Comment Re:Tough (Score 1) 159
It wouldn't be that bad.
Have a 360Â servo with a 80Â-90Â servo mounted on it. Directional mic on top of all that.
Arduino/Pi rotates the first servo 1Â then sweeps the second servo. Or vice versa.
Feed that into an algorithm looking for prop noise. Most drone motors will be IC or electric. An IC will be running between 9K~18K RPM. Electric would be running from 7K on the low end to 30K on the high end. Realistically, an electric for drone use would be on the low end of that spectrum; the higher-RPM motors are usually for fast airplane.
Take the RPM and figure a 2-bladed or possibly a 3-bladed prop. Filter bandpass for 15K~55K. Run that through a doppler-shift algorithm and filter out anything moving slower than 20MPH or faster than 200MPH.
Using that, you should get pretty close.
Once you have the location, feed that to another mount with a spotter-scope and webcam. If the image-detection stuff sees something other than sky or clouds, have it snap a few images and SMS/email them to you.
I'm not entirely sure you will get good enough images to identify the specific UAV using servos programmed for Â. The servos usually range from 900-2100ms of pulse width with 1500 being "centered" on the servo. So, you can get it down to 3-steps per  on a 360 servo and 13-steps on a 90 servo if you use straight PWM and good digital servos.