title_body: When I power up my flight controller and ESC's, I hear a series of beeps. What do all of the beeps mean?
upvoted_answer: The normal blheli startup tones are similar to beep beep beep... boop. boop
  
  The first 3 beeps are the ESC's powering on and initializing then there's a pause followed by two more beeps which means the throttle signal has been received. 
  
  https://youtu.be/_hkzm8ZXsxE?t=58