US DoD Patent RF Hearing Effect
Patent # 6470214 – Explained
US DoD patent RF hearing effect.
Double Sideband Suppressed Carrier Amplitude Modulation and Coherent Detection
Journal of Lightwave Technology August 1, 2008
Demodulation of AM Signals – Restoring/recovering message signal from the received modulated waveform that is generally corrupted by noise.
US DoD patent RF hearing effect examines a method of encoding an input audio signal to produce a double sideband output signal having a frequency, which when transmitted to the head of a receiving subject, will by the radio frequency hearing effect induce a thermal-acoustic signal in the bone/tissue material of the head that replicates the input audio signal and is conducted by the bone/tissue structure of the head to the inner ear where it is demodulated by the normal processes of the cochlea and converted to nerve signals which are sent to the brain, thereby enabling intelligible speech to be perceived by the brain as any other nerve signal from the cochlea, the method comprising: applying an input audio signal to an audio pre-distortion filter with a filter function to produce a first output signal; adding a very low frequency bias to the first output signal to produce a second output signal; applying the second output signal to a square root processor to produce a third output signal; applying the third output signal to a balanced modulator to produce a double sideband output signal, where it is the carrier frequency; and transmitting the double sideband output signal to the head of the receiving subject to create or remove a hearing effect.