[aprssig] PHG to hard use, RNG was: UI-View Bashing

Andre PE1RDW aprs at pe1rdw.demon.nl
Thu Oct 13 16:34:26 CDT 2005

Wes Johnston schreef:

>PHGR is 4 digits, 7 digits if you count the letters PHG before the
>numbers.  Pete pointed out that many folks have to tweek their PHGs to
>make the circle match the real world coverage... and some users don't
>understand we are talking about HAAT and not negative depth relative to
>MSL (hihi).
>So why don't we kill all these birds with one stone...  why don't we
>list PHG as a range in nautical miles?  I can represent 999 miles in
>three digits.  We'd need to also include a direction and let's say, a
>percentage offset for the circle.  As an example...
>R15999  (broken down would be Range 1*45degrees, 0.5*radius, 999 mile
>radius) would draw a range circle that was 999 miles radius with it's
>center offset NorthEast (1), and offset .5*999 miles.
The specs already have a range extension called RNG (aprs specs 1.0 page 
29),  I keep finding it strange that every maesurment in the protocol is 
in miles feet etc but then again most of the protocol was designed to be 
readable by imperial  measurments using hams and not those that use the 
world wide excepted SI standards.

Measuring your range is not that hard, just drive out while a cw beacon 
is transmitting on the radio and antenna you want to use for aprs, do 
that in 4 or more directions and average the distance where the beacon 
picks up fm noise, it is far simpler then figuring out your HAAT and 
tweaking the numbers to make it reflect reality. it might not have 
directivity but very few PHG transmitting station actualy have a 
directivity in the PGH construct anyway or they have a directivity of 
360 thinking that it stands for omni.

It can even be automated by taking the average distance where the 
software picks up moving stations directly, maybe put in a correction of 
a few miles for the range of the mobile itself. I think UI-view can be 
made to handle that with an addon.

73 de Andre PE1RDW

PS I find the dx statistics for digi_ned very informative for judging 
the current range of a digi but more then the best dx needs to be 
triggered with a message (like triggering a path response with ?aprst)

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