Ultrasonics

Background
Description
    Pingers
        Table of Dukane underwater locator beacons
        Dukane SeaCom NA1 Underwater Acoustic Beacon
        Dukane DK100
        Dukane N15F210B
        Dukane DK120
    Flight Data Recorders & Cockpit Voice Recorders
  Cleaner
  Radatron Protector Model 8502 Ultrasonic Burglar Alarm
  Wire Bonder
   Piezo Disks
   Polaroid Sonar One Step Camera
   Audio Spotlight
    Marten Repeller
    Thickness Gauge
Patents
Related
Patents
References
Links

---

Background 

I think "Ultrasonic" dates back to 1923, prior to that such terms as "ultra-sonorous" (1917 patent 1471547) and "superaudible frequencies" (1943 patent 2420676) were also used so searching older literature for ultrasonic may not get the hits that are there under different names. 

Ultrasonic sound (Wiki: Ultrasound) has a frequency that's above human hearing.  Started this page after getting a couple of the Dukane SeaCom NA1 Underwater Accustic Beacons.
Bats (Wiki) use ultrasonic SONAR (Wiki) signals to locate very small insects while they are flying.  The bat detector allows hearing the pingers.

Description

Pingers

Started learning about pingers after the MH-370 (Wiki) search.  Also see the Roswell Connection on the Sonobuoy web page.  These emit a pulse of ultrasonic energy at 37.5 kHz about once per second.  Sonobuoys can NOT hear that frequency, but I think the Broadband Sonar operator on a submarine could hear it if the sub was close enough.  The pinger has a range of around 1 mile when used with the pinger receiver that goes with it, but I suspect the submarine sonar is more sensitive and more directional so a somewhat longer range.  There's a newer pinger that operates arlound 8 kHz to be compatible with underwater voice communications equipment (BQC-1).

Table of Dukane underwater locator beacons

Model	NSN	Operating Life Days	Comments
DK100	5845-01-344-7914	30	37.5 khz operating frequency; up to 20,000 ft operating depth; 28 to 100 deg F operating temp; lithium battery power source; fresh or salt water - replaces the N15F210B with a 6 year shelf life non-replacable battery, 1 to 2 mile range, operates at least 30 days, 4" long x 1.3" dia.  7 oz,
DK120	5845-01-433-3387	30	same as the DK100 except field replaceable 3V Li battery. 4" long x 1.3" dia. (Battery: p/n: 8102007K, Spanner: 810325)
DK130	5845-01-586-4358		Underwater acoustic beacon
DK290			Form, fit & function replacement of DK100/DK120 but with smaller Li battery so easier to ship.
DK480	5845-01-597-0046
N15A260	5845-01-263-3553		Overall Length: 3.780 inches nominal, Frequency Rating: 9.0 kilohertz nominal
N15B217B	5845-01-450-3923	10	Operating depth 20000.0 ft; operating life 10 days, Overall Length: 6.000 inches nominal
N15F210B	5845-01-009-4702		Overall Length: 3.910 inches minimum and 3.930 inches maximum, Overall Width: 1.300 inches minimum and 1.303 inches maximum - 1-1/2 year shelf life with replaceable battery
N15F210BH	5845-01-290-7995
N15F210B/S	5845-01-213-1413
N15M210	5845-01-213-1413
N30A50S	5845-01-295-9114

Dukane battery replacement supplies - TS200 Test Set: for all the DK100 series beacons. The center terminal of the water sensor measures about +3 Volts.

Dukane SeaCom NA1 Underwater Acoustic Beacon

For commercial use, not for black boxes.

Fig 1 NA1 Underwater Acoustic Beacon

Fig 2 Dukane N30A5B Beacon Receiver

This beacon (Fig 1)  is not the Underwater Locator Beacon (Wiki: ULB) used on aircraft Flight Data Recorders (Wiki) or Cockpit Voice Recorders (Wiki) since this NA1 unit does not have a water activated switch. i.e. the NA1 is on whenever the 9V battery is installed.  It is part of the Dukane N30A5B Underwater Beacon Locator (Fig 2) set that includes Receiver model N15A235B.

These are for divers to place to make something they want to return to without leaving a visible buoy at the surface.

