United States Patent |
5,627,521
|
Olsen
,   et al.
|
May 6, 1997
|
Personal microwave and radio frequency detector
Abstract
A self-contained personal microwave and RF detector, which includes, inter
alia, the housing and associated electronics of a standard hearing aid, is
configured to produce an audible indication to a wearer thereof in
response to electromagnetic fields of dangerously high levels within
predetermined frequency ranges.
Inventors:
|
Olsen; Richard G. (Pensacola, FL);
Forstall; John R. (Pensacola, FL)
|
Assignee:
|
The United States of America as represented by the Secretary of the Navy (Washington, DC)
|
Appl. No.:
|
208248 |
Filed:
|
March 9, 1994 |
Current U.S. Class: |
340/600; 324/95; 324/96; 340/539.1; 381/312; 381/322; 381/328 |
Intern'l Class: |
G08B 017/12 |
Field of Search: |
340/600,539
324/95,96
250/250
381/68,68.6,69
342/896
343/894
|
References Cited [Referenced By]
U.S. Patent Documents
4644330 | Feb., 1987 | Dawling | 340/575.
|
5185802 | Feb., 1993 | Stanton | 381/68.
|
5295191 | Mar., 1994 | Van Vroenhoven | 381/68.
|
Foreign Patent Documents |
0549550 | Jun., 1993 | GB | 340/600.
|
Other References
Electronics Engineers' Handbook, Donald G. Fink & Donald Christiansen, 3rd
dition, Electromagnetic Spectrum (pp. 42-43).
|
Primary Examiner: Hofsass; Jeffery
Assistant Examiner: Lieu; Julie B.
Attorney, Agent or Firm: Spevack; A. D., Garvert; William, Wynn; John
Claims
We claim:
1. In a standard hearing aid configured to normally convert input sound
waves into electrical signals and, in turn, into amplified electrical
signals within the audio frequency range, the standard hearing aid
including a housing, a detachable ear-canal shell operatively attached to
the housing, a microphone operatively attached to the housing and the
detachable ear-canal shell for converting the input sound waves into the
electrical signals within the audio frequency range at an output terminal
of the microphone, an amplifier having an input terminal operatively
connected to the output terminal of the microphone for increasing the
level of the electrical signals within the audio frequency range at the
output terminal of the microphone so as to produce at an output terminal
of the amplifier amplified electrical signals within the audio frequency
range, a battery operatively connected to the amplifier for supplying
power thereto, a volume control operatively connected to the amplifier for
controlling the level of the amplified electrical signals within the audio
frequency range at the output terminal thereof and a loudspeaker
operatively connected to the output terminal of the amplifier for
converting the amplified electrical signals within the audio frequency
range into output sound waves which are amplified facsimiles of the input
sound waves and which are radiated, via the detachable ear-canal shell,
into the ear-canal of a wearer, the standard hearing aid being modified to
improve the reception of input modulated electromagnetic waves within a
predetermined microwave frequency range and eliminating the reception of
the input sound waves to produce a self-contained personal microwave
detector, wherein the modification comprises:
disconnecting the output terminal of the microphone from the input terminal
of the amplifier; and
connecting a wire to the input terminal of the amplifier and through and
outside of the housing such that when the input modulated electromagnetic
waves within the predetermined microwave frequency range are received, an
audible signal is produced whose level and frequency is related to the
modulation of the input modulated electromagnetic waves within the
predetermined microwave frequency range thereby warning a wearer of the
self-contained personal microwave detector of the presence of input
modulated electromagnetic waves within the predetermined microwave
frequency range whose levels are dangerously high.
2. The self-contained personal microwave detector of claim 1 further
comprising a plastic sleeve operatively attached to the housing and the
wire to provide strain relief to the wire.
3. The self-contained personal microwave detector of claim 2 wherein the
wire is an insulated copper wire 5 cm in length.
4. The self-contained personal microwave detector of claim 3 wherein the
predetermined microwave frequency range is 2 MHz to 3 GHz.
