The blank PCBs are arranged as 2x2 arrays. The photo below shows the robot arm spinning to the right location in order to lower the SMT component onto the correct footprint...and the board array underneath shifts so that the arm can reach all four boards.
Pick-and-place robots place components down onto a panel of four DATV-Express boards
A short MPEG4 video of the pick-and-place robot in action can be found at:
http://www.W6ZE.org/DATV/
One of the changes that Tom WB6P implemented with this latest etch-update of the board was to flood the ground etch around modulator chip U4 and the SMA RF connector and the upper-right-hand mounting hole. The etch-flood exists on the top layer, ground layer, and bottom layer in order to carry heat away from the modulator. Plenty of heat-conducting-vias were added by Tom to connect all of these layers together. Art ran some temperature tests and reported the top of the modulator has a temperature-rise that is 7C degrees cooler than the earlier etch with no heatsink and no fan.
New Rev E etch produces a U4 temperature rise of 38.9 C (no heatsink)
Older Rev D etch produces a U4 temperature rise of 46.0 C
The new Board Layout (Rev E) used in the Pre-production Design
Further testing by Charles G4GUO and analysis by Jean-Pierre F6DZP (using the Tutioune analyzer) resulted in being able to determine that problems with PCR timing fluctuations were a direct result of the poor clocking inside Hauppauge video-capture unit. A google search was able to confirm that the Conexant chip used inside the Hauppauge units resulted in a 27 MHz clock that jittered and/or skipped enough to produce a PCR that was rejected by most of Art’s STB units. As explained last month, all of the other seven STBs and receivers used by the project team work OK with the Hauppauge-originated PCR timing. Charles implemented a massive software timing design change for the PCR time-stamp where the PC starts with the Hauppauge clock, but then recalculates the time stamp based on the PC timing. Charles came out with the “proof-of-concept” v1.07 software build allowing the PCR timestamps with our own calculated clock as suggested by other internet-found work-arounds. Now all of Art’s STB units and his Tutioune-S2-1600 analyzer can receive DVB-S video and audio OK.
Ken W6HHC spent most of the month working on drafts of a User’s Manual for the DATV-Express hardware and software. The draft of the manual is now up to 17 pages. Tom WB6P just received his first DATV-Express board and now will be the alpha-tester for the User’s Manual.
Charles also presented a short slide presentation (remote from home by Skype) on the DATV-Express for the for the BATC CAT13 convention at Finningley. Charles also explained that the project team expects to have the boards available for general sale in January, however the software is not quite ready, and hence the delay. As mentioned earlier, Charles is looking for programmers willing to help with the software. Contact G4GUO directly at G4GUO@ARRL.net if you are willing to help.
All questions are welcome.
“Full speed ahead”...de Ken W6HHC