Hacking SPOT Personal Satellite Tracker To Pass More Information

For less than $100 you can buy a little tracking module that will upload your location to a satellite. But you’ll only get latitude and longitude information. [Natrium42] spent some time reverse engineering the hardware, and the communications protocol, to allow custom data to be transferred using a SPOT module.

The flat fee for the hardware includes a one-year service plan allowing you to tack your device on the SPOT website. [Natrium42] started poking around in the transmitted data packages, and figured he could push custom messages like altitude data if he had some way to encode it as a valid latitude/longitude package. He found that location data is transmitted as two sets of three bytes each. The four least significant bits of each set get rounded by the server, leaving a total of 40 usable bits between the two data sets. He wrote encoding and decoding functions that will allow you to transfer whatever information you want.

So what is this good for? To get the process working he removed the MSP430 microcontroller from the board and is using his own replacement. So you can transmit GPS data from the onboard module, your own module, or sensor data for anything you’re able to hook up the to the replacement uC.

38 thoughts on “Hacking SPOT Personal Satellite Tracker To Pass More Information

    1. Why is this damn cool? Well, you can drop this in a remote part of the world with no mobile phone service and transmit data via satellite for only $99/yr. A solar powered weather station comes to mind. I’m sure there are hundreds of other possible interesting applications.

  1. This is an awesome hack!

    What is the bandwidth for the custom 40 bits of data? I.e., how often can you upload 40 bit packets, and what is the lag time back to a PC?

    1. The fine print in SPOT’s annual contract states that if one abuses the frequency, additional charges may apply. Therefore, if one wanted to remain compliant, every 10 minutes would be the most frequent schedule advised.

  2. For a backpacker (the target audience for the Spot), this would significantly enhance the usefulness of the device. Out of the box, you are limited to 3 predefined messages – with this hack you could have millions of choices – “pick me up at location 17”, “send more of food item 23”, etc.

  3. may be a good idea that when you post captured data on future gps projects you may not want to do it from your home.

    if you can capture the data with a laptop you may want to go somewhere far from your home so viewers cant trace you to your house.

    especially the legal departments of the makers of the device since they can now send you a dmca notice.

  4. I did the FCC qualification testing for this when I was doing contract work at a test house. This thing is right on the edge of all radiated emissions limits that no matter what you do to mod it, it will violate FCC rules. But, no one will ever know if you don’t actually end up interfering with anything else.

  5. I can see this being hacked to use a single service plan and multiple modules – use a few of the bits as a unit ID and you have several tracking devices for a single low rate if you copy your primary unit’s serial # to the others.

  6. This is pretty awesome. Can you please tackle disabling the ’24hr time-out’ for tracking mode. Unit automatically cancels tracking after 24hrs. this is a pain in the butt. It would be so awesome if one of the readers here could share an easy solution.

    1. One thing I’d really like is if the frequency of position updates could be increased. I would like to track rented jetskis and 10 minutes between updates is useless…. They could be on the other side of the bay in 10 minutes.

      1. @Turkeydinner, Here’s a little tip: If you put a SPOT tracker in ‘Help’ mode, it will send location data every 5 minutes. This mode only lasts for an hour, though, so it may not help your overall cause. I also believe the fine print in a SPOT contract says that if one abuses the tracking frequency terms, additional charges may apply. A GPRS tracker may be your best solution for Jetski (asset tracking).

        I am personally still tuning in on this comment thread to hear if Mike thinks it’s possible to disable the 24-hr time-out. We use SPOT to track multi day adventure races and the athletes ALWAYS forget to reset the tracking daily.

  7. OK, so now the SPOT people have come out with the SPOT Connect which allows for sending small packet messages via bluetooth using a Smart phone.
    Does anyone have details for an RS232 To Bluetooth converter that could emulate the packet format from the smart phone, which would allow for the transmission of text data without having to physically hack into the SPOT unit?

    1. Ron,

      I have documentation from Globalstar on how to use a microcontroller via the USB to talk to the SPOT Connect.

      I’m actually looking for someone that can program the microcontroller for me to disable the 24 hour time limit.

      If you want to know more you can check out my post on Frelancer dot com:

      Project: C programming a TI Microcontroller connected to SPOT Connect


      1. I am glad to hear there are others out there interested in eliminating the 24-hr time out. I am part of a live event tracking company. We use SPOT to track participants, and the 24-hr time out is our biggest obstacle to successful tracking.

  8. I am interested in a much simpler hack. I would like to have a small LED display mounted to the unit that tells me coordinates/elevation. You might ask why I don’t get a GPS, and the answer is battery life. If you are spending 7+ days in the backcountry the fancy map display on the GPS will have long since lost power. The coordinates displayed on the Spot would be cross-referenced against good, old-fashioned paper maps.

  9. One thing to note is that it is a “simplex” device, i.e. uplink only.
    There’s no way for the device to receive data from the satellite.
    Imagine being able to control some remote device just about (almost) anywhere in the world :-)

    The DeLorme inReach provides 2-way communication on the Iridium network (but it’s kind of expensive).

  10. The stoopid thing is a position is really not just lat and long, it is altitude too. Its so daft they did not include altitude data in the position, when its already in the gps data . These units are very popular for hang gliding and paragliding in remote places (I’m in NSW Oz now), but the only way my followers know if I am still flying or landed is when they see two identical positions after a while, or I send the message with a button press.
    I wonder if altitude data is forbidden in some sort of rule somewhere to prevent it being an aviation device? but its only doing what any smart phone can do, just over a more reliable network…
    The gen 3 device has 5 min tracking as std. I guess nobody hacked one of those yet…

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