[aprssig] PHG - dBi or dBd ?
winston at winston1.net
Mon Sep 29 07:28:36 CDT 2008
Add emphasis to the "do not very accurately represent true coverage"....
there's a digi to the west of me which says that it has 2-3 times the
coverage that it really does, at least in the north and west
directions... part of the fun of the rolling hills of the area..
Heikki Hannikainen wrote:
> 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:
> "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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