KR100344793B1 - Apparatus for generating local digital TV for test - Google Patents

Abstract

The present invention relates to an RF signal generator that complies with the ATSC standard. Specifically, the MPEG2 stream stored in the PC's hard disk is read as an ATSC standard stream through an I / O card of a general PC, and the VSB modulation is performed through a VSB remodulator. By outputting as RF signal, it is very inexpensive and small in volume compared to the existing one, so it is easy to move, and it is easy and easy to install and use since it is installed inside or outside of general PC and executed by using O / S for PC. .

Description

Apparatus for generating local digital TV for test}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to digital television (DTV) conforming to the Advanced Television Systems Committee (ATSC) standard, and more particularly, to a test local DTV signal generator that generates an ATSC RF signal that can be received by a digital TV.

The National Television Standards Committee (NTSC) has been in use for decades in television transmission, and has come into the age of coexistence with digital TV in the coming years as the digital TV era has come. The digital TV has a North American standard and a European standard, and the North American standard follows the standard of the Advanced Television Systems Committee (ATSC).

Therefore, development of digital TV-related devices is in progress. However, since the digital broadcasting conforming to the ATSC standard has not been commercialized, companies developing ATSC-type DTV-related devices are equipped with a separate ATSC RF generator to generate the ATSC standard RF signal required for testing and demonstration. Should be.

1 illustrates an ATSC RF signal using an MPEG Test Streamer (MTS), a VSB modulator, an RF up-converter, and the like as an example of such a conventional ATSC RF generator. That is, the MPEG Test Streamer (MTS) analyzes the data compressed in MPEG to generate an MPEG2 stream. For example, the first byte of the MPEG2 compressed stream always starts with 0x47, and 188 bytes constitute one packet.

The VSB modulator performs error correction (FEC), reed-solomon (RS) coding, DC insertion, etc. on the MPEG2 compressed stream to generate a VSB IF (Vestigial Side Band Intermediate Frequency) signal. That is, VSB modulation modulates only the remaining part of one sideband signal of two sidebands generated up and down about a carrier when amplitude is modulated. The terrestrial wave uses 8VSB (8T VSB). Modulation method is adopted.

The RF up-converter converts the VSB IF signal into a desired high frequency (RF) band and then sends the cable or airwave through an RF cable or antenna.

However, the above-described conventional ATSC RF generator is expensive and complicated in various aspects such as installation and usage. That is, the ATSC RF generating apparatus is about hundreds of millions of won, the equipment is large, the movement is inconvenient, and there is a complicated installation and usage.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to generate an ATSC standard RF signal using a memory device and a VSB remodulator, thereby generating a local DTV signal suitable for testing or demonstration due to its low cost and small size. In providing a device.

1 is a block diagram of a conventional ATSC RF generator

2 is a block diagram of an ATSC RF generator according to the present invention

3 (a) to (d) is a view showing a process of converting and restoring an MPEG compressed stream into an ATSC standard stream in FIG.

4 illustrates an example of an internal structure of the VSB remodulator of FIG. 2.

5 (a) to 5 (c) show the structure of a stream input to the VSB remodulator

6 is a diagram illustrating an actual implementation of the VSB remodulator.

Explanation of symbols for main parts of the drawings

100: regular PC 101: hard disk

102: ATSC stream conversion unit 103: I / O card

200: RF signal generator 201: data converter

202: VSB remodulator 203: clock generator

Local DTV signal generator for testing according to the present invention for achieving the above object,

When a data request is input, a data output unit (for example, a general PC) that reads the MPEG compressed stream from a storage unit (eg, a hard disk) in which the MPEG compressed stream is stored, converts it into an ATSC standard stream, and outputs the data. The data output unit is configured to include a RF signal generator for outputting an RF signal by performing VSB modulation when a stream of ATSC standard is input from the data output unit.

The data output unit adds a parity of a predetermined byte for each packet of the MPEG compressed stream and converts the stream into an ATSC standard stream.

The data output unit includes a storage unit for storing an MPEG2 compressed stream, an ATSC stream output unit for reading an MPEG compressed stream stored in the storage unit and converting the MPEG compressed stream into an ATSC standard stream, and receiving a data request from the RF signal generator. Characterized in that it consists of an I / O card to read the stream of the ATSC standard and transmit it to the RF signal generator.

The I / O card is characterized in that the general PCI card.

