CA1084617A - Iceberg detector - Google Patents
Iceberg detectorInfo
- Publication number
- CA1084617A CA1084617A CA266,495A CA266495A CA1084617A CA 1084617 A CA1084617 A CA 1084617A CA 266495 A CA266495 A CA 266495A CA 1084617 A CA1084617 A CA 1084617A
- Authority
- CA
- Canada
- Prior art keywords
- signal
- pulse
- counter
- output
- memory
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/02—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems using reflection of acoustic waves
- G01S15/06—Systems determining the position data of a target
- G01S15/08—Systems for measuring distance only
- G01S15/10—Systems for measuring distance only using transmission of interrupted, pulse-modulated waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/88—Sonar systems specially adapted for specific applications
Landscapes
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Computer Networks & Wireless Communication (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
Abstract
Abstract of the Disclosure The present invention utilizes the steps of lowering an operative ultrasonic pulse transmitter and receiver to the sea floor in the path of a moving iceberg or ice pack, then bouncing ultrasonic pulses against the under-surface of the passing iceberg or an ice pack, and receiving the reflected ultrasonic pulses from the under surface. The time difference between the transmitted and received pulse provides a distance indication of the height of the bottom of the iceberg above the sea floor.
Description
This invention relates to a syst~m for de~ermining the heiyht above -the sea bed of the bottom of an ic~berg or ice ridge of an ice pack. -With increased sub~sea oil exploration activity in the portions of the oceans which are either covered by ice pack or which experience iceberg activity, it has become highly important to avoid accidents caused by the ice. As an example, where an under-sea oil well-head exists, an iceberg, having a depth which allows it to scrape the well-head can break -the well open, allowing oil to spill into the sea. ~learly wide-spread pollution and damage will be caused. Consequently, it is important to know how deep an iceberg reaches, relative to the ocean bottom, in order that tactical steps be taken in time to tow the iceberg to a safer part of the sea, or in order that other steps could be taken to minimize damage to the under-sea installatlon.
, . . . .
While estimates of the depth of icebergs below the surface of the sea have been made on the basis o~ above water .
shape, the reliability of such estimates have been found to 20 be poor- The height to draft ratios for icebergs in various locations have been found to vary very widely.
In addition, the hazards of measuring the draEt of iceberys has heen ~ound to be substantial. As an illustration, the ice masses are usua~ly thousands of -times heavier than the measurement ship itself, and the measurement ship is o~ten ¦ operating in extreme sea condi-tions. For instance, a 1 , . .. .
1 well-head rnay have to be protected from an iceberg in a JI condition of one hundred mile an hour winds, and over six-ty foot ~,laves The approach of a measuring ship to an iceberg which may be decayed and subject to calving is extremely ,1 dangerous.
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~ s discussed by Q.R. ~obe in "PII~SICAL PROPERTIES OF
ICEBERGS" Third ~nternational Conference On Port and Ocean Engineering Under Arctic Conditions, Fairbanks, Alaska, 1975, in working with the U.S. Coast Guard Robe used a transit sonar to measure the drafts of a number of icebergs in the Davis Straight. This procedure required a transducer supported in an outboard position one meter below the water line. The sonar provided a beam of one-half degree in the horizontal and fifty-two degrees in the vertical. Measurements were required with the ship very close to the iceberg, and are made continuously as the ship spirals around and away from the iceberg, until the slant range distance exceeds the range of the sonar. This system requires an assumption that -the last slant angle return comes from the deepest portion ;-of the iceberg, which is not necessarily the case. In addition, the requirement that the ship start its measurement close to the iceberg is highly undesirable, particularly in the often extreme weather conditions such as that noted above.
Clearly, it is desirable to provide a system for measuring the depth of icebergs which does not re~uire -the ship to approach the iceberg.
Until now, it has been virtually impossible to detect with reasonable reliability the height above sea bottom of an iceberg or ice ridge of a slow-moving ice pack, without danger to the measuring ship. The present invention provides such a system.
In addition, the present invention provides a system by ~7hich the instantaneous velocity o~ an iceberg can be measured. Prior to this invention, there was no way of obtaining the icebery's instantaneous velocity; rough radar positioning has provided averages over intervals of at least an hour, and usually a longer time. This also assumes a straight line trajectory o~ the iceberg. In addition, the
, . . . .
While estimates of the depth of icebergs below the surface of the sea have been made on the basis o~ above water .
shape, the reliability of such estimates have been found to 20 be poor- The height to draft ratios for icebergs in various locations have been found to vary very widely.
In addition, the hazards of measuring the draEt of iceberys has heen ~ound to be substantial. As an illustration, the ice masses are usua~ly thousands of -times heavier than the measurement ship itself, and the measurement ship is o~ten ¦ operating in extreme sea condi-tions. For instance, a 1 , . .. .
1 well-head rnay have to be protected from an iceberg in a JI condition of one hundred mile an hour winds, and over six-ty foot ~,laves The approach of a measuring ship to an iceberg which may be decayed and subject to calving is extremely ,1 dangerous.
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,,',','."''"",. ." ",'', ' '" ,, ' ~ , ,' ., , ,'' , ,: ' ,,;:, ". . . . . ..
---` 108~
~ s discussed by Q.R. ~obe in "PII~SICAL PROPERTIES OF
ICEBERGS" Third ~nternational Conference On Port and Ocean Engineering Under Arctic Conditions, Fairbanks, Alaska, 1975, in working with the U.S. Coast Guard Robe used a transit sonar to measure the drafts of a number of icebergs in the Davis Straight. This procedure required a transducer supported in an outboard position one meter below the water line. The sonar provided a beam of one-half degree in the horizontal and fifty-two degrees in the vertical. Measurements were required with the ship very close to the iceberg, and are made continuously as the ship spirals around and away from the iceberg, until the slant range distance exceeds the range of the sonar. This system requires an assumption that -the last slant angle return comes from the deepest portion ;-of the iceberg, which is not necessarily the case. In addition, the requirement that the ship start its measurement close to the iceberg is highly undesirable, particularly in the often extreme weather conditions such as that noted above.
Clearly, it is desirable to provide a system for measuring the depth of icebergs which does not re~uire -the ship to approach the iceberg.
Until now, it has been virtually impossible to detect with reasonable reliability the height above sea bottom of an iceberg or ice ridge of a slow-moving ice pack, without danger to the measuring ship. The present invention provides such a system.
In addition, the present invention provides a system by ~7hich the instantaneous velocity o~ an iceberg can be measured. Prior to this invention, there was no way of obtaining the icebery's instantaneous velocity; rough radar positioning has provided averages over intervals of at least an hour, and usually a longer time. This also assumes a straight line trajectory o~ the iceberg. In addition, the
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--` ~OB~ Lq surEace based techni~ue requires that the ship rnove along withthe target iceberg. In the present method, the transducer acts as a fixed reference and therefore provides the trans t time for the passage of the iceberg. The velocity of the iceberg is calculated as the above-water length divided by the transit interval. Since the surface of the water from below is an almost ideal ultrasonic reflector, the forward and rear edge of the iceberg can be accurately determined as it passes over the transducer. -~
From the determination of draft and velocity, the momentum and kinetic energy can be easily calculated.
The kinetic energy reading thus may be used to dètermine its impact effect .
In addition, the center of mass can be calculated, which will allow a towin~ hawser to be applied to the iceberg at a position allowing the direction of force to be directed through the center of mass. Prior to this, certain icebergs could not be towed as the hawser slipped over the iceberg, -or caused the iceberg to calve. Accordingly, this invention ;
can be used as a tool prior ko towing operation of an iceberg.
Basically/ the present inven-tion utilizes the steps of lowering an operative ultrasonic pulse transmitter and receiver to the sea floor in the path of a moving iceberg or ice pack, with the transducer of the transmitter and receiver facing upwardly, then bouncing ultrasonic pulses against the under-surface of the passing iceberg or an ice pack, and receiving the reflected ul*rasonic pulses from the under surface. The time difference between the transmitted and received pulse provides a distance in-lication of height above the sea floor~ As the iceberg passes, an indicatlon of the minimum distance is obtained. The transmitted pulses can of course be scanned in strips across ths iceberg as it passes, in order to obtain an lndication of the degree
--` ~OB~ Lq surEace based techni~ue requires that the ship rnove along withthe target iceberg. In the present method, the transducer acts as a fixed reference and therefore provides the trans t time for the passage of the iceberg. The velocity of the iceberg is calculated as the above-water length divided by the transit interval. Since the surface of the water from below is an almost ideal ultrasonic reflector, the forward and rear edge of the iceberg can be accurately determined as it passes over the transducer. -~
From the determination of draft and velocity, the momentum and kinetic energy can be easily calculated.
The kinetic energy reading thus may be used to dètermine its impact effect .
In addition, the center of mass can be calculated, which will allow a towin~ hawser to be applied to the iceberg at a position allowing the direction of force to be directed through the center of mass. Prior to this, certain icebergs could not be towed as the hawser slipped over the iceberg, -or caused the iceberg to calve. Accordingly, this invention ;
can be used as a tool prior ko towing operation of an iceberg.
Basically/ the present inven-tion utilizes the steps of lowering an operative ultrasonic pulse transmitter and receiver to the sea floor in the path of a moving iceberg or ice pack, with the transducer of the transmitter and receiver facing upwardly, then bouncing ultrasonic pulses against the under-surface of the passing iceberg or an ice pack, and receiving the reflected ul*rasonic pulses from the under surface. The time difference between the transmitted and received pulse provides a distance in-lication of height above the sea floor~ As the iceberg passes, an indicatlon of the minimum distance is obtained. The transmitted pulses can of course be scanned in strips across ths iceberg as it passes, in order to obtain an lndication of the degree
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of irregularity of the bottom of the iceberg.
