JPWO1999012293A1 - Multi-channel digital data transmission device and method - Google Patents

Abstract

(57) [Abstract] A device for multiplexing multi-channel data, comprising a reference frequency generator (2) which is a clock generating means for generating a master clock, a multiplexing unit (31) which is a multiplexing means for multiplexing a plurality of data into packets, and a TSPP (Transport Stream Packet Pump) board (4) which is equipped with a buffer memory (42) which is a storage means for storing packets sent from the multiplexing unit (31), and which outputs a continuous packet stream based on the master clock.

Description

[Detailed Description of the Invention] Multi-Channel Digital Data Transmission Apparatus and Method Technical Field The present invention relates to a multi-channel data transmission apparatus and method, and more particularly to a multi-channel digital data transmission apparatus and method that uses a counter synchronized with a master clock to calculate the amount of data to be transmitted and the transmission time.

BACKGROUND ART Recently, technologies for digitizing, compressing, and transmitting information have been put into practical use. This has made it possible to broadcast, for example, 100 channels' worth of music to every home via satellite. Such broadcasting requires accurate management of the transmitted data.

However, with conventional data multiplexing devices, it is difficult to accurately manage the data being transmitted and the time required for transmission.

DISCLOSURE OF THE INVENTION The present invention was developed in response to these circumstances. By utilizing GPS (Global Positioning System) signals for data management, it is possible to accurately manage the amount of data transmitted and the time required for transmission.

To solve the above-mentioned problems, the multi-channel data transmission device of the present invention comprises a clock generation means for generating a master clock, a multiplexing means for multiplexing multiple data into packets, and a storage means for storing the packets sent from the multiplexing means. The device outputs the packets stored in the storage means as a continuous stream using a counter synchronized with the master clock.

In order to solve the above-mentioned problems, the present invention provides a multi-channel data transmission method comprising a clock generation step of generating a master clock, a multiplexing step of multiplexing multiple data into packets, and a storage step of storing the packets sent from the multiplexing step, and outputs the packets stored in the storage step as a continuous stream using a counter synchronized with the master clock.

Thus, the multi-channel data transmission apparatus and method of the present invention multiplexes multiple data into packets, stores the packets in storage means, and when reading them out, accurately manages the amount of data transmitted and the time required for transmission by using a counter synchronized with the master clock, and outputs the packets as a continuous stream.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram showing the general configuration of a data multiplexing device embodying the present invention.

FIG. 2 is a block diagram showing the configuration of the multiplexing unit of the data multiplexing device of FIG.

FIG. 3 is a block diagram showing the configuration of a data multiplexing device to which the present invention is applied.

FIG. 4 is a block diagram showing the internal configuration of the data multiplexing device of FIG.

FIG. 5 is a flowchart illustrating the multiplexing process of the data multiplexing device to which the present invention is applied.

FIG. 6 is a diagram for explaining the processing of the multiplexing unit in FIG.

FIG. 7A is a diagram for explaining the processing of the counting unit in FIG.

FIG. 7B is a diagram for explaining the processing of the counting unit in FIG.

Figure 8 shows the correspondence between the PCR counter, the amount of data transferred, and the elapsed time.

FIG. 9 is a block diagram showing the configuration of a data multiplexing device to which the present invention is applied.

FIG. 10 is a block diagram showing the configuration of the data multiplexing device of FIG.

Figure 11 is a block diagram showing the configuration of an editing site for a 100-channel automated digital broadcasting system to which the present invention is applied.

FIG. 12 is a block diagram showing the configuration of a transmission site for a 100-channel automated digital broadcasting system to which the present invention is applied.

FIG. 13 is a block diagram showing the configuration of a data multiplexing device incorporating a reference frequency generator.

FIG. 14 is a block diagram showing the configuration of the data multiplexing device of FIG.

FIG. 15 is a block diagram showing the configuration of a data multiplexing device to which the present invention is applied.

Figure 16 is a block diagram showing the configuration of a data multiplexing device with a built-in modulator.

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the present invention will now be described in detail with reference to the drawings.

As an embodiment of the present invention, the configuration of a data multiplexing device will be described. This data multiplexing device multiplexes 13 channels of data.

As shown in FIG. 1, the data multiplexing device includes a reference frequency generator 2, which is a clock generating means for generating a master clock; a multiplexing unit 31, which is a multiplexing means for multiplexing multiple data into packets; and a TSPP (Transport Stream Packet Pump) board 4, which includes a buffer memory 42, which is a storage means for storing packets sent from the multiplexing unit 31.

In the TSPP board 4, the 27 MHz master clock signal generated by the reference frequency generator 2 is first divided by four in the clock divider 41 to 6.75 MHz, and then further divided by eight to 843.75 kHz, which is then supplied to the buffer memory 42. This 843.75 kHz signal is output as the Transport Stream (TS) 1 transfer clock. 8-bit data is output from the buffer memory 42 at a TS1 transfer rate of 6.75 Mbps.

As shown in FIG. 2, the multiplexing unit 4 includes a multiplexing/packet generation unit 51 that multiplexes multiple data to generate packets; a packet counting unit 52 that counts the number of packets output from the buffer memory; a time measurement unit 53 that measures time; a discrimination unit 54 that determines whether the number of packets counted by the packet counting unit is a predetermined number based on the time measured by the time measurement unit; and a control unit 55 that controls the generation of packets in the multiplexing/packet generation unit in accordance with the discrimination result of the discrimination unit.

This data multiplexing device operates based on signals from GPS (Global Positioning System) satellites. That is, as shown in Fig. 3, in the data multiplexing device, a GPS antenna 1 receives signals from GPS satellites (not shown) and outputs them to a reference frequency generator 2. Based on the input satellite signals, the reference frequency generator 2 generates a master clock with a frequency of 27 MHz and a frequency stability of 5 x ^10-12/ day, and outputs it to a TSPP board 4 built into a personal computer 3. The TSPP board 4 outputs the multiplexed data as a packet stream at a predetermined timing.

The configuration of the personal computer 3 and the TSPP board 4 built into the personal computer 3 will be described with reference to Figure 4. The multiplexing unit 31 multiplexes data recorded on the data recording medium 33 and outputs it to the buffer memory 42. The counting unit 32 generates and manages a program clock reference (PCR) that adds a time reference to the multiplexed data. The multiplexing unit 31 and counting unit 32 are functional blocks that perform processing according to a separately input program. The data recording medium 33 stores data compressed using the Moving Pictures Experts Group (MPEG) format.

The clock divider unit 41 of the TSPP board 4 generates a TS1 transfer clock (CLOCK) based on the master clock input from the reference frequency generator 2 and outputs it to the buffer memory 42, timing signal generator 44, and count unit 32 via the CPU bus 34. Under the control of the DMA (Dynamic Memory Access) control unit 43, the buffer memory 42 stores multiplexed data DMA-transferred from the multiplexer unit 31 via the CPU bus 34 and outputs the stored data in synchronization with the TS1 transfer clock input from the clock divider unit 41. The timing signal generator 44 simultaneously outputs the TS1 transfer clock, data synchronized with the TS1 transfer clock, and timing signals (PYNC, DVALID). The DMA control unit 43 controls the writing of data to the buffer memory 42.

