Improve the stability of digitalDemod()
Improve the stability of digitalDemod()

This is not really the "proper" way to do things since we really want an
anti-aliasing decimator. But, this change at least makes it possible to
use a 5 MHz bandwidth again.

--BRJ

rmcgurrin/Qlab,rmcgurrin/Qlab,Plourde-Research-Lab/Qlab,Plourde-Research-Lab/Qlab,BBN-Q/Qlab,BBN-Q/Qlab,rmcgurrin/Qlab,rmcgurrin/Qlab,BBN-Q/Qlab,Plourde-Research-Lab/Qlab,BBN-Q/Qlab