In the preferred embodiment of the invention, the s transmitted pulse and the first-received echo pulse are stored in an electronic memory. The apparatus is recovered after passage over of the iceberg, and the memory is activated and cleared by reading out the stored signals. A digital readout observable through a window in the apparatus housing can provide the output reading, which is then recorded manually.
Of course the information can be accessed, if s desired, through a connector, and transferred to another printing device on-board ship for a permanent record. ¦~
:
In another embodiment, the information is stored I
on the tape of a tape recorder. Since a greatly increased s ~ memory capacity at relatively small expense is obtained by ; use of the tape recorder, the employment of this form of the invention at the bottom of the sea is highly useful for recording-the distance above the bottom of the sea of the under side of a slow-moving ice pack, since the memory 20 capacity allows deployment for a long period of time. The height above the sea bottom of low-lying ice ridges can accordingly be determined.
In a third embodiment, there is no memory or other storage capability in the apparatus, and a transmit and the echo pulse, upon generation and reception respectively, are transmitted at a different ultrasonic frequency to a hydrophone which is hung at the end of a cable from the side of a ship, waiting a safe distance beside the iceberg to he measured.
Processing, storage (if desired) and display of the ice 39 undersurface height signals above the sea bed, in this case, are obtained aboard ship.
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01 More particularly, the inventive method of determining 02 the height above the sea floor of the lower extremity of an 03 iceberg or ice pack is comprised of the steps of lowering an 04 ultrasonic pulse transmitter and receiver to the sea floor, with ;~
05 a transducer of the transmitter and receiver facing upwardly, in 06 front of a moving iceberg or ice pack, and then bouncing ~07 ultrasonic pulses against the undersurface of a passing iceberg 08 or icepack. The reflected ultrasonic pulses from the 09 undersurface are received, and signals corresponding to the transmitted pulse and the first reflected ultrasonic pulse 11 following the transmitted pulse are relayed to a hydrophone 12 connected to a receiver by a cable hung from the receiver at the 13 surface of the sea. The time difference between the transmitted ~14 and received pulses is recorded, and the time between the transmitted and the first corresponding received, reflected pulse ~16 from the bottom surface of the iceberg or ice pack is 17 determined. The transmitter and receiver are retrieved from the ~18 sea floor after the iceberg or ice pack has passed over.
,;19 In general, the inventive apparatus is comprised ~23 ~24 :1:
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108~ 7 Ol of an ultrasonic underwater transducer means, and pulse generator 02 means connected to the transducer means for applying to the 03 transducer means regular pulses each comprised of an ultrasonic 04 frequency signal. A first counter is provided, as well as means 05 for applying pulses to the counter, representative of 06 predetermined distance of clearance increments. Means is also ~07 provided for applying a representation of the transmitted pulse 08 to the data counter for enabling counting by the counter of the ~09 clearance distance increment pulses ~ circuit applies a ~lO received pulse reflected from the ice undersurface from the 11 transducer means to the counter, for stopping the count of the 12 counter. Means connected to the counter then provides for 13 reading out a signal representative of the count on the counter, 14 whereby a corresponding proportionate distance between the transducer and the bottom of the ice surface can be determined.
16 Remotely controlled means is met for deployment and recovery of ~17 the apparatus from the sea floor.
~l8 A more detailed description of the invention will be 19 obtained by reference to the description below~ and the following , drawings, in which:
21 Figures lA and lB show sections of the sea surface with 22 the inventive apparatus in deployment;
23 Figure 2 shows a front elevation view of the apparatus ~,24 housing;
~25 Figure 3 is a basic block diagram of the invention;
26~ Figure 4 is a more detailed block diagram of the 27 invention;
28 Figure 5, which i8 out of its normal order on the same 29 sheet as Figure 3 shows how Figure~ 6, 7, 8 and 9 are to be placed together; and 31 Figures 6, 7, 8 and 9 together are a detailed schematic -32 diagram of the invention.
33 Turniny irst to Figure lA, an icebery l is shown 34 floating in the sea 2 above the surface of the sea floor 3.
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., -` ~06~;17 In the event the iceberg is large enough, it will scour the bottom of the sea floor, damaging installations which may be located in its path.
In two of the embodiments of this invention, the apparatus is deployed on the sea floor in the path of an oncoming iceberg after being turned on by a ship. The apparatus 4 has an ultrasonic transducer, such as a hydro-phone, facin~ with its maximum transmitting angle vertically toward the surface of the sea. The transmitted ultrasonic 10 pulses will hit the bottom of the iceberg as it passes thereover, and will be reflected back to the apparatus. The transducer picks up the first reflected echo signal and -stores both the transmitted and first reflected echo signal .~
in an electronic memory, or on recording tape. Preferably, however, the information stored will be a representation of -~ the time lapse between the transmitted and first received echo.
After passage of the iceberg, the apparatus 4 is ':~i . .
, retrieved by releasing ballast by remote control and the ;! 20 content of the memory or of the tape recording is read out.
By this means, the distance above the sea floor of the lowest e~tremity of the iceberg can be determined, since time between pulses is directly correlatible into distance, knowing the velocity of sound in water. Should the distance be dangerously small, evasive steps can be taken to move the iceberg away from its dangerous route.
Figure lB depicts an iceberg 1 floating in the sea 2 with a further embodiment of the apparatus ~ deployed on the sea floor 3.
In this embodiment, as with the embodirnen-t of Figure lA, ultrasonic pulse~ are transmitted to the bottom ~f the icebery and are reflected and received by the apparatus.
~owever, in this case a representation oE the transmitted ,, ~L08~
pulse and received reflected pulse are transmit-ted on a different frequency to a hydrophone 5, deployed beside the iceberg at the end of a cable hung from a ship 6. The ultrasonic frequency used by the apparatus 4 to measure the iceberg can usefully be 42 Khz, and -the frequency of transmission to hydrophone 5 can be 25 Khz. Storage and/or reading of the sea bed clearance data signals will be done on board ship.
Figure 2 shows the mechanical assembly of the inventive apparatus. A transducer 7 such as an ultrasonically responsive hydrophone is located at the top of an aluminum case 8, the transducer being protected from damage by an open grill frame 9. The transducer can be similar to type FM-21/22 manufactured by Furuno Corp. A flotation cylinder -~ l0 encloses and surrounds the aluminum case 8 below the ;~ .
transducer 7. The flotation cylinder can be made of a synthetic foam, enclosing bubbles of air or other gas.
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Below 1he bottom of the flotation cylinder is a hermetically sealed window ll, for viewing an internal digital display.
A remote controlled release unit 12 such as Model 1080 manufactured by Inter Ocean Corp. holds a ballast block - 13 tethered to the bottom of case 8. The operation of the release unit is well-known, and its structure does not form part of this invention. The ballast block 13 can be released by ultrasonic remote control signals from the surface ship, by a timed release, or the like. The ballast block is of sufficient weiyht to cause the entire assembly to drop to the bottom of the sea when deployed. The flotation cylinder keeps the aluminum case upwardly directed, with the transducer 30 facing the surface of the sea. Upon rele~se of the ballast 1 block 13 by the release unit 12, the ~lotation cylinder will -~cause the released assembly to rise -to the surface, for _7_ /
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-`` iO~ 7 recovery of the apparatus. ~ flag or other ~rking structure is then deployed in a well-known manner, whereby the assembly can be picked up by a ship at the surface.
he buoyancy provided by the flotation chamber should obviously be such as to be able to raise the entire assembly, when the ballast block 13 has been released.
The system is preferably negatively buoyant by approximately twenty-five pounds on descent. As the ; capsule reaches ten meters depth, a pressure operated switch (not shown) activates the apparatus and transmission of the ultrasonic signal and recording begins. The capsule is designed to have minimum drag in both directions so that it reaches a terminal velocity quickly. Once the iceberg has passed, the capsule releases the anchor which allows the capsule to rise quickly to the surface. Flasher and - radio beacons of well known construction should mark the .1 -~ location for quick recovery by ship.
~, please refer now to Figure 3 and the following general description of the electronic por-tion of the apparatus.
~ pulse generator 14 provides pulses of ultrasonic ~ energy, such as at 42 Khz, for outward transmission and i~ reflection from the bottom surface of an ice pack or iceberg.
This signal is applied to the input of a power ampliEier 15, ~,~ the output of which is applied to ultrasonic transducer 16.
A typical pulse repetition rate is 12 pulses per minute, each pulse being 500 microseconds long, the output pulse power to the transducer being preferably about 100 watts.
The received reflection pulse received by the transducer 16 is applied to one of the two inputs oE a J-K
1ip-flop 17, the output o~ whic~h is connected to the input of a data counter 18, having binary coded decimal ~BCD) output terminals~
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The outpu-t of pulse ~enerator 14 is also connected -to the second input of Elip-flop 17. When a pulse to be ; transmitted is initiated in pulse generator 14, the flip-flop is set to provide an output signal therefrom, and when a return echo from the bottom surface of the ice is rec~ived, the flip-flop is reset, cutting off the output therefrom.
To cause the data counter 18 to count after the flip-flop has been set by the transmit pulse a clock source applies regular pulses on conductor ~0, which causes the 10 constant output level from flip-flop 17 to be pulsed. ;
Accordingly, as long as an output of flip-flop 17 exists, (i.e., during the -time between transmitted and received ~
pulses) the data counter will count. -A preferred cycle period is the equivalent of .2 l meters travel of sound in water. Accordingly, the total ~-i count by counter 18 upon reception of the reflected echo ;
~ pulse will time the distance of transducer 16 from the ., :
, nearest ice surface. The cycle period scaled for .2 meters is the time required for the sound to trave].-to an object .1 meters distant and return.
