A detection system for determining whether at least one electrical circuit has been compromised, said system comprising: at least one circuit probe positioned relative to the at least one electrical circuit and detecting electromagnetic emissions therefrom; a first analysis device electrically coupled to the at least one circuit probe and receiving first electromagnetic emissions detection signals therefrom, said first analysis device identifying first constituent frequencies and their respective first magnitudes in the first electromagnetic emissions detection signals; a comparison processor responsive to the first constituent frequencies and their first magnitudes from the first analysis device , said comparison processor comparing the first constituent frequencies and their first magnitudes to previously stored constituent frequencies and magnitudes obtained from an equivalent circuit to the at least one electrical circuit to determine whether the at least one electrical circuit has been compromised; and a background probe positioned to detect background electromagnetic emissions therefrom and a second analysis device electrically coupled to the background probe and receiving second electromagnetic emissions detection signals therefrom, said second analysis device identifying second constituent frequencies and their respective second magnitudes in the second electromagnetic emissions detection signals from the background probe , said comparison processor subtracting the second constituent frequencies and their second magnitudes in the second electromagnetic emissions detection signals from the background probe from the first constituent frequencies and their first magnitudes in the first electromagnetic emissions detection signals from the circuit probe before comparing resultant constituent frequencies and magnitudes to the previously stored constituent frequencies and magnitudes. at least one circuit probe positioned relative to the at least one electrical circuit and detecting electromagnetic emissions therefrom; a first analysis device electrically coupled to the at least one circuit probe and receiving first electromagnetic emissions detection signals therefrom, said first analysis device identifying first constituent frequencies and their respective first magnitudes in the first electromagnetic emissions detection signals; a comparison processor responsive to the first constituent frequencies and their first magnitudes from the first analysis device , said comparison processor comparing the first constituent frequencies and their first magnitudes to previously stored constituent frequencies and magnitudes obtained from an equivalent circuit to the at least one electrical circuit to determine whether the at least one electrical circuit has been compromised; and a background probe positioned to detect background electromagnetic emissions therefrom and a second analysis device electrically coupled to the background probe and receiving second electromagnetic emissions detection signals therefrom, said second analysis device identifying second constituent frequencies and their respective second magnitudes in the second electromagnetic emissions detection signals from the background probe , said comparison processor subtracting the second constituent frequencies and their second magnitudes in the second electromagnetic emissions detection signals from the background probe from the first constituent frequencies and their first magnitudes in the first electromagnetic emissions detection signals from the circuit probe before comparing resultant constituent frequencies and magnitudes to the previously stored constituent frequencies and magnitudes. <EOS>