_tot in which the generated TOT is stored to the multiplexing unit 22. The transmission period Ct is, for example, 5 seconds.

[0038] The SI generation unit 21C outputs a TS packet P1 containing SI information to the multiplexing unit 22. In the TS packet P1 generated by the SI generation unit 21C and output to the multiplexing unit 22, SDT (Service Description Table), EIT (Event Information Table), BIT (Broadcaster Information Table), etc. are stored as SI information.

[0039] The multiplexing unit 22 generates a stream S1 including the TS packet P1 by multiplexing the TS packets P1 received from each of the encoding unit 21A, the PSI generation unit 21B, and the SI generation unit 21C in the time axis direction. The multiplexing unit 22 outputs the generated stream S1 to the output unit 23. The stream S1 is an example of a first stream.

[0040] The output unit 23 transmits an ASI (Asynchronous Serial Interface) signal including the stream S1 received from the multiplexing unit 22 to the modulation device 221. The ASI signal is an example of a target signal.

[0041] Referring to FIG. 1 again, the modulation device 221 receives an ASI signal from the encoding device 211. The modulation device 221 generates a modulation signal by modulating the stream S1 included in the received ASI signal according to a predetermined modulation method such as OFDM (Orthogonal Frequency Division Multiplexing). The modulation device 221 generates a broadcast signal in the RF (Radio Frequency) band by up-converting the generated modulation signal, and transmits the generated broadcast signal to the STB 401 via the cable television network 411.

[0042] [Problem] For example, when communication between the NTP server 321 and the encoding device 211 is interrupted, the counter 25 in the encoding device 211 cannot be synchronized with the NTP server 321, so the count value of the counter 25 may gradually deviate from the internal time of the NTP server 321. In this case, in the broadcast system 501, a TS packet P1 including a TOT time deviated from the Japanese Standard Time may be transmitted, which may cause problems in operations such as viewing reservations in the STB 401.

[0043] In a conventional broadcast system, it is impossible to detect that the TOT time included in the TS packet P1 is deviated from the Japanese Standard Time.

[0044] Therefore, the broadcast system 501 according to the embodiment of the present disclosure solves the above problems with the following configuration.

[0045] FIG. 3 is a diagram showing the configuration of a modulation device according to the first embodiment of the present disclosure. Referring to FIG. 3, the modulation device 221 includes an ASI reception unit 31, a broadcast wave reception unit 32, a modulation unit 33, an output unit 34, a management unit 35, and a time information processing unit 101. The time information processing unit 101 is an example of a time information management device.

[0046] The management unit 35 can communicate with the control server 322 via the switch 311. The management unit 35 receives control information from the control server 322 via the switch 311 and outputs the received control information to the modulation unit 33 and the output unit 34.

[0047] The ASI reception unit 31 receives an ASI signal from the encoding device 211. The ASI reception unit 31 outputs the received ASI signal to the time information processing unit 101.

[0048] The broadcast wave reception unit 32 receives a broadcast wave including the stream S2 via an antenna (not shown). The stream S2 is an example of a second stream. The stream S2 includes content of terrestrial digital broadcasting or BS digital broadcasting. The broadcast wave reception unit 32 outputs the received broadcast wave to the time information processing unit 101.

[0049] The stream S2 includes TS packets P2 in which audio information, video information, PAT, PMT, TOT, SDT, EIT, BIT, etc. are stored. Hereinafter, the TS packet P2 in which TOT is stored among the TS packets P2 included in the stream S2 is also referred to as "TS packet P2_tot". The TS packet P2_tot is an example of a second time packet. The TOT stored in the TS packet P2_tot is an example of second time information. For example, the TS packet P2_tot is transmitted included in the stream S2 at a transmission period Ct.

[0050] FIG. 4 is a diagram showing the configuration of a time information processing unit in a modulation apparatus according to the first embodiment of the present disclosure. Referring to FIG. 4, the time information processing unit 101 includes receiving units 11A and 11B, TOT acquisition units 12A and 12B, conversion units 13A and 13B, a counter 14, a detection unit 15, and an output unit 16. The receiving unit 11A is an example of a first receiving unit. The receiving unit 11B is an example of a second receiving unit. The TOT acquisition unit 12A is an example of a first acquisition unit. The TOT acquisition unit 12B is an example of a second acquisition unit. The output unit 16 is an example of a stream transmission unit.

[0051] The receiving unit 11A receives an ASI signal including the stream S1. More specifically, the receiving unit 11A receives the ASI signal from the ASI receiving unit 31. The receiving unit 11A acquires the stream S1 from the received ASI signal and outputs it to the TOT acquisition unit 12A and the output unit 16.

[0052] The receiving unit 11B receives a broadcast wave including the stream S2. More specifically, the receiving unit 11B receives the broadcast wave from the broadcast wave receiving unit 32. The receiving unit 11B is, for example, a NIM (Network Interface Module), and generates the stream S2 by performing demodulation processing on the received broadcast wave and outputs it to the TOT acquisition unit 12B.

