[linux-dvb] Re: CX22702 conexant/leadtek support

["Robert Schlabbach" <robert_s@gmx.net>]

From: "Christopher Pascoe" <c.pascoe@itee.uq.edu.au>
> The notes I acquired from LG on their tuner indicated that the IF saw
> filter was to be activated only on the UHF band, and only in Germany.
> If Germany only uses UHF for DVB-T then this change makes sense and
> I'll update this to activate it on 8MHz bandwidth and UHF.
> Is there a logical reason why one would only want to activate said
> filter on a 8MHz transponder but only on UHF (and not VHF) and only
> in one particular country?  Is there some kind of co-channel
> interference that it helps with in this particular environment?

Here in Germany, DVB-T is broadcast both on VHF and UHF, but on VHF with
7MHz bandwidth and on UHF with 8MHz bandwidth. For the hardware I've seen,
this meant that the SAW filter in the tuner needed to be switched to 7MHz
for VHF (<300MHz) frequencies and to 8MHz for UHF (>300MHz) frequencies.

This should work all across Europe, as most countries only use 8MHz UHF
channels anyway, which doesn't interfere with a driver that switches to
7MHz for VHF channels. Italy and Slovenia supposedly use 7MHz VHF as well,
although Italy is supposedly planning to switch their VHF channels from
7MHz to 8MHz at some point in the future, but for now they're using 7MHz
VHF as well.

I have no idea what LG's note was about, though.

Regards,
--
Robert Schlabbach
e-mail: robert_s@gmx.net
Berlin, Germany