Next, the operation of this data multiplexing device will be described with reference to the flowchart of Fig. 5. In step S1, the GPS antenna 1 receives a signal from a GPS satellite and outputs it to the reference frequency generator 2. In step S2, the reference frequency generator 2 determines, based on the input signal, that the frequency is 27 MHz and the frequency stability is 5. In step S3, the clock divider 41 generates a TS1 transfer clock from the input master clock and outputs it to the counter 32 via the buffer memory 42, timing signal generator 44, and CPU bus 34.

The details of the processing by the clock divider 41 in step S3 will be described with reference to FIG.

Dividing the 27 MHz master clock by 2 ² produces a 6.75 MHz clock. The 6.75 MHz clock (corresponding to a TS1 transfer rate of 6.75 Mbps) and the 843.75 kHz TS1 transfer clock (corresponding to a transfer rate per byte (8 bits)) are in an integer ratio relationship with the 27 MHz master clock, so synchronization with the master clock is maintained.

Returning to the description of FIG. 5, in step S4, the multiplexing unit 31 reads the MPEG-compressed data from the data recording medium 33 and multiplexes it. The multiplexed data is DMA-transferred to the buffer memory 42 under the control of the DMA control unit 43 and written therein. In step S5, the multiplexed data, timing signals (PSYNC, DVALID), and TS1 transfer clock are output as a packet stream.

The processing of step S4 will be described with reference to FIG. 6. When multiplexing 13 channels of 256 kbps audio data (audio PES) per channel, the transfer rate of the multiplexed data is as follows: audio data: 256 kbps x 13 = 3328 kbps; the PMT (Program Map Table) corresponding to each channel is 188 bytes and requires 10 times per second, so 10 x 188 x 8 x 13 = 195.52 kbps; and the PCR (Program Clock Reference) is 188 bytes and requires 10 times per second, so 10 x 188 x 8 = 15.04 kbps. Therefore, the effective rate is 3538.56 kbps, which is the sum of the transfer rates of the audio data, PMT, and PCR (hereinafter referred to as effective data).

To transfer this effective data at a TS1 transfer rate of 6750 kbps synchronized with the master clock, we simply multiplex 3211.44 kbps worth of null packets onto the effective data. In other words, the effective rate is 3538.56 kbps + 3211.44 kbps of null packets = 6750 kbps.

The PCR will be explained with reference to Figures 7A and 7B. The PCR is a signal generated by the counter unit 32 and serves as a time reference for decoding multiplexed data. As shown in Figure 7A, the PCR is a counter signal synchronized with the master clock. It consists of two counters: a PCR Extension counter expressed in 9 bits (E0 to E8) and a PCR counter expressed in 33 bits (R0 to R32). The PCR Extension counter periodically counts up from 0 to 299 at 27 MHz, and carries over to the PCR counter at 300. The PCR counter counts up every time the PCR Extension counter counts up one cycle (0 to 299), so it is a 27 MHz/300 = 90 kHz counter. As shown in Figure 7B, for example, if the TS1 transfer rate is 6.75 Mbps and the PCR Extension counter's initial value is 0, the PCR Extension counter's value after one byte (8 bits) is transferred will be 32. After one packet (188 bytes) is transferred, the PCR Extension counter will count 32 x 188 = 6016 times, during which a carry occurs, causing the PCR counter's value to become 20 and the PCR Extension counter's value to become 16.

Because the aforementioned TS1 transfer rate and TS1 transfer clock are synchronized with the master clock, the amount of data multiplexed and written to buffer memory 43 and the elapsed time required for that writing can be easily calculated from the PCR Extension counter and PCR counter values managed by counting unit 32. For example, if the PCR counter value is x and the PCR Extension counter value is y, the amount of data transferred to buffer memory 42 is (300x + y)/32 bytes, and the time required for transfer is (300x + y)/(27 × 106) seconds. This correspondence is shown in Figure 8. Note that the PCR Extension count shown in the figure is the number of times the PCR Extension counter counts up at 27 MHz; in reality, the PCR counter value is incremented every 300 counts.

The above describes an apparatus for multiplexing 13 channels of MPEG-compressed, filed audio data. Next, we will describe a data multiplexing apparatus for multiplexing 12 channels of MPEG-compressed, filed audio data and one channel of real-time data with reference to Figures 9 and 10.

As shown in Figure 9, this data multiplexing device is the same as the data multiplexing device shown in Figures 3 and 4, but with the addition of a distributor 5, a real-time MPEG compressor 6, and a CAPT board 7.

As shown in FIG. 10, distributor 5 distributes the master clock input from reference frequency generator 2 to clock divider 41 in TSPP board 4 and frequency converter 61 in real-time MPEG compressor 6. In real-time MPEG compressor 6, A/D converter 62 samples the input real-time audio signal at the sampling frequency (48 kHz) generated by frequency converter 61, converts it to digital data, and outputs it to encoder 63. Encoder 63 MPEG-compresses the input digital data and outputs it to buffer memory 72 on CAPT board 7 at a transfer rate (256 kbps) synchronized with the master clock.

In the CAPT board 7, the DMA control unit 71 DMA-transfers MPEG-compressed data stored in the buffer memory 72 to the multiplexing unit 31 via the CPU bus 34 at predetermined timing. The multiplexing unit 31 multiplexes the 256 kbps data input from the buffer memory 72 with the 256 kbps data for 12 channels played back from the data recording medium 33. The subsequent processing is similar to that described for the data multiplexing device in FIG. 4, and therefore will not be described here.

Next, a 100-channel automated digital broadcasting system to which the present invention is applied will be described with reference to Figures 11 and 12. Figure 11 primarily shows the configuration of the editing site 101, while Figure 12 primarily shows the configuration of the transmission site 201. This system is an automated digital broadcasting system that broadcasts 100 channels of music files compressed using the Moving Picture Experts Group (MPEG) format using a single satellite transponder. Note that in this specification, the term "system" is used to refer to the entire system composed of multiple devices.

This system consists of an editing site 101 where broadcast programs are produced and a transmission site 201 where the programs are transmitted. The two sites are connected by a dedicated line 103, such as a local area network (LAN). The editing site 101 is equipped with an information source management system 111, a material information management and programming system 112, and a material information registration system 113. The transmission site 201 is equipped with a proprietary server and a 100-channel (channel) transmission system 211, a secondary multiplex satellite transmission system 212, a 100-channel monitoring system 213, and a transmission management system 214.

