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? How can you use the series of beeps you hear when powering up to diagnose issues with your equipment?  Should all of the beeps be synchronized or is it ok if they are slightly off?  Are there different patterns you might hear and if so, what do they all 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