APRS Tracking STER 2008


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WICEN Tasmania (South) goes Horseback - August 2008

 WICEN has provided communications support for Southern Tasmanian Endurance Riders (STER) events for the past three years.  Initially confined to rides in the Wielangta Forest, south of Orford on Tasmania’s East Coast, but latterly for all of their four rides each year, held in different locations.  Early August saw a return to Wielangta’s familiar area so another dimension was proposed to STER President and ride organiser Ossie Owens.  Would he be able to persuade one of the riders to carry a backpack APRS tracker unit?  Ossie came to the party and found us a “willing” and, as it turned out, a winning rider.

 The tracker unit, made up of a Byonics TinyTrak 3 Plus, SiRF III GPS and a Puxing handheld radio, was packed into a stripped out backpack rehydration unit.  (They used to be called water carriers, but apparently we don’t drink these days, we rehydrate).  The GPS was Velcro’ed to one shoulder strap and a ‘rubber ducky’ antenna attached to a bracket providing an antenna mount via the drinking tube hole on the other shoulder strap.  A 1.3 amp hour SLA battery powered the Tracker and GPS; a bit of overkill but a nice fit in the bag.  The standard lithium ion battery looked after the radio.  Earlier problems were overcome by wrapping the Tiny Tracker in aluminium foil, ferrite on all cables and wads of foil around the antenna mounting bracket, made up from scraps of aluminium fabricated to sit firmly in the bag.  Total weight 1.7 kilograms.

The project had multiple purposes.  1 - to give us something interesting to do; 2 - to give the waiting supporters (mainly parents and partners) something interesting to look at, and last but not least, to show how clever we are.  (It’s taking a long time to get our horsey friends to stop calling us the CB’ers!)

 All the WICEN vehicles carried APRS trackers to enable them to be guided from the Base to their checkpoint locations.  On the ground checks confirmed indications from Radio Mobile propagation and mapping software.  Voice comms between Base and the checkpoints was easy with normal mobile 2m gear, so the Base 12 metre telescopic mast and antenna was devoted to APRS.  To ensure good coverage around the course, a digipeater was set up on an accessible hill top.  The display medium was a 17 inch notebook PC running AGW Packet Engine Pro and AGWTracker, USB linked via an Elcom micro TNT to an Icom 208H.  All mounted on an eye level shelf on the WICEN trailer and powered by Honda to complete the Public Relations picture.

 The only problem encountered, by the rider, was constant tapping on her helmet by the antenna.  This was fixed for the second circuit by adjusting the bracket to give 45 degree polarisation and helmet clearance.

 The tracking was perfect around the two 40 kilometre circuits of the course, 80 kilometres in total.  Being able to see the speeds travelled on the varying topography, ranging from flat paddocks, through steep rocky tracks to soft beach sand was a bonus in the “We’re not CB’ers stakes”!  To top it all off, our horse, Madam Pandora ridden by Janine Parr, came in first!

VK7FCDW and VK7ARN hard at it at Base