[0053] The output unit 16 transmits the stream S1 included in the ASI signal. More specifically, the output unit 16 outputs the stream S1 received from the reception unit 11A to the modulation unit 33.

[0054] The TOT acquisition unit 12A acquires the TS packet P1_tot from the stream S1 included in the ASI signal received by the reception unit 11A. More specifically, the TOT acquisition unit 12A refers to the PID (Packet ID) stored in the header of the TS packet P1 included in the stream S1 received from the reception unit 11A, and extracts the TS packet P1_tot from among the TS packets P1 included in the stream S1. The TOT acquisition unit 12A outputs the extracted TS packet P1_tot to the conversion unit 13A.

[0055] If the TOT acquisition unit 12A fails to extract a new TS packet P1_tot within a predetermined-length timeout period from the extraction timing of the immediately preceding TS packet P1_tot, the TOT acquisition unit 12A outputs an error notification indicating that the TS packet P1_tot has been interrupted to the detection unit 15. Also, if the TOT acquisition unit 12A extracts a new TS packet P1_tot after outputting the error notification, the TOT acquisition unit 12A outputs an error cancellation notification to the detection unit 15.

[0056] The TOT acquisition unit 12B acquires the TS packet P2_tot from the stream S2 included in the broadcast wave received by the reception unit 11B. More specifically, the TOT acquisition unit 12B refers to the PID stored in the header of the TS packet P2 included in the stream S2 received from the reception unit 11B, and extracts the TS packet P2_tot from among the TS packets P2 included in the stream S2. The TOT acquisition unit 12B outputs the extracted TS packet P2_tot to the conversion unit 13B.

[0057] When the TOT acquisition unit 12B fails to extract a new TS packet P2_tot within a predetermined-length timeout period from the extraction timing of the TS packet P2_tot extracted immediately before, the TOT acquisition unit 12B outputs an error notification indicating that the TS packet P2_tot has been interrupted to the detection unit 15. Further, when the TOT acquisition unit 12B extracts a new TS packet P2_tot after outputting the error notification, the TOT acquisition unit 12B outputs an error cancellation notification to the detection unit 15.

[0058] The conversion unit 13A receives the TS packet P1_tot from the TOT acquisition unit 12A and acquires the TOT time from the received TS packet P1_tot. For example, the conversion unit 13A converts the acquired TOT time into a target time tt based on a predetermined time. More specifically, the conversion unit 13A converts the acquired TOT time into a target time tt indicating the elapsed time in milliseconds from zero o'clock in the morning of the current day. The conversion unit 13A outputs the converted target time tt to the detection unit 15.

[0059] The conversion unit 13B receives the TS packet P2_tot from the TOT acquisition unit 12B and acquires the TOT time from the received TS packet P2_tot. For example, the conversion unit 13B converts the acquired TOT time into a reference time tr based on a predetermined time. More specifically, the conversion unit 13B converts the acquired TOT time into a reference time tr indicating the elapsed time in milliseconds from zero o'clock in the morning of the current day. The conversion unit 13B sets the count value of the counter 14 to the converted reference time tr.

[0060] The counter 14 is a counter that operates according to the timing of a self-running clock with a 1-millisecond cycle. The counter 14 updates the count value set by the conversion unit 13B at a 1-millisecond cycle.

[0061] For example, when the conversion unit 13B converts the TOT time acquired from the TS packet P2_tot into the reference time tr, the conversion unit 13B diagnoses the TS packet P2_tot based on the converted reference time tr and the current count value of the counter 14.

[0062] More specifically, when the difference between the converted reference time tr and the current count value of the counter 14 is greater than a predetermined value, the conversion unit 13B outputs an error notification indicating that the arrival period of the TS packet P2_tot is abnormal to the detection unit 15. Then, the conversion unit 13B sets the count value of the counter 14 to the reference time tr.

[0063] Also, after outputting the error notification, when the difference between the converted reference time tr and the current count value of the counter 14 becomes less than or equal to the predetermined value, the conversion unit 13B outputs an error cancellation notification to the detection unit 15. Then, the conversion unit 13B sets the count value of the counter 14 to the reference time tr.

[0064] The detection unit 15 detects an abnormality in the TS packet P1_tot based on the comparison result between the TOT included in the TS packet P1_tot acquired by the TOT acquisition unit 12A and the TOT included in the TS packet P2_tot acquired by the TOT acquisition unit 12B.

[0065] More specifically, the detection unit 15 receives the target time tt from the conversion unit 13A and acquires the current count value from the counter 14. The detection unit 15 performs a comparison process of comparing the received target time tt with the acquired count value. In this way, even when the TS packet P1_tot and the TS packet P2_tot do not arrive simultaneously, the TOT included in the TS packet P1_tot and the TOT included in the TS packet P2_tot can be compared by the configuration of comparing the target time tt with the count value of the counter 14.

[0066] FIG. 5 is a time chart showing the comparison process in the time information processing unit according to the first embodiment of the present disclosure.