The RF signal generator is a parallel / serial converter for converting data input in parallel from the I / O card of the data output unit to serial, and VSB-modulated data output from the parallel / serial converter to output an RF signal And a VSB remodulator.

The VSB remodulator is characterized by converting to an RF signal by sequentially performing VSB modulation and digital up-conversion on the ATSC standard stream.

The present invention is to generate an RF signal conforming to the ATSC standard more easily and cheaply using a general PC and VSB remodulator.

Other objects, features and advantages of the present invention will become apparent from the detailed description of the embodiments with reference to the accompanying drawings.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention can be easily used during a test or demonstration by using a memory device for storing data for DTV, a VSB remodulator for generating an RF signal, and a control unit for performing an interface such as clock synchronization between the memory device and the VSB remodulator. To generate an available ATSC standard RF signal.

The storage device can be any one capable of storing data, for example, a ROM, a RAM, a flash card, a hard disk (HDD), or the like can be used. Here, the memory device may be applied to a wider variety of applications, and thus the present invention will not be limited to the above example.

The VSB remodulator may be any one designed to output a VSB RF signal defined in the ATSC standard through VSB modulation.

In the present invention, for convenience of description, it is assumed that the storage device uses a hard disk (HDD), and the hard disk is mounted in a PC. Here, the body on which the memory device is mounted may vary depending on which one is used as the memory device.

2 is a block diagram showing an example of a local DTV signal generating apparatus according to the present invention, a general PC 100 to which a hard disk is mounted, and an RF signal generator having a card type inserted into the general PC 100 ( 200).

In this case, the general PC 100 is a Pentium class, and adds parity for each packet of the MPEG compressed stream stored in the HDD 101 and the MPEG compressed stream stored in the HDD 101 to convert to a stream conforming to the ATSC standard. ATSC stream converter 102 including a program and the like, and the I / O card 103 for transmitting the ATSC stream to the RF signal generator 200 when a data request is received from the RF signal generator 200. It consists of. The I / O card 103 is a general I / O card (eg PCI).

In general, a passage for allowing internal devices such as a central processing unit (CPU), a memory, a disk, and an expansion card to exchange data and signals in a computer is referred to as a "bus." Bus types include an internal bus used to transfer data and signals inside the CPU, an external bus that transfers data between the CPU and memory, memory, and I / O devices, and a system bus that connects between the CPU and memory. . Peripheral Component Interconnect (PCI), a system bus, allows the CPU and peripherals to run at separate clocks rather than running at the same speed, increasing overall system efficiency.

Here, the ATSC stream conversion unit 102 may add parity for each packet of the MPEG compressed stream stored in the HDD 101 to convert the stream into a stream conforming to the ATSC standard, and then store the result in the HDD 101 again. The O card 102 may be output to the RF signal generator 200. That is, the HDD 101 may store an MPEG compressed stream in units of 188 bytes or an ATSC stream in units of 208 (= 188 data + 20 parity) bytes.

In addition, the ATSC stream converter 102 also includes a user interface (UI) function for the user's convenience. In other words, the user selectable functions are displayed as icons on the screen, and the progress of the selected functions is displayed.

The RF signal generator 200 synchronizes the synchronization between the I / O card 102 and the VSB remodulator 202 and converts data input through the I / O card 102 into a VSB remodulator ( 202, a control unit 201 for converting to a format and generating various necessary control signals, a VSB remodulator 202 for VSB modulation of data input through the control unit 201 and outputting the RF signal, and the VSB re- It consists of a clock generator 203 that provides a clock to the modulator 202.

Herein, the control unit 201 of the RF signal generator 200 provides a data request and a clock to the I / O card 102, and the I / O card 102 inputs necessary data when there is a data request. The clock is output to the RF signal generator 200 in synchronization with the clock.

At this time, the clock provided to the I / O card 102 depends on the VSB mode, and also depends on the data read rate of the I / O card 102.

For example, if the VSB mode is 4 (or 8VSBT), and the I / O card 102 can read data in 32-bit units, that is, 4-byte units

The P / S converter 201 converts data output in parallel from the I / O card 103 into serial. In this case, the P / S converter 201 may design the data format from the I / O card 103 to be recognized by the VSB remodulator 202. However, the P / S converter 201 may electrically design the EPLD. Logic Device) contains logic.

