World War II was the "necessity"
that elicited the "mother of invention" activity responsible for many huge leaps
in technology - not the least of which was electronic verbal and non-verbal communications.
By 1951, when this Radio & Television News magazine article on the sate of the art of military electronics was published,
the United States was already in the midst of another war - this time in Korea -
fighting back the frontiers of Communism and despotism. Along with radio and radar,
Loran had become
a major means of ocean and air navigation. A fair description of the operational
details, including timing diagrams, is included in the text. Loran-A, the original
system as it came to be known, was fully decommissioned in 1980, thereafter supplanted
by Loran-C. With
the advent of GPS,
and Glonass navigation
systems and their low equipment and installation costs, Loran-C was eventually no
longer needed either, causing it to be decommissioned in the U.S. in 2010. Norway's Loran-C stations, the last operational stations, were
scheduled to close in 2016. In case you are wondering, this is a
Radio-Radar-Sonar in Naval Applications
Fig. 1 - A radar-equipped PT boat.
By Samuel Freedman
Technical Products and Services Co., Santee, California
Radio-electronics plays a vital role in all naval operations. Vast laboratories
work night and day to keep the U. S. Navy ahead in such developments.
A discussion of radio, radar, and sonar equipment in naval . applications must,
of necessity, be confined to declassified information at this time. Nevertheless,
naval electronics today embraces all phases of radio and its offshoots, as developed
during the past half century. It is used extensively on land, on the sea, under
the surface of the sea, and in the air. It includes infrared, guided missiles, and
atomic developments. It covers the entire frequency spectrum from very high powered,
very low frequency stations (below 20 kc.) through the various frequency bands used
for radiotelegraphy, radioteletype, radiotelephony, facsimile, and television. It
extends to the microwave region for radar and communications. It continues still
further to infrared or invisible light and even to the radioactive band of the electromagnetic
spectrum where frequencies may be as high as 100 trillion megacycles or more - regions
where electromagnetic waves are also known as rays or particles.
Although many of these naval applications are paralleled or even exceeded by
the Army and the Air Force, the use of electronics extends into the activities of
the Bureau of Ships, Bureau of Aeronautics, Bureau of Ordnance, training activities
of the Bureau of Personnel, and, on a small but expanding scale, into the activities
of the Bureau of Medicine and Surgery.
The Navy today has many major multi-million dollar laboratories and test centers
which are wholly or primarily concerned with electronics. Their work overlaps only
because electronics affects every phase of naval operations in such a way that so
far it has been impractical to establish a single "Bureau of Electronics." These
major laboratories and test centers include such installations as: The David Taylor
Model Basin near Washington, D. C.; The Naval Research Laboratory of the Office
of Naval Research in Anacostia, D. C. and its annex on Chesapeake Bay; The Naval
Ordnance Laboratory in White Oak, Maryland, for the Bureau of Ordnance; The Special
Devices Laboratory of the Office of Naval Research at Sands Point, Long Island;
The Underwater Sound Laboratory of the Bureau of Ships and the Office of Naval Research
at New London, Connecticut. The Naval Air Development Station at Johnsville, Pennsylvania;
The Naval Air Test Center at Patuxent, Maryland; The Naval Air Missile Test Center
at Point Mugu, California; The Naval Ordnance Test Station at Inyokern, California;
and The Navy Electronics Laboratory of the Bureau of Ships at San Diego, California.
The staffs of these laboratories, which are made up of both naval and civil service
personnel, range from a few hundred to several thousand employees. In addition,
this force is backed up by other activities in common with other defense services
and the large laboratories of the National Advisory Committee on Aeronautics, such
as the Ames Aeronautical Laboratory at Moffett Field, California. Their work is
further reinforced by contracts and subcontracts for research, development, and
production which are awarded to various industrial firms, universities, and laboratories
in the United States. University contracts may cover strictly naval research problems
or may be awarded in conjunction with the parallel requirements and interests of
the other defense services.
This research program also reaches into such activities as those of the Radio
Technical Committee for Aeronautics, the Air Navigation Development Board, the Research
and Development Board, and the Radio Technical Committee for the Marine Services,
etc., all of which are primarily civilian in nature.
Although the United States is singularly blessed in having a vast production
potential, the Armed Services have not left their development programs to chance.
Hundreds of millions of dollars have been spent in the past five years on research,
development, and the production of prototypes.
Those who were familiar with the Navy electronics organization during World War
II will find that the Navy's dominant electronics organization, the Bureau of Ships,
has continued to operate more or less intact although with a skeleton force. There
have been practically no changes in the code organization setup other than those
necessary to take care of new developments. The Bureaus of Aeronautics and Ordnance
have likewise developed programs to take care of the electronics requirements of
their particular branches. The small wartime Office of Patents and Inventions and
the subsequent Office of Research and Inventions has been greatly expanded and is
currently operating under the designation of the Office of Naval Research with a
fine field laboratory of its own. Electronics, originally confined to naval communications
apparatus, has now grown until it reaches into every phase of naval activity. In
addition to its communications uses, electronics now serves in the fields of navigation
The advent of radar on naval vessels, including several different types which
perform specialized tasks, has skyrocketed the number of electron tubes in operation
aboard such craft. This same condition also applies to aircraft and submarines.
