ARLA/CLUSTER: Projetos para a implementação da Televisão Digital de Amador

[João Gonçalves Costa]

DATV-Express Project - March update report

Charles Brain G4GUO has completed a new YouTube video to describe the Digital Amateur Television Version 2 PCBA

Art WA8RMC finished performing the basic electrical tests with the "testing software" on the new "first-article" prototype PCBA and found everything working as planned. Art was successful in producing 18.6 dBm of output on 1.3 GHz in early March... and then sent the board to Charles G4GUO to begin more thorough testing and to begin making some software changes.

Charles had the new board transmitting DVB-S and DVB-S2 video within a couple of hours after Parcelforce delivered the box to his QTH. Charles's first reports included:
* Min operating frequency 72.5 MHz
* Max operating frequency 2.48 GHz
* Noise sidebands -55db (about 30db better than previous board)
* Very clean QPSK constellation

I have added three new photos using the new v2 board to the PHOTOS area of this Yahoo Group, in the "DATV-Express Project" album. the photos show first DVB-S video received, the clean QPSK constellation achieved with new etch and a spectrum view of the new board.

During March, Charles was able to accomplish quite a lot of improvements to the DATV-Express software design, as he has summarized below:
Host code
* Now being compiled under Ubuntu 12.04 LTS
* Development environment has been updated to Qt5.01 Creator

FX2 code
Added proper support for USB2 VBUS monitoring

FPGA code
* Interpolation increased from x4 to x8
* Pulse shaping filter increased to 95 taps (root raised cosine compensated response).
* Programmable symbol rate generator added with the current range 2 MS/sec to 6 MS/sec in fractional steps.
* I2C configuration of modulation parameters has been added
* Delayed IQWRT clock added.
* DAC has so far been tested up to 48 Msamples/sec

No etch errors have been found in the second layout, so huge compliments are deserved by our PCB layout guru, Tom WB6P. Art WA8RMC is busy building up a second prototype board. Charles also has plans to get the entire DVB-S protocol to run on the FPGA rather than on the Linux host PC. That way...the whole host thing can also be run on a small ARM-based computer, like a Raspberry Pi or perhaps the MK808.

"full speed ahead"...de Ken W6HHC

Watch DATV-Express Version 2 PCBA
http://www.youtube.com/embed/OXh-anABYaU?rel=0


Digital Amateur TV Yahoo Group
http://groups.yahoo.com/group/DigitalATV
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