In this system, music is broadcast to each user via satellite, so CDs are used as the information source. Information source management system 111 manages these CDs, i.e., media, and the music recorded on the CDs as sound sources. For this purpose, information source management system 111 has a CD inventory management server 121, to which a hard disk (mirror disk) 122 and an MO autochanger 123 are connected. This hard disk 122 registers information necessary for the MO disks driven by the MO autochanger 123, forming a database.

Twelve inventory management personal computers (PCs) 124 are also connected to the CD inventory management server 121. Note that in this specification, when it is necessary to distinguish between these inventory management PCs, they will be referred to as inventory management PC 124-1 through inventory management PC 124-12; when no distinction is necessary, they will simply be referred to as inventory management PC 124.

Furthermore, the information source management system 111 is provided with three network printers 125-1 to 125-3, an image scanner 126, a barcode reader 127, and four barcode printers 128-1 to 128-4.

Network printer 125 is used to print various forms. Barcode printer 128 is used to print barcodes to be attached to the CDs under management. Barcode reader 127 is used to read the barcodes attached to each CD. Image scanner 126 is used to import sheet music, lyrics, and other information attached to the CDs.

All information regarding CDs is stored in a database on hard disk 122. CD inventory control is performed as follows:

1. The CD inventory manager registers CD order request information from the inventory management PC 124 to the CD inventory management server 121, and sends a CD order form, which is output from the server 121 via the network printer 125, to the buyer to place the order.

2. As soon as a CD arrives in stock, the CD inventory manager registers the receipt information on the inventory management PC 124 and enters all information about the CD media necessary for inventory management searches, as well as all information about the music (sound source) recorded on the CD, into the database of the CD inventory management server 121. This information includes text-entered information such as the title, artist name, time, genre, and keywords, as well as jacket images entered using the image scanner 126. It also includes electronically entered information such as lyrics, detailed information about the album or music, photos, MIDI data, and karaoke start timing.

The information entered here relates to the album (all songs on the CD) and the songs, as well as information associated with and related to them, and does not include management information or history related to transmission or broadcasting (this information is registered in the programming server 141, as described below).

3. The CD inventory management server 121 stores the information on the hard disk 122, issues CD media management numbers in the order they are received, and issues barcode labels from the barcode printer 128.

4. The CD inventory manager stores the CDs on the management shelf in the order of their CD media management numbers.

5. The CD user can borrow a CD by going to the reception desk of the information management system 111 and providing the CD medium management number.

The information source management system 111 also manages other media such as DAT, compact cassettes, and records.

One CD inventory management server 121 has a mirrored hard disk 122, performs a full backup once a week using an MO disk, and backs up the information entered on that disk (differential) every day.

Twelve client inventory management PCs 124 handle ordering, inventory entry, information entry, search, and rental. The maximum amount of information that can be stored is 1 million songs.

The material information management and programming system 112 is composed of two programming servers 141-1 and 141-2 and fifteen programming PCs 142-1 through 142-15 connected to them. Each programming server 141 has a hard disk (not shown). The material information management and programming system 112 manages the music contributed to the broadcast and organizes the program schedule. This schedule records the material to be broadcast, its broadcast start time, and the broadcast interval. All music material information required for broadcast and the program schedule for each channel are stored on the hard disk of the programming server 141. Note that, here, "material" refers to music compressed (encoded) into files, and "material information" refers to information on material required for upcoming broadcasts that has been encoded by the material information registration system 113 or for which an encoding request has been made.

Material information management and program scheduling are performed as follows: The program scheduler creates a program schedule for the channel he or she is responsible for using the programming PC 142.

1. The program organizer searches the programming server 141 for the material information for the song they want to broadcast. Once they find the desired material, they drag the song into the programming frame on the programming PC 142's graphical user interface (GUI). The playing time of the dragged song is the actual time it will be broadcast. In the programming frame, the song is marked as "recorded."

2. The program organizer searches the material information of the program server 141 for the music piece they wish to broadcast. If the desired material is not found, the program organizer searches the CD inventory management server 121.

Once the desired song is found, drag it into the orchestration frame on the GUI of the orchestration PC 142.

At this time, the playing time of the dragged song is the time for CD inventory management, and may differ from the actual recorded time. In this case, the material information has not yet been registered (encoded), and the song will be listed as "unrecorded" in the programming schedule. Unrecorded songs are sequentially notified to the material information registration system 113 as recording candidates, and once encoded, the "unrecorded" status is changed to "recorded" material on the programming server 41. At this time, the playing time of the material will become the actual time when it is broadcast.

If the desired song is not found after searching the CD inventory management server 121, a CD order request is output to the CD inventory management server 121, and the song is then considered a tentative candidate. Once the song is received and registered in the CD inventory management system, it is encoded through the above-mentioned procedures, and all songs are finally marked as "recorded" in the programming frame.

3. Once all songs are "recorded" within the programming frame, the programmer performs a consistency check on the GUI of the programming PC 142. This consistency check automatically checks whether the specified material is evenly distributed within the programming frame and whether the playback time and inter-song (silence) times are within specified limits. For example, if a one-hour program is to air 12 songs, each approximately five minutes long, and 11 songs are exactly five minutes long and one song is six minutes long, the total playback time would exceed the programming frame (one hour). Furthermore, if all songs were exactly five minutes long, there would be no silence between songs, creating an unnatural broadcast. Therefore, the programmer sets a minimum (e.g., 1.5 seconds) and maximum (e.g., 3 seconds) limit for the inter-song (silence) times when broadcasting the material, and checks whether the inter-song (silence) times fall within these ranges when all songs are evenly distributed.

If it doesn't fit, either replace it with a different duration, or use a shorter orchestration and add some prepared material at the end of the orchestration slot to adjust the time so that it passes the check.

The playing times of these materials are calculated based on the times in the material information database (encoded materials) on the programming server 141, not the times in the database of the CD inventory management server 121.

In this way, a one-day schedule (file) for one channel is created. Finally, the programming manager approves this schedule, and the approved schedule (file) is locked to prevent rewriting and transferred via dedicated line 103 to external hard disk 221A of server 221 owned by transmission site 201.

4. In this way, the programming server 141 stores a schedule for each channel and broadcast date as a database. The programming server 141 also stores, as material information, data on materials already stored on the external hard disk 221A of the ownership server 221 as broadcast material, as well as data on future broadcast schedules and unrecorded materials to be stored on the external hard disk 221A of the ownership server 221. This data is stored based on data extracted from the database of the CD inventory management server 121 for items necessary for broadcasting, with additional information about the broadcast, such as the broadcast date, broadcast channel, and program organizer, added.

The two scheduling servers 141-1 and 141-2 each have an external hard disk (not shown) and operate in dual mode. Fifteen scheduling PCs 142-1 through 142-15 create scheduling tables by searching the scheduling server 141 and the CD inventory management server 121. The scheduling server 141 can store up to 100,000 pieces of information.

