[aprssig] Re: PHG in APRS and Xastir?

[Robert Bruninga]

>> I was surprised to see an Xastir station without any
>> PHG data.  I thought UIview was the only software
>> that omitted this fundamental dimension to APRS?
>
>Chapter 7 of the spec... says:
>  "A fixed-length 7-byte field may follow APRS position data. 
>  This... extension may be one of the  following:
>       PHGphgd ...Power ... Height/Gain/Directivity"
>       ....   ....
>I read that to say that PHG is an optional field...

Ah, what it should have implied is that that field is used
differently for Home, Mobile, WX and DF stations.  Home
stations should include their PHG, Mobiles include their
CSE/SPD,  WX stations include Wind DIR/SPD and
DF stations making a signal report include DFS data in that
field.

>That's the reason there's a DISABLE togglebutton 
>on the dialog. 

Thanks,  I hope that that button defaults to the
condition that includes this PHG data in his packet unless 
the  owner specifically takes action to disable it?
thanks....

> The other main reason is to keep packets very short, 
> giving a higher success rate.

I would encourage everyone to transmit PHG.  Home fixed
stations only transmit once every 30 mnutes and  knowing
someone's relative RF performance is just as important
to the RF network and other RF users as his location.
It is one of the fundamental dimensions in the RF domain
that APRS is supposed to convey..

A 5W station on a rubber duck  2 miles away is very different
from a 50W station at 100' that is 10 miles away, and
knowing their location but without PHG data makes them 
appear similar.  But there is a factor of 100 or more
difference between their relative RF performance.

APRS was supposed to show that.

thanks, anything you can do to help improve the
PHG situation would help...

Such as: 
1) Make sure PHG defaults to on,
2)  Does XASTIR display the Omni-DF data? (DFS reports)
3) Does XASTIR have a one-button method for
    reporting a signal strength report in the DFS format?

If not, then something for the future do list.
thanks..

Bob

>> To see the evolving Omni-DF solution display, see:
>>
>> http://www.ew.usna.edu/~bruninga/dfing.html 
>
>That's cool, and good practice.  Good luck finding the station!