[linux-dvb] Re: tda10045 frontend tuning-issues?

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

From: "Andreas Witte" <Andreaz@t-online.de>
> Just a question. Are tuning speed/problems a common problem with that
> frontend? I use a technotrend and an avermedia 771 dvb-t card in my
> PC and realized that the tda10045 is much more slower/unsurer in tuning
> that the mt352.
>
> Is that known? Im using both cards with a room antenna. The aver is
> tunign fine in somewhat 300ms. The technotrend sometimes takes forever
> to get a lock and nothing happens. This is frustrating, since ive no
> idea where i can look for any error and that this "feature" isnt anyhow
> reproducable. Somtimes it gets a lock real fast, sometimes it takes a
> bit, sometimes he didnt get a lock.

While I'm not using the Linux driver, I _do_ see that the TDA10045H takes
quite a while to lock, ~650ms on 8MHz channels and ~750ms on 7MHz channels.
I suspect this is due to the 8K transmission mode used here, because if the
TDA10045H looks at a fixed number of OFDM symbols to determine lock, that
number will be 4 times as high with 8K mode vs 2K mode. I.e. if the
TDA10045H was optimized for 2K mode (as used in the UK), it will lock fast
there, but very slow here with 8K mode.

I suppose Philips could fix this with a DSP firmware update, but it seems
Philips considers the TDA10045H obsolete already and there will be no
further updates :(

However, I haven't noticed the "takes forever to get a lock" issue here.
Incidentally, I happen to have that with a different receiver card, but
never with the Philips card, this one locks quite reliably for me, albeit
slowly.

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