The material information registration system 113 has eight CD players and amplifiers 151-1 through 151-8, and eight MPEG encoders 152-1 through 152-8 that encode the playback output of the CD players and amplifiers 151-1 through 151-8 and output the encoded data to eight registration PCs 153-1 through 153-8. The registration PCs 153-1 through 153-8 receive data from the encoders and decoders 152-1 through 152-8 and output it to the DSU 225-3 at the transmission site 201 via the router 173-3, terminal adapter (TA) 172-3, and digital service unit (DSU) 171-3 via the dedicated line 103.

Eight live PCs 161-1 through 161-8 are also connected to the registration PCs 153-1 through 153-8. Data output from these live PCs 161-1 through 161-8 is decoded by MPEG decoders 162-1 through 162-8, and then supplied from codecs (Coder-Decoders) 163-1 through 163-8 via dedicated line 103 to codecs 224-1 through 224-8 at the sending site 201.

At this time, the outputs of the MPEG decoders 162-1 through 162-8 are added to inputs from microphones (not shown) as appropriate, and the resulting signals are output from the codec 163.

An archive MO changer 155 is connected to the archive control PC 154, and archive data is stored on an MO disk driven by the archive MO changer 155. This archive control PC 154 is connected to the registration PC 153, live PC 161, inventory management server 121, programming server 141, programming PC 142, etc., as well as to the proprietary server 221 via router 173-2, terminal adapter 172-2, and DSU 171-2 via dedicated line 103, and via DSU 225-2, terminal adapter 226-2, and router 227-2 at the transmission site 201.

The material information registration system 113 plays music from a storage medium such as a CD using a CD player and amplifier 151, compresses (encodes) it using an MPEG encoder/decoder 152 to create a material file, and transfers it to a proprietary server 221 via a registration PC 153, a router 173-3, a terminal adapter 172-3, a DSU 171-3, a leased line 103, a DSU 225-3, a terminal adapter 226-3, and a router 227-3. It also has the function of deleting material from the proprietary server 221 or transferring material from the proprietary server 221 to a router 227-2, a terminal adapter 226-3, and a router 227-3. This system realizes the following functions: transferring music to archive MO changer 155 via DSU 225-2, leased line 103, DSU 171-2, terminal adapter 172-2, router 173-2, and archive control PC 154; and randomly selecting music from proprietary server 221 and playing it via router 227-3, terminal adapter 226-3, DSU 225-3, leased line 103, DSU 171-3, terminal adapter 172-3, router 173-3, registration PC 153, MPEG encoder/decoder 152, and CD player and amplifier 151.

If the material information management/progress programming system 112 searches the programming server 141 for material information about a song the programmer wants to broadcast, but the desired material is not found, the programmer searches the CD inventory management server 121. If the desired material is found, the programmer drags the song into the programming slot on the programming PC 142's GUI. In this case, the material information has not yet been registered (encoded), so the song appears as "unrecorded" in the programming slot. The unrecorded song is then notified to the material information registration system 113 via the dedicated line 103 as a recording candidate.

The material information registration clerk reserves the songs to be registered from among these unrecorded songs, i.e., from the material registration candidate list. This is to prevent overlapping work with other clerks. After making the reservation, the material information registration clerk goes to the rental desk of the information source management system 111 and borrows the desired CD media. At this time, the material information retrieved on the programming PC 142 is from the database of the CD inventory management server 121, so the desired CD media can be retrieved immediately using the CD media management number.

At the material registration booth, a check is made to electronically match the songs on the CDs that have actually been checked out against the songs that are candidates for material registration. When registering a CD for inventory management, a unique value is calculated for each song using a specific formula based on the playing time, track number, etc., and this value is stored in the database as a matching ID. When the song is actually checked out, the value calculated by this formula is checked again to see if it matches.

The confirmed music is played on a CD player and amplifier 151, encoded in real time by an MPEG encoder/decoder 152, and stored as an MPEG file on a hard disk (not shown) in the registration PC 153. The written file (material) is transferred via a dedicated line 103 to an external hard disk 221A of the proprietary server 221 at the transmission site 201. The file (material) stored on the external hard disk 221A of the proprietary server 221 at the transmission site 201 is then transferred via the dedicated line 103 to a hard disk (not shown) in the registration PC 153 at the programming site 101. The material information registration officer plays back the file (material) transferred from the proprietary server 221 using the MPEG encoder/decoder 152 and listens to the sound from start to finish. After the audition process, material that passes muster is marked as "recorded."

The music can be converted into an MPEG file in the following manner.

1. Music (baseband) is played back by a real-time playback device (e.g., a CD player) serving as a CD player and amplifier 151, compressed by a real-time encoder serving as an MPEG encoder/decoder 152, and stored on a hard disk (not shown) provided in the registration PC 153.

2. Data is read by an Nx speed playback device such as a CD player and amplifier 151, for example an 8x speed CD-ROM player, and compressed by an 8x speed encoder such as an MPEG encoder/decoder 152, and stored on a hard disk (not shown) of the registration PC 153. N is a number greater than 1, including a decimal point.

3. Data is read by a variable speed playback device (e.g., a CD-ROM player) serving as a CD player and amplifier 151, and is temporarily stored in the internal memory or hard disk of the direct registration PC 153, where it is encoded by software and stored on the hard disk. Note that variable speed here includes burst read control.

4. An externally encoded file is received and stored on a hard disk (not shown) of the registration PC 153.

In the material information registration system 113, music is sent for live broadcast by a disc jockey (DJ) by using an MPEG decoder 162 to decode and play files (material) transferred from the proprietary server 221 via the router 227-2, terminal adapter 226-2, DSU 225-2, dedicated line 103, DSU 171-2, terminal adapter 172-2, router 173-2, and live PC 161. The live PC 161, acting as a DJ terminal, searches the programming server 141 to determine whether the desired music has already been recorded. The material is transferred from the proprietary server 221 at the transmission site 201 via the dedicated line 103, and the music is played (decoded) by the decoder 162. At this time, the audio signal picked up by a microphone (not shown) is A/D converted and superimposed (mixed) on the output of the MPEG decoder 162.

Furthermore, the high-speed, expensive external hard disk 221A of the proprietary server 221 has a limited capacity and will eventually reach capacity. Therefore, the capacity of the proprietary server 221's external hard disk 221A is constantly monitored, and materials eligible for deletion are displayed on the archive control PC 154 according to set criteria. These criteria include, for example, materials that have been broadcast less than twice within a year, or music that has been designated as a deletion candidate after broadcast has ended. Conversely, materials designated as not eligible for deletion when registered are excluded from the deletion candidate list. The material manager can automatically select which music to actually delete from the deletion candidate list, which to archive to MO disk, and which to exclude from the deletion candidate list. Music archived on the MO disk of the archive MO changer 155 can be returned to the proprietary server 221's external hard disk 221A via batch processing when necessary for programming. For this reason, the proprietary server 221 and the archive control PC 154 are interconnected via a route including a router 227-2, a terminal adapter 226-2, a DSU 225-2, a leased line 103, a DSU 171-2, a terminal adapter 172-2, and a router 173-2.