5. In a standard hearing aid configured to normally convert input sound
waves into electrical signals and, in turn, into amplified electrical
signals within the audio frequency range, the standard hearing aid
including a housing, a detachable ear-canal shell operatively attached to
the housing, a microphone operatively attached to the housing and the
detachable ear-canal shell for converting the input sound waves into the
electrical signals within the audio frequency range at an output terminal
of the microphone, an amplifier having an input terminal operatively
connected to the output terminal of the microphone for increasing the
level of the electrical signals within the audio frequency range at the
output terminal of the microphone so as to produce at an output terminal
of the amplifier amplified electrical signals within the audio frequency
range, a battery operatively connected to the amplifier for supplying
power thereto, a volume control operatively connected to the amplifier for
controlling the level of the amplified electrical signals within the audio
frequency range at the output terminal thereof and a loudspeaker
operatively connected to the output terminal of the amplifier for
converting the amplified electrical signals within the audio frequency
range into output sound waves which are amplified facsimiles of the input
sound waves and which are radiated, via the detachable ear-canal shell,
into the ear-canal of a wearer, the standard hearing aid being modified to
improve the reception of input modulated electromagnetic waves within a
predetermined microwave frequency range and eliminating the reception of
the input sound waves to produce a self-contained personal microwave
detector, wherein the modification comprises:
removing the microphone from the housing;
connecting an output terminal of a detector diode to the input terminal of
the amplifier;
connecting an output terminal of a miniature microwave amplifier to an
input terminal of the detector diode; and
connecting a wire to an input terminal of the miniature microwave amplifier
and through and outside of the housing so as to improve the reception of
the input modulated electromagnetic waves within the predetermined
microwave frequency range, and such that when the input modulated
electromagnetic waves within the predetermined microwave frequency range
are received, an audible signal is produced whose level and frequency is
related to the modulation of the input modulated electromagnetic waves
within the predetermined microwave frequency range thereby warning a
wearer of the self-contained personal microwave detector of the presence
of input modulated electromagnetic waves within the predetermined
microwave frequency range whose levels are dangerously high.
6. The self-contained personal microwave detector of claim 5 further
comprising a plastic sleeve operatively attached to the housing and the
wire to provide strain relief to the wire.
7. The self-contained personal microwave detector of claim 6 wherein the
wire is an insulated copper wire 7 cm in length.
8. The self-contained personal microwave detector of claim 7 wherein the
predetermined microwave frequency range is 3 GHz to 22 GHz.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a personal microwave and radio frequency
(RF) detector. More particularly, the present invention relates to a
self-contained personal microwave and RF detector which can be worn in a
user's ear and provides an instantaneous audible warning of dangerously
high electromagnetic fields.
2. Description of the Prior Art
Electromagnetic radiation hazards to personnel are presently detected by
survey of an area with handcarried instruments, or instruments which are
fastened to a user's clothing, to detect whether electromagnetic radiation
in the area exceeds permissible exposure limits. For example, U.S. Pat.
No. 5,168,265 to Aslan discloses a personal electromagnetic radiation
monitor worn by a user who may be exposed to potentially harmful levels of
electromagnetic energy in the 2-18 GHz frequency range. The Aslan monitor
has a two piece housing with a resilient clip mounted on a back wall of
the housing for allowing a user to carry the monitor on a belt or shirt
pocket. A pair of mutually orthogonally disposed antenna elements receive
electromagnetic energy for detection.
When detected electromagnetic energy is above a preset threshold, the Aslan
monitor actuates a periodic audible warning tone with an increasing
repetitive rate as the level of exposure increases. The Aslan monitor also
includes an ear plug assembly allowing the monitor to be used in high
noise environments. A hollow tube, having a pneumatic ear plug mounted on
one, is coupled to the monitor housing. A warning tone produced by the
monitor is transmitted to a user's ear through the tube of the ear
assembly.
U.S. Pat. No. 4,539,567 to Brewer discloses another small personal
microwave monitor device attached to the clothing of a user and adapted
for use from 2-15 GHz. The Brewer monitor provides field alarms, field
monitors, accumulated dose alarms and integrated dose monitoring of
microwave radiation. Brewer discloses a variety of antenna configurations
for permitting use at other frequencies, for example, between 0.9-2 GHz as
well as 15-30 GHz.
U.S. Pat. No. 4,301,406 to Shriner discloses a microwave detector
conveniently carried or worn by a user. One embodiment of the Shriner
detector includes a very low-wattage gaseous-discharge lamp having
electrodes connected to the ends of a pair of antenna wires. A second
embodiment of the Shriner detector shaped like a fountain-pen. Yet another
embodiment shaped like a bracelet or finger ring.
