[ On Monday, September 3, 2001 at 19:32:47 (-0300), Jared D. McNeill wrote: ]
> Subject: Re: Hauppauge WinCast/TV cards
>
> I seem to be getting a very bad picture on some of the lower channels --
> what could be causing this? It wasn't this bad when plugged into my
> television set, and it seems the higher the channel number, the clearer
> the picture. Channel 2 is almost unviewable -- channels 29 and up are very
> clear.

That's kinda weird.  In North America the CATV channels are in a kind of
strange order due to the requirement for 2-13 to match the broadcast
frequencies (for users of now ancient sets).

2-6 are at the bottom of the band; 95-99 and 14-22 are between 6 and 7
(in that order); 7-13 are next and 23-158 go up from there.

There's nothing special about 29 and up other than they are certainly
well above the traditional broadcast TV frequencies (29 starts at
253.2625 MHz).

UHF broadcast doesn't start until 471.2500 MHz, which is just above 65
CATV, and the UHF carrier frequencies do not match any CATV carriers so
far as I know (though sometimes they're not offset enough for older
tuners to avoid ghosting and other crap if you're right near a
high-power UHF xmitter).

Now interestingly the audio for channel 6 (and CATV 95-97) are in the FM
broadcast band and sometimes you can tune in to the TV sound on your FM
radio....  Oddly my little Grundig G2000A can't pick up anything on
87.75, the frequency for channel 6, though I thought there was still a
channel 6 transmitter locally....

I'm betting though that the RF front-end on that card is nothing
spectacular from a design and construction perspective....  There may
even be incomplete or improper shielding to keep the digital signals and
their harmonics from interfering and there's certain to be lots of noise
anyhwere between 25MHz and 250MHz on the inside of any modern PC (and
probably lots of strong harmonics above that...).

-- 
							Greg A. Woods

+1 416 218-0098      VE3TCP      <gwoods@acm.org>     <woods@robohack.ca>
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