3D Robotics


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.

From Hackaday:

[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.

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  • By the way, I was wrong in my earlier post. The SPOT communicator is transmit only. It can not receive messages, although the Globalstar system does offer two way (duplex) services also, transmission and reception is done on different frequency bands.

    SPOT is based on the Simplex Transmitter Unix STX2 (the first spot anyway, the SPOT Connect seems to have a newer and more integrated transmitter.

    Instead of buying and hacking a SPOT, you could just buy the STX2-module. It communicates with simple AT-commands, but then you need to get a special subscription for it. Probably not worth the hassel compared to getting the SPOT connect.

    Also, note that the light yellow coverage areas in the map means that there is 96% to 99% probability of getting a single message through within 20 minutes. But since it is transmit only you can never be certain if the message gets though properly.

  • There are quite a few different competing satellite phone networks, both Low Earth Orbit and geosynchronus.

    This SPOT system uses Globalstar, wich can also be used for sat-phones. It is LEO and has 44 satellites. Any globalstar satellite needs to be within reach of a ground station to be of use, that is why there are some white spots on the coverage map. Also, the satellites inclination means they can't cover the poles.

    Iridium on the other hand is also LEO, but a far more complex system using 66 satellites (and a bunch of spares). These satellites can communicate with each other if they have a clear line of sight, and therefore they do not need a direct visual of a ground base station, they can relay it through another satellite. This improves coverage a lot. Also, the Iridium satellites run from pole to pole, and therefore, pole coverage is excellent. Iridium covers pretty much all of the world, wich is a big plus compared to Globalstar.

    However, anyone can just pick up a SPOT Communicator for $150 and pay the $100 yearly subscription and be able to send position from the built in GPS and messages from any smart phone, from most places of the world. This is actually pretty cheap compared to using any voice sat-phone on Globalstar, Iridium or any other network. And as long as you can live with the limitations of just transmitting small messages it will work fine.

    Globalstar also offer phone service for $40 per month, plus $50 activation fee plus $500 for the phone. Coverage for full duplex data and phone service is not as good as the map posted here, it does not work at all in sub-saharan africa or south east asia, but they are planning to build new base stations to cover these areas within a year. Coverage for the simplex data service is as the map posted here. They also offer rather nice modems and modules, both simplex data, duplex data and voice, to integrate their service with whatever you like, but the SPOT is the cheapest by far.

  • Do you know if Iridium have something similar? (And preferably duplex)

  • IIRC the Sparkfun setup is capable of interfacing with a GPS module which can respond to a phone call with a GPS coordinate. So you lose your plane somwhere, you call a number, and the module replys with an SMS message with its location.

  • Very different SPOTs indeed.

    The Smart Personal Objects Technology that was built into watches and coffee-makers is based on FM-radio and is one way only, it broadcasted weather and some other info, is one-way, and only reaches as far as the FM-radio station it uses.

    The SPOT LLC who makes the SPOT Connect and Satellite GPS Communicator on the other hand is a subsidiary of Globalstar and uses Globalstars satellite network, same as some satellite phones and other things do. It can send and receive small messages in most parts of the world, but not at the poles, sub-Saharan africa and parts of south east asia due to the orbits of the satellites.

  • This is definately not the same SPOT as the microsoft one.

  • 3D Robotics

    Monroe: it can both send and receive. 

  • Well, the Spot Connect can do two-way messaging over blutooth to a Smartphone, but I'm not sure if they got it working on this hack?

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