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by Charles Brain G4GUO G4GUO@ARRL.NET

2012 BATC CONVENTION. DATV-Express. by Charles Brain G4GUO G4GUO@ARRL.NET. DATV-Express. The main DATV-Express team members. Ken Konechy - W6HHC PGM Manager Art Towslee - WA8RMC Hardware Tom Gould - WB6P PCB Layout Charles Brain - G4GUO Software. 2. DATV-Express.

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by Charles Brain G4GUO G4GUO@ARRL.NET

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  1. 2012 BATC CONVENTION DATV-Express by • Charles Brain G4GUO G4GUO@ARRL.NET

  2. DATV-Express The main DATV-Express team members • Ken Konechy - W6HHC PGM Manager • Art Towslee - WA8RMC Hardware • Tom Gould - WB6P PCB Layout • Charles Brain - G4GUO Software 2

  3. DATV-Express Goals of the Project • Significantly reduce the price of Digital-ATV transmitters • Provide an open platform for future DATV development • Help educate the community and ourselves about new technologies. • Get more DATV stations on-air • Encourage more people to get licensed • By product will be a Software Defined Transmitter for the 23 cms band with a B/W of up to 8 MHz. 3

  4. DATV-Express It all started when I bought a USRP2 4

  5. DATV-Express Overview of DATV-Express System System Block Diagram for DATV-Express DATV Transmitter 5

  6. DATV-Express Overview of Hardware Board • USB2 Interface Cypress CY7C68013A • FPGA Altera EP2C8T144CN • DAC Analogue Devices AD9767ASTZ • Clocks • PLL/modulator for 1.3 GHz ADRF6750A • Buffer amplifier GVA-84+ ~20 mW • Optional symbol rate generator Si570 • DC-DC power supplies allows single 12V input 6

  7. DATV-Express Overview of Hardware Board – cont’d Block Diagram for DATV-Express Hardware Board 7

  8. DATV-Express First prototype 8

  9. DATV-Express Overview of PC Software • Operating System - Linux 32/64-bit then Win32 • Loads FX2 firmware (Control Transfer) • Loads FPGA firmware (EP1) • Controls 1.3 GHz PLL (EP1) • Controls symbol rate generator (EP1) • I/Q offset calibration (EP1) • Provides GUI 9

  10. DATV-Express Overview of PC Software – cont’d • Take program/transport stream from capture device • Converts to a transport stream with correct PIDS • Adds SI Table information • Adds FEC • Does interleaving • Keeps symbol rate constant, no overruns or under runs by adding Null transport packets • Generates either IQ symbols or a bitstream • Talks to exciter board via USB interface (EP2) 10

  11. DATV-Express GUI Screen-shot (current)

  12. DATV-Express Overview of Hardware Board Software FX2 code (USB chip has 8051) C/ASM • Programs FPGA • Manages USB FIFO interface with FPGA • I2C interface with 1.3 GHz PLL • I2C interface with symbol rate generator • I2C interface to FPGA • General Housekeeping FPGA code, Verilog, Altera Quartus II • Interpolates symbols to final sample rate • Channel filter • Writes to DAC 12

  13. DATV-Express DATV-Express Minimum System Specs • DVB-S protocol • QPSK modulation (will allow other modulations) • Frequency Range:  950–1575 MHz (allowed by ADRF6750 chip) • 1240–1300 MHz (allowed in USA) • 1240–1325 MHz (allowed in Europe) • Symbol-Rate: • Adjustable: 1 MSymb/sec -to- 5 MSymb/sec • Forward Error Correction is selectable • RF output ~ 20 mW buffered (SMA connector) • Video Capture card allows for NTSC or PAL • Initially designed for one video stream • Operating system – first Linux-32/64 then Win32 13

  14. DATV-Express Current Project Status • First prototype PCB built • Linux GUI, DVB-S and DVB-T code working • Basic FPGA code working • Version 2 PCB being laid out 14

  15. DATV-Express Proof-of-Progress – 1st DVB-S Transmission 15

  16. DATV-Express DVB-S 1.2 GHz spectrum 16

  17. DATV-Express QPSK constellations (with noise) 17

  18. DATV-Express DVB-S2 32APSK Constellation 18

  19. DATV-Express 6 MHz DVB-T spectrum with I/Q balance problem & filter passband ripple 19

  20. DATV-Express 1.3 GHz 7 MHz DVB-T on a PC with a Realtek USB Dongle and DVBDream 20

  21. DATV-Express What about DVB-T, DVB-S2, 8VSB etc? • “Yes, they are possible....” • “But, the team is only committed to DVB-S” • We already have experimental support for Firewire/DV video input, text overlays, testcards, FFMPEG transcoding, 1080i HD and DVB-T. 21

  22. DATV-Express What about RaspberryPi ? “Yes, it should be possible....” • Pi has hardware H.264 encoding / decoding and will have a 5 Megapixel camera soon. Has USB2 interface. No on board sound in. • Code needed on Pi to convert raw H.264 data into a valid DVB transport stream and to load FPGA code on Express board. Can probably re-use some code already written. • Need to wait for Pi foundation to write all the required hardware libraries to support camera. • Express, will have to move FEC coding to FPGA so board supports transport stream. Only space for DVB-S 22

  23. DATV-Express Conclusion and Plans • Hope to have final production PCB ready around Christmas time • Intend to provide incremental software releases during the life of the board. • Add DVB-S2 and maybe DVB-T2 • Depends on demand but maybe a matching receiver optimized for < 2 Msymbols/s?

  24. DATV-Express Useful Links: • My blog http://www.g4guo.blogspot.co.uk/ • Follow me on Twitter @G4GUO

  25. DATV-Express Thank-you all!

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