DVB Master Technical Reference Manual Version 1.05 August 12, 1999

Transcription

1 DVB Master Technical Reference Manual Version 1.05 August 12, 1999

2 Manual Updates Rev 1.03 May 6, Add dvbtest.exe description and stuffing utility Rev 1.04 May 11, Modify stuffing utility for Hex; modify "Driver Support" and "The Kernel Driver for N T 4" descriptions Rev 1.05 Aug 11, 1999 Delete the installation of the key for the registry as no longer necessary Aug 11, 1999 Page 9- Corrected formulas for calculating Stuffing ii

3 Table of Contents: INTRODUCTION... 1 DATA TRANSMISSION USING DVB... 1 DVB ASI OPERATION... 1 Figure 1 - DVB ASI Coaxial Transmission Link as used in the DVB Master... 2 DVB MASTER SEND DESCRIPTION... 2 TRANSMIT CLOCK TRIM CONTROL... 3 K28.5 OR STUFFING DATA... 3 CONTROL OF DATA DISPERSION... 3 CONTROL OF DATA RATE... 3 DVB MASTER RECEIVE DESCRIPTION... 3 RECEIVE INDICATOR LED... 4 BYTE ALIGNMENT... 4 RUNNING DISPARITY (RD)... 4 TRANSPORT PACKET TIMING... 4 DVB MASTER SPECIFICATIONS... 5 OVERVIEW... 5 DRIVER SUPPORT... 6 SAMPLE APPLICATION SOFTWARE... 7 HARDWARE SPECIFICATIONS:... 7 ORDERING INFORMATION:... 7 CABLE AND CONNECTOR SPECIFICATIONS... 7 WINDOWS NT 4 INSTALLATION... 8 DRIVER INSTALLATION... 8 USING DVBTEST.EXE... 8 STUFFING CALCULATION UTILITIES PT188.EXE AND PT204.EXE... 8 DVB MASTER PROGRAMMING INFORMATION... 9 THE KERNEL DRIVER FOR NT PCI BRIDGE PROGRAMMING FOR DVB MASTER SEND... 9 DVB MASTER SEND REGISTER INFORMATION DVB MASTER RECEIVE REGISTER INFORMATION PACKET TIMING FOR DVB MASTER SEND WARRANTY SERVICE POLICY LIFE SUPPORT POLICY AIRCRAFT OR SPACECRAFT POLICY iii

4 Introduction The DVB Master consists of a set of boards, which separate out the functions of transmission and reception of the DVB stream. The DVB Send is a PCI computer card with a BNC type connector, which will accept DVB Asynchronous Serial Interface (ASI) standard inputs. Similarly, the DVB Send uses a BNC connector and is capable of transmitting a DVB ASI stream. The DVB Master has been designed to provide a transmission system for DVB/MPEG-2 Transport Streams (TS) between different remote locations. The DVB Master does not include the RF Converter section necessary to receive DVB from a satellite and it does not include the circuitry necessary to scramble and unscramble the MPEG-2. The DVB Master can be used to transmit MPEG-2 Transport Packets that may come from different sources and therefore may have different data rates. DVB ASI uses a constant transmission rate so the transmitter and receiver use the same clock rate, that is 270 MHz. The DVB Master Receive uses a Phase Locked Loop (PLL) to recover the clock. The Input to the DVB Master Receive accepts MPEG-2-Bytes and the DVB Master Send will output MPEG-2-Bytes. Data Transmission Using DVB Although the transmission protocol used by the DVB standard is designed for MPEG-2 TS data, the DVB Master cards can be used to transmit any data and can maintain byte alignment, much the same as done in the HDLC data transmission. The DVB standard provides a Link-Layer interface for Half-Duplex data transmission and can quite happily transmit data files as well as MPEG-2 video files. DVB ASI Operation The DVB Master boards follow the CENELEC EN : 1998 standard. Referring to Figure 1 below, Layer 2 is defined as the MPEG-2 Standard ISO/IEC (Systems). Layers 1 and 0 are based on a subset of ANSI Standard X3T11, Levels FC-1 and FC-0. The accompanying description explains the processing of the data input as it is converted to a DVB ASI output and as it is received and converted back to a data stream on the PCI bus. Although the diagram shows an MPEG-2 Transport Stream (TS) being used, it is true that any data stream can be packaged and transported in the same way. The advantage of the DVB ASI for use with MPEG-2 Transport Streams is fourfold: 1. High speed (270 MHz) transport system over coaxial cable 2. DVB ASI coaxial maintains byte alignment 3. DVB ASI automatically inserts synchronization words if data isn't ready 4. Very low transport overhead allows just about all of the available bandwidth to be used 1

