Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
ACOUSTIC BEACONS
1151281
This lnvention relates to acoustic beacons for objects in oceanic
regions and are to be used primarily~to indicate the position of ~oats
or other objects present below water, for example, after a wreck.
The locating of wrecks to-day is a difficult, time-consuming and
often expensive task. Often it occurs by chance as a result of fishing
operations whereby parts of the wreck are plcked up making it posslble
to determine the position, Active localislng of wrecks can be achieved
by means of acoustlc fish-detection equipment, such as fathometers or
sonars, or by way of side-searching sonars. If the position of the
object sought after is roughly known, underwater television cameras
can also be used.
Hitherto, acoustic beacons or markers have tended to ~e toc expensive
and/or too unrellable in operation after an extended period of storage
under the de~anding condltions prevailing on board ship.
~ nited States Patent Speclfication No, 3,7c3,443 (Irick) dlscloses
underwater sound source assemblies which are ejectably mounted on
rocke*s, aircraft, watercraft, precious cargo or any mobile device that
may travel over water, to facil tate location and recovery of the device
when submerged.
United States Patent Specification No. 3,992,692 (Filer) discloses a
self-contained acoustic beacon activated by a sea-water switch for
providing an lndependent method of locating and recoverlng a floating or
submerged recoverable target.
A main objective of the present inventlon is, therefore, to create a
inexpensive acoustic beacon or marker which, when in a submergea condition,
automatically transmits a localising signal capable of belng picked up
by means of suitable detection equipment. ~ore especially, there is a
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need for an acoustic beacon or marker with a practical
design which permits manufactu~e at a reasonable cost and
storage in a condition of readiness on vessels or objects
which are exposed to sinking in water, without the risk of
functional breakdown.
According to the present invention an acoustic
beacon suitable for use on a boat and arranged to operate
only if the boat is submerged which comprises a pipe-shaped
housing spring-loadedly receiving a battery between a first
end plug sealingly engaging internal walls of said housing
at one end of the latter and contact means, printed ciruit
means disposed between said contact means and a second end
plug sealingly engaging internal walls of said housing at
the opposite end of said housing, a pressure switch arranged
in and projecting outwardly from said second end plug, a
membrane clamped against said second end plug adjacently
outward of said pressure switch and allowing the pressure
from water surrounding said beacon to be transferred to said
pressure switch to switch on the latter once this pressure
exceeds a predetermined limit as said beacon falls in said
water, means for transmitting sound coaxially supported on
the external walls of said housing and towards said opposite
end of the latter and electrically connected to said printed
circuit means to receive signal pulses therefrom when said
printed circuit means is supplied with electric current from
said battery with the switching on of said pressure switch.
This design provides a simple construction with
inexpensive components and, moreover, provides a favorable
radiation effect while being easy to make durable against
conditions prevailing during storage and use.
In order that the invention can be more clearly
understood, a preferred embodiment thereof will now be
described, by way of example, with reference to the
accompanying drawing which is an axial section of an
acoustic beacon.
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Referring to the drawing, the acoustic beacon has
a housing in the form of a pipe 11 made of
corrosion-resistant or surface-treated material. At one end
of pipe 11, there is arranged a battery 12 in the form of
one or more monocells of conventional design. One terminal
of battery 12 forms an abutment against a contact screw 13
which is fixed on a contact piece 14 within the pipe 11.
The other terminal forms an abutment against a compression
spring 15 which is pressed against the battery 12 in order
to hold it fast and provide contact with an end plug 16
which forms a seal against internal walls of pipe 11 by
means of gasket 17, the plug being fastened with two locking
screws 18 which pass through pipe 11.
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Up to the contact piece 14, there are arranged one or more sheets 19
with printed circuits which support electronic parts of the transmitter.
~his sheet can be designed ln a fundamentaLly known manner and will,
1;herefore, not be described further here. Sheet 19 is supported at the :~
other end by an intermediate piece 20 which is held in place by a
second end plug 21. In a manner sLmilar to end plug 16, end plug 21 is
made tight against pipe 11 by means of a gasket 22 and is held fast
by two locking screws 23.
In addition, there is arranged in end plug 21, for example, by screwing,
a pressure switch 24 with an activating means 25 which projects
outwardly of the end of the plug, the pressure switch being fastened
wlth locking nuts 26. me activating means 25 is isolated from the
surroundings by means of a membrane 27 of appropriate material, for
example, rubber, which is held fast on the end plug 21 by means of
clamping ring 28 which is fixed with a series of screws 29. in order
to reduce the risk of wear on the membrane 27 under thc influence of
the activating means 25, there is arranged between the membrane and
means 25 , a pressure plate 33 preferable made of metal or a hard f
synthetic plastics material.
~y means of pressure switch 24, the transmitter on the sheet or
sheets 19 is connected, that is to say is supplied with electric
current so that there are emitted signal pulses of prdetermined form
and frequency via an oulet lead 30.
~ead 30 is connected to a transmitter or transducer 31 composed of
a ceramic material and having the shape of a pipe which is arranged
externally on the p.Lpershaped housing 11 at the membrane end. The
transducer 31 and the external portion of the lead 30 are molded into
an external pipe-shaped block 34 of suitable molding material.
The pressure switch 24 is arranged so that it is activated, that is
to say switched on, when the pressure which acts on the membrane 27
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exceeds a certain threshold value which corresponds to a specified
particular depth.
Such a beacon or marker can first and foremost beused to mark
sunken vessels. However, it can also be used for other purposes, for
example, for marking fishing operations and the like. A natural
application will be in connection with a pressure-registering sensor
so that in addition to givlng position, the transmitter wlll also
indicate depth. As a result, the possibility is open for fishing
boats to utilise the transmitter also to provide information
concerning the depth of the fishing operation. This is relevant,
for example, in purse seining and trauling.
The beacon or marker of the present invention is extremely quick
to operate, the pressure switch starting the +ransmission
instantaneously when the predetermined depth is reached.
The transmitter will thus be an acoùstic transmitter. It can, for
example, send out pulses having a length of the order of magnitude
of 30 ms approximately every 4 seconds. Commercial sonar equipment
will then be able to be used for sounding and detection.