These are powered by the common 9V battery.  The plastic bottom of the battery compartment has a tapered slot that gives the battery terminals access.  If the negative battery terminal is toward the wide end of the slot and the positive battery terminal toward the narrow end of the slot the battery will install properly and when pressed down you will feel the contact springs, but if installed in the reverse direction the battery will not go down enough to allow the cover to be installed and when pressed will not move.

I'm guessing this is a pulsed beacon, just like the ones used on the aircraft black boxes since that mode of operation greatly extends the battery life.

I tried using the CSE Batdetector and heard nothing on both of my NA1 beacons.

Sonobuoys were developed during W.W.II to find enemy submarines.  One of the first, if not the first, U.S. sonobuoy is the CRT-1.  This was also used as the basis of the Project Mogul balloons (Wiki), one of which crashed at Roswell NM.

Dukane DK100

This is a current model pinger that has a factory replaceable battery.  The DK120 is the same pinger with a user replaceable battery.
Marked: Replace beacon by end of: Oct 2009.  So it has been in storage for 12 years and still pings when the sea water switch is shorted to the body. (YouTube Dukane Underwater Locator Beacons).
In the video the DK100 has a ring to the ping, but the N15F210B is more of a thud.  That's an artifice of who the "CSE Batdetecdtor" had the LO set.  After setting the knob to 3/4 of the way between 30 and 40 KHz both pingers are "pinging".

Dukane N15F210B

Marked:
Underwater Acoustic Beacon, Model N15F210B, Dukane Corporation, Ultrasonics Division, St. Charles, Illinois,
Replace Battery By [sticker] 10-91 (the battery is 30 years overdue for replacement).
Dimensions: 1.300" diameter x 3.975" long overall.
Battery cover pin wrench: 3/32" dia x 13/16" c-c
Sense end cover pin wrench: 0.028" dia x 0.8985" c-c
Weight: 5.0 ounces.

Documents

Underwater Acoustic, Beacon N15F210B, Test Sets 42A12 and 42A12A, Underwater Acoustic Locator System N30A5B, 1983

I'm guessing the N15F210B runs from a "C" size battery that's around 3 Volts (maybe 2 series connected 1.35V Mercury batteries (Wiki) = 2.7 V).
On order: 14500 Li AA battery, 3.7 V & Battery Adapter so AA battery fits "C" battery outline.  This should allow testing using a CSE Batdetector.

DMM Tests

Fluke 87 V:
Red (+) lead battery compartment terminal:
- to case: 456k Ohms after settling, diode mode (1 mA) 1.070 V;
- to sea water switch terminal: Ohms: 70k Ohms after settling, diode mode (1 mA): OL
Black (-) lead battery compartment terminal:
- to case: 3M Ohms still going up, diode mode (1 mA) OL
- to sea water switch terminal: Ohms: 60k Ohms after settling, diode mode (1 mA): OL

Fig 1 Dukane N15F210B Contact on left end senses sea water and turns on the beacon.

Fig 2 Dukane N15F210B battery can be replaced by using a spanner wrench.

Fig 3 Battery Compartment battery about 2" long x 1" dia This is the size of a "C" battery, but needs to be 3V instead of 1.5V. Note a spring for each end of battery maybe to protect it from mechanical shock? The black rubber sleeve inside the battery compartment makes it smaller than a "C" cell.  The cell fits inside the metal case. The sleeve is probably required for the battery to survive a crash.

Dukane DK120

-2.966 Volts between the sea water contact and the body.
These have been on the market at many hundreds to a thousand dollars, but I suspect that they are now (2022) becoming obsolete, replaced by longer lasting pingers.

Fig 1

Flight Data Recorders & Cockpit Voice Recorders

The purpose of the above pingers is to facilitate finding the FDR and CVR (Wiki). The Minifon wire recorder was the impetus for the cockpit voice recorder.
YouTube: WHY don't we upload BLACK BOXES to the cloud?, 17:30 -

Ultrasonic Cleaner

World Precision Instruments Inc. Model PUC-Y with Connoisseurs Delicate Jewelry Cleaner

Modes of operation are Off, medium Pulsed and High constant.

