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Reply To: XBee Networks of Mayfly Loggers – 900Mhz

Home Forums Mayfly Data Logger XBee Networks of Mayfly Loggers – 900Mhz Reply To: XBee Networks of Mayfly Loggers – 900Mhz

Shannon Hicks

    We have successfully used dozens of Xbee Pro 900HP radios with Mayfly boards for our logger network here at the Stroud Center and at other locations. You can program the modules to be in “pin-sleep mode”, meaning you can toggle the sleep mode by driving a pin high or low. You can also use cyclic sleep and other “smart” sleep methods if you want to implement a mesh network. In our locations, we’re fine with just a central coordinator that stays constantly powered and connected to an ethernet jack. Whatever radio traffic it hears from the sleeping logger nodes, it relays to our online database. I wrote about it earlier this year in another thread: https://www.envirodiy.org/topic/connecting-to-the-internet/

    Nowadays you can buy dedicated base station modules that do the same thing as my homemade version, but almost 6 years ago when I first built it, there were very few reliable and affordable options.

    The 900MHZ Xbee radios have a much better range in our forested terrain than the 2.4GHZ radios. In open and relatively flat areas, I’ve gotten almost a mile of distance between the logger and the base station. Your results will vary depending on the gain and placement of your antennas, and probably more importantly the topography and forest density. In terms of battery usage, they are very efficient when compared to the cellular modules we use in the hundreds of areas where we don’t have a base station. The radios sleep constantly just like the loggers, and when it’s time for a transmission, they are powered for a fraction of a second and then return to sleep.

    I use both the RPSMA modules as well as the U.FL models, depending on what sort of enclosure I’m mounting the Mayfly in.
    I use weatherproof bulkhead RPSMA fittings that mount the antenna on the enclosure, and sometimes they are a continuous, 1-piece design with a u.fl connector on the inside end. It also depends on how much physical abuse the radio module is going to see. The RPSMA fittings are much more appropriate if you’ll be moving the board or cables around frequently, since the u.fl connectors are somewhat fragile and finicky, and will fail quickly if you make-break the connection too many times.