hverkuil at xs4all
Jul 19, 2007, 9:30 AM
Post #3 of 3
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Re: WinTV PVR500 Banding / Ghosting Issues - LNA Mode?
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On Thursday 19 July 2007 16:57:38 Hans Verkuil wrote:
> > Hans Verkuil wrote:
> >>> http://bryars.eu/gallery/tvcapture/wintv150_cap
> >>> http://bryars.eu/gallery/tvcapture/wintv500_cap
> >>
> >> The PVR500 is basically just a single card with two PVR150 units
> >> on it, so from the point of view of the driver there is NO
> >> difference between a PVR150 and a PVR500. They are handled exactly
> >> the same.
> >
> > There are reports of people having problems online with these cards
> > and Hauppauge are giving people a download with a program to
> > change the tuner to "LNA mode" some alternate tuning mode, does
> > anyone know what this LNA mode is? Do the linux tuners support it?
> > I'm going to find a machine to put windows onto and install this
> > card and test it with the windows driver and the LNA utility and
> > see if it make a difference.
>
> That's specific to PVR-500 cards that have the Samsung tuner. It is
> an issue with that tuner, not with the PVR-500 vs PVR-150. Basically,
> avoid that tuner if you can, it's a crap tuner. 'LNA' stands for Low
> Noise Amplifier which is a circuit on the tuner used to amplify
> channels with a low signal. By default that circuit is on, but for
> channels with a strong signal you have to turn it off manually, which
> is what that tool is for. Yuck.
>
> >> What does make a difference is that the PVR500 splits the antenna
> >> signal internally and so requires a better quality signal. The
> >> other difference is that the your PVR500 has a different tuner,
> >> but the Philips tuner is generally quite good (avoid PVR500's with
> >> a Samsung tuner, BTW).
> >
> > Well, This banding occurs on a good quality signal too, even on a
> > 30cm bit of coax from an RF Modulator on a Satellite receiver. I
> > put an attenuator in line and it just made the picture fuzzier and
> > still have banding. I have ordered another card to test to see if
> > the one I have is just broken.
>
> Hmm, I don't have a PVR500 handy to test myself, but I don't think
> I've seen banding like that. I can check later to see if the Philips
> tuner is properly setup (I think I have the datasheet for that
> tuner).
>
> > Have hauppauge changed to using the Philips instead of the Samsung,
> > vica versa, different ones in different areas for PAL/NTSC or just
> > whatever is cheapest on the day they order a batch to be
> > manufactured?
>
> They seem to change tuners several times a year, most TV card
> suppliers do.
>
> >> You could try to capture from the composite or S-Video input, this
> >> bypasses the tuner circuitry and should give completely identical
> >> results for the PVR150 and PVR500.
> >
> > Pretty much, yes, arguably marginally better on the 150 still, but
> > not enough different that I could say this with certainty, and
> > certainly no extreme banding like I see when RF Tuned.
>
> OK, so the problem is in the tuner or antenna signal quality. Good to
> know.
>
> I'll do some more checks later today.
I checked the datasheet and the tuner settings look good. However, I did
see one note suggesting alternate values for cable TV. Try the attached
patch against the drivers/media/video/tuner-types.c file in the kernel
sources. I've no idea if that helps, let me know what happens.
Regards,
Hans
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tuner-types.c.diff
