BATC Forum

Sorta taken an interest in DATV, so new to it, so not too flames please.

I can get RF out in substantial quantities on 70, 23, 13 cms and moderate levels on 6,&3 cms
For an upconverter on 70 cms , I can mix with the 1152 MHz LO for 23 cms, and then fed it to a SAT Rx I bought yesterday.

The Tx side I just need to modify one of the Dolphin boards to utilise qradrature mixer and use it to get about 25~30 W out.
( I've heard a few people describe these boards as 100W , they are not, the vias in the output stage are too small and would burn easily)
I'd be interested in any work that's been done so far so as to save time.

I've been looking at the poor man's DATV, and wondering if there is an alternative way of getting a data stream out in quadrature, Id prefer a I&Q stream as it avoids putting filters after mixers, The Hauppauge PVR is not cheap at the moment, and a bit of an over kill for what is needed.

Has there been any work with getting a data stream out of an ethernet port , which would require multiplexing and demux at the other end, or even better out of the parallel port on the PC, the later would require no multiplexing, I think.

I'm open to any advice at the moment

thanks


Richard G8JVM

g8jvm wrote: The Hauppauge PVR is not cheap at the moment

You can pick them up used for around £12 on eBay if you are patient.

Mpeg compression is quite computationally expensive so doing it in
hardware takes quite a load off the P.C.

- Charles G4GUO

Thanks for that Charles, I'll wait patiently, that's not normal for me,

I've reread the poor mans stuff several times now, and I'm think the first couple of times I misunderstood it.
I was thinking the reason for using the PVR was to get a mpeg2 stream out of it, but it seem it is only to encode incoming video.
If I was running windows, I could see the point of getting as much processing away from the PC as possible.
However, running linux on an AMD dual core processor I can compile two hefty bits of software without crippling it to much, and watch TV at the same time from the on board card.

So it should be able to handle it. Reading Robs page again I see PVR-150 PCI. Like a prat I've googled on PVR-150 and all that come up is Happauge's new HD external box, that is expensive. £150 + not £50 for what I should be looking for.
I'll start looking for the correct thing now.
I also need to source the hardware as well.

thanks
73 Richard

The trick is to have a look at a real PVR-150 card (on eBay or Google) the Conexant
Encoder chip is quite distinctive. Then look for video capture cards on eBay that
have the same chip. I bought a PVR-500 (dual channel) OEM card, the
seller didn't know what it was for £15. Just don't pay too much. There is a lot of
support using v4l for these cards. People are throwing them out because
the TV part does not receive Freeview

Video playback requires much less processing than encoding does. You still
have to capture the video before you compress it of course.

Your PC is going to have to do Reed Solomon and Convolutional FEC encoding as
well. My Dual core laptop uses about 55% CPU to transmit 4 MS/S but I am
doing more of the processing in the PC than the system you are looking at does.
For the laptop I use a USB PVR (again bought used) it appears as /dev/video0.

- Charles