[0067] Referring to FIG. 5, for example, at time t1, the TOT acquisition unit 12B acquires the TS packet P2_tot from the stream S2 and outputs it to the conversion unit 13B. The conversion unit 13B acquires the TOT time from the received TS packet P2_tot, converts it to the reference time tr, and sets the count value of the counter 14 to the reference time tr.

[0068] Next, at time t2 after time t1, the TOT acquisition unit 12A acquires the TS packet P1_tot from the stream S1 and outputs it to the conversion unit 13A. The conversion unit 13A acquires the TOT time from the received TS packet P1_tot, converts it to the target time tt, and outputs the target time tt to the detection unit 15. The detection unit 15 receives the target time tt from the conversion unit 13A and compares the received target time tt with the current count value of the counter 14. The detection unit 15 detects an abnormality of the TS packet P1_tot based on the comparison result between the target time tt and the count value.

[0069] Similarly, at times t3, t5, and t7, the TOT acquisition unit 12B acquires the TS packet P2_tot from the stream S2 and outputs it to the conversion unit 13B. The conversion unit 13B acquires the TOT time from the received TS packet P2_tot, converts it to the reference time tr, and sets the count value of the counter 14 to the reference time tr.

[0070] Also, similarly, at times t4, t6, and t8, the TOT acquisition unit 12A acquires the TS packet P1_tot from the stream S1 and outputs it to the conversion unit 13A. The conversion unit 13A acquires the TOT time from the received TS packet P1_tot, converts it to the target time tt, and outputs the target time tt to the detection unit 15. The detection unit 15 receives the target time tt from the conversion unit 13A and compares the received target time tt with the current count value of the counter 14. The detection unit 15 detects an abnormality of the TS packet P1_tot based on the comparison result between the target time tt and the count value.

[0071] For example, the detection unit 15 detects an abnormality in the TS packet P1_tot based on the difference in processing time based on the difference in the formats of the ASI signal and the broadcast wave.

[0072] More specifically, the detection unit 15 calculates the absolute value Va of the difference obtained by subtracting the count value and a predetermined offset value from the target time tt. The offset value is preset based on the time required for the demodulation process in the receiving unit 11B.

[0073] The detection unit 15 compares the absolute value Va with a predetermined threshold value Th1. When the absolute value Va is less than or equal to the threshold value Th1, the deviation amount of the TOT time of the TS packet P1_tot is within the allowable range, and it is determined that the TS packet P1_tot included in the stream S1 is normal.

[0074] On the other hand, when the absolute value Va is greater than the threshold value Th1, the detection unit 15 determines that the deviation amount of the TOT time of the TS packet P1_tot exceeds the allowable range, and the TS packet P1_tot included in the stream S1 is abnormal.

[0075] When the detection unit 15 determines that the TS packet P1_tot is abnormal, it transmits determination information indicating the determination result to the control server 322 via the switch 311. When the control server 322 receives the determination information, it performs a process of notifying the administrator of the control server 322 of the determination result indicated by the determination information.

[0076] For example, when the detection unit 15 receives an error notification from the TOT acquisition unit 12A, it stops the comparison process until it receives an error cancellation notification from the TOT acquisition unit 12A. Also, for example, when the detection unit 15 receives an error notification from the TOT acquisition unit 12B, it stops the comparison process until it receives an error cancellation notification from the TOT acquisition unit 12B. Also, for example, when the detection unit 15 receives an error notification from the conversion unit 13B, it stops the comparison process until it receives an error cancellation notification from the conversion unit 13B.

[0077] Further, for example, the detection unit 15 stops the comparison process during an adjustment period from the timing when a leap second is inserted or deleted until a predetermined time has elapsed. Note that, during the adjustment period, instead of stopping the comparison process, the detection unit 15 may perform the comparison process using a threshold value Th2 that is larger than the threshold value Th1 instead of the threshold value Th1.

[0078] Referring again to FIG. 3, the modulation unit 33 receives the stream S1 from the time information processing unit 101. The modulation unit 33 generates a modulation signal by modulating the received stream S1 according to a predetermined modulation method such as OFDM according to the control information received from the management unit 35, and outputs the generated modulation signal to the output unit 34.

[0079] The output unit 34 generates a broadcast signal in the frequency band indicated by the control information received from the management unit 35 by up-converting the modulation signal received from the modulation unit 33, and transmits the generated broadcast signal to the STB 401 via the cable television network 411.

[0080] [Operation flow] FIG. 6 is a flowchart defining an example of an operation procedure when the time information processing unit according to the first embodiment of the present disclosure acquires TOT from a broadcast wave.

[0081] Referring to FIG. 6, first, the time information processing unit 101 starts receiving and demodulating a broadcast wave including the stream S2 (step S11).

[0082] Next, the time information processing unit 101 waits for the arrival of the TS packet P2_tot (NO in step S12), and when detecting the TS packet P2_tot among the plurality of TS packets P2 included in the stream S2 (YES in step S12), acquires the TS packet P2_tot from the stream S2 (step S13).