In the present invention configured as described above, the RF signal generator 200 outputs a data request, an interface reference clock (IRC) to the I / O card 103, and the I / O card 103 is a data request and an IRC. The data is read from the HDD 101 and sent to the RF signal generator 200 in accordance with the synchronization. For example, the NI PCI DIO 32HS card supports a signal changing mode, in which an external PCLK1 clock (IRC 2.69 MHz in the RF signal generator 200) is received.

3 illustrates a process of converting and restoring an existing MPEG2 compressed stream to an ATSC standard format, that is, a VSB remodulator format, and showing a 4 (8T) VSB mode as an example.

First, the stream called TRP in FIG. 3A is an MPEG transport stream, that is, an MPEG compressed stream stored in the HDD 101. The first byte always starts with 0x47 and 188 bytes constitute one packet. In other words, the MPEG compressed stream is composed of packets having a length of 188 bytes. The first byte is a sync byte and has the same value Ox47 for all packets.

The ATSC stream converter 102 is programmed, and 20 bytes of parity are inserted (e.g., filled with 0) as shown in FIG. 3 (b) after every 188 sections of the MPEG compressed stream having a structure of 188 + 188 + 188. Create a stream that conforms to the ATSC standard. In the present invention, 188 bytes of data + 20 bytes of parity are referred to as one data segment. In addition, there is a field sync for every 313 sections of the data segment, and the field sync puts 208 bytes.

The above example shows the 4 (8T) VSB mode as an example. Since the other VSB modes have different field sync and data segment intervals, the ATSC stream must be made according to the ATSC standards 2, 4, 8, 8T, and 16 VSB modes.

When the ATSC stream is generated by the ATSC stream converter 102 as described above, the I / O card 103 reads the ATSC stream in 32-bit units as shown in FIG. 3 (c) to parallel the RF signal generator 200. Will output For example, the I / O card 103 simultaneously reads data using four ports and outputs the data in parallel in 32-bit units. That is, when the NI PCI DIO 32HS card is used as the I / O card 103 and data is read in 32 bits, a general PC can be used as it is because it does not place a heavy burden on the PC. If data is read in 16-bit or 8-bit units, it puts too much burden on the CPU, and reading in 64-bit units increases the CPU price.

The P / S converter 201 of the RF signal generator 200 is an 8-bit parallel data format that the VSB remodulator 202 can recognize data input in 32-bit units as shown in FIG. (The first byte is 0x47) and output to the VSB remodulator 202.

4 is an internal structure of the VSB remodulator 202, which outputs a data request and an IRC to the I / O card 103, and outputs data In_Data [7: 0] and data from the I / O card 103. FIG. Valid data_valid and a clock (2.69MHz). In this case, the VSB remodulator 202 does not operate when the synchronization between the data In_Data [7: 0], the data valid (Data_valid), the clock (2.69 MHz) and the master clock (86 MHz) is not performed, so that the synchronization is performed. The PLL circuit can be designed externally as needed.

FIG. 5 illustrates three signals input into the VSB remodulator 202 chip. The first byte of one packet must be 0x47. In addition, as shown in (b) of FIG. 5, the data should be read in polling of In_Byte_Clk (eg, 2.69 MHz). In addition, the data valid signal must be high for 188 intervals for the data and during the 20-byte parity period and for the field sync interval repeated for every 313 data segments as shown in FIG. That is, the data valid signal is a signal that distinguishes only pure data portions excluding additional data such as a parity signal in one packet, and may be generated by counting synchronous bytes starting from Ox47 to 188. This distinguishes the data valid signal since the parity code added to the MPEG transport stream is required only for ECC decoding. The same applies to the field synchronization signal.

At this time, the ATSC stream output from the general PCI I / O card 103 is stored in the input buffer 301 and then output to the VSB processing unit 302 in synchronization with a clock. The VSB processor 302 performs VSB modulation on the ATSC stream to generate a VSB IF signal, and the filter and digital up-converter 303 converts the VSB IF signal into 4 (8T) defined in ATSC standard A / 53 Annex D. Convert to VSB RF signal. The RF signal is converted into an analog signal by the D / A converter 304 and then filtered by a band pass filter (BPF) 307 and output to RF channels 3 and 4. The BPF 307 has a 12 MHz bandwidth, for example, to protect signals of RF channels 3 and 4, and has a center frequency of 65.97 MHz.

