problem with HDTV antenna (100% signal, bad picture)

[cmcquistion]

I've had an HDTV card for a while (Dvico Fusion 5 Lite) and I had it working, but needed to adjust the antenna, to get better signal strength on some channels.

I took my laptop up to the attic, so I could watch the VBSignal Strength meter, running on the BTV Server (via VNC), while adjusting the antenna, to get best signal on various channels. I got everything adjusted to the point that most of the channels are coming in at 100%, some around 90%, and one channel at about 80%. The problem is, somewhere in the process of adjusting my antenna, upgrading to BTV 4.3, and adding some new video capture cards, my HDTV ability went to crap.

VBSignalMeter reports my signal strength great, but when I try to watch ANY of the HD channels, I get really choppy performance, as if I have a bad signal. This happens on all three of my BTV systems (one server and two Link machines.) All have different hardware and I don't believe that it is a playback issue, but a recording issue.

Any tips on what I can do to get my HDTV back?

*EDIT* It is looking like it ~might~ be a shared IRQ issue, so I will check that.

[cmcquistion]

Figured out the problem after lots of trial and error.

My Nvidia DualTV card was sharing an IRQ with my Nvidia video card (which also shares an IRQ with the built-in Ethernet.) This wasn't a problem for the video card, DualTV card, or ethernet. I could record shows with either the Dvico Fusion 5 Lite or the Nvidia DualTV card, but if I recorded on both, simultaneously, it messed up the recording on the Fusion 5 Lite (which wasn't sharing an IRQ with anything.) I swapped cards around, hoping to get the video card to not share IRQ's with anything. I couldn't do it, due to the number of cards in my system (one PVR-500 (which uses two IRQ's), one ATI 550, one Fusion 5 Lite, one Nvidia DualTV, and one Geforce 6200 video card.) I also have a V-Box HDTV USB capture device, which never seems to have any problems and "appears" to get much more signal strength than the Dvico Fusion 5 Lite.

Ultimately, I swapped the cards around so the Hauppauge PVR-500 was sharing one of its two IRQ's with the video card. This seemed to clear up my issues and I am able to record 7 shows (two HD, five SD) at once, without any more choppiness.

I never would have guessed that Nvidia's capture card would cause problem for a different tuner, because it was sharing an IRQ with the Nvidia video card, considering the fact that I ~can~ have a Hauppauge card sharing and IRQ with the video card and it does NOT cause problems for the other cards. I suspect that it has something to do with the IRQ sharing going haywire or something to do with PCI latency issues.