[0083] Next, the time information processing unit 101 acquires the TOT time from the TS packet P2_tot, and converts the acquired TOT time into the reference time tr (step S14).

[0084] Next, the time information processing unit 101 sets the count value of the counter 14 to the converted reference time tr (step S15).

[0085] Next, the time information processing unit 101 waits for the arrival of a new TS packet P2_tot (NO in step S12).

[0086] FIG. 7 is a flowchart defining an example of an operation procedure when the time information processing unit according to the first embodiment of the present disclosure acquires a TOT from an ASI signal and performs a comparison process.

[0087] Referring to FIG. 7, first, the time information processing unit 101 starts receiving an ASI signal including a stream S1 (step S21).

[0088] Next, the time information processing unit 101 waits for the arrival of a TS packet P1_tot (NO in step S22), and when detecting the TS packet P1_tot among a plurality of TS packets P1 included in the stream S1 (YES in step S22), the time information processing unit 101 acquires the TS packet P1_tot from the stream S1 (step S23).

[0089] Next, the time information processing unit 101 acquires a TOT time from the TS packet P1_tot and converts the acquired TOT time into a target time tt (step S24).

[0090] Next, the time information processing unit 101 compares the converted target time tt with the current count value of the counter 14. More specifically, the time information processing unit 101 calculates an absolute value Va of a difference obtained by subtracting the count value and the offset value from the target time tt (step S25).

[0091] Next, when the absolute value Va is equal to or less than a threshold value Th1 (YES in step S26), the time information processing unit 101 determines that the TS packet P1_tot is normal (step S27).

[0092] Next, the time information processing unit 101 waits for the arrival of a new TS packet P1_tot (NO in step S22).

[0093] On the other hand, when the absolute value Va is less than or equal to but greater than the threshold Th1 (NO in step S26), the time information processing unit 101 determines that the TS packet P1_tot is abnormal (step S28).

[0094] Next, the time information processing unit 101 transmits determination information indicating the determination result to the control server 322 via the switch 311 (step S29).

[0095] Next, the time information processing unit 101 waits for the arrival of a new TS packet P1_tot (NO in step S22).

[0096] Note that in the time information processing unit 101 according to the embodiment of the present disclosure, the detection unit 15 is configured to detect an abnormality of the TS packet P1_tot based on the difference in processing time based on the difference in format between the ASI signal and the broadcast wave. However, the present disclosure is not limited thereto. The detection unit 15 may be configured to detect an abnormality of the TS packet P1_tot without considering the difference in processing time. More specifically, the detection unit 15 calculates the absolute value Vb of the difference between the target time tt and the count value instead of the absolute value Va, and compares the calculated absolute value Vb with the threshold Th1. Then, when the absolute value Vb is less than or equal to the threshold Th1, the detection unit 15 determines that the TS packet P1_tot is normal, while when the absolute value Vb is greater than the threshold Th1, the detection unit 15 determines that the TS packet P1_tot is abnormal.

[0097] In addition, in the modulation device 221 according to the embodiment of the present disclosure, although the broadcast wave receiving unit 32 is configured to receive a broadcast wave including content of terrestrial digital broadcast or BS digital broadcast, it is not limited thereto. The broadcast wave receiving unit 32 may be configured to receive a broadcast wave including content of advanced BS digital broadcast. In this case, the TOT acquisition unit 12B in the time information processing unit 101 extracts an NTP packet including time information from the stream S2 included in the broadcast wave received by the receiving unit 11B instead of the TS packet P2_tot. The NTP packet is an example of the second time packet. The time information stored in the NTP packet is an example of the second time information.

[0098] Next, another embodiment of the present disclosure will be described with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals and their description will not be repeated.

[0099] <Second Embodiment> This embodiment relates to a broadcast system 502 that detects an abnormality in a time packet included in a modulation signal, as compared with the broadcast system 501 according to the first embodiment. Except for the content described below, it is the same as the broadcast system 501 according to the first embodiment.

[0100] FIG. 8 is a diagram showing the configuration of a broadcast system according to the second embodiment of the present disclosure. Referring to FIG. 8, the broadcast system 502 includes a modulation device 212 instead of the encoding device 211 and a modulation device 222 instead of the modulation device 221, as compared with the broadcast system 501.

[0101] The modulation device 212 receives NTP information from the NTP server 321 via the switch 311, and based on the received NTP information, performs a process of synchronizing a counter (not shown) with the NTP server 321.

[0102] The modulation device 212 generates a stream S3 including a plurality of TS packets P3 in which voice information, video information, PAT, PMT, TOT, SDT, EIT, BIT, etc. are stored. The stream S3 is an example of a first stream. Hereinafter, the TS packet P3 in which TOT is stored is also referred to as "TS packet P3_tot". The TS packet P3_tot is an example of a first time packet. The TOT stored in the TS packet P3_tot is an example of first time information.

[0103] The modulation device 212 generates the TS packet P3_tot at a transmission timing according to the transmission period Ct. More specifically, at the transmission timing, the modulation device 212 acquires the count value of a counter (not shown) and converts it into a TOT time, and generates a TOT including the converted TOT time and a continuity index CC. The modulation device 212 generates a stream S3 including the TS packet P3_tot in which TOT is stored.