Therefore, if the programming server 141 determines that the material specified on the schedule is archived material, at a predetermined time, it controls the archive control PC 154 through batch processing to read the material stored in the archive MO changer 155, transfer it to the storage server 221, and store it there.

Of course, the program producer can manually transfer the archived material to the proprietary server 221 as needed and store it there.

Furthermore, archived materials designated on the progress chart may be automatically transferred to the holding server 221 by batch processing, and the user may be given the option to terminate or continue the holding function as needed. This prevents archived materials from being accidentally restored to the holding server 221.

The proprietary server and 100-channel transmission system 211 has two proprietary servers 221-1 and 221-2. A hard disk (disk array) 221A having a capacity of, for example, 500 GB is connected to the proprietary server 221. The proprietary server 221 is connected to programming server 141 via router 227-1, terminal adapter 226-1, DSU 225-1, leased line 103, DSU 171-1 of programming site 101, terminal adapter 172-1, and router 173-1.

Nine transmission servers 223-1 through 223-9 are connected to proprietary server 221 via hub 222 on dedicated line 103. Each of transmission servers 223-1 through 223-9 has a built-in CAPT board and a TSPP board. Each of transmission servers 223-1 through 223-9 is also connected to a 20 GB hard disk (not shown).

The outputs of MPEG encoders 229-1 through 229-9 are supplied to the CAPT boards built into the transmission servers 223-1 through 223-9. The MPEG encoders 229-1 through 229-9 supply the data to codecs 224-1 through 224-8 of the programming site 101, which then encode and output the input data via switch 228.

Of the transmission servers 223-1 through 223-9 and MPEG encoders 229-1 through 229-9, one transmission server 223 and one MPEG encoder 229 are used as spares (standby) and are intended to be used in place of other transmission servers 223 or MPEG encoders 229 in the event of a malfunction.

The master clock 230 generates a 27 MHz master clock based on a GPS time correction signal received by a GPS antenna (not shown) and supplies it to the TSPP boards built into the transmission servers 223-1 to 223-9 and to the MPEG encoders 229-1 to 229-9.

Of the transmission servers 223-1 through 223-9 and the MPEG encoders 229-1 through 229-9, one transmission server 223 and one MPEG encoder 229 are designated as spares (standby) and are used in place of other transmission servers 223 or MPEG encoders 229 in the event of a malfunction.

In the proprietary server and 100-channel transmission system 201, proprietary server 221 stores on its external hard disk 221A the MPEG-encoded music material required for broadcast, a program schedule, and all system configuration (information necessary for controlling the entire system) required to transmit 100 channels of data.

Here, a single transmission server 223 performs format conversion and multiplexing for up to 13 channels using software.

In this embodiment, the capacity of the external hard disk 221A of the proprietary server 221 is 500 gigabytes (GBytes). This corresponds to a storage capacity of approximately 50,000 songs, assuming each song is 5 minutes long and the data rate is 256 kbit/s, as shown below.

Requirements: Sampling frequency: 48 kHz Quantization bit depth: 16-bit Audio mode: STEREO Compression ratio: 1/6 (256 kbps) Playing time: 5 minutes Calculation formula: 48 kHz x 16-bit x 2 x (1/6) x 60 x 5 x (1/8) = approximately 10 Mbytes Approximately 500 Gbytes / approximately 10 Mbytes = 50,000 songs The file size for all other configurations required for 100-channel streaming, including the timeline, is extremely small compared to the volume of the material.

The programming site 101 accesses the proprietary server 221 in the following cases:

1. Transfer of schedules for each channel and each broadcast date from the material information management and program scheduling system 112.

2. Transfer (registration) of materials from the material information registration system 113.

3. Transfer of materials to the material information registration system 113 (listening, music playback).

4. Deletion of materials in the proprietary server 221 from the material information registration system 113.

5. Transfer or delete materials from the material information registration system 113 to the archive MO changer 155.

6. Restoring materials from the archive MO changer 155 of the material information registration system 113.

The system configuration files stored on the proprietary server 221 are as follows:

Common time: The entire transmission system shares the correct time.

Bitrate Table: Define the bitrate of the music channel to be transmitted.

Channel combination table: Defines the channels handled by the transmission server 223.

MUX active status: Indicates the active system of the secondary multiple satellite transmission system 212.

PMT (Program Map Table): Program Map Table Service Correspondence Table: A correspondence table between management channel numbers and broadcast service numbers.

The broadcasting system referred to here includes the programming server 141, proprietary server 221, broadcasting server 223, switching control PC 282, and multiplexer controller (MXC) 244. Among these, proprietary server 221 can store common information for the broadcasting system, which can be referenced and updated at any time during system operation.

In this embodiment, there are nine transmission servers 223, eight of which are in active use and one is a backup. Each transmission server 223 receives as input material files from multiple channels (up to 13 channels in this embodiment) from the storage server 221, or material streams from a real-time encoder 229 that performs MPEG compression (encoding) in real time. The inputs are then converted in real time by software into MPEG System standard transport streams (TS) and multiplexed.

The transmission server 223 also multiplexes the Program Map Table (PMT) and Program Clock Reference (PCR). This is called primary multiplexing. In addition to the active data, time data, and invalid data from multiple channels, it also multiplexes portions of the Program Specific Information (PSI) defined by the MPEG standard, such as PCR packets and PMT packets. It is also possible to multiplex other PSI, such as the Program Association Table (PAT) and Network Information Table (NIT), and even user-defined packets other than PSI.

In this embodiment, when a total of 100 channels are broadcast, six of the eight transmission servers 223 perform primary multiplexing of 13 channels, one performs primary multiplexing of 12 channels, and the remaining one performs primary multiplexing of 10 channels. These signals are converted into electrical signals and output in parallel to two multiplexers (MUX) 241-1 and 241-2, the active and standby systems of the secondary multiplexed satellite transmission system 212. Similar outputs are also output in parallel to the TS audio monitor 263. All of the electrical signals flowing through these transmission cable paths are from the transmission servers 223 to the multiplexers 241 and TS audio monitor 263, and contain TS data, clock sync (CLOCK, SYNC), and data valid (DVALID).

At the end of each day (4:00 AM), the transmission server 223 sequentially reads the necessary broadcast material files from its external hard disk (not shown) according to the schedule for the multiple channels it is responsible for, obtained the previous day. At the same time, the MPEG encoder 229 converts the MPEG-encoded material stream in real time into parallel MPEG system transport stream packets, creates PMT packets, inserts null packets, multiplexes PCR packets, and then stamps the PCR packets with time information before outputting them.