U.S. Pat. No. 4,032,910 to Hollway et al. discloses a portable detector for
producing an alarm when placed in a microwave field having a power density
greater than a predetermined limit. One embodiment of the Hollway detector
includes a dipole antenna connected to filament leads of an incandescent
lamp mounted on a card which can be pinned to the lapel of a user. An
alarm is signalled by a glow from the lamp filament.
While these and other known microwave radiation detectors provide an
indication of detection of a microwave field, there is still a need for a
microwave and radio frequency (RF) detector which provides an
instantaneous acoustical warning of dangerously high electromagnetic
fields, permitting workers to perform their normal tasks while wearing
protective equipment such as helmets, goggles, ear muffs, etc. Further,
there is a need for a simple, compact, self-contained microwave and RF
detector having long battery life and operates over an extremely broad
band of frequencies, for example, 2 MHz to 22 GHz. Additionally, there is
a need for providing a user with immediate knowledge of the presence of
radar or RF transmitting devices operating in the vicinity of the user.
Existing radar detection devices are comparatively large, externally worn,
that is, worn on the user's clothing, and limited to operation at
microwave frequencies.
SUMMARY OF THE INVENTION
The present invention provides these and other advantages by providing a
self-contained electromagnetic radiation detector apparatus including an
antenna for producing a received electromagnetic radiation signal and a
detector, coupled to the antenna, for producing an audible indication in
response to the received electromagnetic radiation signal, wherein the
detector fits into an ear canal of a user. Preferably, the detector
includes a body and an amplifier portion of a hearing aid. The audible
indication produced by the detector is related to a modulation of the
received electromagnetic radiation signal, and when the received
electromagnetic radiation signal is a continuous wave, the audible
indication is an audible quieting produced by the detector.
According to one aspect of the present invention, the radiation detector
apparatus includes a detector diode, having a first terminal coupled to
the antenna and a second terminal coupled to the detector, for detecting
and providing the received electromagnetic radiation signal to the
detector. According to another aspect, the radiation detector apparatus
further includes an amplifier having an input coupled to the antenna and
an output coupled to the first terminal of the detector diode, for
amplifying the received electromagnetic radiation signal.
Other features of the present invention are that the detector apparatus
includes a volume control for controlling a volume of an audible
indication and an acoustical cavity for storing the antenna, and that the
antenna includes a strain relief.
The present invention also provides a self-contained electromagnetic
radiation detector including a body having an ear canal shell for fitting
into an ear canal of a user, an antenna for producing a received
electromagnetic radiation signal, and an amplifier, disposed within the
body and coupled to the antenna, for producing an audible indication in
response to the received electromagnetic signal. Preferably, the ear canal
shell is detachable. A detector diode, having a first terminal coupled to
the antenna and a second terminal coupled to the amplifier, can be
included for detecting and providing the received electromagnetic
radiation signal to the detector. Further, an amplifier, having an input
coupled to the antenna and an output coupled to the first terminal of the
detector diode, can be used for amplifying the received electromagnetic
radiation signal.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention can be more fully understood from the following detailed
description of the invention when considered in conjunction with the
accompanying Figures which form a part of this application, in which the
same components are indicated with the same reference numerals, and in
which:
FIG. 1 shows a perspective view of a personal microwave and RF detector
according to the present invention;
FIG. 2 shows a schematic block diagram of a first embodiment of the present
invention; and
FIG. 3 shows a schematic block diagram of a second embodiment of the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, the present invention is a self-contained personal
microwave and radio frequency (RF) detector 10 for providing a user with
an instantaneous audible warning when modulated electromagnetic fields of
dangerously high levels in the frequency range of 2 MHz-22 GHz are
detected. The detector 10, worn in the ear canal, allows a user to perform
normal duties while being warned of high levels of beamed, reflected or
reradiated energy that might unintentionally occur in a workplace. A first
embodiment schematically shown in FIG. 2 provides detection of microwave
and RF signals covering a frequency range of about 2 MHz to about 3 GHz. A
second embodiment schematically shown in FIG. 3 provides detection of
microwave and RF signals covering a range of about 3 GHz to 22 GHz.
