Principle of operation
Semiconductor Electronics are used in all modern electronics and are made using Silicon. When high frequency radio signals are transmitted directly over silicon they produce a strong second (2nd) harmonic frequency of that radio signal. Other materials such as some bi-metals or oxidised metals can respond with a third (3rd) harmonic signal.
The EDD-24XT transmits a focused directional signal on 2.4 GHz (ISM Band Type B). It receives on 4.8GHz (Second Harmonic) and 7.2GHz (Third Harmonic).
The highly sensitivity receiver will respond to any signals produced on the 2nd Harmonic by even the smallest piece of Silicon such as that used in SIM Cards, Mobile Phones, Bugging Devices, Voice Recorders, Covert Video cameras etc. Importantly those devices do not have to be in use, in standby or even have any power connected to them to be detected.
The 3rd Harmonic receiver acts as a valuable confirmation for signals that may be ambiguous or are not a threat such as those in oxidised metals, bimetals etc.