The jewelry cleaner has a basket inside the container, so you just put the jewelry in the basket and put water in the cleaner to couple the ultrasound to the cleaner.
Note:  If jewelry in put directly in the metal bowl it might destroy the stones because the jewelry would be hitting the metal bowl, so a few layers of cloth or a basket &Etc. is needed to seperate keep what's being cleaned from touching the metal.

Do not know what the two clamps held, didn't come with the cleaner.

These are made in a number of sizes, larger ones for industrial cleaning applications and this one I have for cleaning jewlerey.

Radatron Protector Model 8502 Ultrasonic Burglar Alarm

I was hoping that this was a microwave Doppler unit, but it's ultrasonic.  As received both ultrasonic sensor cans were loose inside the unit.  They were supposed to be in holes in the wood front panel, so would not have worked.  I was able to get them back into the holes using a screwdriver prior to unfolding the top.  For more Radatron products see Radar Warning Receivers - Radatron.

Fig 1 Radatron Protector Model 8502 Ultrasonic Burglar Alarm	Fig 2 Radatron Protector Model 8502 Ultrasonic Burglar Alarm
Fig 3 Radatron Protector Model 8502 Ultrasonic Burglar Alarm	Fig 4 Radatron Protector Model 8502 Ultrasonic Burglar Alarm

Ultrasonic Gold Wire Bonder

When I was designing Radar Warning Receiver microwave modules where we built the circuit using raw diode chips (not in packages) some of the wire bonding machines used an ultrasonics to shake the bonding tip to put energy into the bond.  In order to fuse the pure gold wire with the pure gold mound on the diode top contact it takes a combination of energy (heat plus ultrasonic) and pressure to get the metal to fuse.

Piezo Disks

There was a magazine article about using a piezo disk to listen to the 32768 Hz oscillator in modern digital watches and thus be able to adjust the watch to be more accurate.

Tweeter Speakers

These have been suggested as a way to hear things like bats.

Polaroid Sonar One Step Camera

The range finder mechanism uses ultrasonic sound and so might be a way to get a sensitive ultrasonic microphone.

Holosonics Audio Spotlight

These are installed by replacing the ceiling tile in a commercial shop with the special ultrasonic speaker.  When someone stands directly below the speaker only they hear the audio sales pitch.

Wiki: Sound from ultrasound.  Safe use: "Exposure to more intense ultrasound over 140 dB[citation needed] near the audible range (20–40 kHz) can lead to a syndrome involving manifestations of nausea, headache, tinnitus, pain, dizziness and fatigue...".  This sounds like Havana Syndrome (Wiki) to me. NYT comment 2021 May 13.

A narrow beam of ultrasonic sound at about 65 kHz is modulated with an audio signal.  Only people within the narrow beam can hear the audio. Used in stores where if you're standing in the right spot (marked with a decal on the floor) you hear the pitch, but nearby people do not hear anything.  Also used in magic acts where the "mind reader" is the only one in the beam.

4823908 Directional loudspeaker system, "A parametric loudspeaker utilizes nonlinearity of air relative to ultrasonic waves for producing an audio frequency having super directivity"
6778672 Audio reception control arrangement and method for a vehicle,
7391872 Parametric audio system, Frank Joseph Pompei, App: 1999-04-27, -
8027488 Parametric audio system,  F. Joseph Pompei, MIT, 2005-07-13 -
YouTube - Naval Post Graduate School -
also see: Gamewell - Long Range Acoustic Devices (LRAD) (Wiki) - These work with technology very similar to the Audio Spotlight, except they are intended for use a loudhailers that work at distances where conventional PA systems fail.  Developed after the Cole Incident (Wiki, Loudspeaker-History)  where sailors tried to tell a nearby boat to move away, but were not sure the small boat heard the warning.

Marten Repeller

eBay title: "12V Car Vehicle UltraSonic Under Hood Mice Rat Pest Repellent Mouse Repeller US", under $20 delivered.
Draws about 6 mA in standby.  At switch on audio tone and three blinks of the LED, then growling noise for a couple of seconds then nothing.

Using the CSE Bat detector  I can hear a sequence of very weak tones that sound reminiscent of electronic music.  These only happen every now and then, maybe once a minute or two.  During the tones the current is about 35 mA and when there are no tones the current is about 5 mA.  This seems more like playing music for mice than trying to disturb them.