5 Layer 2 Layer 1 Layer 0 MPEG-2 TS from the PCI Computer Bus 8B/10B Coding Sync Byte (FC Comma) Insertion Parallel/Serial Conversion Amplifier/ Buffer Coupling/ Impedance Matching BNC Connector DVB Master Send Coaxial Cable MPEG-2 TS to the PCI Computer Bus 8B/10B Decoding Sync Byte (FC Comma) Deletion Clock/Data Recovery & Serial/Parallel Conversion Amplifier/ Buffer Coupling/ Impedance Matching BNC Connector DVB Master Receive Figure 1 - DVB ASI Coaxial Transmission Link as used in the DVB Master DVB Master Send Description MPEG-2 TS data is presented to the MPEG Send card over the PCI bus. The source of the data may be a disk file or live video encoded in real time by an MPEG-2 encoder card. The MPEG-2 data must be in the form of Transport Packets. The data is transferred from the system main memory to the input FIFO by a DMA controller located on the PCI bridge chip. On receipt of the data it is 8B/10B coded to produce one 10-bit word for each 8-bit byte presented. The 10-bit words are then passed through the parallel-to-serial converter which operates at a fixed 270 Mbits/sec. If the parallel-toserial converter requests a new input word and the data source does not have one ready, a synchronization word is automatically inserted. The synchronization word used here is the K28.5 character, which is a comma character in the 8B/10B-coding table. This table is described in the X3T11 standard and is the one used by DVB ASI interface layer-1. There is an advantage in using this synchronization word with MPEG-2 streams. The ASI Interface layer-2 definition uses the MPEG-2 Transport Stream packet syntax with the additional requirement that every Transport Packet be preceded with at least two K28.5 synchronization characters. Although the 8B/10B receivers can generally maintain synchronization (once initially synchronized) without interspersed synchronization codes, this leading synch byte requirement will allow re-synch within one transport packet in the event that a line disturbance causes a loss of sync. Once the synchronization words are inserted, the data is shifted out at the 270 Mbits clock rate to Layer 0. Layer 0 consists of line drivers, impedance matching circuits, an isolation transformer and the BNC connector. 2

6 Transmit Clock Trim Control The DVB Master Send has a control loop designed to allows the transmit clock to be adjusted over a small range. This has been provided to allow the DVB Transmitter to operate with an MPEG-2 Encoder card which does not have a trim on the encoding rate. A control word must be written to the DAC, which is used to modulate a VCXO oscillator over a range of 100 ppm. K28.5 or Stuffing Data DVB ASI uses the K28.5 character (comma) to fill bandwidth when no data is available to be transmitted. These characters serve four main purposes. 1. To provide a means of identifying data byte boundaries for establishing byte alignment 2. A method of controlling the distribution of the data in the transmitted stream (to make it more linear and less bursty) 3. To control the rate that data is transmitted 4. As an idle character when no data is ready for transmission Control of the stuffing, is done by adjusting parameters in the Registry Key for the Windows NT 4 driver. Please see "Stuffing Calculation Utilities pt188.exe and pt204.exe" in a later section of this manual. Control of Data Dispersion A certain number of K28.5 characters are required to be used by the DVB standard. In the minimum case, at least two K28.5 characters must appear in front of each Layer-2 Transport Packet (either 188 or 204 byte packets). In addition, the K28.5 characters can be stuffed between MPEG bytes. As a minimum, the standard requires that the K28.5 be transmitted within a 5-byte window. The receiver ensures that the first byte received after the second K28.5 will have valid byte alignment. Beyond this, extra characters may be inserted as needed between bytes and/or between packets to make sure that the MPEG data is spread-out evenly over time. Control of Data Rate The result of adding extra data stuffing characters, either between MPEG Transport Stream Packets or between MPEG data words, is that the throughput of the original MPEG data is throttled. If, for instance, an MPEG-2 Transport Stream must be transmitted at 2M bits/second over a DVB ASI communications link running at 270 Mbits/second, then redundant stuffing data must be added. The K28.5 characters can be added between MPEG-2 Packets, to create a stream with padding gaps between the Packets. Alternatively, K28.5 characters can be added between every n number of MPEG Transport bytes. Calculation of the rate is described later in this manual under the section "Packet Timing for DVB Master Send". DVB Master Receive Description Receive data arriving at the BNC connector is fed through a coupling transformer and then to the HOTLink receiver chip. The receiver recovers the clock using a PLL then recovers the data and sends it to a serial to parallel converter. A detector circuit turns-on 3

