Topband: Skimmer calibration

Markku Oksanen ww1c at outlook.com
Tue Sep 2 02:34:36 EDT 2014




ALL
I have tested RBN / skimmer raw data and Excel with preprocessing with CSVed to confirm station performance after many major CW contests I have been in.
In order to see how a station covers a certain target area, I typically take one hour timeslots, one country or in the case us US, one zone to select the RBN listeners and then calculate the averages and variance of RBN measurements.  Typically you I try to find some 50-100 measurements / TX station / hour for comparisons. In  The outcome is averages varying between 10 to 30 dB and a variance of about 10 dB which is really quite a big number.  This variance contains all the differences between RBN listerner station antennas, propagation, QSB etc.,  however the general grouping of stations to "high performance" (OH8X, OH2BH, OH4A), "good" and "normal" holds quite well if you know what antennas stations have at this end. A high stack is a high stack, always.
Although it has been tempting to do, to me it seems to be statistically impossible to confirm much smaller than 3-5 dB difference between stations using this method.  This is if you know the variance, number of measurements and the difference between averages of measurements and perform a student's p-test to  confirm if the averages are really different or not.   The rough groupings hold really well though, difference between normal and high performance stations holds.  And I can see where my own signal sits in these groupings.
MarkkuWW1C/OG2A/OH2RA







 		 	   		  


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