A method of testing an electronic device includes measuring radio frequency emissions at a plurality of positions relative to a trusted unit of a particular electronicdevice during operation of the trusted unit, and measuring radio frequency emissions at the same plurality of positions relative to a second unit of the particular electronic device. For each of the plurality of positions, the radio frequency emissions measured from the second unit are compared to the radio frequency emissions measured from the trusted unit. The method then determines whether there is any frequency at which the measured amplitude of the radio frequency emissions from the second unit and the measured amplitude of the radio frequency emissions from the trusted unit exhibit a statistically significant difference.