7 a green LED indicator if an input signal is present. The parallel data then passes through an 8B/10B decoder, to convert the 10-bit words back into the original 8-bit words that were transmitted. The original byte alignment is also recovered at the serial/parallel converter stage. The 8B/10B-decoder searches for the K28.5 character, and on finding the character, it assumes that it marks the boundary for the start of the byte alignment. The synchronization characters are then removed from the data to leave the original transmitted data. The parallel 8-bit words are stored in a 2K byte FIFO and then transferred to the host computer main memory by a DMA controller. Receive Indicator LED A green Receive Indicator LED is mounted on the bracket of the DVB Master Receive card. This indicator will light up when a signal is present on the BNC input of the card. The LED will light up even if a valid MPEG-2 TS is not present since it will detect stuffing characters. It can be used to show that the cable is connected and that there is continuity to the transmitter. Byte Alignment Byte alignment is of critical importance when receiving and storing data. If data is received in serial form, as in this case, there must be a way of telling when a word begins so that it can be stored in memory on correct byte boundaries. The DVB standard specifies that the K28.5 character be used for this purpose. The K28.5 character is part of the 10B. It is one of the extra characters, which are not needed to encode an 8B byte of data and can therefore be used for this special purpose. Running Disparity (RD) The DVB Master Receive does not support the Running Disparity (RD) error indication at this time. The DVB Master Receive will reject an incoming byte with an RD error. Transport Packet Timing The DVB Master cards are capable of transmitting a high-speed stream of data over the 270 Mbps link. If the source of the MPEG-2 TS is live video then the Transport Packets will be distributed in the DVB ASI stream since they are being produced at a fixed rate. Unused bandwidth will automatically be filled with K28.5 data stuffing characters if the transmit FIFO is not kept full. However, if the source of the MPEG-2 TS is a disk file, then the PC will transmit the Transport Packets as fast as the file system will allow. Data stuffing may then be added either by using padding bytes between packets, or adding stuffing data between data bytes, or a combination of both. In applications where the PC receives a DVB ASI stream and then must re-transmit it, care must be taken to preserve the original data stuffing. This must be done to preserve the original transmission rate of the MPEG Transport Packets. When the DVB Master Send is used to transmit a Transport Packet stream to another manufacturer's equipment, care must be taken to make sure that data is distributed in the 4

