[aprssig] APRStt for SAR using UTM grid!

Robert Bruninga bruninga at usna.edu
Mon Jun 17 13:24:42 CDT 2013


We need to resolve this.  I was told by some SAR folks that for all voice
reporting during a SAR mission, that the XXX,YYY resolution was for the
10km square grid with resolution to 10 meters for the purpose of generally
knowing where everyone was.  Additional digits were only used if higher
resolution or a different area was of interest.

Are you saying that not all groups use this convention?
Bob, WB4APR

-----Original Message-----
From: aprssig-bounces at tapr.org [mailto:aprssig-bounces at tapr.org] On Behalf
Of Tom Hayward
Sent: Monday, June 17, 2013 10:48 AM
To: TAPR APRS Mailing List
Subject: Re: [aprssig] APRStt for SAR using UTM grid!

On Sun, Jun 16, 2013 at 6:22 AM, John Langner WB2OSZ <wb2osz at comcast.net>
wrote:
> Here is another APRStt implementation which includes processing of UTM
> coordinates.
>
> http://home.comcast.net/~wb2osz/Version%200.7/APRStt-Implementation-No
> tes.pd
> f
>
> DTMF decoding is done in software so no special hardware is required.

This is a good start, but you've implemented a non-standard UTM truncation
system:

> The xxx and yyy ranges would extend over a 10 x 10 km area with 10 meter
resolution.

Typical UTM truncation (as in the MGRS and USNG spec) is an order of
magnitude higher, so xxxyyy extends over a 100km x 100km area with 100
meter resolution. To add resolution, add a 10m digit to give you xxxxyyyy
format.

Tom KD7LXL
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