2596678 Wild life chaser, Jr William W Gross, 1952-05-13, - battery powered, wind switched horn
2922999 Nuisance control technique and apparatus therefor, Carlin Benson, Alcar Instruments, 1960-01-26, - ultrasonic control of animal, bird and insect nuisances - cites magnetostrictive devices.
3058103 Device for chasing pests, Norman R Evans, 1962-10-09, - two alternating tones, maybe 20 kHz and 35 kHz.  High power level (push pull tube amp).
3305824 Pest repelling device, Miles N Brooks, Walter H Nelsen, 1967-02-21, -

Fig 5  Marten (mouse?) Repeller. Runs on 12 VDC <= 20 mA.

Fig 6 Looks like a uC driving a LED and the speaker. There's provision for a second function/speaker/device). The lower left pin on the DC regulator IC shows 5.0 Volts.

Thickness Gauge

Got this modern one after getting the Biddle magnetic Thickness gauge.
EM2271 Paint Thickness Tester

3538752 Ultrasonic thickness measuring apparatus, Hillel Weinbaum, AMF (Wiki), 1970-11-10, - cites 6 prior art patents.

Patents

2447333 Ultra-audible sound reception, Harvey C Hayes, Navy, App: 1931-12-30 (SECRET) Pub: 1948-08-17, 367/141; 73/649; 310/335; 73/645; 310/326; 340/566 - while a directional hydrophone at 800 Hz should be about 30' in diameter, one for 40 kHz needs to only be 1.5" to have good directional properties.  Propellers (he have have been talking about when cavitating) make a lot of noise in the 20 kHz to 60 kHz range.  Described is an untuned receiver that covers 50 kHz and lower with fairly flat response.
2542594 Supersonic communication system, Tiffany Carter, App: 1946-05-13, W.W.II, Pub: 1951-02-20, - way before the Holosonics audio spotlight
3192516 Vibration detector, Alan B Simpkins, Robert H Hamilton, HP, 1965-06-29, - leak detection (HP 4918A, YouTube)
4287581 Ultrasonic fluid leak detector, Dory J. Neale, Sr., 1981-09-01, - pistol shaped gas leak detector
4987769 Ultrasonic leak detection, David J. H. Peacock,Michael D. Dorsett, 1991-01-29, -

A "UE Systems Ultraprobe 2000 WTG-1 Ultrasonic Detector Kit" was on eBay with these patent numbers:
3421109 Frequency selective amplifier and oscillator circuits employing piezoelectric elements to control frequency, Alpha M Wiggins, George Allen Harris, Euphonics Corp, 1969-01-07, -
3592967 Ultrasonic detector, George A Harris, 1971-07-13, - probe for detecting gas leaks
3782180 Method for detecting leaks in condenser tubes, G Harris, 1974-01-01, - steam condenser pinholes or thin wall detection
3978915 Condenser with leak detecting apparatus, George A. Harris, E F I Inc, 1976-09-07, - steam condenser pinholes or thin wall detection
4416145 Ultrasonic leak detecting method and apparatus, Mark Goodman, John R. Zeno, Marty Borruso, UE Systems Inc, 1983-11-22, - probe uses Exar 2206 Function Generator (datasheet.pdf) "...function generator arranged to provide AM suppressed carrier operation. When such an integrated circuit is biased to the middle of its range, the carrier signal it is intended to produce, i.e. a signal slightly different than the received ultrasonic signal, will be suppressed. By adding the ultrasonic signal to the biasing level for this circuit the output will be only the sum and difference signals between the ultrasonic input and the carrier generated by the circuit. The sum signal is filtered out and the difference signal is used to drive headphones with which one can listen for leaks, or a meter by which to indicate them. The bias for establishing the sup pressed carrier operation is under the control of a feed back loop which senses when carrier signal is present in the output signal, integrates the sensed carrier signal over a period of time to arrive at an average value, and uses the average value to vary the bias such that the carrier signal is eliminated."
RE33977 Ultrasonic leak detecting method and apparatus, Mark Goodman, John R. Zeno, Marty Borruso, 1992-06-30, - was 4416145
4823600 Ultrasonic transducer and current loop transmitter, Michael Biegel, Mark Goodman, UE Systems Inc, 1989-04-25, -
0151115 ?
0303779 ?
---------------------- other UE Systems patents --------------

