Back in 2004, in the day before ubiquitous smart phones and data networks, Microsoft and some hardware partners such as Fossil and Swatch introduced SPOT (Smart Personal Objects Technology) watches, which used a satellite constallation to send 41-character messages to low-power devices anywhere in the world. The idea is that you would register with a service and you could get weather or sports data on your watch anywhere. They flopped, but the satellite constellation is still operating.
Now you can buy Spot radio hardware and a service that let's you SEND messages, too. So who needs an expensive satellite data service for long-range UAVs? Just lower your data rate and send just what you need as SPOT messages. It's $150 for the hardware, $100 a year for the service, $20 for the breakout board, $0.10 per message.
[Nate] over at Sparkfun put up a great tutorial for using the SPOT personal satellite communicator with just about any microcontroller. These personal satellite transmitters were originally intended to pair with the bluetooth module of a smart phone, allowing you to send a short 41-character message from anywhere in the world. Now, you can use these neat little boxes for getting data from remote sensors, or even telemetry from a weather balloon.
[Nate]‘s teardown expands on [natrium4] and [Travis Goodspeed]‘s efforts in reverse-engineering the SPOT satellite communicator. The hardware works with theGlobalstar satellite constellation only for uplink use. That is, you can’t send stuff to a remote device with a SPOT. After poking around the circuitry of the original, first-edition SPOT, [Nate] pulled out a much cheaper SPOT Connect from his bag of tricks. Like the previous hacks, tying into the bluetooth TX/RX lines granted [Nate] full access to broadcast anything he wants to a satellite sitting in orbit.
We’ve seen the SPOT satellite messaging service put to use in a high altitude balloon over the wilds of northern California where it proved to be a very reliable, if expensive, means of data collection. Sometimes, though, XBees and terrestrial radio just aren’t good enough, and you need a satellite solution.
The SPOT satellite service has an enormous coverage area, seen in the title pic of this post. The only major landmasses not covered are eastern and southern Africa, India, and the southern tip of South America. If anyone out there wants to build a transatlantic UAV, SPOT, and [Nate]‘s awesome tutorial, are the tools to use.