[linux-dvb] Re: ANNOUNCE: dvbtune-0.3

[Dave Chapman <dave@dchapman.com>]

On Sunday 17 March 2002 13:42, Arpi wrote:
> Hi,
> 
> > It can also dump the Service Information as an XML file and contains a 
> > utility to convert this XML file into a channels.conf file for VDR.  
Scripts
> 
> sounds interesting. what about adding automatic transpoder search/scan
> function? i'll may do it, if you're interested.
> i've started to write such app, but i stopped because i don't know how that
> service and other information stuff works, so my app just scans the freq
> range.

There are two approaches to searching a satellite for transponders.  

The first is to use the Network Information data broadcast as part of the SI. 
This partly works, but doesn't always give you the complete set of 
transponders.  The "-x" option in dvbtune does this (sort of).  You specify 
the first transponder to tune to, and then -x will recursively scan all 
transponders listed in the first transponder.

The second is to scan the frequency range.  This can work fine if you know 
the possible symbol rates you are searching for, but with the Technotrends 
cards, it is very hard to search for unknown symbol rates.  However, this 
shouldn't be a problem for satellites like Astra (19 or 28 east) and Hotbird.

However, the most reliable solution I have found is to write a short script 
that extracts the transponder frequencies from a website like 
www.lyngsat.com, and then use another script (such as the one included with 
dvbtune) to scan all those transponders for channels.  This is how I create 
my own channel lists.

Regards,

Dave.



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