[linux-dvb] Re: New UK DVB-T channels testing

[Mike Grant <mgg@ecs.soton.ac.uk>]

Justin Cormack wrote:
> ok, have more or less worked out how to do this. The only thing is what
> frequency these channels are on. I cant work out how to convert from channel
> number to frequency for the uk...

 From http://www.linuxstb.org/dvb-t/index.shtml:

centre frequency = (UHF Channel Number)*8 + 306

This gives you a frequency in MHz.  VDR uses kHz (MHz * 1000) and 
dvbstream, etc use Hz (MHz * 1000000) so you'll need to pad it out to 
the correct length.

Also note that most channels have an offset from the centre frequency, 
which must also be added.  You can find these offsets by looking at your 
local transmitter info on:

http://www.itc.org.uk/uk_television_sector/reception_advice/digital_trans_guide/index.asp?region=show_all

For example, the Rowridge transmitter has multiplex 1 on channel 23, 
offset -167kHz (listed as '-') and multiplex B on channel 32, offset 
+167kHz (listed as '+').  No offset is listed as '0'.  So,

multiplex 1 freq in kHz = (23 * 8 + 306) * 1000 - 167 = 489833 kHz
multiplex B freq in kHz = (32 * 8 + 306) * 1000 + 167 = 562167 kHz

When converting these to Hz, I tend to assume the ITC meant 166.666..kHz 
rather than 167kHz so I get 489833334Hz and 562166667Hz instead of 
489833000Hz and 562167000Hz.  I don't think that it matters though..

Have fun,

Mike Grant.



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