The only word of caution I would suggest with using an Android for investigation, is make sure you turn on "Airplane Mode" so that you don't contaminate any EMF readings. The signal output from one of those phones can be pretty strong, and in the upper Ghz range. So it can raise havock with many EMF meters. This is especially true if you're in a low signal area, the power output gets ramped up on the phones when the signal strength is weak.