8 DVB ASI stream so the receive buffer does not overflow. It is assumed that the Transport Stream clock will be extracted and determined by other equipment since the DVB Master Receive card does not do this. DVB Master Specifications Separate receive and send cards provide an efficient, low cost solutions Programmable stuffing options between bytes and between packets OEM software support via Microsoft NT 4 Drivers (drivers for other OSs under development) Efficiently captures or transmits DVB/ASI data (188 or 204 byte packets) Operates with PCI bus computers using Intel Pentium-compatible processors Provides an interface for Layer-0 and Layer-1 of the DVB Serial Transmission Link (ASI) standard 270M bits/sec interface speed Bit error rate to one part in Uses the Cypress CYB933 HOTLink controller LED shows valid data on receiver Clock Rate Trim for MPEG Encoder synchronization on DVB Master Send card Overview Digital Video Broadcasting (DVB) is the next step in video broadcast standardization. Prior to DVB, there were no universal standards for MPEG-2 transmission and equipment from different manufacturers did not always work together. To solve that, the Digital Video Broadcasting Standards Association created DVB as the standard interface to facilitate the integration of MPEG-2 based video delivery from multiple manufacturers. DVB defines standards for television (HDTV), multiple simultaneous standard definition television (SDTV), and communication to mobile TV receivers with choice of multicast and/or unicast. By using a DVB interactive return channel, enhanced user services can include customized web and television content, distance learning, interactive ordering and more. Our DVB Master boards are the first on the market to provide low cost integrated DVB/ASI Receive and Send functions. They are in the forefront of a new generation of PCI Bus cards enabling Windows NT Pentium computers to surpass proprietary systems in features, scalability and cost effectiveness. At speeds up to 270M bits/sec, the DVB Master is engineered to work efficiently in satellite, terrestrial, cable, SMATV and MDS systems where MPEG-2 is the chosen standard. This product was created to allow integrators to create computer-based set-top boxes, IRDs or video servers and transmission networks which are more flexible and customizable to their needs The DVB Master Send/Receive cards are an efficient and low cost method of transmitting a DVB ASI compatible stream, which may originate in a PCI computer system. The computer may be a program server, with material either on hard disk or the DVB stream may come from a live video source. It may, for example, be used as a 5

9 server to transmit program material to a Multiplexer box for insertion into a transport stream. This is shown in Figure 1. PCI Host Computer DVB Master Send + Large Disk Array DVB Program Stream Multiplexer DVB Transport Stream output Figure 1 DVB Transport Stream input In another example shown in Figure 2, the DVB Master Send and Receive may be used to interface with WAN cards to produce a high bandwidth multiple T1 connection for transmitting MPEG 2 from point to point. PCI Computer PCI Computer DVB Data Stream DVB Master Receive + 4x WAN Master + 4x IM-T1-CSU 4xT1 DVB Master Receive + 4x Wan Master + 4X IM-T1-CSU DVB Data Stream Figure 2 As shown in Figure 3, the DVB Master Receive is a single function board and can be used in IRD s which are designed around PCI bus computers for decoding single program transport streams. DVB Program or Transport Stream DVB Master Receive + MPEG 2 Hardware Decoder board Video Out Monitor Figure 3 Driver Support A Windows NT 4.0 Kernel driver works with either the DVB Master Send or receives board. This NT driver uses Asynchronous I/O to communicate with application programs. The driver communicates with the DVB Master Send and Receive using the advanced Link List DMA mode with scatter-gather, 1M buffers and overlapped I/O give very high throughput while using the minimum of system resources. Drivers for other operating systems are currently under development. 6

10 Sample Application Software A test program, dvbtest.exe allows two boards operating in one system, to be connected together with a coaxial cable. The same test program can be used to run boards in separate systems. This program will work with both Transmit and Receive boards. This program is an example of a typical interface to the Kernel driver, and can be used as a starting point for custom applications. Source code is provided. Hardware Specifications: Standards Meets CENELEC EN : 1998 Physical Characteristics DVB Send DVB Receive Width 4.2 in. (106.5 mm) Same Length 6.88 in. (174.5 mm) Same Thickness 0.4 in. (10.1 mm) Same Weight 3.9 oz (111g) 3.5 oz. (99g) Power Requirements +5V, 220 ma (Max) +5V, 370 ma (Max) +12V, 7.5 ma (Typ) V, 7.2 ma (Typ) --- Environmental Operating Temperature 0 to 55 o C Same Operating Humidity To 90%, non-condensing Same Connector DVB Input BNC 75 ohm --- DVB Output --- BNC 75 ohm Coaxial cable 75 ohm cable Same Status Indicators --- Receive LED Receive FIFO size --- 2K bytes Operating System Windows NT Same Bus Interface PCI 2.1, 5V Same Ordering Information: Hardware DVB-S DVB-R DVB Transmit Board DVB Receive Board Software DVB-KNT4 NT 4 Kernel Mode DVB Transmit and Receive Driver Cable and Connector Specifications The coaxial cable and BNC connectors should have a 75 ohm characteristic impedance. Links of more than 100 m can be achieved using RG59 BU, while links of more than 200 m are possible using RG216U. 7