Furthermore, at the time of day change, transmission server 223 reads the schedule for the next day for multiple channels it is responsible for from proprietary server 221 and copies the materials needed for the next day's broadcast from proprietary server 221 to transmission server 223's external hard disk 223A (not shown) in accordance with the schedule. This allows for a grace period until the next day in the event of a malfunction in proprietary server 221 or a delay in the delivery of the schedule. Furthermore, in the unlikely event that proprietary server 221 malfunctions for more than two days or the schedule is not delivered, the previous day's schedule can be used (copied) instead, preventing accidents in which no broadcast is performed at all.

In this embodiment, the capacity of the external hard disk 223A of the transmission server 223 is assumed to store two days' worth of content. When overlapping material exists, such as between today's and tomorrow's content, the disk space required is reduced compared to when completely unique material is broadcast on each channel, or even across all channels. In other words, in an extreme case, if one material is broadcast on all channels for two consecutive days, the disk space required is only the space required for one material file. Furthermore, depending on the operation, it is possible to configure certain channels to have shorter programming and certain channels to have longer programming.

If one of the eight transmission servers 223 fails and becomes unable to transmit, broadcasting on all channels (e.g., channel 13) served by that transmission server 223-i will cease. Therefore, all processes running on the failed transmission server 223-i are switched to the backup transmission server 228-j (9/8 redundancy switchover). The switching control PC 282, described below, rewrites the configuration of the proprietary server 221 and then notifies each transmission server 223 and MXC 244 that the configuration has been rewritten. The backup transmission server 228-j obtains the progress table for the channel served by the failed transmission server 228-i from the proprietary server 221, and begins transmission by directly reading the material files required for current transmission from the proprietary server 221 according to the progress table.

At the same time, MXC 244 switches the input channel of MUX 241. That is, it closes the input gate of MUX 241 where the failure occurred and opens the input gate that was previously closed as a backup. This immediately resumes broadcasting (recovery).

During this time, transmission server 223-j searches the progress schedule for the channel it is responsible for for material files that will be needed for the current day and the following day, reads them from proprietary server 221, and sequentially copies them to external hard disk 223A-j (not shown). In other words, since the file transfer time from proprietary server 221 to transmission server 223 is faster than the time it takes to read the material files to be transmitted, transmission of the material to be transmitted is completed without waiting for the completion of copying of all material, and the copying is completed in the meantime. As a result, transmission server 223-j, which was on standby as a backup, ultimately has the same settings as the failed transmission server 223-i. This eliminates the need to return the backup machine to active use after a switch due to a failure; the failed transmission server 223-i can then be kept on standby as a backup machine while it is repaired.

In the secondary multiplex satellite transmission system 212, the outputs of transmission servers 223-1 through 223-9 are supplied to multiplexer 241-1. Multiplexer 241-1 is controlled by MXC 244-1 and selects outputs from eight predetermined transmission servers 223, outputting them to modulator 242-1. Modulator 242-1 modulates the input data using the QPSK method and outputs the resulting signal to selector 243.

Similarly, multiplexer 241-2 is controlled by MXC 244-2 to select the output of transmission server 223 and output it to modulator 242-2. Modulator 242-2 modulates the input signal using the QPSK method and outputs it to selector 243.

Data is transferred from the transmission server 223 to the MXC 244 and TS audio monitor 263 via DVB (Digital Video Broadcasting) parallel, LVDS, or the like.

Selector 243 is controlled by switching control PC 282 to select one of the signals input from modulator 242-1 or modulator 242-2, and outputs the selected signal to the satellite via an intermediate frequency (IF) processing circuit (not shown).

Additionally, multiplexer 241 and MXC 244 are supplied with appropriate signals from a broadcast management system (not shown) that manages the entire broadcast.

The secondary multiplex satellite transmission system 212 has a transmission system A and a transmission system B. The outputs of transmission servers 223-1 through 223-9 are supplied to a multiplexer 241-1 constituting transmission system A. Multiplexer 241-1 is controlled by an MXC 244-1 and selects outputs from eight predetermined transmission servers 223, outputting the selected outputs to a modulator 242-1. Modulator 242-1 modulates the input data using the QPSK method and outputs the resulting signal to a selector 243.

Similarly, the multiplexer 241-2 constituting the transmission system B is controlled by the MXC 244-2, selects the output of the transmission server 223, and outputs it to the modulator 242-2. The modulator 242-2 modulates the input signal in QPSK format and outputs it to the selector 243.

Data is transferred from the transmission server 223 to the MXC 244 and TS audio monitor 263 via DVB (Digital Video Broadcasting) parallel, LVDS, or the like.

The selector 243 is controlled by the switching control PC 282 to select one of the signals input from the modulator 242-1 or the modulator 242-2, and outputs the selected signal to the satellite via an intermediate frequency (IF) processing circuit (not shown).

Additionally, multiplexer 241 and MXC 244 are supplied with predetermined signals as needed from a broadcast management system (not shown) that manages the entire broadcasting system.

In the secondary multiplexed satellite transmission system 212, TSs, which are primarily multiplexed with PES (Program Elementary Stream) packets, PMT packets, and PCR packets for 13 channels, supplied from eight transmission servers 223, are input to a multiplexer 241. The multiplexer 241, which serves as a secondary multiplexer, multiplexes and outputs all packets to be transmitted to the satellite, including these packets, packets other than PMT required for program selection, program guide packets, program management packets, and customer management packets. The output is then QPSK modulated by a QPSK modulator 242, which adds an error correction code to the output, and outputs it as a modulated signal.

The MXC 244 receives the next day's operation data (which specifies the overall broadcast operation) from the broadcast management system (not shown) at 26:30 every day, creates a PMT file at 27:50, and transfers it as PMT.new to the proprietary server 221 via the hub 222. The MXC 244 also transfers to the multiplexer 241 the transmission settings and schedules for all packets to be transmitted to the satellite, including packets other than PMT required for program selection, program guide packets, program management packets, and customer management packets.

The configuration for transmission or reception will be described from the perspective of the centrally located active MXC 144-1 (or 144-2).

The MXC 244 consists of two units, MXC 244-1 (MXC-A) and MXC 244-2 (MXC-B), which independently control the A and B systems. However, only the active MXC 244 sends control information to the transmission server 223 via the hub 222, to the TS audio monitor 263 via another hub (not shown), and to the switch console of the 100-channel monitor 261 of the 100-channel monitor system 213 via the other hub and the channel setter PC 262. Active and standby units are identified by configuration on the proprietary server 221.

One of the primary roles of the MXC 244 is to set various parameters, including initial parameter settings, and then not participate in transmission operations unless an abnormality is detected. Another role is to monitor abnormalities, monitoring each peripheral device and notifying the alarm PC 283 of any abnormalities (alarms). In response to switching instructions from the switching control PC 282, the MXC 244 controls switching according to the configuration on the proprietary server 221.