[0104] The modulation device 212 generates a modulation signal by modulating the generated stream S3 according to a predetermined modulation method such as OFDM. The modulation device 212 transmits the generated modulation signal to the modulation device 222. The modulation signal generated by the modulation device 212 is an example of a target signal.

[0105] FIG. 9 is a diagram showing the configuration of a modulation device according to a second embodiment of the present disclosure. Referring to FIG. 9, the modulation device 222 includes a modulation signal receiving unit 36 instead of the ASI receiving unit 31 and a time information processing unit 102 instead of the time information processing unit 101 compared with the modulation device 221. The time information processing unit 102 is an example of a time information management device.

[0106] The modulation signal receiving unit 36 receives a modulation signal from the modulation device 212. The modulation signal receiving unit 36 outputs the received modulation signal to the time information processing unit 102.

[0107] FIG. 10 is a diagram showing the configuration of a time information processing unit in a modulation device according to a second embodiment of the present disclosure. Referring to FIG. 10, the time information processing unit 102 includes a receiving unit 11C instead of the receiving unit 11A as compared with the time information processing unit 101. The receiving unit 11C is an example of a first receiving unit.

[0108] The receiving unit 11C receives a modulation signal including the stream S3. More specifically, the receiving unit 11C receives the modulation signal from the modulation signal receiving unit 36. The receiving unit 11C is, for example, a NIM, and generates the stream S3 by performing demodulation processing on the received modulation signal and outputs it to the TOT acquisition unit 12A and the output unit 16.

[0109] The output unit 16 outputs the stream S3 received from the receiving unit 11C to the modulation unit 33.

[0110] The TOT acquisition unit 12A acquires the TS packet P3_tot from the stream S3 included in the modulation signal received by the receiving unit 11C. More specifically, the TOT acquisition unit 12A refers to the PID stored in the header of the TS packet P1 included in the stream S3 received from the receiving unit 11A, and extracts the TS packet P3_tot from the TS packets P3 included in the stream S3. The TOT acquisition unit 12A outputs the extracted TS packet P3_tot to the conversion unit 13A.

[0111] Note that the time information processing unit 102 according to the embodiment of the present disclosure is configured to include the receiving unit 11C instead of the receiving unit 11A, but is not limited thereto. The time information processing unit 102 may be configured to include the receiving unit 11C in addition to the receiving unit 11A. In this case, either one of the receiving unit 11A and the receiving unit 11C outputs a stream to the output unit 16 and the TOT acquisition unit 12A.

[0112] Next, another embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

[0113] <Third Embodiment> This embodiment relates to a broadcast system 503 capable of switching the TS packets tot to be transmitted, compared with the broadcast system 501 according to the first embodiment. Except for the content described below, it is the same as the broadcast system 501 according to the first embodiment.

[0114] [Configuration and Basic Operation] FIG. 11 is a diagram showing the configuration of a broadcast system according to the third embodiment of the present disclosure. Referring to FIG. 11, the broadcast system 503 includes a modulation device 223 instead of the modulation device 221 compared with the broadcast system 501.

[0115] FIG. 12 is a diagram showing the configuration of a time information processing unit in the modulation device according to the third embodiment of the present disclosure. Referring to FIG. 12, the time information processing unit 103 further includes a switching unit 41, a time management unit 42, a time counter 43, and a generation unit 44 compared with the time information processing unit 101. The switching unit 41 includes a TOT blocking unit 41A, a selection unit 41B, and a multiplexing unit 41C. The TOT blocking unit 41A is an example of a removal unit. The modulation device 223 includes a time information processing unit 103 instead of the time information processing unit 101 compared with the modulation device 221.

[0116] The receiving unit 11A outputs the stream S1 acquired from the ASI signal to the TOT acquisition unit 12A and the switching unit 41.

[0117] The TOT acquisition unit 12A extracts the TS packet P1_tot from among the TS packets P1 included in the stream S1, and outputs the extracted TS packet P1_tot to the conversion unit 13A and the switching unit 41.

[0118] The TOT acquisition unit 12B extracts the TS packet P2_tot from among the TS packets P2 included in the stream S2, and outputs the extracted TS packet P2_tot to the conversion unit 13B and the time management unit 42.

[0119] The time management unit 42 receives the TS packet P2_tot from the TOT acquisition unit 12B and acquires the TOT time from the received TS packet P2_tot. The time management unit 42 sets the count time of the time counter 43 to the acquired TOT time.

[0120] The time counter 43 is a counter that operates according to the timing of a self-running clock with a 1-millisecond period. The time counter 43 updates the count time set by the time management unit 42 at a 1-millisecond period.

[0121] The generation unit 44 generates a TS packet P4_tot based on the TOT stored in the TS packet P2_tot. More specifically, the generation unit 44 acquires the count time of the time counter 43 at the transmission timing according to the transmission period Ct, generates a TOT including the count time as the TOT time, and generates a TS packet P4_tot in which the generated TOT is stored. The generation unit 44 outputs the generated TS packet P4_tot to the switching unit 41. The TS packet P4_tot is an example of a third time packet.

