2012 BATC CONVENTION

DATV-Express

by • Charles Brain [email protected]

G4GUO

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

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

DATV-Express

It all started when I bought a USRP2

4

DATV-Express

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

5

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

DATV-Express

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

7

DATV-Express

First prototype

8

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

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

DATV-Express

GUI Screen-shot (current)

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

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

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

DATV-Express

Proof-of-Progress – 1st DVB-S Transmission

15

DATV-Express

DVB-S 1.2 GHz spectrum

16

DATV-Express

QPSK constellations (

with noise) 17

DATV-Express

DVB-S2 32APSK Constellation

18

DATV-Express

6 MHz DVB-T spectrum with I/Q

balance problem & filter passband ripple 19

DATV-Express

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

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

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

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?

DATV-Express

Useful Links:

 My blog http://www.g4guo.blogspot.co.uk/  Follow me on Twitter @G4GUO

DATV-Express

Thank-you all!