[aprssig] creating a race course

[Robert Bruninga]

The following response to a question on the UIview list
was censored from the list.  But since it does answer the 
question about alternatives for placing event "courses" on 
APRS maps, I thought I would post it here where people are
a bit more open minded about looking at alternatives
and creative solutions...

>> Q: I would like to be able to recreate a course map for a 
>> marathon... so that the race officials can track the support
>> vehicles and the runners when they are on the course.
>
> One problem is having enough trackers on everything you want 
> to track.   Here is a tangential answer but it is what we have done
> for all local races since 1994 or so.    We use the old APRSdr.exe
> which is a version of APRSdos designed to dead-reckon all
> objects along an event course.  The course is simply drawn
> onto the map using the purple color  and then any objects
> placed on that route, will be dead-reckoned along that
> route to the end transmitting 1 minute reports as if they
> each had their own GPS.   They will appear to all viewers on all
> other software just like any other moving station.
>
> The operator of the APRSdr station just keeps an ear on the
> voice nets to see how close to reality his moving objects
> are and updates their position based on what he hears if
> any object is slightly ahead or behind.  Updating it is as easy
> as clicking it with the mouse and moving it to the reported
> position.  It will continue to move from that point..
> In general, it does a good job of giving all viewers the gereral
> idea of when such-and-such is about to come into view..
>
> The advanteage is that ANYTHING moving along the course 
> can be tracked.  And in a race like a marathon, you can guarantee 
> that the "LEADER" is running about 9 knots even if he stumbles 
> and falls (someone else just becomse the LEADER)...
>
> About the only thing we found that we reallly need a tracker on
> is the tail-end-charlie who's movements are unpredictible.
> We set the lead woman at 8kts and the "pack" at 7.  ANd
> any other noteables at an appropriate rate.  For example
> during the Annapolis 10k, there is a juggler who runs the
> entire run while juggling.  But we put him on the map and
> everyone can track him too...
>
> APRS being a low duty-cycle "sampled" tracking system was
> fundamentlaly designed around dead-reckoning to provide
> smooth tracks inbetween the infrequent updates.  Unfortunately
> many APRS clones left all of that functionality out.  So that
> thier Icons just 'jump' from place to place as reports come in
> with no visual clues as to how old any given Icon's position
> is....
>
> Since dead reckoning works so well in this kind of application, we 
> dont even bother trying to outfit a bunch of bikes and mobiles 
> anymore for small races.  Others viewing the moving objects
> on their APRS screens do not even see the difference.
>
>de WB4APR, Bob