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Patent Number: |
6470214 |
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Case ID: |
0 |
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Patent Title:
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Method and device for implementing the radio frequency hearing effect
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Status: |
ACTIVE |
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Status Date: |
6/5/2005 10:39:44 AM |
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Issue Date:
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10/22/2002 |
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Filed Date:
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12/13/1996 |
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Serial #:
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766687 |
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Assignee Name:
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The United States of America as represented by the Secretary of the Air (Washington, DC)
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Inventor(s):
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O'Loughlin, James P. ,
Loree, Diana L. |
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BACKGROUND OF THE INVENTION
This invention relates to the modulating of signals on carriers, which are
transmitted and the signals intelligibly recovered, and more particularly,
to the modulation of speech on a carrier and the intelligible recover of
the speech by means of the Radio Frequency Hearing Effect.
The Radio Frequency ("RF") Hearing Effect was first noticed during World
War II as a subjective "click" produced by a pulsed radar signal when the
transmitted power is above a "threshold" level. Below the threshold level,
the click cannot be heard.
The discovery of the Radio Frequency Hearing Effect suggested that a pulsed
RF carrier could be encoded with an amplitude modulated ("AM") envelope.
In one approach to pulsed carrier modulation, it was assumed that the
"click" of the pulsed carrier was similar to a data sample and could be
used to synthesize both simple and complex tones such as speech. Although
. . . . More |
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A modulation process with a fully suppressed carrier and input preprocessor
filtering to produce an encoded output; for amplitude modulation (AM) and
audio speech preprocessor filtering, intelligible subjective sound is
produced when the encoded signal is demodulated using the RF Hearing
Effect. Suitable forms of carrier suppressed modulation include single
sideband (SSB) and carrier suppressed amplitude modulation (CSAM), with
both sidebands present.
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What is claimed is:
1. A method of encoding an input audio signal a(t) to produce a double
sideband output signal having a .omega..sub.c carrier 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 a(t) to an audio pre-distortion filter with
an As(f) filter function to produce a first output signal a(t)As(f);
adding a very low frequency bias A to the first output signal to produce a
s . . . . More |
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