MXC 244-1 and MXC 244-2 monitor each other by requesting the writing of dummy data every five minutes, for example, and confirming its execution. If the standby MXC notifies the alarm PC 283 of an abnormality in the active MXC, the monitor (person) determines this and controls the switching control PC 282 to switch the active and standby MXCs.

The role of the active MXC 244 is as follows:

・Receives various transmission control information from the broadcast management system ・Transmits PMT files to the proprietary server 221 ・Receives configuration information such as time and active/backup designation from the proprietary server 221 ・Notifies the alarm PC 283 of abnormalities ・Receives switching instructions from the switching control PC 282 ・Configures and monitors the active MUX 241 ・Switches the input channel of the active MUX 241 in the event of an abnormality in the transmission server 223 ・Transmits errors on the input channel of the active MUX 241 ・Configures and monitors the active QPSK modulator 242 ・Monitors the backup MXC 244 ・Configures and monitors the TS audio monitor device 263 ・Configures and monitors the channel setter PC 262 The roles of the backup MXC 244 are as follows:

Receives various transmission control information from the broadcast management system. Receives configuration information such as time and active/standby designation from the proprietary server 221. Notifies the alarm PC 283 of abnormalities. Receives switching instructions from the switching control PC 282. Configures and monitors the standby MUX 241. Switches the standby MUX 241's input channel in the event of an abnormality in the transmission server 223. Transmits errors on the standby MUX 241's input channel. Configures and monitors the standby QPSK modulator 242. Monitors the active MXC 244. As mentioned above, there are two multiplexers 241, two QPSK modulators 242, and two MXCs 244, one for system A and one for system B, which operate independently and in parallel. The output of each QPSK modulator 242 is supplied to the selector 243, and the switching control PC 282 performs this switching. This switches the active and standby systems (A/B switching). The MUX 244 independently transfers settings and schedules to each MUX 241, but only the active MUX 124 transmits PMT files to the proprietary server 221, configures and monitors the TS audio monitor 263, and configures and monitors the channel setter PC 262.

The 100-channel monitor system 203 has an audio 100-channel monitor 261. This audio 100-channel monitor 261 is supplied with the outputs of modulators 242-1 and 242-2 and the output of a TS audio monitor 263. Furthermore, this audio 100-channel monitor 261 is also supplied with a received IF signal obtained by receiving radio waves from a satellite using a receiver (not shown) and demodulating the received signal. Furthermore, the audio 100-channel monitor 261 is supplied with the output of an OA listening PC 265 after being decoded by an MPEG decoder 266. The audio 100-channel monitor 261 can monitor these inputs as needed. A channel setter PC 262 controls the 100-channel monitor 261.

The 100-channel monitor system 203 monitors whether all channels are being transmitted correctly. It first receives radio waves transmitted from the satellite and distributes them to 100 receiving devices (IRDs, not shown). Each IRD plays back the audio, which is then simultaneously displayed on the peak level meters for all 100 channels on the 100-channel monitor 261. The monitor can check the transmission status at a glance by observing the meter movement. The 100-channel monitor 261 is also equipped with a level detection device (not shown). If the level drops below -50 dB (silence) for 30 seconds or more, the indicator on the peak level meter flashes red and an alarm sounds to alert the monitor. The monitor can then select the channel and output the audio to the speaker to investigate whether there is a problem. The level threshold and detection time settings are configurable.

If an abnormality is detected in the satellite transmission system, the input to the 100 channel monitor 261 is simultaneously switched from the IRD output (CS-IF) to the output of the QPSK modulator 242 in the active system, and the audio before satellite transmission is confirmed using the peak level meter for channel 100 and one audio signal selected on the switch console 341. If necessary, the input is switched to the output of the QPSK modulator s42 in the Senbi system, and the audio before satellite transmission is confirmed using the peak level meter for channel 100 and one selected audio signal.

If further problems exist, the TS audio monitor 263 demultiplexes and extracts one channel of transport stream (TS) from the output of the transmission server 223, i.e., the primary multiplexed stream before input to the MUX 241. The decoded TS is then decoded by the decoder 264 and confirmed using 100-channel peak level meters and one selected audio. Since each transmission server 223 simultaneously multiplexes 13 channels, a single TS audio monitor 263 can simultaneously decode up to 13 channels of TS and output 13 channels of audio. By installing eight TS audio monitors 263 (one of the nine is a spare), 100 channels of audio can be output simultaneously.

The switch console 341 of the 100-channel monitor 261 has 100 selection switches, each of which corresponds to a channel number.

On the other hand, because the output of the TS audio monitor 263 physically corresponds to the output of each transmission server 223, when 9/8 redundancy switching is performed, the output of the TS audio monitor 263 no longer corresponds to the channel number. Therefore, in this embodiment, the channel setter PC 262 sets which inputs the 100 selector switches on the switch console of the 100-channel monitor 261 will select and output, in accordance with the switching information.

Furthermore, while the channel setter PC 262 controls the switch console of one 100-channel monitor 261, the setting files that control the selection switches are transferred from two MXCs 244. Therefore, communication with the MXCs 244 is performed via a network using the LAN as dedicated line 103, and communication with the switch console of the 100-channel monitor 261 is performed via RS-422.

If the problem occurs upstream of the transmission server 223, it may be due to the material on the proprietary server 221. Therefore, the on-air (OA) listening PC 265 can directly read the problematic material file from the proprietary server 221 and decode it with the MPEG decoder 266 for confirmation. The OA listening PC 265 and MPEG decoder 266 function as a playback device 265.

For example, if there is an abnormality in the sound that was broadcast and received, it is necessary to determine whether the abnormality was in the recorded material itself or whether the abnormality occurred during the transmission process. Therefore, the OA listening PC 265 specifies the date and channel on which the abnormality occurred and displays the progress chart. When the abnormal material is specified on the progress chart, the OA listening PC 265 reads the specified material from the proprietary server 221 and plays it back. This makes it possible to determine whether there was an abnormality in the material itself.

The transmission management system 214 includes switching control PCs 282-1 and 282-2, and the output of an in-station clock 284 that performs timekeeping is supplied to the switching control PC 282. The transmission management system 214 also includes office monitor PCs 281-1 and 281-2 and an alarm PC 283.

The OA monitor PC 281, the switching control PC 282, the alarm PC 283, and the OA listening PC 285 of the transmission management system 214 are connected to the MXC 244 of the secondary multiple satellite transmission system 212.

The transmission management system 214 monitors and switches between the proprietary server, the 100-channel transmission system 211, and the secondary multiple satellite transmission system 212. All alarms generated by each system are notified to the alarm PC 283, which sounds a chime with one of four tones depending on the response level, and the alarm number and message appear on the alarm PC 283's display screen. Response methods can also be viewed using a GUI. The alarm PC 283 also allows viewing of the alarm log for each system, allowing the user to understand how the problem occurred. The system monitor becomes aware of an abnormality through the alarm on the alarm PC 283. The system monitor determines the fault condition and response from the contents displayed on the alarm PC 283, and performs switching operations from the switching control PC 282 as necessary.

