G4GUO has also been moving forward towards adding DVB-S2 protocol to the Windows software for the DATV-Express board. To this goal he has ported his Linux DVB-S2 implementation over to Windows. The actual implementation is a C++ class and runs almost entirely on the host. This means DVB-S2 uses more CPU resources than the DVB-S implementation does. As Charles explains, the DVB-S2 protocol is just too large to fit inside the FPGA coding (as the DVB-S coding does) so it has to run on the Windows PC.
Prototype of Users Interface for running DVB-S2 protocol on Windows.
The incentive to port the DATV-Express linux coding for DVB-S2 over to Windows is that the recent AMSAT-UK conference announced that the DVB-S2 would take a starring role in the new Es'hailSat-2 geostationary satellite to be launched in 2017-Quarter-3. Dave G8GKQ explained with the graph below that DVB-S2 protocol is more robust and can provide better signal-to-noise (called CN - aka carrier-to-noise) ratio reception in weak signal environments. The biggest DVB-S2 problem for hams today is that commercial receivers for DVB-S2 protocol do NOT receive Symbol-Rates below 1 MSymb/sec. The good news is that hams are looking at solving this RX low-Symbol-Rate limitation.
This graph shows that DVB-S2 protocol is more robust compared to DVB-S protocol by at least 5 dB
(courtesy of Dave G8GKQ)
Ken W6HHC had some time to play with the free vMix Basic software companion-product for the Express_DVB-S_Transmitter on Windows. The nice new feature is that vMix can be set to use a JPEG file as a video source for a “test pattern” or a beacon-like photo. See the screen-capture below using Ken’s favorite “test pattern JPEG” in the upper-right corner. (No more Imprex hardware box is needed any more for my “test pattern generation” from JPEGs!!). The final vMix feature Ken confirmed is he can configure vMix to perform a slide-show function from a group of JPEG files.
An example of running vMix Basic video software with one camera and one “Test Pattern” JPEG
Ken also finished the “production release” version of the Users Guide for Windows (draft09). This latest draft (based on the v1.11 software) clarified some of the details for GOP used in video compression encoders, thanks to the notes and suggestions provided by Noel G8GTZ. The latest Users Guide for Windows PDF can be downloaded from the project web site at http://WWW.DATV-Express.com using the DOWNLOADS page.
Finally, Charles G4GUO has been asked to create a video to go with his CAT16 talk at the end of September and that is going to be time consuming no doubt.
"Project speed set to slow" ...de Ken W6HHC