What’s Next?
The XBee comes with several antenna options, and the high-power version has a working range of over a mile. If I re-shaped my electronics a bit and powered it with a button-cell battery, I think I could probably put the whole assembly inside an Estes model rocket payload compartment and look at the acceleration of various model rockets. I should probably go with the ±18g accelerometer chip in that case!
I’ve measured acceleration so far, but the XBee A/D converters can measure any 3.3V signal. If the sensor has an output voltage, you can probably make it work with the XBee. You could measure pressure, temperature, humidity, whatever!
The 10-bit A/D converters are a serious limitation, though. One way around this would be to use sensors that do their own A/D conversion, and use the XBee for purely digital communications. This chip, for example, measures barometric pressure to 17-bit precision — enough to measure a the pressure difference corresponding to a 10-cm change in elevation! It communicates via I2C protocol, though, and I haven’t figured out how to connect I2C directly to XBee. I could connect the sensor to an Arduino, then use the XBee to communicate from the Arduino to the computer, but that’s another whole layer of complexity and mass.
I’ll think of something, eventually. If you think of something, or do interesting things with the XBee as a result of these pages, please let me know!
Associate Professor of Physics