One of the two switching control PCs 282-1, 282-2 is set as the active system, and switching operations are enabled for input. Switching operations cannot be input from the standby switching control PC 282. The switching control PC 282 obtains the accurate time from the station clock 284 and sets it in the proprietary server 221. Each peripheral device obtains the accurate time by referencing the proprietary server 221. Based on input from the system supervisor, the switching control PC 282 switches the transmission server 223 to the standby system (9/8 redundancy switching) and switches the output of the QPSK modulator 242 (A/B switching) using the selector 243. At that time, the switching control PC 282 rewrites the configuration of the proprietary server 221 and then notifies each peripheral device that the configuration has been rewritten. This triggers each peripheral device to obtain the new configuration from the proprietary server 221 and switch its operation.

Furthermore, switching of the output of the QPSK modulator 242 (A/B switching) is performed by instructions from the switching control PC 282 when the selector 243 is set to remote. However, it is also possible to set the selector 243 to local and forcibly perform the switching from the front panel of the selector 243 itself. In this case, the switching control PC 282 is notified that a switch has been made on the selector 243 itself, and uses this information to switch the configuration of the proprietary server 221. Furthermore, the OA monitor PC 281 can monitor the music transmission status from the transmission server 223.

When a channel is selected from the GUI on the OA monitor PC 281, the scheduled events (music pieces) for that channel are displayed as a list (i.e., the contents of the schedule). Furthermore, the title, performer, performance time, and remaining time of the currently playing music piece (event) are highlighted in a different color, allowing the user to see the current play status, past play history, and future play schedule at a glance. Furthermore, the status of the OA monitor PC 281 is obtained from the playout server 223, and event updates are based on the operation of the playout server 223, so abnormal or stopped status of the playout server 223 can also be monitored.

In the above explanation, the master clock is generated based on a signal from GPS and input to the TSPP board 4 from an external source. However, as shown in Figures 13 and 14, the entire system can be reduced in size by installing a reference frequency generator 45 on the TSPP board 4 that has the same level of frequency stability as a reference frequency generator that uses GPS.

As shown in Figure 15, all control signal packets, such as NIT and PAT, specified in broadcasting standards are multiplexed using software processing similar to that of the multiplexer 31 in Figure 5. This allows the data to be supplied directly from the TSPP board 4 to the modulator (MODU) 8, where it is modulated and sent over the transmission path. Furthermore, as shown in Figure 16, by incorporating the modulator (MODU) 8 into the computer 3 as a board, data can be output directly from the computer 3 over the transmission path.

It goes without saying that the present invention is not limited to 100-channel music broadcasting, but can also be easily applied to data broadcasting of any digitized information.

In this embodiment, the MPEG compression method is used, but this is for illustrative purposes only; other compression methods, such as AC-3 and ATRAC, can also be used. The present invention is also applicable when no compression is used.

In this embodiment, the transmission path has been described assuming a satellite, but the transmission path may also be terrestrial waves, optical space, optical cable, coaxial cable, or other real-time transmission paths, or magnetic tape, optical tape, magnetic disk, optical disk, or other storage-type transmission paths.

In addition, while the master clock is generated using GPS in this embodiment, the master clock may be generated based on a standard signal generator using, for example, rubidium or cesium, as long as it is highly accurate and meets the time accuracy specifications.

As described above, the 100-channel digital data transmission device and method uses a counter synchronized to the master clock to measure the multiplexed data, enabling accurate management of the amount of data transmitted and the time required for transmission.

─────────────────────────────────────────────────────── (Note) This publication is based on the publication published internationally by the International Bureau of Patents (WIPO). The effect of the international publication of the Japanese patent application (Japanese utility model registration application) related to this publication arises pursuant to Article 184-10, Paragraph 1 of the Patent Act (Article 48-13, Paragraph 2 of the Utility Model Act) and is unrelated to this publication.

Claims (14)

[Claims] 1. A multi-channel digital data transmission device comprising: clock generation means for generating a master clock; multiplexing means for multiplexing multiple pieces of data into packets; and storage means for storing the packets sent from the multiplexing means; and wherein the device outputs the packets stored in the storage means as a continuous stream using a counter synchronized with the master clock. 2. The multi-channel digital data transmission device described in claim 1, wherein the clock generation means generates a master clock with higher accuracy than the clock used for multiplexing by the multiplexing means. 3. The multi-channel data transmission device according to claim 1, wherein the multiplexing means performs the process of multiplexing multiple data to form a packet stream in software. 4. The multi-channel data transmission device according to claim 1, wherein the multiplexing means multiplexes effective data, time data, and invalid data from multiple channels. 5. The multi-channel data transmission device according to claim 1, wherein the multiplexing means multiplexes a portion of program specific information (PSI) including a program clock reference (PCR) and a program map table (PMT). 6. The multi-channel data transmission device of claim 1, wherein the multiplexing means comprises: a multiplexing/packet generation means; a packet counting means for counting the number of packets output from the storage means; a time measurement means for measuring time; a determination means for determining whether the number of packets counted by the packet counting means is a predetermined number based on the time measured by the time measurement means; and a control means for controlling the generation of packets by the multiplexing means in accordance with the determination result of the determination means. 7. The multi-channel data transmission device according to claim 6, wherein the multiplexing/packet generation means multiplexes effective data, time data, and invalid data from multiple channels. 8. The multi-channel data transmission device according to claim 6, further comprising a time data adding means for adding time data to packets generated by the multiplexing means in accordance with the number of packets counted by the packet counting means. 9. The multi-channel data transmission device according to claim 1, wherein the clock generation means generates a master clock using a time calibration signal from a GPS satellite. 10. The multi-channel data transmission device of claim 1 further comprises frequency division means for dividing the master clock of the first frequency generated by the clock generation means by a power of two to generate a clock of a second frequency, and for outputting the packets stored in the storage means as a continuous stream using a counter synchronized with the clock of the second frequency. 11. The multi-channel data transmission device according to claim 1, further comprising: external packet input means for receiving packets input from an external device; and the multiplexing means multiplexes the packets based on the external packets input to the external packet input means to generate packets. 12. A multi-channel digital data transmission method comprising: a clock generation step for generating a master clock; a multiplexing step for multiplexing multiple data into packets; and a storage step for storing the packets sent from the multiplexing means; and wherein the packets stored in the storage step are output as a continuous stream using a counter synchronized with the master clock. 13. The multi-channel data transmission method according to claim 12, wherein the multiplexing step multiplexes data, time data, and invalid data from multiple channels. 14. The multi-channel data transmission method according to claim 12, wherein the multiplexing step multiplexes a portion of program specific information (PSI) including a program clock reference (PCR) and a program map table (PMT).