In the event the embodiment shown in Flgure lB is provided, the data counter can be deleted, and the ou-tput of the flip-flop 17 applied to an ultrasonic transmitter (not shown) of different frequency than the frequency transmitted by transducer 16, as noted earlier. The second ultrasonic frequency can be turned on and off by the operation of the flip-flop, allowing hydrophone 5 to receive an ultrasonic pulse having length proportionate to the transducer 16 lower ice surface dis-tance.
Alternatively, a pul~;e corresponding to the trans-mitted pulse can be sent to hyclrophone 5, Eollow0d by a pulse corresponding to the return echo pulse, by a transmitter ~ 9_ .
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lVl~6.~7 connected in place of flip-~lop 17. The time between pulses will be interpreted by receiving circuitry on board ship as propor-tionate to the aforenoted ice to transducer distance.
In the embodiment corresponding to Figure lA, however, the data from the scD output terminals 19 of data counter 18 will be applied to data input terminals of a . -memory 21. An address counter 22 has its input connected to , the output of pulse generator 14, having an output count signal indexed each time a transmitted pulse is generated. . .
10 The output of the address counter 22 is applied to address input terminals 23 of memory 21. :
. Each time a transmitted pulse is generated, the address counter generates a new memory address signal at its - - ,: -output, designating to memory 21 the location where the next data signal is to be stored. The data counter 18 counts , sequentially.under influence of the 0.1 meter clock pulses, -and stops counting upon reception of a return echo. The count signal at the output terminals 19 is applied to the :
data input terminals of memory 21, and stbred at the address . : .
~2 20 location designated by the address counter 22.
The pulse generator 1~ then generates another .~ transmitted pulse, which indexes the address counte.r 22 to designate the next memory 21 address location, and the entire sequence repeats.
¦~ A set of readout terminals 24 of memory 21 pro-vides an output signal to digital readout 25, which can be a digital light-emitting diode display,. a paper tape print mechanism, etc.
~: rJhile the above has been a description o~ the hasic structure and operation o~ the appa~atus, more detail will be apparent with the following description with reference to the block diagram of Figure 4.
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`` 10t~ 7 Transmit pulse gcnerator 26 is provided with a remotely operated start switch ~7. Preferably, the start swi-tch is magnetically operated from outside the apparatus housing through the wall of the housing, whereby hermetic sealing can be retained,-yet the transmitter initiated by passing a magnet adjacent the switch. The power circuit (not shown) will be similarly turned on.
The output level is applied to an astable m~ltivibrator which generates a one second period output wave. The output signal is applied to a pulse rate counter 28. A reset signal is applied to the rate select circuit.
The output of the rate select counter is connected to one shot multivibrator 31, to provide accurate square waves of predetermined period as an output signal.
A clock 32 provides a signal to a decoding circuit 33, whereby a 42 Khz square wave output signal is produced.
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This signal is applied to power amplifier 34 along with the output pulses of multivibrator 31. The output pulses are .
applied to the power amplifier 34. The power amplifier 34 ` 20 thus provides a 42 Khz output signal during periods of the pulses of multivibrator 31.
The output signal of power amplifier 34 is passed through impedance matching trans~ormer 35, and is applied -to the terminals of transducer 36. Accordingly, there will be produced yowerful bursts o~ 42 Khæ energy in pulses deter-t mined by pulse generator 26 and rate select counter 28.
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- The first return echo received by transducer 36 after each transmitted pulse is applied -to variable gain ampli~ier 37. In order to reduce the swamping action which 30 the high powexed transmitted pulse would have on the amplifier 37, a limiter 38 is connected in the return signal path from transducer 36.
The output of variable gain amplifier 37 is applied . " .
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to Schmi tt -trigger 39 to produce a properly formed square - . .
wave, which square wave is applied to the K input of a J-K - -flip-flop 40. The J input of flip-flop 40 is connected to '~
the output of one shot multivibrator 31.
The output of flip-flop 40 is connected to one of the inputs of NAND gate 41, which has its output connected -to the first portion of a group of sCD counters 42a, 42b, ~
42c, and 42d. These counters are serially cascaded in a ' well-known manner. The output of counter 42a is binary ''' 10 coded decimal (sCD) in tenths of a meter, the output oE
- counter 42b B CD in units of a meter, the output of counter 42c BCD in tens oE meters, and the output of counter 42d BCD '~
in hundreds of meters. Rese't pulse source 30 is connected' ~
to each of the counters 42, as'well as to flip-flop 40. ~ -The output of the 42 Khz decode circuit 33 is applied to a divider circuit 43, in which sequential output ' ' ;' pulses are provided at intervals corresponding to the time taken for an ultrasonic impulse in water to travel 0.2 meters. The 0.2 meter output pulses are applied from the 20 output of divider circuit 43 to a second input of NAND gate 41.
~i ' Since it is desired to increase -the gain of the receiver portion of khe'circuit with increasing distance of J the reflection surface from the transducer to accommodate ~, reception o weaker signals, it is preferred to increase the s~ gain of variable gain ampliier 37 with the delay in reception of a reflection signal from the -time of emission of a transmitted ' pulse. An arbitrary but useful distance of switching was utlized at 87 meters, 174 meters and 261 meters, the latter '~ 30 two figures being the second and third multiples oE 87 ~'~ meters ; The 87 meter point is obtained by a signal on counters 42b and 42c at the 1, 2, 4 and 80 meter output , .,,.,~- , , .
, lO~ lq terminals, which added together, provide a signal at 87 meters and multiples thereof. These terminals are connected to the input of variable gain counter 44, which has its output connected via bus 45 to variable gain control terminals of variable gain amplifier 37. Accordingly, each time the counters 42 reach the 87 meter count or multiples thereof, 1 ~.
variable gain counter 44 will index, switching the gain of variable gain amplifier 37 to successively higher values.
A semi-conductor 12,288 bit memory containing individual memory chips 46 a - 46 l is provided to store the distance count BCD output ~rom counters 42a - 42d. Each of the chips has a data input lead which is connected to one of (~ the output leads of counters 42a - 42d.
il An address counter 47 is provided, having an input connected to the output of one shot multivibrator 31. Each time a transmlt pulse appears at the output of multivibrator ! ~ 31, the address counter 47 will be caused to advance one digit. The address counter output terminals 48 are connected to all memory chips 46 in parallel, Consequently, data applied to the individual chips from counters 42a - 42d will be stored ak the address locations designated by address counter 47, in the memory.
A co~lmon write input lead 49 of the memory is con-neGted via one shot multivibrator 50 from the output of Schmitt trigger 39. Consequently, a write enable pulse will appear ~7ith the reception of a received reflected pulse, ;
causing the me~ory at that time to store the data already counted by counters 42a - 42d Eollowing the transmit pulse.
The specific circuit of the pre~erred embodiment , 30 will now be described with reference to Figures 6, 7, 8 and .' 9 A transducer 51, such as a hydrophone transponder ''',~, ,." . . ,, .. :,., : ., ,, ~ . . . . . .
','',,,'',, " ,,','" ,,,',," ' ' '" ' ' ' 6~q is connected ~hrough isolatiny resistors 52a and 52b to impedance matching transformer 53. The primary of transformer ~ -53 is shunted by opposite polarity diodes 54a and 54b which perform a limiting function to keep excessive amplitude signals, such as the transmitted pulses, from overloading the receiver. ~ -The secondary winding of transformer 53 is coupled -~
to the input of high gain, high slew ra-te differential amplifier 55, such as National Semiconductor type LM218, which has the series of capacitor and resistor 56a and 56b connected from its output to one of its input terminals, in parallel with resistor 56c, which passive components are ~ `
provided to increase the alrqady high slew rate.
- The output of differential ampli~ier 55 is capaci-tively coupled to a variable gain amplifier comprising linear amplifier 57 which can be the same type as amplifier ~ 55, which is shunted by the parallel circuits of capacitor `Yj 58a in series with resistor 58b, in parallel with analog i~ switch 59. Input signals to the analog switch 59 at leads ;j 20 VGl, VG2, VG3 and VG4 establish one or other of the parallel feedback resistors 60a, 60b, 60c or 60d, changing -the gain o the amplifier logarithmically.
The output signal o~ ampliier 57 is applied to a ., , multiple feedback band pass aative filter 61 using National Semiconductor type LM218 ampliier, which filter has been j designed to reject noise outside a pass band between 38 and 45 Khz, passing signals at its tuned frequency o~ 42 Khz.
The ou~put signal is capacitively coupled to a detector and level shifter circuit comprising diodes 62A and 62B
as a detector and diode 62C as a level shifter to clamp the ~- positive excursion of the detected signal to ~5V.
The level shifted signal is then applied to a .5chmitt trigger 63, such a3 Motorola type 14584, to provide "
. , , ~0~4~;~L7 a well formed pulse output, then through a signal inverter 64 -to one of the inputs of NAND gate 65. The output signal of NAND gate 65 will be referred -to STP.
To produce the transmitted ultrasonic pulses, a latch circuit 66 comprised of a pair of cross-coupled NAND
gates has one of its two inputs connected through a resistor to a positive source of potential, and is shunted to ground by start switch 67. Preferably the start switch is of the type which switches closed under influence of an external magnetic field. In order to start the entire sequence, a magnet will be brought close to the switch outside of the hermetically sealed housing, and the start switch thereby operated.
The output of latch 66 is applied to one input of an astable multivibrator 70 thereby enabling the multi-vibrator to begin functioning. The period of this multivibra-tor is set for a one second time period. Its - output is applied to the clock input of the pair of series connected sample rate selection counters 71A and 71B. The --..
20 output terminals of the counters 71A and 71B are each connected ¦~ through switch~s 72A - 72E respectively to diodes 73A - 73E.
The anodes of the diodes are connected toyether to the inputs of one shot Jnultivibrators 74 and 174, through one shot 74 to one of the inputs of NAND gate 75 and from -the output thereof through inverting amplifier 76. The output lead and signal of inverting amplifier 76 is designated XMIT. The output of one shot 174 is applied through inverter 176 to provide the signal path ~ K.
