[OZAPRS] Proximity detection

[Merv Joyce]

Andrew

I just calculate the Great Circle Distance from the two positions and
compare this with a "minimum motion" distance to determine whether I
want to send a new position.  This is how I avoid sending unnecessary
position updates when not moving in my aprs4ppc program.

Merv (VK4ZE)

-----Original Message-----
From: ozaprs-bounces at aprs.net.au [mailto:ozaprs-bounces at aprs.net.au] On
Behalf Of Andrew Rich
Sent: Wednesday, 22 August 2007 11:50 PM
To: Aprssig
Cc: ozaprs
Subject: [OZAPRS] Proximity detection


Gudday

If you get a micro, and you know from a GPS where you are, and then you
pick up another position, one would assume you can then apply a basic
"is there anyone in my box" calculation ?

For example

I am at

2734.44 15206.20 and another object is at
2734.45 15206.20 - does not match - outside the box

2734.44 15206.20 and another object is at
2734.44 15206.20 - match - inside the box

I spose the size of the area depends on how many significant digits of
the position you use ?

You could make it tighter by comparing more digits, and wider if you
compare less ?

Comments ?

------------------------------------------------------------------------
----
Andrew Rich VK4TEC
vk4tec at people.net.au
http://www.tech-software.net



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