Additionally, the present invention has applications where a user requires
immediate knowledge of the presence of radar or RF transmitting devices
operating in the vicinity.
When radiation is detected by the present invention, an audible tone is
produced which is related to the modulation of the detected radiation.
That is, the audible tone is related to, for example, a pulse repetition
interval (PRI) of a microwave signal. The shorter the PRI of the detected
signal, the higher the frequency of the tone produced. Presence of a
continuous wave (CW) signal can also be detected and distinguished from a
modulated signal by an audible quieting in the output of the detector. In
one embodiment of the present invention, sensitivity of the detector
circuitry is increased allowing detection of relatively weak fields for
determining, for example, presence of radar signals at great distances.
Referring again to FIG. 1, the self-contained personal microwave and RF
detector 10 uses a housing 12 and associated electronics (not shown) of a
standard hearing aid 14, such as a Bausch and Lomb hearing aid model
"Sound Choice" for example. For purposes of the present invention, the
associated electronics (not shown) comprises a microphone having its input
operatively attached to and within an acoustic cavity 16 of the housing
12. The output terminal of the microphone (not shown) is operatively
connected between a volume control 18, which is operatively attached to
the housing 12, and the input terminal of an amplifier (not shown). The
output of the amplifier is operatively connected to a transducer (not
shown) but also operatively attached to and within the acoustic cavity 16
of the housing 12. A battery (not shown) for powering the amplifier is
operatively connected thereto and is operatively attached to a battery
compartment door 20 of the housing 12. The housing 12 of the hearing aid
14 further includes a detachable ear-canal shell 22 which is preferably
supplied in a plurality of sizes for fitting the ear canals of different
users. The battery (not shown) is changed by opening the battery
compartment door 20. The battery compartment door 20 and the battery (not
shown) serve as an on/off switch by permitting the insertion and/or
removal of the battery. The volume of sound from the transducer (not
shown) of the associated electronics (not shown) is controlled, inter
alia, by volume control 18. In use, the self-contained personal microwave
and RF detector 10 is fitted into a user's ear canal, as shown in FIG. 1.
In the first embodiment of FIG. 2, the output terminal of the microphone
(not shown) of the associated electronics (not shown) of hearing aid 14 is
disconnected from the input terminal of the amplifier (not shown) of the
associated electronics (not shown) and replaced with a short length of
insulated copper wire 24. The insulated copper wire 24 serves as an
antenna for receiving hazardous level microwave and RF signals. The
insulated wire 24 is rolled-up (at 7) in acoustical cavity 16 when the
self-contained personal microwave and RF detector 10 is not in use. The
length and size of the insulated copper wire 24 can vary depending on
specific applications. For example, a 5 cm length piece of #30 AWG
insulated copper wire or a 4 inch length of #33 AWG insulated copper wire
can be used. The insulated copper wire 24 passes through plastic sleeve 4
which provides strain relief. Plastic sleeve 28 is preferably 2 cm in
length. In operation, the insulated copper wire 24 can be bent for optimum
orientation, depending upon the particular application, for receiving
electromagnetic radiation.
In the second embodiment of FIG. 3, the microphone (not shown) of the
associated electronics (not shown) of hearing aid 14 is removed and
replaced by a zero-bias Schottky detector diode 30, such as an HSCH-3486,
for example. The output terminal of the detector diode 30 is coupled to
the input terminal of the amplifier (not shown) of the associated
electronics (not shown) of the hearing aid 14. In this embodiment, an
insulated copper wire 24', i.e., a 7 cm length of #30 AWG copper wire,
serves as an antenna and is connected to the input terminal of a miniature
microwave amplifier 32, which, in turn, has its output terminal connected
to the input terminal of the detector diode 30, aforementioned. The
miniature microwave amplifier 32 is powered by the battery (not shown).
The insulated copper wire 24' also passes through plastic sleeve 28 (see
FIG. 1) for strain relief. Miniature microwave amplifier 32, detector
diode 30 and the insulated copper wire 24' allow detection of relatively
weak fields for determining the presence of radar or other modulated RF
signals at great distances.
Those skilled in the art, having the benefits of the teachings of the
invention as described herein, can effect numerous modifications therein.
These modifications are to be construed as being encompassed by the
appended claims.
* * * * *