The second input of NAND gate 65 is tied to a signal 30 path called RX BLK (or receiver blank). The RX BLK signal was derived from a one shot 174 which has an output synchronous to but longer than the transmit one shot. This RX BLK prevents the transmitted pulse from generating an immediate STP pulse.
,...... . . . . . . .
, 10~6~7 The XMIT lead is connected to one oE ~he inputs of NAND gate 77, while the other input of NA~D yate 77 is connected to the 42KHz signal. The output of NAND gate 77 is applied ; through inverting amplifier 78 to the base of grounded emitter transistor 79, which is transformer 80 coupled to the base of grounded emitter transistor 81. The collector of this transistor i-s transformer 82 coupled to push-pull grounded emitter transistor 83A and 83B.
The collector circuits of transistors 83A and 83B
` 10 are connected in push-pull -through impedance matching transformer 84 to the terminals of transducer 51, one of the leads being connected through a paralleled pair of reversely - coupled diodes 85A and 85B. These diodes provide a minimurn level control, which prevents the back EMF signal from being applied to transformer 84, and thereby protects transistors 83A and 83B from high reverse voltages.
;i A crys~al 86 controlled oscillator 87 preferably of 1 Mhz, is connected to the input of a decoding circuit 88 which uses a pair of Intel type 4518 decoders and type 4027 20 flip-flop, the output of which is a 42 Khz ultrasonic signal.
This is applied to the second input of NAND gate 77.
It may be seen that the l Mhz oscillator signal is decoded to 42 Khz and applied to a power amplifier comprising the circuit involving transis-tors 79, 81, 83A and 83B.
However, the power arnplifier is enabled only during the period of receipt of pulses on -the XMIT lead, which is controlled by the rate select switches 72A - 72E. ~2 Khz bursts of signal are therefore genera-ted, and upon application to transducer 51, are transmitted through the water to the 30 lower ice sur~ace.
A second decoding circuit 89 of similar type as decoding circuit 88 has its input connected to the output o~
oscillator 87, and provides, in the same manner as decoding ., 6~
circuit 88, a pulsing signal having a frequency correspondingto 0.1 meters. In sea water, this is 67.5 microseconds per cycle. This signal is di~ided by 2 and the output clocks are then equal to the travel distance in 0.1's of meters.
Turning now to the conversion circuit of the period between the transmitted and received pulse to a data signal, the STP lead is connected to inverter 90, which has its output connected to the K input of J-K flip-flop 91, the XMIT lead being connected to the J input thereof. One output of flip-flop 91 is connected to one of the inputs of .. . ..
NAND gate 92, which output is connected to the input of series connected binary coded decimal counters 93A, 93B, 93C
and 93D, which may be Motorola type 14518. The second input of NAND gate 92 is connected to the 0.1 meter pulse source -89. -In operation, transmitting a pulse provides an input to flip-flop 91, causing its output to go to high ~-potential level, providing an input to NAND gate 92. Pulses from the 0.1 meter pulse source causes NAND gate 92 to provide a pulsing output signal, which causes BCD counters -~
93A - 93D to sequentially count in tenths of a meter. With the output terminals of counters 93B, 93C, and 93D sucaessively in units, tens, and hundreds, every ten 0.1 meter counts an additional one meter will be registered on the output of the BCD counters.
' '' ' ' ' When an echo pulse is received from the hottom surface of the iae, a pulse is obtained at the STP lead, which is applied to the K input o~ flip-flop 91. This , ~' .
causes the output of the ~lip-flop to cease, stopping the counting by counters 93A - 93D. The signa~l at the output terminals of counters 93~ - 93D is thus an indication o~ the time difference between the transmitted and received echo signal, which, given a constant velocity of sound in water, ,, ~ ,,,', . , ,IV~lq is proportional to the distance be-tween the transducer and the bottom of the ice surface.
~ The XMIT lead is also connected to one of the ,~ inputs of NAND gate 94 which has its output connected to one ; of the inputs of NAND gate 95, which has its output connected ~ through an inverting amplifier to the input of binary address ,~ counter 96. This counter can be Motorola type 14040. Each transmitting pulse will index the address counter 96 which ' ~ provides a sequencing address signal at one of its output '; 10 terminals A0 - A9. ~ -' The last stage of memory address counter 96 is ORed -~
` with a power via inverter reset signal via inverter amplifier ,, 97 and NAND gate 98, and resets latch 66 to prevent memory ` overflow. ~ , -, An externally obtained read-advance RD ADV
, signal is applied to the second input of NAND gate 95, to ' drive the address counter when the signals stored in memory are to be read out. This read-advance signal can be obtained from a printer interface circuit or the like. ' 'I
The STP lead'is also connected to one shot multivibrator 100, through NAND gate 101 to provide a write signal on the ,~
l, WRITE lead to store data in memory.
,l To operate the analog switch 59 at the 87, 174 and 261 meter distance levels, the BCD leads 1, 2, 4 and 80 o~ ' -counters 93B and 93D are connected through diodes 102A -102D
l, to the input of counter 103. This counter can be Motorola ',~ type 14017. The anodes of diodes 102A - 102D are connected together, and to a resistor which is further connected to a j positi,ve source of potenti,al. The output leads of counter ,~,' 30 103 are connected respectively through linear ampliflers 104A - 104D to the VGl, VG2, yG3, and VG4 respective input3 of analog switch 59.
Accordingly, when an 87, 174 or 261 (or other mul-~.... . .
~, , ~- lLo~ q tiple of 87) count appears as outpu-t of counters 93A - 93D, counter 103 will be indexed, and an output sequentially provided on one of the leads 104A - 104D. The gain of ~ -analog switch 59 will therefore be controlled, and i~creased, - so as to be more sensitive to a reduced amplitude echo ; signal resulting from a greater distancing of transmlssion and reflection from the lower ice surface.
Turning now to memory chips 10 4A - 10 4 1, each chip is organized to store 1,024 words of 12 bits per word, ~ -10 providing a maximum of 12, ~88 data bits capacity.
Each chip has a sCD data input, shown as lead numerals 1, 2, 4, 8, 10, 20, 40, 80, 100, 200, 400 and 800 ::, ~ respectively. The address leads 105 are connected identically ,.! to each chip, through buffer amplifiers 106A - 106 1 to the -address leads A0 - A9.
Each memory chip also contains an output lead which corresponds in data to the data input lead as described ;
above. In addition, a WRITE enable lead 107 is connected to all the memory chips in parallel.
Accordingly, each time a first echo pulse correspond- -l ing to a transmitted pulse is received, a pulse will appear 1 :
on the STP lead, causing as described earlier, the cessation '~ of counting by counters 93A - 93D. The address counter had been indexed by the transmission oE a transmit pulse, providiny a new memory address output signal. -¦ The siynal appearing on the STP lead also operates one shot multivibrator 100, causing an output pulse to -r ".,.'', appear on the WRITE lead. This enables the memory chips ' 104A - 104 1, causing them to store the data applied thereto 30 on the data input lead ~rom the counters 9~3~ - 93D, a-t the address indicated by the siynal on the output leads oE
address counter 96.
~7hen reading inEormation, a well known digital , . . . . .
. .
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10~,6~ , display or printer is connected either manually or by loyic (not shown) to the output data leads 108~ - 108 1, and either printed out or illuminated on a digital display. For reading, a READ pulse is applied to the second input of NAND
gate 101, preventing a WRITE enable pulse to be applied to -the memory. ~ith an advancing signal obtained from the -- -printer applied to the second input of NAND gate 95 (or from ~
a manual input), the address counter 96 is sequentially ~ ; -indexed through all memory addresses.
Accordingly, it may be seen that all memory address locations can be read, and the minimum distance indication for a particular iceberg or ice ridge provided, since it is the first received echo which stops counting of the distance increments. The first echo is of course received from the nearest (lowest) ice surface. The minimum distance indication between the bottom of the sea where the transducer is located and the underside of the ice is therefore obtained.
An array of piezoelectric crystal transducers can of course be used in place of the single transducer noted.
20 Two lines of transducers can be used, one line for transmission and one for reception. By applying transmit signal pulses to one or more of the transmi~sion transducers in sequence, a strip across the bottom of the iceberg or ice ridge can be scanned.
It will be understood that various additional or alternative structures can be used in fabricating this invention by persons skilled in the art understanding this invention. Various manual controls, other forms of memory, etc. can be provided. For instance, the entire semi-conductor 30 memory, address, and data counting circuit can be eliminated, and the transmit and received pulses on the XMIT and STP
leads be applied to the input of a tape recorder. ~he recorded tape can then be retrieved and the recorded signal " ", ~.()8~6~L7 applied to circuitry for determining the -time difference between the transmitted and received pulse, -to determine the aforenoted ice clearance.
All variations and additions are intended to be ;~ within the scope of this invention, upon falling within the -scope of the appended claims.
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of irregularity of the bottom of the iceberg.
In the preferred embodiment of the invention, the s transmitted pulse and the first-received echo pulse are stored in an electronic memory. The apparatus is recovered after passage over of the iceberg, and the memory is activated and cleared by reading out the stored signals. A digital readout observable through a window in the apparatus housing can provide the output reading, which is then recorded manually.
Of course the information can be accessed, if s desired, through a connector, and transferred to another printing device on-board ship for a permanent record. ¦~
:
In another embodiment, the information is stored I
on the tape of a tape recorder. Since a greatly increased s ~ memory capacity at relatively small expense is obtained by ; use of the tape recorder, the employment of this form of the invention at the bottom of the sea is highly useful for recording-the distance above the bottom of the sea of the under side of a slow-moving ice pack, since the memory 20 capacity allows deployment for a long period of time. The height above the sea bottom of low-lying ice ridges can accordingly be determined.
