> In tboltmon, the signal "strength" indications are displayed in units > called 'AMU' for which I've been unable to find a definition.
Amplitude Measurement Units? There was a discussion about this some years ago. The TBolt (and other Trimble receivers) give a user the choice of reported GPS signal level in either AMU or dBc units. Mark Sims (Heather author) collected data using both units to create a cross-reference. I've attached his data (file: 2010-Sims-TBolt-AMU-dBc.zip).
His reply from 2010 is here: > From: "Mark Sims" <hol...@hotmail.com> > To: <time-n...@febo.com> > Sent: Saturday, February 13, 2010 8:48 AM > Subject: [time-nuts] Thunderbolt AMU to dBc conversion > > The data was collected in 0.1 dB / AMU steps. There was a lot of noise > in the raw data (maybe ± 1 dB or AMU), but the general trend of the > curve was quite distinct. I smoothed it out by hand and filled in a few > (maybe 15) of the missing steps that had no signal. > > The 0.1 resolution of the raw data causes the piecewise linear steps in > the data. I was going to run a smoothing filter over it, but the curve > is pretty good as-is (especially considering how it was generated). > > Heather now uses a table lookup from 0.0 to 25.5 AMU with a linear > approximation over 25.5 AMU to convert AMU values to dBc values when > drawing the signal level map if the receiver is in AMU mode. The plots > collected in AMU mode and dBc mode are virtually indistinguishable> (within the normal variation seen between two different runs in dBc mode).
The entire thread is worth reading from the archives. [1] [2] See also table 7.3 on page 124 of: ftp://geodesy.noaa.gov/pub/abilich/papers/ABilichThesis.pdf /tvb [1] https://www.febo.com/pipermail/time-nuts/2010-February/044968.html[2] http://lists.febo.com/pipermail/time-nuts_lists.febo.com/2010-February/027397.html
<<attachment: 2010-Sims-TBolt-AMU-dBc.zip>>
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