Art WA8RMC had an extremely busy month on the project. He ordered 100 blank PCB’s from Sunstone for the pre-production run of boards. Art also placed the order for the solder-paste stencil/mask. This will allow the robots to later assemble the PCBA board without hand-soldering. But Art was having extreme frustration receiving video and audio at his QTH. Now Charles G4GUO has 6 different STB/receivers that all worked perfectly. Ken W6HHC has one STB that received video perfectly. At that point, using v1.04 DATV-Express software, the best that Art could report was “full QUALITY and blank screens” on three STBs…and an occasional flash of video and “raspy audio” on the fourth STB.
Charles G4GUO tapped into the experience the DigiLite team and Brian G4EWJ explained that one short-cut taken by DATV-Express software to NOT implement the PCR (Program Clock Ref) field in the Transport Stream (TS) would cause problems. The PCR field was implemented in v1.05….but the results on Art’s STBs did not improve?!? Art has Tutioune software with a S2-1600 receiver card as developed by Jean Pierre F6DZP. Art’s screen shots of Tutioune analysis tool revealed some irregularities. Charles sent a TS file to Jean Pierre F6DZP and to Rod G6TTD/KG6TTD (TSreader for MPEG-2) to get feedback utilizing their experience. Jean Pierre explained that the audio bitrate was not correct. Charles could now see that the audio bitrate was being calculated incorrectly, fixed the audio bitrate calcs and sent a new v1.06 of the software to Art. Now Art can receive video and audio on one of the four STBs. Charles is suspicious that the PID setting may not still correct between Art’s DATV-Express board and the STBs that refuse to work correctly. (Oh the joys of testing prototype designs ….hi hi)
Charles G4GUO was able to compile the DATV-Express software onto Raspberry-Pi and transmit a 1 MSymb/sec DVB-S signal. Raspberry-Pi does not have a lot of computing power…so 1 MSymbol/sec is the maximum on the Raspberry-Pi until Charles ports more PC functionality into the board FPGA. Next Charles compiled DATV-Express software on a Sabre Lite board from Element14 (Freescale i.MX6 Quadcore) and could successfully transmit DVB-S signal at 4 MSymbols/sec FEC=7/8.
Ken W6HHC continued to test new software releases to make sure that nothing became broken at his testing lab. G4GUO had implemented a TS file recording switch into v1.05, so it was “cool” for Ken to be able to capture his TS stream and then play it back or send it off for someone else to view. Charles pointed the team to a useful (and free) TS analysis tool called DVBinspector. The DVBinspector provides lots of info about TS stream details...like measured data-bit rates, and PIDs being used, etc.
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The DVBinspector tool can display bit rates of audio packets and video packets in the Transport Stream
The blank PCB boards should arrive soon. Everything appears to be on schedule to receive and test the pre-production assembled boards in October (maybe ten or twenty boards). The team is continuing the investigation of Art’s “no video displayed” problems
“full speed ahead”…de Ken W6HHC