[0122] The detection unit 15 performs the above-described comparison process, and when it determines that the TS packet P1_tot included in the stream S1 is abnormal, outputs a switching instruction to the switching unit 41. Further, after the detection unit 15 outputs the switching instruction to the switching unit 41, when it determines that the TS packet P1_tot included in the stream S1 is normal, that is, when it determines that the abnormality of the TS packet P1_tot included in the stream S1 has been resolved, outputs a switching-back instruction to the switching unit 41.

[0123] When the detection unit 15 detects an abnormality in the TS packet P1_tot, the switching unit 41 switches the TS packet tot included in the stream S1 transmitted by the output unit 16 from the TS packet P1_tot to the TS packet P4_tot including the sequence value adjusted based on the TS packet P1_tot.

[0124] For example, when the abnormality of the TS packet P1_tot is resolved, the switching unit 41 switches back the TS packet tot included in the stream S1 transmitted by the output unit 16 from the TS packet P4_tot to the TS packet P1_tot.

[0125] (Processing in the switching unit) The TOT blocking unit 41A removes the TS packet P1_tot from the stream S1 included in the ASI signal. More specifically, the TOT blocking unit 41A refers to the PID stored in the header of the TS packet P1 included in the stream S1 received from the receiving unit 11A, and removes the TS packet P1_tot among the TS packets P1 included in the stream S1. The TOT blocking unit 41A outputs the stream S1 from which the TS packet P1_tot has been removed to the multiplexing unit 41C.

[0126] The selection unit 41B selects either the TS packet P1_tot or the TS packet P4_tot. The selection unit 41B outputs the selected TS packet tot to the multiplexing unit 41C.

[0127] More specifically, the selection unit 41B receives the TS packets P1_tot and P4_tot from the TOT acquisition unit 12A and the generation unit 44. In the initial state, the selection unit 41B outputs the TS packet P1_tot among the received TS packets P1_tot and P4_tot to the multiplexing unit 41C.

[0128] When the selection unit 41B receives a switching instruction from the detection unit 15, it switches the TS packet tot output to the multiplexing unit 41C from the TS packet P1_tot to the TS packet P4_tot. More specifically, when the selection unit 41B receives a switching instruction from the detection unit 15, it stops outputting the TS packet P1_tot to the multiplexing unit 41C and waits for the arrival of the TS packet P4_tot from the generation unit 44. When the selection unit 41B receives the TS packet P4_tot from the generation unit 44, it changes the continuity index CC of the received TS packet P4_tot to a value obtained by adding 1 to the value of the continuity index CC of the TS packet tot that was previously output to the multiplexing unit 41C. Then, the selection unit 41B outputs the TS packet P4_tot including the changed continuity index CC to the multiplexing unit 41C.

[0129] Also, when the selection unit 41B receives a switching-back instruction from the detection unit 15, it switches the TS packet tot output to the multiplexing unit 41C from the TS packet P4_tot to the TS packet P1_tot. More specifically, when the selection unit 41B receives a switching-back instruction from the detection unit 15, it stops outputting the TS packet P4_tot to the multiplexing unit 41C and waits for the arrival of the TS packet P1_tot from the TOT acquisition unit 12A. When the selection unit 41B receives the TS packet P1_tot from the TOT acquisition unit 12A, it outputs the received TS packet P1_tot to the multiplexing unit 41C.

[0130] The multiplexing unit 41C multiplexes the TS packet tot selected by the selection unit 41B onto the stream S1 from which the TS packet P1_tot has been removed by the TOT blocking unit 41A. More specifically, the multiplexing unit 41C multiplexes the TS packet tot received from the multiplexing unit 41C onto the stream S1 received from the TOT blocking unit 41A, and outputs the stream S1 multiplexed with the TS packet tot to the output unit 16.

[0131] The output unit 16 outputs the stream S1 received from the switching unit 41 to the modulation unit 33.

[0132] [Operation flow] FIG. 13 is a flowchart defining an example of an operation procedure when a time information processing unit according to a third embodiment of the present disclosure performs a process of switching TS packets included in a stream.

[0133] Referring to FIG. 13, first, the time information processing unit 103 starts receiving an ASI signal including the stream S1 and outputting the stream S1 to the modulation unit 33 (step S31).

[0134] Next, the time information processing unit 103 waits for an abnormality to occur in the TS packet P1_tot in the stream S1 included in the received ASI signal (NO in step S32). When it is determined that an abnormality has occurred in the TS packet P1_tot (YES in step S32), the TS packet tot in the stream S1 output to the modulation unit 33 is switched from the TS packet P1_tot to the TS packet P4_tot (step S33).

