This is something I have been reading about rather than having done it myself, so I may be wrong about details, but here's what I understand. The Doppler radar setup will give you a beat frequency between your tranmitter and receiver. IIRC, Doppler frequency is 1/(1+2v/c), so for instance when an object moving at 1m/s is lit up by 5GHz, the receiver will return a 33Hz beat frequency signal. This is within audio range, so you can read it with a sound cape or USB dongle, or directly via BBB digital or analog I/O pins, if you're careful about not burning them up with excess voltage.
You can get the speed by measuring the frequency, but you can't get actual distance unless you do time-of-flight measurement on well-defined pulses, which is tricky because radar waves move at the speed of 1 foot/nanosecond. On a Beaglebone it's pretty hard to measure timing to a resolution much better than a microsecond or so, so your distance measurement would be to within 1000 feet. On Sat, Oct 5, 2013 at 5:41 PM, Dennis Ogbe <[email protected]> wrote: > > Hi guys, > > I'm totally new to MCUs and the Beagleboard and I'm a little overwhelmed by > the amount of information out there. > For a class project, I need to sample a signal (the beat signal out of a > FMCW radar module, the frequency is not higher that audio), detect its > frequency, and use this frequency value to calculate the range and/ or speed > of my target. > > I'm pretty sure that I can use either the beagleboard-xm or the beaglebone > black for this, but I'm confused about a couple things. I hope that I can > get help here! > > Can I just use the CPU on the BB-xM or the BBB to sample the audio and do > the necessary processing or would I have to use the xM's DSP or an audio > cape for the BBB? I have written simple DSP applications in C before, and so > far I have used JACK to get my samples from the sound card. Could I do the > same thing on the Beagleboard? Would grabbing samples for computations in a > C program also work by using ALSA? > > In order to detect the frequency of my signal, I believe that I will have to > take chunks of the signal, take the FFT and detect the peak in the resulting > array. Can I do these operations on a beagleboard without significant delay? > > Thanks for your help! > > Dennis > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/groups/opt_out. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
