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[aprssig] PHG - dBi or dBd ?

Heikki Hannikainen hessu at hes.iki.fi
Mon Sep 29 12:08:48 UTC 2008


   Hi Chuck,

On Mon, 29 Sep 2008, Chuck Kimball wrote:

> I've noticed that aprs.fi is using dBi for it's display of the info
> provided by PHG.
>
> In looking through Bob's and most other references of PHG they only
> specify dB not specifying dipole or isotropic.
> So which is it?   Do I need to reprogram my digis with dBi numbers?

The APRS Spec addendum 1.1 clarifies the specification that it is dBi:

   http://eng.usna.navy.mil/~bruninga/aprs/aprs11.html

   "The Antenna Gain in the PHG format on page 28 is in dBi."

The PHG circles do not very accurately represent true coverage, so if they 
*roughly* match with your mobile (half-sized circles) or fixed station 
(full-sized circles) coverage, and if it's hard to reprogram the digis, I 
wouldn't go through an awful lot of effort to change the configuration.

   - Hessu, OH7LZB





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