Poor Short-Sighted Man’s DATV system for Windows
Posted: Sun Nov 07, 2010 5:51 pm
Building on the excellent work of F4DAY, Rob M0DTS and others, I’ve been working on a variation of the system, which produces live video using Windows. With help from several of this parish, this is now undergoing field trials.
The system uses a free PVR program http://www.gbpvr.com and the Hauppauge PVRx50 / USB range of video capture devices.
I’ve written a single Windows program which reads data from the end of the file produced by GBPVR and converts it into a transport stream which it sends over the USB port to the serialiser. It uses much less cpu time than the current Linux setup. At 4MS/s, it takes about 3% of cpu time on my 2.3GHz Core2 Duo. Rob has run it at 4MS/s on his 700MHz laptop where it takes 14% of cpu time. It has been written to be able to multiplex several program inputs together, although that needs more work and is not currently available.
It works with the current serialiser as used by Rob, which has fixed 1/2 FEC processing. I’ve built a new, faster serialiser using an FT2232H module, which can do all the FECs, although the Windows program can do all the FECs itself. I think it should be possible to get it up to 8MS/s. I’m running at 5MS/s at the moment as I don’t have Nyquist filters to go any higher. It uses 2 chips plus the FT2232H USB module, on a single-sided PCB. The FIFO is 13kB. There’s a configuration utility to set up the symbol rate, FEC, PIDs and programme info.
The Short-Sighted reference is because I’ve tried to use through-hole components as much as possible. The new serialiser is through-hole, apart from an SD card socket which is an SMD, although not too difficult at 2mm pin spacing. Pre-processed transport stream files can be played off the SD card. This isn’t working on the new MK2 serialiser as yet. The new MK1 serialiser was SD card only with no PC connection and I have yet to move the SD card functionality to the MK2.
I estimate that the serialiser will cost about £40-45 to build. The FT2232H module makes it expensive, but I can hardly see the pins on the FT2232H chip, never mind solder them.
I’ve built a modulator based on the RF2480 chip which is 1.27mm pin spacing. It needs more work and as I’m much happier with digital rather than analogue, I’m hoping I can persuade someone to take that on.
If anyone would like to help with the testing and try the Windows software with their PMDATV hardware, please let me know. If you can make your own PCBS, I can give you the artwork for the new serialiser. Rob has kindly agreed to host all the details on his web site. Hardware and software files will appear there in time. In the meantime, please contact me directly here or via my callsign at mem dot batc dot org dot uk.
Brian
The system uses a free PVR program http://www.gbpvr.com and the Hauppauge PVRx50 / USB range of video capture devices.
I’ve written a single Windows program which reads data from the end of the file produced by GBPVR and converts it into a transport stream which it sends over the USB port to the serialiser. It uses much less cpu time than the current Linux setup. At 4MS/s, it takes about 3% of cpu time on my 2.3GHz Core2 Duo. Rob has run it at 4MS/s on his 700MHz laptop where it takes 14% of cpu time. It has been written to be able to multiplex several program inputs together, although that needs more work and is not currently available.
It works with the current serialiser as used by Rob, which has fixed 1/2 FEC processing. I’ve built a new, faster serialiser using an FT2232H module, which can do all the FECs, although the Windows program can do all the FECs itself. I think it should be possible to get it up to 8MS/s. I’m running at 5MS/s at the moment as I don’t have Nyquist filters to go any higher. It uses 2 chips plus the FT2232H USB module, on a single-sided PCB. The FIFO is 13kB. There’s a configuration utility to set up the symbol rate, FEC, PIDs and programme info.
The Short-Sighted reference is because I’ve tried to use through-hole components as much as possible. The new serialiser is through-hole, apart from an SD card socket which is an SMD, although not too difficult at 2mm pin spacing. Pre-processed transport stream files can be played off the SD card. This isn’t working on the new MK2 serialiser as yet. The new MK1 serialiser was SD card only with no PC connection and I have yet to move the SD card functionality to the MK2.
I estimate that the serialiser will cost about £40-45 to build. The FT2232H module makes it expensive, but I can hardly see the pins on the FT2232H chip, never mind solder them.
I’ve built a modulator based on the RF2480 chip which is 1.27mm pin spacing. It needs more work and as I’m much happier with digital rather than analogue, I’m hoping I can persuade someone to take that on.
If anyone would like to help with the testing and try the Windows software with their PMDATV hardware, please let me know. If you can make your own PCBS, I can give you the artwork for the new serialiser. Rob has kindly agreed to host all the details on his web site. Hardware and software files will appear there in time. In the meantime, please contact me directly here or via my callsign at mem dot batc dot org dot uk.
Brian