11 Windows NT 4 Installation Driver Installation This section is provided to give the ease and accessibility to adding the Driver for the Computer Modules DVB Transmitter or Receiver. Once all files have been extracted to the appropriate directory double click in the file named install.bat Using dvbtest.exe The executable file DVBTest.exe is a program that is used to check the functionality of the Computer Modules DVB Transmit and/or Receive cards. NOTE: This program is set up only to be used as a test program between two computer systems, connected using 75 ohm coaxial cable. One system using the Computer Modules DVB Transmit card and the other using the Computer Modules DVB Receive card. 1. Create a new shortcut on the desktop with the path to the DVBTest.exe file 2. Double click on the new shortcut 3. A command window will open and the program will be running inside 4. There will be three sets of numbers in this command window 5. The first number is the scan number and will increment by one each time there is data either Transmitted or Received 6. The second number is the Transmit number, which is only used when the system has a Computer Modules DVB Transmit card installed. This number will show the amount of data being transmitted. If the card is not installed, the number will show zero 7. The third number is the Receive number, which is only used when the system has a Computer Modules DVB Receive card installed. This number will show the amount of data being received. If the card is not installed, the number will show zero Stuffing Calculation Utilities PT188.EXE and PT204.EXE These two utilities calculate the (Hex) inter-byte and inter-packet stuffing values for the Computer Modules DVB-ASI Transmitter board. PT188.EXE provides the values for 188 byte transport stream packets and PT204.EXE provides the values for 204 byte transport stream packets. PT188.EXE and PT204.EXE These two utilities calculate the inter byte and inter packet stuffing values for the Computer Modules DVB-ASI Transmitter board. PT188.EXE provides the values for 188 byte transport stream packets and PT204.EXE provides the values for 204 byte transport stream packets. Example: Packet size = 188 Transport stream bit rate = 2 Megabits/sec 8

12 In a command window run PT188.EXE as follows: PT PT188.EXE will return the following to the screen: IB=6B (hex) IP=69 (hex) packet rate = transport stream bit rate = transport stream byte rate = Where IB is the inter byte stuffing value and IP is the inter packet stuffing value. The following formulas are used to calculate the stuffing values: IB=(8* )/(bit rate) - 1 (IB is rounded down to an integer in the range 0-255) IP=(8* *(packet size))/(bit rate) - (packet size) ((packet size) - 1)*IB (IP is rounded up or down to the nearest integer in the range ) If suitable values cannot be found, an error message is printed. DVB Master Programming Information The Kernel Driver for NT 4 A Windows NT 4.0 Kernel driver works with either the DVB Master Send or receives board. This NT driver uses Asynchronous I/O to interface with application programs. Asynchronous I/O is described in the Microsoft DDK for NT 4. The driver communicates with the DVB Master Send and Receive using the advanced Link List DMA mode with scatter-gather, 1M buffers and overlapped I/O give very high throughput while using the minimum of system resources. Drivers for other operating systems are currently under development. PCI Bridge Programming for DVB Master Send It is advisable to download the technical manual for the PLX9080 bridge chip and to carefully read the sections on DMA and Interrupts. The following order should be followed when programming the DVB Masters for the indicated functions. 9

