Freakduino 900 MHz Goes Long Distance

Arduino Technology
Freakduino 900 MHz Goes Long Distance


Designed by Chris “Akiba” Wang of Tokyo Hackerspace and its geiger counter project, Freaklabs’ Freakduino combines an Arduino with a built-in wireless board, giving you the ability to transmit data wirelessly without buying extra components.

The new Freakduino 900 Mhz v2.1a packs two main improvements. First, Akiba’s original flavor board sported 2.4 GHz, but the new Freakduino 900 MHz features range over hertz:

I originally designed this circuit a few years back when I was looking for something to do long distance wireless sensor links, on the order of kilometers or tens of kilometers. 2.4 GHz gets a bit hard to drive that far since higher frequencies have more attenuation in free space as well as a difficult time going through objects. Lower frequencies have much less attenuation and are able to travel through obstacles more easily so they’re ideal for situations where range is valued over speed. In sensor networks, data rate usually has a low priority compared to battery life and communications range.

However, he hasn’t just switched up the radio; power management has been improved:

The hardware is optimized for low power operation and in sleep modes, only consumes 300 uA at 3V (2-AA batteries). This would theoretically allow 2 AA batteries to power this device for months with proper power management and low duty cycles. The battery boost circuitry differs from the standard Freakduino series in that it has two separate boost circuits. During transmission, the front end amplifier puts a lot of power into the signal so the boost converters were doubled up to support both the wireless circuitry and still have spare current for other devices attached to the board.

The hidden advantage to the Freakduino is that Akiba makes them compatible with a ruggedized enclosure he sells, making them perfect for outdoor or hazardous conditions. There’s a custom proto board on one end, and they come with a lovely silicone bumper that fits around the plastic box. Finally, Akiba will be selling the boards at a 10% discount for a few days, so shop early!

12 thoughts on “Freakduino 900 MHz Goes Long Distance

  1. JD90 says:

    Oh hey, a nice circuit to have, available without the too-common Kickstarter/Indiegogo style panhandling.

  2. Me says:

    This doesn’t sound legal to use.

    Is this type accepted in the various countries where it will be sold? I don’t see an FCC ID on the board in the picture. Is it on the back?

    In the US I don’t believe there is any license-free service at 900Mhz that allows for power levels likely to reach kilometers or 10s of kilometers. You could do it with ham radio. You need a license and you need to send your callsign every 10 minutes. You can even do it without type acceptance but they can’t legally sell it in mass without type acceptance. Transmitting without type acceptance is only legal here with low volume homebrew type stuff.

    There may be other US radio services one could use this under, I don’t know but if there are I’m sure they require expensive licenses. I’m guessing obtaining such licenses would be out of the range of anything one would spend to use hobbyist type hardware. As for other countries… I don’t know specifics. Most are pretty similar though.

    Does anyone out there know more about this? What radio service is this expected to be used under, Part 15, Amateur, ‘sneak permit’?

    1. Me says:

      Ok, I wrote that in response to just the summary. I just read the description of the product over at Freakduino and there it is only talking about going 100s of feet. Also, the board includes encryption. I guess it is meant to be used for Part15. It still needs an FCC ID though for use in the US. I hope that’s on the bottom of the board somewhere.

  3. Freakduino 900 MHz Goes Long Distance akibafreak says:

    I think you read the wrong product description. That was for the standard Freakduino with a 2 mW, 2.4 GHz radio. This one has a 500 mW amplifier on the front end. In the US, FCC allows up to 1W in the 900 MHz ISM (license free) band and up to 1.5W using point to point antennae. In Europe, the R&TTE directive allows up to 500 mW in the 869 MHz band. These devices are mainly designed for use in remote locations with little infrastructure and requiring long distances to an infrastructure link. They were originally designed for environmental monitoring for projects I work with academia or NPOs on.

    1. Gary Nutbeam says:

      It does need to be FCC licensed and have passed testing, to be sold in the US. I’ve just went through licensing a 900MHz open source module, a bit like the XBee, but we call it the OBee. So all this is fresh in my mind.

  4. marcellenormand says:

    Aww… it sounds extremely cool by but the headline made me think that the Arduino processor was running at 900MHz rather than the usual 16MHz !! That would be extreme!

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My interests include writing, electronics, RPGs, scifi, hackers & hackerspaces, 3D printing, building sets & toys. @johnbaichtal

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