6339961 Ultrasonic detecting lubrication apparatus with acoustically isolated transducer, Mark A Goodman, William Bishop, John R. Zeno, 2002-01-22, - listens to Zerk grease fitting (Wiki, US1697217)
6341518 Ultrasonic standard, Mark A. Goodman, Betty J. R. Chavez, 2002-01-29, -
6707762 System and method for heterodyning an ultrasonic signal, Mark A. Goodman, William Bishop, U E Systems, 2004-03-16, - adds microprocessor.

Underwater ultrasound

Some of these patents look a lot like the transducer on the CRT-1 sonobuoy that dates to W.W.II.
2761118 Magnetostrictive transducer, John D Wallace, 1956-08-28, - hollow tube (10) of magnetostrictive material is driven by a coil inside the tube with a high permeability core and end caps.
2803807 Audible Underwater Signal, F.E. Butler, Navy, Aug 20, 1957, - for use on practice torpedo, triggered by the exploder to make a very loud noise.
2974204 Transducer, Michael C Supitilov, Du Kane Corp, 1961-03-07, - speaker/microphone maybe the Du Kane company only makes audio/visual products?
3119888 Method of making a transducer diaphragm, Michael C Supitilov, Dukane Corp, 1964-01-28, - actually Du Kane
3249913 Ultrasonic underwater sound generator, Henry L R Smyth, David M Makow, Stanley K Keays, National Research Council of Canada, 1966-05-03, - maybe the first ULB - simple one transistor squegging oscillator (Joule Thief) schematic, runs on 4 ea 5.4V Mercury batteries (21.6V).

3587038 Ultrasonic homing beacon and communication equipment for underwater swimmers, Frank Massa Jr, Dynamics Corp America, Jun 22, 1971 - 367/118, 367/120, 367/910 

Calls:
1385795 Method of and apparatus for detecting and locating sound, &c. Elias E Ries, (Jun 20, 1912) Jul 26, 1921, 367/120, 342/350
                Stereo underwater microphones & stereo headphones
3005183 Underwater transmitter Fred M Mayes, (Jan 10, 1951) Oct 17, 1961, 367/137, 181/125, 367/142, 114/20.1, 102/395, 367/166 

Calls:
2460316 Echo ranging and listening gear, Horace M Trent, Thomas F Jones, (Jul 31, 1944), Feb 1, 1949, 367/107, 367/137, 340/566, 367/901
                 Battery operated device capable of use for the location of submarines by direct audio listening: super audio listening or by echo ranging.

3079583 Sonar calibrator Herbert R Beitscher, George A Coates, Royal H Akin, Sec of Navy, Feb 26, 1963, 367/13, 455/84, 331/59, 73/1.82, 331/69, 367/910, 455/78 - small cylindrical battery powered transistor based 20 kHz barium titanate transducer is placed in contact with the sonar transducer and can check Rx or Tx functionality.
3123798 Fish finder, Rollind  & John Holloway Electronics World, Mar 3, 1964, 367/94, 367/910, 181/125, 367/104, 367/173, 43/17.1 -
                 Detector for sound & ultrasound
3320581 Piezoelectric voice range transducer, Sims Claude C, May 16, 1967, 367/157 -    stack of ferroelectric elements
3489993 Ultrasonic homing beacon and communication equipment for underwater swimmers, Frank Massa Jr, Dynamics Corp America, Jan 13, 1970, 367/120, 367/910 - a 40 to 80 kHz range directional receiver for use by an underwater diver to locate a beacon.