In a third embodiment, there is no memory or other storage capability in the apparatus, and a transmit and the echo pulse, upon generation and reception respectively, are transmitted at a different ultrasonic frequency to a hydrophone which is hung at the end of a cable from the side of a ship, waiting a safe distance beside the iceberg to he measured.
Processing, storage (if desired) and display of the ice 39 undersurface height signals above the sea bed, in this case, are obtained aboard ship.
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.. . .
01 More particularly, the inventive method of determining 02 the height above the sea floor of the lower extremity of an 03 iceberg or ice pack is comprised of the steps of lowering an 04 ultrasonic pulse transmitter and receiver to the sea floor, with ;~
05 a transducer of the transmitter and receiver facing upwardly, in 06 front of a moving iceberg or ice pack, and then bouncing ~07 ultrasonic pulses against the undersurface of a passing iceberg 08 or icepack. The reflected ultrasonic pulses from the 09 undersurface are received, and signals corresponding to the transmitted pulse and the first reflected ultrasonic pulse 11 following the transmitted pulse are relayed to a hydrophone 12 connected to a receiver by a cable hung from the receiver at the 13 surface of the sea. The time difference between the transmitted ~14 and received pulses is recorded, and the time between the transmitted and the first corresponding received, reflected pulse ~16 from the bottom surface of the iceberg or ice pack is 17 determined. The transmitter and receiver are retrieved from the ~18 sea floor after the iceberg or ice pack has passed over.
,;19 In general, the inventive apparatus is comprised ~23 ~24 :1:
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108~ 7 Ol of an ultrasonic underwater transducer means, and pulse generator 02 means connected to the transducer means for applying to the 03 transducer means regular pulses each comprised of an ultrasonic 04 frequency signal. A first counter is provided, as well as means 05 for applying pulses to the counter, representative of 06 predetermined distance of clearance increments. Means is also ~07 provided for applying a representation of the transmitted pulse 08 to the data counter for enabling counting by the counter of the ~09 clearance distance increment pulses ~ circuit applies a ~lO received pulse reflected from the ice undersurface from the 11 transducer means to the counter, for stopping the count of the 12 counter. Means connected to the counter then provides for 13 reading out a signal representative of the count on the counter, 14 whereby a corresponding proportionate distance between the transducer and the bottom of the ice surface can be determined.
16 Remotely controlled means is met for deployment and recovery of ~17 the apparatus from the sea floor.
~l8 A more detailed description of the invention will be 19 obtained by reference to the description below~ and the following , drawings, in which:
21 Figures lA and lB show sections of the sea surface with 22 the inventive apparatus in deployment;
23 Figure 2 shows a front elevation view of the apparatus ~,24 housing;
~25 Figure 3 is a basic block diagram of the invention;
26~ Figure 4 is a more detailed block diagram of the 27 invention;
28 Figure 5, which i8 out of its normal order on the same 29 sheet as Figure 3 shows how Figure~ 6, 7, 8 and 9 are to be placed together; and 31 Figures 6, 7, 8 and 9 together are a detailed schematic -32 diagram of the invention.
33 Turniny irst to Figure lA, an icebery l is shown 34 floating in the sea 2 above the surface of the sea floor 3.
,' ~ ' .
., -` ~06~;17 In the event the iceberg is large enough, it will scour the bottom of the sea floor, damaging installations which may be located in its path.
In two of the embodiments of this invention, the apparatus is deployed on the sea floor in the path of an oncoming iceberg after being turned on by a ship. The apparatus 4 has an ultrasonic transducer, such as a hydro-phone, facin~ with its maximum transmitting angle vertically toward the surface of the sea. The transmitted ultrasonic 10 pulses will hit the bottom of the iceberg as it passes thereover, and will be reflected back to the apparatus. The transducer picks up the first reflected echo signal and -stores both the transmitted and first reflected echo signal .~
in an electronic memory, or on recording tape. Preferably, however, the information stored will be a representation of -~ the time lapse between the transmitted and first received echo.
After passage of the iceberg, the apparatus 4 is ':~i . .
, retrieved by releasing ballast by remote control and the ;! 20 content of the memory or of the tape recording is read out.
By this means, the distance above the sea floor of the lowest e~tremity of the iceberg can be determined, since time between pulses is directly correlatible into distance, knowing the velocity of sound in water. Should the distance be dangerously small, evasive steps can be taken to move the iceberg away from its dangerous route.
Figure lB depicts an iceberg 1 floating in the sea 2 with a further embodiment of the apparatus ~ deployed on the sea floor 3.
In this embodiment, as with the embodirnen-t of Figure lA, ultrasonic pulse~ are transmitted to the bottom ~f the icebery and are reflected and received by the apparatus.
~owever, in this case a representation oE the transmitted ,, ~L08~
pulse and received reflected pulse are transmit-ted on a different frequency to a hydrophone 5, deployed beside the iceberg at the end of a cable hung from a ship 6. The ultrasonic frequency used by the apparatus 4 to measure the iceberg can usefully be 42 Khz, and -the frequency of transmission to hydrophone 5 can be 25 Khz. Storage and/or reading of the sea bed clearance data signals will be done on board ship.
Figure 2 shows the mechanical assembly of the inventive apparatus. A transducer 7 such as an ultrasonically responsive hydrophone is located at the top of an aluminum case 8, the transducer being protected from damage by an open grill frame 9. The transducer can be similar to type FM-21/22 manufactured by Furuno Corp. A flotation cylinder -~ l0 encloses and surrounds the aluminum case 8 below the ;~ .
transducer 7. The flotation cylinder can be made of a synthetic foam, enclosing bubbles of air or other gas.
~ ,, .
Below 1he bottom of the flotation cylinder is a hermetically sealed window ll, for viewing an internal digital display.
A remote controlled release unit 12 such as Model 1080 manufactured by Inter Ocean Corp. holds a ballast block - 13 tethered to the bottom of case 8. The operation of the release unit is well-known, and its structure does not form part of this invention. The ballast block 13 can be released by ultrasonic remote control signals from the surface ship, by a timed release, or the like. The ballast block is of sufficient weiyht to cause the entire assembly to drop to the bottom of the sea when deployed. The flotation cylinder keeps the aluminum case upwardly directed, with the transducer 30 facing the surface of the sea. Upon rele~se of the ballast 1 block 13 by the release unit 12, the ~lotation cylinder will -~cause the released assembly to rise -to the surface, for _7_ /
, ' .
. .
-`` iO~ 7 recovery of the apparatus. ~ flag or other ~rking structure is then deployed in a well-known manner, whereby the assembly can be picked up by a ship at the surface.
he buoyancy provided by the flotation chamber should obviously be such as to be able to raise the entire assembly, when the ballast block 13 has been released.
The system is preferably negatively buoyant by approximately twenty-five pounds on descent. As the ; capsule reaches ten meters depth, a pressure operated switch (not shown) activates the apparatus and transmission of the ultrasonic signal and recording begins. The capsule is designed to have minimum drag in both directions so that it reaches a terminal velocity quickly. Once the iceberg has passed, the capsule releases the anchor which allows the capsule to rise quickly to the surface. Flasher and - radio beacons of well known construction should mark the .1 -~ location for quick recovery by ship.
~, please refer now to Figure 3 and the following general description of the electronic por-tion of the apparatus.
~ pulse generator 14 provides pulses of ultrasonic ~ energy, such as at 42 Khz, for outward transmission and i~ reflection from the bottom surface of an ice pack or iceberg.
This signal is applied to the input of a power ampliEier 15, ~,~ the output of which is applied to ultrasonic transducer 16.
A typical pulse repetition rate is 12 pulses per minute, each pulse being 500 microseconds long, the output pulse power to the transducer being preferably about 100 watts.
The received reflection pulse received by the transducer 16 is applied to one of the two inputs oE a J-K
1ip-flop 17, the output o~ whic~h is connected to the input of a data counter 18, having binary coded decimal ~BCD) output terminals~
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. .
The outpu-t of pulse ~enerator 14 is also connected -to the second input of Elip-flop 17. When a pulse to be ; transmitted is initiated in pulse generator 14, the flip-flop is set to provide an output signal therefrom, and when a return echo from the bottom surface of the ice is rec~ived, the flip-flop is reset, cutting off the output therefrom.
To cause the data counter 18 to count after the flip-flop has been set by the transmit pulse a clock source applies regular pulses on conductor ~0, which causes the 10 constant output level from flip-flop 17 to be pulsed. ;
Accordingly, as long as an output of flip-flop 17 exists, (i.e., during the -time between transmitted and received ~
pulses) the data counter will count. -A preferred cycle period is the equivalent of .2 l meters travel of sound in water. Accordingly, the total ~-i count by counter 18 upon reception of the reflected echo ;
~ pulse will time the distance of transducer 16 from the ., :
, nearest ice surface. The cycle period scaled for .2 meters is the time required for the sound to trave].-to an object .1 meters distant and return.
In the event the embodiment shown in Flgure lB is provided, the data counter can be deleted, and the ou-tput of the flip-flop 17 applied to an ultrasonic transmitter (not shown) of different frequency than the frequency transmitted by transducer 16, as noted earlier. The second ultrasonic frequency can be turned on and off by the operation of the flip-flop, allowing hydrophone 5 to receive an ultrasonic pulse having length proportionate to the transducer 16 lower ice surface dis-tance.
Alternatively, a pul~;e corresponding to the trans-mitted pulse can be sent to hyclrophone 5, Eollow0d by a pulse corresponding to the return echo pulse, by a transmitter ~ 9_ .
.
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.
lVl~6.~7 connected in place of flip-~lop 17. The time between pulses will be interpreted by receiving circuitry on board ship as propor-tionate to the aforenoted ice to transducer distance.
