> It’s smart to avoid using wireless devices like mobile phones or GPS systems, since they have digital signatures... Could someone explain how a GPS receiver (especially one which doesn't utilize DGPS of any sorts) would have any sort of digital signature which could be measured from a drone?
Locating Noncooperative Radio Receivers Using Wideband Stimulated Emissions[2]
A Practical Superheterodyne-Receiver Detector Using Stimulated Emissions[3]
1. https://ieeexplore.ieee.org/abstract/document/6857348