Calls:
2935728 Underwater object locator, Adolph R Morgan, Rca Corp, (Feb 15, 1946), May 3, 1960, 367/101, 367/910, 367/107, 367/116
                probably classified during W.W.II.  Uses an FM modulated (not pulsed) ultrasonic signal in the 500 kHz to 1 MHz range.
3005183 (see above)
3079583 (see above)
3123798 (see above)
3262094 Discontinuous hollow cylindrical transducer, Camp Leon W, Jul 19, 1966, 367/156, 367/151 - magnetostrction transducer

Calls:
2311079 Transducer, Parr Jr Josephus O, (Mar 28, 1940) Feb 16, 1943, 367/182, 336/30 - broader bandwidth & more efficient
2468837 Magnetostrictive transducer, Peck Jr Robert L, Bell Telephone Labor Inc, (Aug 2, 1945) May 3, 1949, 367/168, 366/127
2631271 Tubular hydrophone, A.L. Thuras, Sec of Navy, Mar 10, 1953, 367/168 - a device for generating or receiving sound signals at sonic or ultrasonic frequencies, and more particulary to an underwater transdecer of the tublar magnetostrictive type having a toroidal-would coil for converting compressional wave energy into electrical energy or vice versa.

2521136 Hydrophone, A.L. Thuras, Sec of Navy, (Apr 28, 1949) Sep 5, 1950, 310/26, 381/190, 367/168, 381/163

Calls:
 
2005741 Magneto-strictive sound generator, Hayes Harvey C, (Dec 15, 1932) Jun 25,1935, 367/178, 318/118, 181/157, 367/168, 381/190, 310/26 

2398117 Magnetostrictive oscillator, Elias Claesson Per Harry, Fabian Rost Helge, (May 3, 1941) Apr 9, 1946 - 367/151, 381/190, 310/26, 367/156

            2438926 Magnetostrictive supersonic transducer, Mott Edward E, Bell Telephone Labor Inc, (Aug 18, 1944) Apr 6, 1948 - 367/168, 381/190, 335/215, 310/26

2834000 Sound detecting device, Wiggins Alpha M, Electro Voice, (Dec 9, 1953) May 6, 1958, 367/155, 367/173 - barium titanate & aluminum stack
2891232 Hydrophone for directional listening buoy, Heinrich O Benecke, (Jun 28, 1955) Jun 16, 1959, 367/151, 367/153, 343/844
3021504 Apparatus for controlling the effective compressibility of a liquid, William J Toulis, Feb 13, 1962, 367/150, 181/402, 367/151 - shaping underwater beam  to 60 kHz.
3160769 Magnetostrictive transducer, Abbott Frank R, Dec 8, 1964, 310/26, 367/168, 367/156, 318/118, 367/160 -

3686656 Sunken vessel locator, Charles D Richards, 1972-08-22, - a pressure (or dissolving pill) sea water switch turns on an under water noise maker.
3780926 Ultrasonic rigid horn assembly, P Davis, Dukane Corp, 1973-12-25, -
3986161 Underwater directional guidance apparatus, John A. MacKellar, SEA SCAN, 1976-10-12, - A cylindrical "pinger" & directional hydrophone.
3992692 Programmable underwater acoustic beacon, Armand Jay Filer, Navy, 1976-11-16, - Rate and duration of ultrasonic pulse set by dip switches.
4131505 Ultra-sonic horn, Paul H. Davis, Jr., Dukane Corp, 1978-12-26, -
4312054 Acoustic beacons, Bard Holand, Sintef AS, 1982-01-19, - sleeve shaped transducer mounts around the outside of the cylindrical body.  Uses a pressure switch.
4635242 Underwater signalling device, James E. Hart, 1987-01-06, - wristwatch like device with manual Off-Momentary-On switch.
5010529 Underwater transmitter apparatus, Kenneth A. Maynus, SOS Ltd, 1991-04-23, - manual On-Off switch for use by divers.
9829565 Underwater acoustic beacon location system, Steven E Crocker, Navy, 2017-11-28, - method for locating ULB

3559161 - cross correlation to estimate distance, but no range improvement
4951263 - a ULB Tx spread spectrum signal - List of sea crashes (Wiki:KAL007, AI182, TWA841) Pinger Mfg: Dukane, Data Sonics, Sonatech & EFCOM Subsea Technology, existing pingers have a range of about a mile.
8005584 Acoustic command link to retrieve submerged flight data, Owen E. Flynn, 2011-08-23 - Flight Data Recorder (& Cockpit Voice Recorder) can send data over ultrasonic link
8727263 - beacon floats free of the downed aircraft

Related

Bats
Sonobuoys - CRT-1

References

HP Journal, May 1967, HP Delcon 4918A Ultrasonic Translator - translates 36 - 44 KHz (40 kHz LO) to 4 kHz-0-4kHz, i.e. it folds two frequency ranges into one.