In the embodiment corresponding to Figure lA, however, the data from the scD output terminals 19 of data counter 18 will be applied to data input terminals of a . -memory 21. An address counter 22 has its input connected to , the output of pulse generator 14, having an output count signal indexed each time a transmitted pulse is generated. . .
10 The output of the address counter 22 is applied to address input terminals 23 of memory 21. :
. Each time a transmitted pulse is generated, the address counter generates a new memory address signal at its - - ,: -output, designating to memory 21 the location where the next data signal is to be stored. The data counter 18 counts , sequentially.under influence of the 0.1 meter clock pulses, -and stops counting upon reception of a return echo. The count signal at the output terminals 19 is applied to the :
data input terminals of memory 21, and stbred at the address . : .
~2 20 location designated by the address counter 22.
The pulse generator 1~ then generates another .~ transmitted pulse, which indexes the address counte.r 22 to designate the next memory 21 address location, and the entire sequence repeats.
¦~ A set of readout terminals 24 of memory 21 pro-vides an output signal to digital readout 25, which can be a digital light-emitting diode display,. a paper tape print mechanism, etc.
~: rJhile the above has been a description o~ the hasic structure and operation o~ the appa~atus, more detail will be apparent with the following description with reference to the block diagram of Figure 4.
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`` 10t~ 7 Transmit pulse gcnerator 26 is provided with a remotely operated start switch ~7. Preferably, the start swi-tch is magnetically operated from outside the apparatus housing through the wall of the housing, whereby hermetic sealing can be retained,-yet the transmitter initiated by passing a magnet adjacent the switch. The power circuit (not shown) will be similarly turned on.
The output level is applied to an astable m~ltivibrator which generates a one second period output wave. The output signal is applied to a pulse rate counter 28. A reset signal is applied to the rate select circuit.
The output of the rate select counter is connected to one shot multivibrator 31, to provide accurate square waves of predetermined period as an output signal.
A clock 32 provides a signal to a decoding circuit 33, whereby a 42 Khz square wave output signal is produced.
~ . .
This signal is applied to power amplifier 34 along with the output pulses of multivibrator 31. The output pulses are .
applied to the power amplifier 34. The power amplifier 34 ` 20 thus provides a 42 Khz output signal during periods of the pulses of multivibrator 31.
The output signal of power amplifier 34 is passed through impedance matching trans~ormer 35, and is applied -to the terminals of transducer 36. Accordingly, there will be produced yowerful bursts o~ 42 Khæ energy in pulses deter-t mined by pulse generator 26 and rate select counter 28.
'I
- The first return echo received by transducer 36 after each transmitted pulse is applied -to variable gain ampli~ier 37. In order to reduce the swamping action which 30 the high powexed transmitted pulse would have on the amplifier 37, a limiter 38 is connected in the return signal path from transducer 36.
The output of variable gain amplifier 37 is applied . " .
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.
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to Schmi tt -trigger 39 to produce a properly formed square - . .
wave, which square wave is applied to the K input of a J-K - -flip-flop 40. The J input of flip-flop 40 is connected to '~
the output of one shot multivibrator 31.
The output of flip-flop 40 is connected to one of the inputs of NAND gate 41, which has its output connected -to the first portion of a group of sCD counters 42a, 42b, ~
42c, and 42d. These counters are serially cascaded in a ' well-known manner. The output of counter 42a is binary ''' 10 coded decimal (sCD) in tenths of a meter, the output oE
- counter 42b B CD in units of a meter, the output of counter 42c BCD in tens oE meters, and the output of counter 42d BCD '~
in hundreds of meters. Rese't pulse source 30 is connected' ~
to each of the counters 42, as'well as to flip-flop 40. ~ -The output of the 42 Khz decode circuit 33 is applied to a divider circuit 43, in which sequential output ' ' ;' pulses are provided at intervals corresponding to the time taken for an ultrasonic impulse in water to travel 0.2 meters. The 0.2 meter output pulses are applied from the 20 output of divider circuit 43 to a second input of NAND gate 41.
~i ' Since it is desired to increase -the gain of the receiver portion of khe'circuit with increasing distance of J the reflection surface from the transducer to accommodate ~, reception o weaker signals, it is preferred to increase the s~ gain of variable gain ampliier 37 with the delay in reception of a reflection signal from the -time of emission of a transmitted ' pulse. An arbitrary but useful distance of switching was utlized at 87 meters, 174 meters and 261 meters, the latter '~ 30 two figures being the second and third multiples oE 87 ~'~ meters ; The 87 meter point is obtained by a signal on counters 42b and 42c at the 1, 2, 4 and 80 meter output , .,,.,~- , , .
, lO~ lq terminals, which added together, provide a signal at 87 meters and multiples thereof. These terminals are connected to the input of variable gain counter 44, which has its output connected via bus 45 to variable gain control terminals of variable gain amplifier 37. Accordingly, each time the counters 42 reach the 87 meter count or multiples thereof, 1 ~.
variable gain counter 44 will index, switching the gain of variable gain amplifier 37 to successively higher values.
A semi-conductor 12,288 bit memory containing individual memory chips 46 a - 46 l is provided to store the distance count BCD output ~rom counters 42a - 42d. Each of the chips has a data input lead which is connected to one of (~ the output leads of counters 42a - 42d.
il An address counter 47 is provided, having an input connected to the output of one shot multivibrator 31. Each time a transmlt pulse appears at the output of multivibrator ! ~ 31, the address counter 47 will be caused to advance one digit. The address counter output terminals 48 are connected to all memory chips 46 in parallel, Consequently, data applied to the individual chips from counters 42a - 42d will be stored ak the address locations designated by address counter 47, in the memory.
A co~lmon write input lead 49 of the memory is con-neGted via one shot multivibrator 50 from the output of Schmitt trigger 39. Consequently, a write enable pulse will appear ~7ith the reception of a received reflected pulse, ;
causing the me~ory at that time to store the data already counted by counters 42a - 42d Eollowing the transmit pulse.
The specific circuit of the pre~erred embodiment , 30 will now be described with reference to Figures 6, 7, 8 and .' 9 A transducer 51, such as a hydrophone transponder ''',~, ,." . . ,, .. :,., : ., ,, ~ . . . . . .
','',,,'',, " ,,','" ,,,',," ' ' '" ' ' ' 6~q is connected ~hrough isolatiny resistors 52a and 52b to impedance matching transformer 53. The primary of transformer ~ -53 is shunted by opposite polarity diodes 54a and 54b which perform a limiting function to keep excessive amplitude signals, such as the transmitted pulses, from overloading the receiver. ~ -The secondary winding of transformer 53 is coupled -~
to the input of high gain, high slew ra-te differential amplifier 55, such as National Semiconductor type LM218, which has the series of capacitor and resistor 56a and 56b connected from its output to one of its input terminals, in parallel with resistor 56c, which passive components are ~ `
provided to increase the alrqady high slew rate.
- The output of differential ampli~ier 55 is capaci-tively coupled to a variable gain amplifier comprising linear amplifier 57 which can be the same type as amplifier ~ 55, which is shunted by the parallel circuits of capacitor `Yj 58a in series with resistor 58b, in parallel with analog i~ switch 59. Input signals to the analog switch 59 at leads ;j 20 VGl, VG2, VG3 and VG4 establish one or other of the parallel feedback resistors 60a, 60b, 60c or 60d, changing -the gain o the amplifier logarithmically.
The output signal o~ ampliier 57 is applied to a ., , multiple feedback band pass aative filter 61 using National Semiconductor type LM218 ampliier, which filter has been j designed to reject noise outside a pass band between 38 and 45 Khz, passing signals at its tuned frequency o~ 42 Khz.
The ou~put signal is capacitively coupled to a detector and level shifter circuit comprising diodes 62A and 62B
as a detector and diode 62C as a level shifter to clamp the ~- positive excursion of the detected signal to ~5V.
The level shifted signal is then applied to a .5chmitt trigger 63, such a3 Motorola type 14584, to provide "
. , , ~0~4~;~L7 a well formed pulse output, then through a signal inverter 64 -to one of the inputs of NAND gate 65. The output signal of NAND gate 65 will be referred -to STP.
To produce the transmitted ultrasonic pulses, a latch circuit 66 comprised of a pair of cross-coupled NAND
gates has one of its two inputs connected through a resistor to a positive source of potential, and is shunted to ground by start switch 67. Preferably the start switch is of the type which switches closed under influence of an external magnetic field. In order to start the entire sequence, a magnet will be brought close to the switch outside of the hermetically sealed housing, and the start switch thereby operated.
The output of latch 66 is applied to one input of an astable multivibrator 70 thereby enabling the multi-vibrator to begin functioning. The period of this multivibra-tor is set for a one second time period. Its - output is applied to the clock input of the pair of series connected sample rate selection counters 71A and 71B. The --..
20 output terminals of the counters 71A and 71B are each connected ¦~ through switch~s 72A - 72E respectively to diodes 73A - 73E.
The anodes of the diodes are connected toyether to the inputs of one shot Jnultivibrators 74 and 174, through one shot 74 to one of the inputs of NAND gate 75 and from -the output thereof through inverting amplifier 76. The output lead and signal of inverting amplifier 76 is designated XMIT. The output of one shot 174 is applied through inverter 176 to provide the signal path ~ K.
The second input of NAND gate 65 is tied to a signal 30 path called RX BLK (or receiver blank). The RX BLK signal was derived from a one shot 174 which has an output synchronous to but longer than the transmit one shot. This RX BLK prevents the transmitted pulse from generating an immediate STP pulse.
,...... . . . . . . .
, 10~6~7 The XMIT lead is connected to one oE ~he inputs of NAND gate 77, while the other input of NA~D yate 77 is connected to the 42KHz signal. The output of NAND gate 77 is applied ; through inverting amplifier 78 to the base of grounded emitter transistor 79, which is transformer 80 coupled to the base of grounded emitter transistor 81. The collector of this transistor i-s transformer 82 coupled to push-pull grounded emitter transistor 83A and 83B.
