1. Digital Video TV Modulator project
DigiLiteZL
Digital Video TV
Modulator project
Mark Atherton, ZL3JVX, New Zealand

2. Mark Atherton, ZL3JVX, New Zealand
Why ?
Amateur TV may need to go digital by 2012
Educational platform
Completely open source project
General purpose Digital TV development platform
Possibility of building a PC-less DATV repeater
Mark Atherton, ZL3JVX, New Zealand

3. Mark Atherton, ZL3JVX, New Zealand
How ?
Building on Digilite (UK) project
FPGA rather than dsPIC based
DigiLite compatible
Team effort
First attempt managing an open source project
FPGA designer works for Google
RF guy works for Tait
As Charles says ‘you get to order the pizza and sweep the floor’
Mark Atherton, ZL3JVX, New Zealand

4. Mark Atherton, ZL3JVX, New Zealand
Status
2 units built and completely working based on DigiLite (UK)
1 partial kit sent to FPGA designer in US
BOM up to date
Schematic marked up
Verilog of modulator nearly ready for simulation
Web site up
1100+ hits
Want comments about alternate configurations
Other possible uses
Mark Atherton, ZL3JVX, New Zealand

5. Mark Atherton, ZL3JVX, New Zealand
What is Digital TV ?
A mix of video, audio and data
Majority of Video coding uses MPEG2
Majority of Audio coding uses MPEG2 or Dolby Digital
Different modulation for Terrestrial, Cable and Satellite
US and Europe use different terrestrial modulation
Satellite modulation mainly used by Hams, even for terrestrial
Broadcast Digital Video is just a continuous stream of data
Data rate is in the region of 4-45Mb/s
Modulator depends on the medium
Mark Atherton, ZL3JVX, New Zealand

6. What does a broadcast stream contain ?
One or more program(s)
Each program generally contains one or more audio channel
“Radio” channels are audio only
Each program generally contains zero or more video channels
System Information (SI) tables that provide context
Possibly also Electronic Programme Guide (EPG) tables
Mark Atherton, ZL3JVX, New Zealand

7. Mark Atherton, ZL3JVX, New Zealand
Video processing
Acquire analogue video, convert to baseband digital, ~270Mb/s
Compress using MPEG2 encoder, 2-10Mb/s
Wrap in packets of 188 bytes, add packet identifier (VPID)
Now called a Video Packetized Elementary Stream (VPES)
Mark Atherton, ZL3JVX, New Zealand

8. Mark Atherton, ZL3JVX, New Zealand
Audio processing
Acquire analogue audio, convert to baseband digital, ~1.5Mb/s
Compress, using audio encoder, around 200kb/s
Wrap in packets of 188 bytes, add packet identifier (APID)
Now called the Audio Packetized Elementary Stream (APES)
Mark Atherton, ZL3JVX, New Zealand

9. Mark Atherton, ZL3JVX, New Zealand
System Information
188 byte metadata (tables) giving context to the complete stream
Program Association Table (PAT)
Always located at PID 0
Number of programs present in the stream, and where
List of PMTs
Program Map Table (PMT)
Binding audio and video into programs
Electronic Programme Guides
What’s-on-next etc.
Mark Atherton, ZL3JVX, New Zealand

10. Mark Atherton, ZL3JVX, New Zealand
System Multiplex
A mix of video, audio and SI tables
Padded to required data rate using null packets
Resulting data is called a “Transport Stream”
Mark Atherton, ZL3JVX, New Zealand

11. Mark Atherton, ZL3JVX, New Zealand
DigiLite (UK)
Low cost satellite modulator project from the UK
Requires closed source pre-processed TS
Closed source dsPIC
External LO
USB 2.0 data interface
Digital power from PC (via USB)
Mark Atherton, ZL3JVX, New Zealand

12. Mark Atherton, ZL3JVX, New Zealand
DigiLiteZL - 1
On board, or external LO
Direct interface to DE0-nano FPGA board
Plug in baseband IQ filters
USB 2.0 data interface
Digital power from PC (via USB)
PICKIT2 programming header for dsPIC
Single ext 5V analog supply
Low cost Digital TV development platform
(very) extensible, replaces dsPIC with FPGA
Many other possible data sources
Ethernet
ASI
Mark Atherton, ZL3JVX, New Zealand

13. Mark Atherton, ZL3JVX, New Zealand
DigiLiteZL - 2
Where to go from here
PC-less standalone repeater
Video source from modified consumer DVR
User interface using soft processor
UDP over Ethernet
Needs 100 base T
Mark Atherton, ZL3JVX, New Zealand

14. Mark Atherton, ZL3JVX, New Zealand
DigiLiteZL - 3
Mark Atherton, ZL3JVX, New Zealand