13 1 - Software Reset a) Save PLX registers (PCI Configuration registers and Local Configuration Registers) b) Set bit 30 of the plx CNTRL register c) Clear bit 30 of the plx CNTRL register d) Restore PLX local configuration registers e) Restore PLX PCI configuration registers 2 - Program Stuffing Counts 3 - Program FIFO PAE and PAF levels a) Set bit 0 of configuration register to 1 and bit 1 to 0 (enables FIFO programming and disables transmitter b) Write PAE lsb to TX FIFO s c) Write PAE msb to TX FIFO s d) Write PAF lsb to TX FIFO s e) Write PAF msb to TX FIFO s f) Set bit 0 of configuration register to 0 and bit 1 to 1 (Disables FIFO programming and enables transmitter 4 - Start Transmit DMA a) Set PLX DMAMODE0 register to 0x00021f43 b) Set PLX DMADPR0 register to address of first descriptor and set bit 0 to 1 to indicate descriptor located in PCI address space c) Write 0x03 to PLX DMACSR0 register to start DMA DVB Master Send Register Information Configuration/Command Register (Offset = 0): Field Description 0 0 = Normal FIFO operation, 1 = Writes to FIFO s program PAE and PAF levels in the following order: PAE-lsb, PAE-msb, PAF-lsb, PAF-msb = Enable Transmitter, 0 = Disable Transmitter 2 0 = Frame Size 188, 1 = Frame Size UNUSED set to 0 24 DAC 0 25 DAC 1 26 DAC 2 27 DAC 3 28 DAC 4 29 DAC 5 30 DAC 6 31 DAC 7 Status Register (Offset = 0) 1 Must write same values to all FIFO s using 32 bit writes with D7-D0 = D15-D8 = D23-D16 = D31-D24. Four writes are required to set programmable flag levels 10

14 Field Description 0 Returns Configuration Register bit 0 1 Returns Configuration Register bit 1 2 Returns Configuration Register bit 2 TX FIFO s (Offset = 4) 32 Bit write only Stuffing Counts (Offset = 8) Field Description 7-0 Stuffing characters between each data byte transmitted 31 8 Stuffing characters between each frame DVB Master Receive Register Information CONFIGURATION REGISTER (Offset = 0; write only): Field Description 31 Fifo Mode: 1 = Normal operation; 0 = Programming mode 30 1 = Program FIFO command; 0 = do nothing 29 1 = Reframe HotLink Receiver; 0 = Normal Operation 28 1 = Enable Receiver; 0 = Disable Receiver 27 1 = Enable Overflow Interrupt; 0 = Disable Overflow Interrupt 26 1 = Reset Overflow Command; 0 = Do nothing Unused, set to FIFO Programmable Almost Full Flag level 10 0 FIFO Programmable Almost Full Flag level STATUS REGISTER (Offset = 0; read only) Field Description 31 FIFO Mode: 1 = Normal Operation; 0 = Programming Mode 30 1 = FIFO Programming in Progress; 0 = FIFO Programming Complete 29 1 = Reframe HotLink Receiver; 0 = Normal operation 28 1 = Receiver Enabled; 0 = Receiver Disabled 27 1 = Test Register Busy; 0 = Test Register Available 26 1 = FIFO Overflow; 0 = FIFO OK 25 1 = FIFO Almost Full 24 1 = FIFO Almost Empty 23 1 = FIFO Full 22 1 = FIFO Empty FIFO Programmable Almost Full Flag level 11

15 10-0 FIFO Programmable Almost Full Flag level FIFO Data Register (Offset = 4; read only) This register can be used to read data from the FIFO using I/O instructions. Test Register (Offset = 4; write only) This register can be used to write data into the FIFO for test purposes. Only write to this register when the receiver is disabled and bit 27 of the status register is 0. Packet Timing for DVB Master Send K K M1 M M M M M K K M1 K M1 M K K28.5 Sync Character MPEG Sync Byte (47 Hex) MPEG Transport Stream Data N k28.5 sync characters between data bytes Start of packet K28.5 sync characters P K28.5 sync characters between packets PF = Packet Frequency PT = Packet Time IB = Number of sync characters between data bytes IP = Number of sync characters between last data byte of packet and sync byte of next packet (must be 2) FS = Size of packet (188 or 204) PT = FS IP + (FS -1) * IB 27,000,000 (sec) PF = FS ,000,000 + IP + (FS - 1) * IB (Packets/sec) DATA RATE = 8 * FS (Bytes/sec) Note: This data rate assumes that the transmit FIFO s never run out of data. If the transmit FIFO s do run out of data extra K28.5 sync characters will be sent until data is available. 12