The collector circuits of transistors 83A and 83B
` 10 are connected in push-pull -through impedance matching transformer 84 to the terminals of transducer 51, one of the leads being connected through a paralleled pair of reversely - coupled diodes 85A and 85B. These diodes provide a minimurn level control, which prevents the back EMF signal from being applied to transformer 84, and thereby protects transistors 83A and 83B from high reverse voltages.
;i A crys~al 86 controlled oscillator 87 preferably of 1 Mhz, is connected to the input of a decoding circuit 88 which uses a pair of Intel type 4518 decoders and type 4027 20 flip-flop, the output of which is a 42 Khz ultrasonic signal.
This is applied to the second input of NAND gate 77.
It may be seen that the l Mhz oscillator signal is decoded to 42 Khz and applied to a power amplifier comprising the circuit involving transis-tors 79, 81, 83A and 83B.
However, the power arnplifier is enabled only during the period of receipt of pulses on -the XMIT lead, which is controlled by the rate select switches 72A - 72E. ~2 Khz bursts of signal are therefore genera-ted, and upon application to transducer 51, are transmitted through the water to the 30 lower ice sur~ace.
A second decoding circuit 89 of similar type as decoding circuit 88 has its input connected to the output o~
oscillator 87, and provides, in the same manner as decoding ., 6~
circuit 88, a pulsing signal having a frequency correspondingto 0.1 meters. In sea water, this is 67.5 microseconds per cycle. This signal is di~ided by 2 and the output clocks are then equal to the travel distance in 0.1's of meters.
Turning now to the conversion circuit of the period between the transmitted and received pulse to a data signal, the STP lead is connected to inverter 90, which has its output connected to the K input of J-K flip-flop 91, the XMIT lead being connected to the J input thereof. One output of flip-flop 91 is connected to one of the inputs of .. . ..
NAND gate 92, which output is connected to the input of series connected binary coded decimal counters 93A, 93B, 93C
and 93D, which may be Motorola type 14518. The second input of NAND gate 92 is connected to the 0.1 meter pulse source -89. -In operation, transmitting a pulse provides an input to flip-flop 91, causing its output to go to high ~-potential level, providing an input to NAND gate 92. Pulses from the 0.1 meter pulse source causes NAND gate 92 to provide a pulsing output signal, which causes BCD counters -~
93A - 93D to sequentially count in tenths of a meter. With the output terminals of counters 93B, 93C, and 93D sucaessively in units, tens, and hundreds, every ten 0.1 meter counts an additional one meter will be registered on the output of the BCD counters.
' '' ' ' ' When an echo pulse is received from the hottom surface of the iae, a pulse is obtained at the STP lead, which is applied to the K input o~ flip-flop 91. This , ~' .
causes the output of the ~lip-flop to cease, stopping the counting by counters 93A - 93D. The signa~l at the output terminals of counters 93~ - 93D is thus an indication o~ the time difference between the transmitted and received echo signal, which, given a constant velocity of sound in water, ,, ~ ,,,', . , ,IV~lq is proportional to the distance be-tween the transducer and the bottom of the ice surface.
~ The XMIT lead is also connected to one of the ,~ inputs of NAND gate 94 which has its output connected to one ; of the inputs of NAND gate 95, which has its output connected ~ through an inverting amplifier to the input of binary address ,~ counter 96. This counter can be Motorola type 14040. Each transmitting pulse will index the address counter 96 which ' ~ provides a sequencing address signal at one of its output '; 10 terminals A0 - A9. ~ -' The last stage of memory address counter 96 is ORed -~
` with a power via inverter reset signal via inverter amplifier ,, 97 and NAND gate 98, and resets latch 66 to prevent memory ` overflow. ~ , -, An externally obtained read-advance RD ADV
, signal is applied to the second input of NAND gate 95, to ' drive the address counter when the signals stored in memory are to be read out. This read-advance signal can be obtained from a printer interface circuit or the like. ' 'I
The STP lead'is also connected to one shot multivibrator 100, through NAND gate 101 to provide a write signal on the ,~
l, WRITE lead to store data in memory.
,l To operate the analog switch 59 at the 87, 174 and 261 meter distance levels, the BCD leads 1, 2, 4 and 80 o~ ' -counters 93B and 93D are connected through diodes 102A -102D
l, to the input of counter 103. This counter can be Motorola ',~ type 14017. The anodes of diodes 102A - 102D are connected together, and to a resistor which is further connected to a j positi,ve source of potenti,al. The output leads of counter ,~,' 30 103 are connected respectively through linear ampliflers 104A - 104D to the VGl, VG2, yG3, and VG4 respective input3 of analog switch 59.
Accordingly, when an 87, 174 or 261 (or other mul-~.... . .
~, , ~- lLo~ q tiple of 87) count appears as outpu-t of counters 93A - 93D, counter 103 will be indexed, and an output sequentially provided on one of the leads 104A - 104D. The gain of ~ -analog switch 59 will therefore be controlled, and i~creased, - so as to be more sensitive to a reduced amplitude echo ; signal resulting from a greater distancing of transmlssion and reflection from the lower ice surface.
Turning now to memory chips 10 4A - 10 4 1, each chip is organized to store 1,024 words of 12 bits per word, ~ -10 providing a maximum of 12, ~88 data bits capacity.
Each chip has a sCD data input, shown as lead numerals 1, 2, 4, 8, 10, 20, 40, 80, 100, 200, 400 and 800 ::, ~ respectively. The address leads 105 are connected identically ,.! to each chip, through buffer amplifiers 106A - 106 1 to the -address leads A0 - A9.
Each memory chip also contains an output lead which corresponds in data to the data input lead as described ;
above. In addition, a WRITE enable lead 107 is connected to all the memory chips in parallel.
Accordingly, each time a first echo pulse correspond- -l ing to a transmitted pulse is received, a pulse will appear 1 :
on the STP lead, causing as described earlier, the cessation '~ of counting by counters 93A - 93D. The address counter had been indexed by the transmission oE a transmit pulse, providiny a new memory address output signal. -¦ The siynal appearing on the STP lead also operates one shot multivibrator 100, causing an output pulse to -r ".,.'', appear on the WRITE lead. This enables the memory chips ' 104A - 104 1, causing them to store the data applied thereto 30 on the data input lead ~rom the counters 9~3~ - 93D, a-t the address indicated by the siynal on the output leads oE
address counter 96.
~7hen reading inEormation, a well known digital , . . . . .
. .
" "
10~,6~ , display or printer is connected either manually or by loyic (not shown) to the output data leads 108~ - 108 1, and either printed out or illuminated on a digital display. For reading, a READ pulse is applied to the second input of NAND
gate 101, preventing a WRITE enable pulse to be applied to -the memory. ~ith an advancing signal obtained from the -- -printer applied to the second input of NAND gate 95 (or from ~
a manual input), the address counter 96 is sequentially ~ ; -indexed through all memory addresses.
Accordingly, it may be seen that all memory address locations can be read, and the minimum distance indication for a particular iceberg or ice ridge provided, since it is the first received echo which stops counting of the distance increments. The first echo is of course received from the nearest (lowest) ice surface. The minimum distance indication between the bottom of the sea where the transducer is located and the underside of the ice is therefore obtained.
An array of piezoelectric crystal transducers can of course be used in place of the single transducer noted.
20 Two lines of transducers can be used, one line for transmission and one for reception. By applying transmit signal pulses to one or more of the transmi~sion transducers in sequence, a strip across the bottom of the iceberg or ice ridge can be scanned.
It will be understood that various additional or alternative structures can be used in fabricating this invention by persons skilled in the art understanding this invention. Various manual controls, other forms of memory, etc. can be provided. For instance, the entire semi-conductor 30 memory, address, and data counting circuit can be eliminated, and the transmit and received pulses on the XMIT and STP
leads be applied to the input of a tape recorder. ~he recorded tape can then be retrieved and the recorded signal " ", ~.()8~6~L7 applied to circuitry for determining the -time difference between the transmitted and received pulse, -to determine the aforenoted ice clearance.
All variations and additions are intended to be ;~ within the scope of this invention, upon falling within the -scope of the appended claims.
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Claims (17)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An apparatus for deployment at the sea floor and for determining the clearance of the bottom surface of an iceberg or ice pack from the sea floor comprising:
(a) ultrasonic underwater transducer means, (b) pulse generator means connected to the transducer means for applying to the transducer means regular pulses, each pulse being comprised of an ultrasonic frequency signal, (c) a first counter, (d) means for applying pulses to the counter representative of predetermined distance of clearance increments, (e) means for applying a representation of the transmitted pulse to the counter for enabling counting by said counter of said (d) pulses, (f) means for applying a received pulse from the transducer means reflected from the bottom of the ice surface to the counter for stopping the count of said counter, (g) means for reading out a signal representative of the count on said counter, whereby a corresponding proportionate distance between the transducer and bottom of the ice surface can be determined, (h) means for transmitting said signal representative of said count via said transducer to a second transducer at a different location, and (i) remotely controlled means for deployment and recovery of said apparatus from the sea floor.
(a) ultrasonic underwater transducer means, (b) pulse generator means connected to the transducer means for applying to the transducer means regular pulses, each pulse being comprised of an ultrasonic frequency signal, (c) a first counter, (d) means for applying pulses to the counter representative of predetermined distance of clearance increments, (e) means for applying a representation of the transmitted pulse to the counter for enabling counting by said counter of said (d) pulses, (f) means for applying a received pulse from the transducer means reflected from the bottom of the ice surface to the counter for stopping the count of said counter, (g) means for reading out a signal representative of the count on said counter, whereby a corresponding proportionate distance between the transducer and bottom of the ice surface can be determined, (h) means for transmitting said signal representative of said count via said transducer to a second transducer at a different location, and (i) remotely controlled means for deployment and recovery of said apparatus from the sea floor.