[0135] Next, the time information processing unit 103 waits for the abnormality in the TS packet P1_tot in the stream S1 included in the received ASI signal to be resolved (NO in step S34). When it is determined that the abnormality in the TS packet P1_tot has been resolved (YES in step S34), the TS packet tot in the stream S1 output to the modulation unit 33 is switched back from the TS packet P4_tot to the TS packet P1_tot (step S35).

[0136] Next, the time information processing unit 103 waits again for an abnormality to occur in the TS packet P1_tot (NO in step S32).

[0137] Note that, in the time information processing unit 103 according to the embodiment of the present disclosure, it is assumed that the switching unit 41 is configured to switch the TS packet tot included in the stream S1 transmitted by the output unit 16 back from the TS packet P4_tot to the TS packet P1_tot when the abnormality of the TS packet P1_tot is resolved. However, the present disclosure is not limited to this. The switching unit 41 may be configured to perform a process of switching the TS packet tot included in the stream S1 without performing a process of switching back the TS packet tot included in the stream S1.

[0138] Also, in the time information processing unit 103 according to the embodiment of the present disclosure, it is assumed that the switching unit 41 includes a TOT blocking unit 41A, a selection unit 41B, and a multiplexing unit 14C. However, the present disclosure is not limited to this. Instead of including the TOT blocking unit 41A, the selection unit 41B, and the multiplexing unit 14C, the switching unit 41 may include a unit that outputs the stream S1 received from the receiving unit 11A as it is to the output unit 16 in a state where no abnormality has occurred in the TS packet P1_tot, and switches the TS packet P1_tot included in the stream S1 received from the receiving unit 11A to the TS packet P4_tot in a state where an abnormality has occurred in the TS packet P1_tot.

[0139] Also, in the time information processing unit 103 according to the embodiment of the present disclosure, it is assumed that the time information processing unit 103 includes a time counter 43. However, the present disclosure is not limited to this. The time information processing unit 103 may be configured not to include the time counter 43. In this case, the time management unit 42 receives the TS packet P2_tot from the TOT acquisition unit 12B, acquires the TOT time from the received TS packet P2_tot, and outputs the acquired TOT time to the generation unit 44. Then, the generation unit 44 generates a TS packet P4_tot in which the TOT including the TOT time received from the time management unit 42 is stored, and outputs the generated TS packet P4_tot to the switching unit 41. However, with a configuration including the time counter 43, even when the arrival of the TS packet P2_tot is interrupted, the generation of the TS packet P4_tot at the transmission cycle Ct can be continued.

[0140] Next, other embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

[0141] <Fourth Embodiment> This embodiment relates to a broadcast system 504 that transmits the TOT acquired from the broadcast wave to the encoding device 211 as compared with the broadcast system 501 according to the first embodiment. Except for the content described below, it is the same as the broadcast system 501 according to the first embodiment.

[0142] FIG. 14 is a diagram showing the configuration of a broadcast system according to the fourth embodiment of the present disclosure. Referring to FIG. 14, the broadcast system 504 includes a modulation device 224 instead of the modulation device 221 as compared with the broadcast system 501.

[0143] FIG. 15 is a diagram showing the configuration of a time information processing unit in the modulation device according to the fourth embodiment of the present disclosure. Referring to FIG. 15, the time information processing unit 104 further includes a time management unit 42, a time counter 43, and a transmission unit 45 as compared with the time information processing unit 101. The transmission unit 45 is an example of a time information transmission unit. The modulation device 224 includes a time information processing unit 104 instead of the time information processing unit 101 as compared with the modulation device 221.

[0144] The transmission unit 45 transmits time information based on the TOT included in the TS packet P2_tot to the encoding device 211. More specifically, the transmission unit 45 periodically or irregularly acquires the count time of the time counter 43 and transmits the time information indicating the acquired count time to the encoding device 211 via the switch 311.

[0145] Referring again to FIG. 2, the management unit 24 in the encoding device 211 receives time information from the time information processing unit 104 in the modulation device 224 via the switch 311. The management unit 24 updates the count value of the counter 25 based on either the NTP information received from the NTP server 321 or the time information received from the time information processing unit 104. For example, if the management unit 24 can receive NTP information from the NTP server 321, it updates the count value of the counter 25 based on the received NTP information. On the other hand, for example, if the management unit 24 cannot receive NTP information due to a communication interruption with the NTP server 321, it updates the count value of the counter 25 based on the time information.

[0146] The above embodiments should be considered as illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and it is intended that all modifications within the meaning and scope equivalent to the scope of the claims be included.

[0147] Each process (each function) of the above-described embodiment is realized by a processing circuit including one or more processors. The processing circuit may be configured by integrating one or more memories, various analog circuits, various digital circuits, etc. in addition to the one or more processors. The one or more memories store programs (instructions) for causing the one or more processors to execute each process. The one or more processors may execute each process according to the program read from the one or more memories, or may execute each process according to a logic circuit designed in advance to execute each process. The processor may be various processors suitable for computer control, such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), and an ASIC (Application Specific Integrated Circuit). Note that the plurality of physically separated processors may cooperate with each other to execute each process. For example, the processors mounted on each of a plurality of physically separated computers may cooperate with each other via a network such as a LAN (Local Area Network), a WAN (Wide Area Network), and the Internet to execute each process. The program may be installed in the memory via the network from an external server device or the like, or may be distributed in a state stored in a recording medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disk Read Only Memory), and a semiconductor memory, and may be installed in the memory from the recording medium.