16 WARRANTY Computer Modules, Inc. warrants its products are free from defects in material and workmanship and will conform to published specifications for one year from date of shipment. The warranty is in lieu of any other warranty, expressed or implied. In no event will sellers be liable for special or consequential damages as a result of any alleged breach of this warranty provision. Our liability will be limited to replacing or repairing, at our option, any defective units which are returned, freight prepaid, to our plant. Equipment or parts that have been subject to abuse, misuse, accident, alteration, neglect, unauthorised repair or installation are not covered by this warranty. Computer Modules, Inc. will have the right of final determination as to the existence and cause of defect. Except for the expressed warranties stated above, all warranties are disclaimed, including implied warranties of merchantability and fitness for a particular purpose. SERVICE POLICY Any product, which fails to perform according to specifications, will be repaired free of charge during the warranty period. There will be a service charge for all repairs after the warranty has expired and for any repairs during the warranty period which are not covered by the warranty. To return a product for repair, call Computer Modules, Inc. for a Return Material Authorisation (RMA) number. The product should be carefully packaged and shipped prepaid showing the RMA number on the shipping label. Include a short statement of the problem; return address information and the telephone number of a technical contact for further information. In the case of non-warranty repairs, a purchase order for repair charges must also be included. LIFE SUPPORT POLICY Computer Modules products are not authorised for use as critical components in life support devices or systems without the expressed written approval of the president of Computer Modules, Inc. AIRCRAFT OR SPACECRAFT POLICY Computer Modules, Inc. products are not authorised to be installed in, or used or contained within any aircraft or spacecraft whatsoever. 13

17 DVB-CTS Description The DVB-CTS software is a sample application for Windows NT 4 that was developed for demonstration purposes. It is supplied with source code so that a user can modify or extend it for different applications. This software consists of two parts, one for saving a received DVB stream to disk and the other to transmit a file from disk over the DVB transmitter. The lscopy.exe program is an application that will accept an input from the DVB ASI Receiver board and save it to hard disk as a file. This input can be an MPEG TS, or any other data, which can be transmitted by the DVB ASI link. The speed of the hard disk will have to be chosen to make sure it is capable of storing the data as it arrives in real-time. The DVB ASI link is capable of transmitting data at rates up to about 31 MBytes/sec. A standard IDE drive will not be capable of capturing data produced at this rate. We have done some testing with a single fast IDE drive and have found that by setting the DVB driver (rx) to 8 buffers of 0x , depending on capture speed & have captured 13.5 MByte / sec to WD expert 18GB 7200Rpm ATA-66 disk with Abit be6 motherboard with 128MB memory and a 300Mhz celeron. Higher speed drives are available and it is advertised that striping SCSI multiple high-speed drives raid 0 can get sustained MByte / sec write test speed but we have not experimented with this. The same lscopy.exe program, using different command line switches, can transmit a file out through the DVB Master Transmitter board. It will transmit at the maximum rate that the communications channel and file system will allow. If no stuffing (maximum transmission rate) is selected for the DVB Master Transmitter, then the rate will most likely be limited by the disk drive. The DVB standard allows stuffing characters to be added to the data stream by the transmitter. Stuffing characters can be added between bytes and between packets. The DVB Master Send driver installation applet allows the inter-byte and inter-packet stuffing to be selected. Two utility programs for calculating the data rate for different stuffing are supplied with the NT driver. PT188.EXE and PT204.EXE programs can be used to calculate the inter-byte and inter packet stuffing parameters for a given data rate. The stuffing character is automatically stripped from the stream when a DVB ASI receiver receives it and therefore only the original data is saved to disk. The stuffing may be added to limit the bandwidth of the DVB link and therefore to control the transmission rate to be less than the sustained maximum of the disk drive