[time-nuts] Thunderbolt AMU to dBc conversion

Arnold Tibus Arnold.Tibus at gmx.de
Sun Feb 14 01:07:05 UTC 2010


Magnus, 

completing my pevious remarks, 
I found a better match with the following formula:

C/N0(dBHz) = 19 log(AMU) + 25 

It does look perhaps a bit odd to use '19' instead '20' but together 
with the offset of 25 it inclines a bit the curve to fit well for 
AMU 2 to AMU 15. If ever a real precise value will be possible - I doupt it. 
Perhaps the Thunderbolts do have small differences in conversion 
factors? 
Can wet expect high precision here as it is not a measurement device 
for reception levels?

Arnold


On Sun, 14 Feb 2010 00:50:57 +0100, Magnus Danielson wrote:

>Arnold,

>Arnold Tibus wrote:
>> Magnus & Mark,
>> 
>> for my Thunderbolt system I found a very good correlation 
>> between AMU and dBc/ Hz ( observed on my system using 
>> the ThunderboltMonitor watching over long time stable satellite signals )
>> when I use the Formula: C/N0(dBHz) = 20 log(AMU) + 23.5.

>It would work well, but for lower AMU values (in particular 0) it would 
>not work so well. Something like the above was my initial assumption. 
>The availability of AMU=0.0 for a 20 dBc/Hz signal suggests a little 
>more happens.

>Cheers,
>Magnus








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