[0148] The above description includes the features appended below. [Appendix 1] A first receiving unit that receives a target signal including a first stream, a second receiving unit that receives a broadcast wave including a second stream; a first acquisition unit that acquires a first time packet, which is a time packet including time information, from the first stream included in the target signal received by the first receiving unit; a second acquisition unit that acquires a second time packet including second time information from the second stream included in the broadcast wave received by the second receiving unit; a detection unit that detects an abnormality of the first time packet based on a comparison result between first time information, which is the time information included in the first time packet acquired by the first acquisition unit, and second time information, which is the second time information included in the second time packet acquired by the second acquisition unit; The detection unit sets the time indicated by the first time information included in the first time packet acquired by the first acquisition unit in a counter, and detects an abnormality of the first time packet based on a comparison result between the time indicated by the second time information included in the second time packet acquired by the second acquisition unit and the count value of the counter. A time information management device.

[0149] [Appendix 2] A time information management device, comprising: a processing circuit; The processing circuit: receives a target signal including a first stream; receives a broadcast wave including a second stream; acquires a first time packet, which is a time packet including time information, from the first stream included in the received target signal; acquires a second time packet, which is the time packet, from the second stream included in the received broadcast wave; detects an abnormality of the first time packet based on a comparison result between first time information, which is the time information included in the acquired first time packet, and second time information, which is the time information included in the acquired second time packet. A time information management device.

Explanation of Signs

[0150] Receiving units 11A, 11B, 11C TOT acquisition units 12A, 12B Conversion units 13A, 13B Counter 14 Detection unit 15 Output unit 16 TS generation unit 21 Encoding unit 21A PSI generation unit 21B SI generation unit 21C Multiplexing unit 22 Output unit 23 Management unit 24 Counter 25 ASI receiving unit 31 Broadcast wave receiving unit 32 Modulation unit 33 Output unit 34 Management unit 35 Modulation signal receiving unit 36 Switching unit 41 TOT blocking unit 41A Selection unit 41B Multiplexing unit 41C Time management unit 42 Time counter 43 Generation unit 44 Transmission unit 45 Time information processing units 101, 102, 103, 104 Encoding device 211 Modulation devices 212, 221, 222, 223, 224 Switch 311 NTP server 321 Control server 322 STB 401 Cable TV network 411 Broadcast systems 501, 502, 503, 504

Claims

1. A first receiving unit that receives a target signal including a first stream; A second receiving unit that receives a broadcast wave including a second stream; A first acquisition unit that acquires a first time packet, which is a time packet including time information, from the first stream included in the target signal received by the first receiving unit; A second acquisition unit that acquires a second time packet including second time information from the second stream included in the broadcast wave received by the second receiving unit; A time information management device comprising: a detection unit that detects an abnormality of the first time packet based on a comparison result between first time information, which is the time information included in the first time packet acquired by the first acquisition unit, and second time information, which is the second time information included in the second time packet acquired by the second acquisition unit.

2. The time information management device according to claim 1, wherein the detection unit detects an abnormality of the first time packet based further on a difference in processing time based on a difference in format between the target signal and the broadcast wave.

3. The time packet includes a sequence value, The time information management device further comprises: A generation unit that generates a third time packet, which is a time packet including time information, based on the second time information; A stream transmission unit that transmits the first stream included in the target signal; A switching unit that, when an abnormality of the first time packet is detected by the detection unit, switches the time packet included in the first stream transmitted by the stream transmission unit from the first time packet to the third time packet including the sequence value adjusted based on the first time packet. The time information management device according to claim 1 or claim 2.

4. The time information management device according to claim 3, wherein the switching unit switches back the time packet included in the first stream transmitted by the stream transmission unit from the third time packet to the first time packet when the abnormality of the first time packet is resolved.

5. The switching unit comprises: A removal unit that removes the first time packet from the first stream included in the target signal; A selection unit that selects either the first time packet or the third time packet. The time information management device according to claim 3, further comprising a multiplexing unit that multiplexes the time packet selected by the selection unit onto the first stream from which the first-time packet has been removed by the removal unit.

6. The time information management device further comprises an external device that synchronizes time with an NTP (Network Time Protocol) server for time information based on the second time information, and includes a time information transmission unit that transmits the time information to the external device that is the source of the target signal, the time information management device according to claim 1 or claim 2.

7. A time information management method in a time information management device, comprising: receiving a target signal including a first stream; receiving a broadcast wave including a second stream; obtaining a first time packet that is a time packet including time information from the first stream included in the received target signal; obtaining a second time packet including second time information from the second stream included in the received broadcast wave; detecting an abnormality of the first time packet based on a comparison result between the first time information that is the time information included in the obtained first time packet and the second time information included in the obtained second time packet.

Images