01-26-2019, 06:26 AM
No need to worry too much about background noise when running ultrasonic, I think. It's a very high frequency, there's little chance it got covered up by lower frequencies. So finishing up the loops on your phone on the go is an effective way of doing so. 
I do the same thing when I have to: phone in pocket, speaker end sticking out. 
I do the same thing when I have to: phone in pocket, speaker end sticking out.
"A man who is doing his True Will has the inertia of the Universe to assist him." - A. Crowley