The Songs of Insects by George W. Pierce (Wiki, Pierce Oscillator), 1949. - he built equipment to hear and generate ultrasonic signals for insects and W.W.I SONAR.
patents:
 879061 Rectifier for alternating currents, George W Pierce, Massachusetts Wireless Equipment Co, 1908-02-11, -
 923699 Wireless telegraphy, George W Pierce, Massachusetts Wireless Equipment Co, 1909-06-01, -
1112549 Apparatus for amplifying or detecting electrical variations, George W Pierce, 1914-10-06, - strange looking tube probably to avoid patent.
1450749 Apparatus for and method of controlling electric currents, George W Pierce, (Peter Cooper Hewitt), 1923-04-03, - radio remote control
1576459 Electric retardation line, George W Pierce, Submarine Signal Co, App: 1921-12-24, Pub: 1926-03-09, - Delay Line, includes design equations
1682712 Electric compensator, George W Pierce, Submarine Signal Co, App: 1919-06-25, Pub: 1928-08-28, - SONAR with binaural output (see: Sonobuoy\SONAR)
1750124 Vibratory system and method, George W Pierce, 1930-03-11, -
    RE19461 Vibratory system and method, George W Pierce, 1935-02-12, -
1882393 Magnetostrictive vibrator, Pierce George Washington, 1932-10-11, - 
1882394 Magnetostrictive vibrator, Pierce George Washington, 1932-10-11, -
1882395 Frequency indicator, Pierce George Washington, 1932-10-11, -
1882396 Magnetostrictive transformer, Pierce George Washington, 1932-10-11, -
1882397 Magnetostrictive vibrator, Pierce George Washington, 1932-10-11, -
1882398 Magnetostrictive vibrator, Pierce George Washington, 1932-10-11, -
1882399 Magnetostrictive vibrator, Pierce George Washington, 1932-10-11, -
1882400 Vibratory device, Pierce George Washington, Buckingham Stephen Alvord, Pierce Chemical Co, 1932-10-11, -
1882401 Loud speaker, Pierce George Washington, 1932-10-11, -
1889153 Acoustic electric energy converter, Pierce George Washington, 1932-11-29, -
2014410 Electromagnetostrictive vibrator, Pierce George Washington, 1935-09-17, -
2014411 Apparatus for electromagnetostrictive transmission and reception, Pierce George Washington, 1935-09-17, -
2014412 Magnetostrictive transmitter, Pierce George Washington, 1935-09-17, -
2014413 Magnetostrictive receiver, Pierce George Washington, 1935-09-17, -
2063944 Direction, transmission, and reception method and system, Pierce George Washington, 1936-12-15, -
2063945 Diaphragm and method, Pierce George Washington, 1936-12-15, -
2063946 Sound communication system, Pierce George Washington, 1936-12-15, -
2063947 Compensator, Pierce George Washington, 1936-12-15, -
2063948 Compensator and method, George Washington Pierce, Atherton Noyes Jr, 1936-12-15, -
2063949 Magnetostrictive vibrator, Pierce George Washington, 1936-12-15, -
2063950, 2063951, 2063952 Apparatus for transmission and reception, Steinberger Raymond Leonard, 1936-12-15, - directional SONAR
2133642 Electrical system, Pierce George Washington, 1938-10-18, - Crystal oscillator at Ultrasonic or RF frequencies.
2133643 Electrical system, Pierce George Washington, 1938-10-18, -
2133644 Electrical system, Pierce George Washington, 1938-10-18, -
2133645 Electrical system, Pierce George Washington, 1938-10-18, -
2133646 Electrical system, Pierce George Washington, 1938-10-18, -
2133647 Electromechanical vibrator, Pierce George Washington, 1938-10-18, -
2133648 Electrical system, Pierce George Washington, 1938-10-18, -

Links

PRC68, Alphanumeric Index of Web pages, Contact, Products for Sale
Page Created 24 Oct 2015