[linux-dvb] Re: scanning

[Johannes Stezenbach <js@convergence.de>]

Robert Schlabbach wrote:
> From: "D. Ratner" <dr_spam_free@yahoo.com>
> > is there a utility out there that if given a
> > frequency, it will scan for any usable data?
> >
> > In otherwords will check all polarities and symbol
> > rates etc for data.
> 
> All symbol rates? Let's see: The STV0299B has 20 bits for the symbol rate
> setting, that's 1,048,576 possible symbol rates. Even if you spend only
> 10ms checking each symbol rate, it'll take 3 hours to scan all symbol
> rates. Add polarity and it'll be 6 hours. Add the 5 possible Viterbi FEC
> rates and it'll take over a day...
> 
> Also, for low symbol rates, you'll have to wait much longer for a signal
> lock, it can sometimes take several seconds to lock. If you wait 10 seconds
> on each possible combination of symbol rate, polarization and FEC rate,
> you'll spend over a thousand days, i.e. over three years scanning just a
> single frequency.

The Zarlink MT312 claims to support fast scanning for symbolrates.
http://products.zarlink.com/product_profiles/MT312.htm

Johannes


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