XBee USB
XBee and the USB Interface arrived in the post today. The USB interface is FTDI based so I'll have to install the driver for MacOSX. Fun!
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XBee
Ordered some 60mw XBee modules and a USB XBee interface from http://robosavvy.com for the Mashroc telemetry project. I'm going to be building a small PIC based board for the rocket end of the system and running some tests to check range and see if there are any doppler related problems. I did a few quick and dirty doppler calculations which came up with :- Source f = 2400000000 Hz Source Velocity vs = 118 m/s (Guessed) Medium Velocity v = 3000000 m/s (Approximately Light) Observed fo = 2399905603.71292 Hz Observed delta do = -94396.2870793343 Hz I found from a zigbee spec online (must find a better source) the frequency tolerance is 40ppm which I took to mean 2400*40 = 96 KHz. So we're just inside the tolerance. Bear in mind this is worst case doppler with freq source moving directly away from the observer.