[linux-dvb] Re: Signal Strength (was: private channels on Telekom cable)

[John McCormac <jmcc@hackwatch.com>]

On Thu, 20 Sep 2001, Markus Erhardt wrote:

> > Don't underestimate this digital technology. DVB-s can be received
> > 100% error free even if the signal power is so small that no analog
> > reception would be possible.
> 
> is this true? I've got a WinTV Nova and used the Windows-Software to test

Very unlikely. If the signal is bad then there will be data corruption as
well. Error correction can only help so much but if the signal is too bad
then there will be errors. On digital video this causes blocking and
freezing of the picture. 

The % reading on the Windows software is not really that reliable.
On the Hauppauge software, there is an estimated S:N value in dB. This is
perhaps a more reliable estimate of the signal level. Most analgoue
recievers start to develop interference on the picture (sparklies) as the
level approaches 7 dB. An S/N of 12 dB used to be considered broadcast
quality. On a small (60 cm dish with a universal LNB) I have (50-64%) over
most channels on Astra. I should probably be using a larger dish though as
I would not say that there is enough of a margin for losses due to rain
fade.

Regards...jmcc



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