[linux-dvb] [RFC] SNR units in tuners

Richard Scobie r.scobie at clear.net.nz
Sat Oct 18 20:56:11 CEST 2008

Devin Heitmueller wrote:

> At this point the goal is to understand what the value means for
> different demods.  For the simple cases where the answer is "it's the
> SNR in 0.1db as provided by register X", then it's easy.  If it's "I
> don't really know and I just guessed based on empirical testing, then
> that is useful information too.

According to the datasheet, the carrier to noise ratio for the BSRU6 
front end, (which contains an stv0299), can be calculated in dB using 
the following information:

Register ADD 24 NIRH 8 bits (MSB of noise indicator)

Register ADD 25 NIRL 8 bits (LSB of noise indicator)

C/N (dB) = -0.0017 * NIR + 19.02



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