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SPOT on APRS

Firstly what is a spot? Well in it's simplest form it is a personal tracker. This is a small handheld, or belt worn, device that well acquire it's position from a the GPS satellites and relay this on command back via the Globalstar network. It can also provide an automated position fix every 10 minutes as well as having assistance and emergency messages available. To have a look at these things try the spot webpage.

Now as can be seen from the above we have two systems here that are involved in the reporting and display of positions so it seems natural that the two should get together. From an amateur's perspective here are a few of reasons why we did this:

  1. While most of the reports from mobiles are done on VHF it has the least amount of coverage of all of the possible options. A spot will provide almost global coverage.

  2. APRS messages can be submitted via HF however the radio you are using for this becomes dedicated to the task if you are looking to run the tracking full time. A spot frees up this radio needed to transmit the APRS data meaning you can operate HF mobile while still letting people know where you are.

  3. Size and power requirements for a spot are considerably less than those for a HF / Tiny Trak combination. This makes it a viable option for those hiking or just pedestrian mobile. A spot will run for days on a single set of batteries.

Operation is fairly straight forward and occurs in 2 steps.

We collect the data from the SPOT servers.

We submit it to the APRS network under the users callsign.

This system is still in the development stage however is showing a lot of promise. If you're an amateur, even a foundation call, and have a spot feel free to contact me with your email address and callsign and we'll add you to the list of units we're watching.

Here's a few we have running:

VK2JAP-13 This Gunter who may or may not be out and about.

VK2BOS-13 Steve with some occasional use.

VK2US-13 My own SPOT with some occasional use.

Recently 2 changes have been made to the core application. Firstly the system has now been se to handle multiple APRS servers and cycle between these two until a successful connection is made as well as in the event that an established connection to an APRS server is lost.

The other change was to send a message twice at 60 second intervals. It was noticed that a number of reports correctly captured from the SPOT site failed to appear on the network even though there was a connection to the server and it appears that the message had been send. This second send appears to have solved this. I’m investigating a more eloquent solution such as monitoring the second server to see if it sends out the report but this will take time.

Regards & 73's

Peter.

Contact Peter VK2US

 

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