Revised Signal Strength Calculations

Posted by James Watson on 07 Jun, 2018

I've made a change to the way that the Signal Strength is calculated. Previous versions of Proppy derived Signal Strength from the monthly median field strength (dB(1uV/m)) Es, El or Ei (depending on distance) produced by ITURHFProp. This takes into account the characteristics of the transmitter site (antenna gain power etc.) but does not consider the receive site characteristics as 'E' represents the field strength at the receive site's geographic location. This approach is normally favoured by broadcasting coverage planners. However, in smaller networks using equipment in which assumptions regarding the type of antenna used at the receiving site, it is probably more useful to derive the Signal Strength from the Median received power, 'Pr' (dBW). The conversion to S-Meter units is made in accordance with IARU Region 1 Technical Recommendation R.1, defining S9 for the HF bands to represent a receiver input power of -73dBm (-103dBW).

This change means that the receive antenna is now included in the calculation of Signal Strength which I feel will be more useful to users when planning links. The update also includes few very minor bug-fixes and a back-end code tidy up which may improve the site's operation.


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