FIG. 6 illustrates an example of an actual implementation of the RF signal generator 200. The data request and the IRC are transmitted to the I / O card 103 through an SCB-68 connector, and the I / O card 103 sends 32. It receives a bit signal. The EPLD (eg, ALTERA 7128) converts 32-bit parallel data (4 byte reads) into 8-bit parallel data. 162244,164245 is a common buffer and converts the EPV's 5V signal into a 3.3V or VSB remodulator 3.3V signal into a 5V signal. The VSB remodulator receives an ATSC stream with parity added every 188 bytes and converts the RF signal into a RF signal through a VSB encoding process (ie, VSB modulation, RF up-conversion, D / A conversion, etc.). The 86 MHz clock is the master clock, and the BPF protects signals on RF channels 3 and 4. BNC is a commonly used connector.

As described above, the present invention allows many companies that develop ATSC-related DTV reception equipment to obtain RF signals and transport streams conforming to the ATSC standard at a lower cost, and were developed on a general PC basis. That is, streams can be generated more easily using the Graphical User Interface (GUI) of Windows 95/98 / NT. Therefore, the present invention can be used in all parts requiring the ATSC standard VSB RF signal.

In addition, according to the present invention, the RF signal of the 2,4,8,8T, 16 VSB system, which is the ATSC standard, can be obtained only by developing the format change software of the stream.

The present invention generates an ATSC standard RF signal very easily and inexpensively using a general PC. In particular, in the present invention, the I / O card is a PCI type card, the entire transmission equipment is put into the PC, and the structure is simple. That is, the price of the ATSC RF generating device was hundreds of millions of units, but according to the present invention, since the RF signal generating unit is further included in the general PC value, it is sufficient for several million won.

In this case, the RF signal generator may be designed as a single board or integrated with the I / O card. Integrating it into a single card has the advantage of reducing the volume of the PC. When designing as a single board, it is possible to easily generate an ATSC RF signal by attaching it externally even if it is not a general PC, for example, a computer such as a notebook. have.

In the meantime, the present invention can be applied to a more expanded concept in which all broadcast programs can be directly generated from a computer by replacing a digital video cassette recorder used in a broadcasting station in the future.

As described above, according to the ATSC RF generating apparatus according to the present invention, the MPEG2 stream stored in the hard disk of the PC is read as a stream conforming to the ATSC standard through the I / O card of the PC, and the VSB is read through the VSB remodulator. By modulating and outputting as RF signal, it is very inexpensive and small in volume compared to the existing one, and it is easy to move. Also, it can be installed and used inside the PC and then executed by using O / S (operating system) for PC. Simple and easy

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (9)

(correction) The MPEG compressed stream is stored in the storage unit in advance, and when a data request is input, the MPEG compressed stream is read from the storage unit, converted into an ATSC standard stream, and output in parallel. An output unit, If necessary, a data request is made to the data output unit. When an ATSC standard stream is inputted from the data output unit, the RF signal generator converts the serial signal into a serial signal and performs a residual sideband (VSB) modulation to output the RF signal. ATSC RF generator characterized in that it comprises a. The method of claim 1, ATSC RF generator, characterized in that the data output unit is a general personal computer. The method of claim 1, wherein the data output unit ATSC RF generating apparatus characterized by adding a parity of a predetermined byte for each packet of the MPEG compressed stream to convert to a stream of the ATSC standard. The method of claim 1, wherein the data output unit A storage unit for storing the MPEG2 compressed stream, An ATSC stream output unit for reading an MPEG compressed stream stored in the storage unit and converting the MPEG compressed stream into an ATSC standard stream; ATSC RF generating device characterized in that it comprises an I / O card to read the stream of the ATSC standard and transmit to the RF signal generator when there is a data request from the RF signal generator. The ATSC RF generating apparatus of claim 4, wherein the I / O card is a general PCI card. The method of claim 1, wherein the RF signal generator A parallel / serial conversion unit for converting data input in parallel from the I / O card of the data output unit into serial; And a VSB remodulator for VSB modulating the data output from the parallel / serial converter and outputting the RFB signal as an RF signal. 7. The method of claim 6, wherein the VSB remodulator ATSC RF generator, characterized in that for converting the RF signal by performing a VSB modulation, digital up-conversion sequentially to the ATSC standard stream. The method of claim 1, And the RF signal generator is embedded in the data output unit. The ATSC RF generating apparatus of claim 1, wherein the RF signal generator is an external type mounted outside the data output unit.