2. An apparatus as defined in claim 1, further comprising:
(i) a memory for receiving said signal representative of the count on said counter as data, (ii) an address counter connected between the pulse generator means and an address input to the memory for incrementing the storage address for each succeeding count signal from the first counter, and (iii) means for providing a signal to the memory representative of the received pulse from the transducer means for enabling the memory to store said count signal at the address designated by the address counter prior to transmission.
(i) a memory for receiving said signal representative of the count on said counter as data, (ii) an address counter connected between the pulse generator means and an address input to the memory for incrementing the storage address for each succeeding count signal from the first counter, and (iii) means for providing a signal to the memory representative of the received pulse from the transducer means for enabling the memory to store said count signal at the address designated by the address counter prior to transmission.
3. An apparatus as defined in claim 2, further including means for providing a further signal to the memory and a signal to the address counter for enabling the memory to sequentially apply on a read bus the count signal content at each memory address for transmission.
4. An apparatus as defined in claim 2 or 3, further including a variable gain amplifier connected in the signal path between the transducer means and the first counter, and a gain control counter connected to predetermined output terminals of the first counter and to the variable gain amplifier, for increasing the gain of the variable gain amplifier by increments with the count by said first counter of predetermined time counts and multiples thereof.
5. An apparatus for determining the clearance of the bottom surface of an iceberg or ice pack from the sea floor, comprising:
(a) an ultrasonic transducer means for use under water, (b) a variable gain amplifier haying its input connected in a signal path to the transducer means, (c) a limiter circuit connected across the input signal path of the variable gain amplifier, (d) a J-K flip flop, having one input connected to the output signal path of the variable gain amplifier, (e) a NAND gate having one input connected to one output of said flip flop, (f) a series of binary coded decimal (BCD) counters, having its input connected to the output of the NAND gate, and having BCD output terminals, (g) a transmit pulse generator, having its output connected to the second input of said flip flop, (h) an ultrasonic generator means, the output of the transmit pulse generator being connected thereto to enable the outputting of an ultrasonic signal for the period of each transmit pulse, the output of the ultrasonic generator means being connected to the transducer means, (i) means for providing a repetitive distance increment signal to a second input of the NAND gate, for incrementing the series of BCD counters after the initiation of counting by said BCD counters upon reception of a transmit pulse by said flip flop, (j) a gain control counter having its input con-nected to predetermined ones of the BCD counter output terminals, and its output connected to gain control terminals of the variable gain amplifier, for increasing the gain of the variable gain amplifier by predetermined amounts upon.
the count by said BCD counters of predetermined numbers of distance increment signals, whereby the counting of said increments by said BCD counters is terminated upon the reception of a reflected ultrasonic signal pulse, (k) and means for reading the output signal from the series of BCD counters upon termination of the counting.
(a) an ultrasonic transducer means for use under water, (b) a variable gain amplifier haying its input connected in a signal path to the transducer means, (c) a limiter circuit connected across the input signal path of the variable gain amplifier, (d) a J-K flip flop, having one input connected to the output signal path of the variable gain amplifier, (e) a NAND gate having one input connected to one output of said flip flop, (f) a series of binary coded decimal (BCD) counters, having its input connected to the output of the NAND gate, and having BCD output terminals, (g) a transmit pulse generator, having its output connected to the second input of said flip flop, (h) an ultrasonic generator means, the output of the transmit pulse generator being connected thereto to enable the outputting of an ultrasonic signal for the period of each transmit pulse, the output of the ultrasonic generator means being connected to the transducer means, (i) means for providing a repetitive distance increment signal to a second input of the NAND gate, for incrementing the series of BCD counters after the initiation of counting by said BCD counters upon reception of a transmit pulse by said flip flop, (j) a gain control counter having its input con-nected to predetermined ones of the BCD counter output terminals, and its output connected to gain control terminals of the variable gain amplifier, for increasing the gain of the variable gain amplifier by predetermined amounts upon.
the count by said BCD counters of predetermined numbers of distance increment signals, whereby the counting of said increments by said BCD counters is terminated upon the reception of a reflected ultrasonic signal pulse, (k) and means for reading the output signal from the series of BCD counters upon termination of the counting.
6. An apparatus as defined in claim 5, in which the (k) means is comprised of an ultrasonic transmitter of different frequency than the frequency of the signal generated by the ultrasonic generator means, further comprising means for applying a representation of both the transmit pulse and reflected ultrasonic signal pulse to the transmitter for transmission to an external hydrophone.
7. An apparatus as defined in claim 5, in which the (k) means is comprised of a memory having a data signal input, an address signal input and a write enable input, the data signal input being connected to the BCD output terminals of the series of BCD counters; and further comprising an address counter having its input connected to the output of the transmit pulse generator and its output connected to the address input of the memory; the write enable input of the memory being connected to the output signal path of the variable gain amplifier for enabling the storage of the count signal as data from the series of BCD counters at an address designated by the output signal of the address counter which is activated by a transmit pulse, upon reception by the transducer means of a reflected transmit pulse.
8. Apparatus as defined in claim 7, further including means for sequentially advancing the memory through all addresses, to output on a memory output bus the signals stored at the memory address locations, and a display means for displaying sequentially numbers corresponding to the BCD
count signal stored at each memory location.
count signal stored at each memory location.
9. An apparatus as defined in claim 5, in which the (k) means is comprised of a tape recorder, further com-prising means for applying a representation of both the transmit and reflected ultrasonic signal pulses to the tape recorder for continuous recording and storage.
10. An apparatus as defined in claim 1, 5 or 8, further including a waterproof housing for said apparatus, a buoyancy chamber at the top of the housing, a removable ballast outside the bottom of the housing, for orienting said transducer in a vertically transmitting position while immersed in the sea, and remote control means for releasing the ballast to allow the housing to be buoyed to the surface of the sea.
11. A method of determining the height above the sea floor of the lower extremity of an iceberg or ice pack comprising:
(a) lowering an ultrasonc pulse transmitter and receiver to the sea floor, with a transducer of the transmitter and receiver facing upwardly, in front of a moving iceberg or ice pack, (b) bouncing ultrasonic pulses against the undersurface of a passing iceberg or an ice pack, (c) receiving the reflected ultrasonic pulses from said undersurface, (d) relaying signals corresponding to the transmitted pulse and said first reflected ultrasonic pulse following the transmitted pulse to a hydrophone connected to a receiver by a cable hung from said receiver at the surface of the sea, (e) recording the time difference between said transmitted and received pulses, (f) determining the time between a transmitted and the first corresponding received, reflected pulse from the bottom surface of the iceberg or ice pack, and (g) retrieving the transmitter and receiver from the sea floor after the iceberg or ice pack has passed thereover.
(a) lowering an ultrasonc pulse transmitter and receiver to the sea floor, with a transducer of the transmitter and receiver facing upwardly, in front of a moving iceberg or ice pack, (b) bouncing ultrasonic pulses against the undersurface of a passing iceberg or an ice pack, (c) receiving the reflected ultrasonic pulses from said undersurface, (d) relaying signals corresponding to the transmitted pulse and said first reflected ultrasonic pulse following the transmitted pulse to a hydrophone connected to a receiver by a cable hung from said receiver at the surface of the sea, (e) recording the time difference between said transmitted and received pulses, (f) determining the time between a transmitted and the first corresponding received, reflected pulse from the bottom surface of the iceberg or ice pack, and (g) retrieving the transmitter and receiver from the sea floor after the iceberg or ice pack has passed thereover.
12. A method as defined in claim 11, in which step (e) includes recording an electronic signal representative of the time of the first reflected ultrasonic pulse following a transmitted pulse in a memory.
13. A method as defined in claim 12, in which the memory is located in a housing for the pulse transmitter and receiver, including the step of retrieving the pulse transmitter and receiver, and displaying the content of each location of the memory, in sequence.
14. A method as defined in claim 11, 12 or 13, in which step (b) includes sequentially scanning the ultrasonic pulses in lines transverse to the direction of movement of the iceberg or ice pack.
15. An apparatus as defined in claim 1, 2 or 3 in which said means for transmitting is comprised of means for transmitting said signal via said transducer at a different frequency than the frequency of said ultrasonic frequency signal.
16. An apparatus as defined in claim 1, 2 or 3 in which said signal representative of said count is comprised of pulses having length proportionate to the distance of the bottom of the ice surface from the sea floor.
17. Apparatus as defined in claim 1, 2 or 3 in which said signal representative of said count is comprised of pulses spaced time periods having length proportionate to the distance of the bottom of the ice surface from the sea floor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA266,495A CA1084617A (en) | 1976-11-24 | 1976-11-24 | Iceberg detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA266,495A CA1084617A (en) | 1976-11-24 | 1976-11-24 | Iceberg detector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1084617A true CA1084617A (en) | 1980-08-26 |
Family
ID=4107357
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA266,495A Expired CA1084617A (en) | 1976-11-24 | 1976-11-24 | Iceberg detector |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1084617A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102012020093A1 (en) * | 2012-10-12 | 2014-04-17 | Eads Deutschland Gmbh | Arrangement for locating, detecting and monitoring icebergs, has unmanned aircraft which is equipped with image detecting unit, where control center is provided for controlling unmanned aircraft |
-
1976
- 1976-11-24 CA CA266,495A patent/CA1084617A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102012020093A1 (en) * | 2012-10-12 | 2014-04-17 | Eads Deutschland Gmbh | Arrangement for locating, detecting and monitoring icebergs, has unmanned aircraft which is equipped with image detecting unit, where control center is provided for controlling unmanned aircraft |
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