During World War II, the average submarine carried equipment using considerably
more than 500 electronic tubes, but today that number has been increased and the
range of the craft has been expanded as a result of improved and increased radio,
radar, and sonar equipment aboard such vessels.
Fig. 1 is an example of the use of radar equipment aboard even the smallest
naval craft. Visible on top of the mast is the "thinking cap" of the PT boat. This
so-called "Radome" bulb houses the antenna of the radar set aboard the vessel. Radar
has proven invaluable to the hard-hitting PT boat because they operate chiefly under
the cover of darkness. Under such conditions, radar's electronic eye pierces this
Stygian gloom for a horizon and indicates targets as to direction and distance,
in addition to providing warning of navigational hazards. When a PT boat operates
against a large enemy vessel, it enjoys the advantage in that the larger ship yields
a much stronger indication on the PT's radar screen and for a greater distance than
the PT registers on the larger ship's screens. The PT because of its smaller dimensions
and because it is fabricated of wood has poorer reflective properties and is, therefore,
harder to pick up on the radar screen of the enemy vessel.
Fig. 2 - A naval communication room at the Cheltenham, Maryland,
Naval Radio Station. In this installation both manual equipment and the newer radioteletype
units are used.
Fig. 3 - Radar equipment in operation at the Naval Research
Fig. 4 - Loran receiver indicator aboard a Coast Guard vessel.
Many devices, usually considered as "land-based," have now been adapted to aircraft
and seagoing uses. One such unit is the radioteletype. Fig, 2 shows a battery of
radio apparatus and the radio teletypes used in naval communications. The Navy has
adapted teletype to radio operation and has produced a workable combination which
eliminates the need for an operator to decode a series of dots and dashes. The unit
is an ordinary teletype which is connected by means of a converter to the radio
transmitting and receiving apparatus. When receiving, the converter changes radio
impulses into electrical energy which actuates the teletype. The transmitting process
is identical. The unit has a gross speed of 60 words-per-minute as compared with
25 words-per-minute for fast radiotelegraphy. Radioteletype was first used under
combat conditions during World War II at Iwo Jima and later proved itself at Okinawa
and during the air strikes against the Japanese mainland. It is widely used now
and, for example, when the President of the United States travels on a naval vessel,
radio teletype is used to maintain constant contact with his office in Washington.
Fig. 3 shows one of the many types of radar installations likely to be encountered
on naval vessels. More compact versions have been developed for use on submarines
and in aircraft. Developed independently by American, British, French, and German
scientists during the decade preceding World War II, the refinement of radar equipment
received its greatest impetus upon the opening of hostilities. First used in the
detection of surface objects in the near distance and under conditions of poor visibility,
radar's range and versatility was extended to provide long range detection of airborne
as well as surface objects, improve accuracy in fire control, provide safety in
navigation, and facilitate the identification of distant and unrecognizable planes
and ships. Present day equipment is now practically foolproof.
Figs. 4, 5, and 6 show a loran installation (LOng-RAnge-Navigation) which developed
as an offshoot of radar for sea and air navigation. Kept under wraps during World
War II, it was declassified after the war to permit its use by merchant marine vessels
and civilian aircraft. The Coast Guard operates the necessary land stations required
for its use. Fig. 4 shows a navigating officer aboard ship operating a loran
receiver-indicator to obtain data regarding the position of his vessel. Fig. 5
illustrates the principle of operation of the device. Two stations in the prewar
160 meter radio amateur band transmit in such a manner that the master station (the
one which initiates the pulsing event) actuates and is followed by a pulse transmission
(40 microseconds later) by another station (called the slave station) which may
be as much as 300 miles distant. There can only be one place within the radio receiving
range of about, 600 miles ground wave or 1400 miles skywave where a predetermined
time difference in reception of those two pulses will exist. By reference to a loran-type
of map, a line of position can be determined for that pair of stations whose signals
arrive with that specified time difference.
Fig. 5 - The Loran timing sequences.
With this arrangement, the location of a ship can be pinpointed to within a quarter
of a mile. The use of low frequencies and high intermittent pulsed power makes reception
of the loran signals possible for hundreds of miles. By picking up another pair
of stations (the slave station for one pair can also serve as the master station
with respect to a station beyond it) another loran line of position can be provided
so as to give another positional reference line. This second line can then intersect
with the one plotted for the first pair of stations. If a third pair of stations
can be received, the location of the ship can be determined beyond doubt. Many pairs
of loran stations can utilize the same frequency channel by using different pulse
repetition rates. In this way only one pair of pulses will show up as stationary
ones for a particular group selection when viewed on the cathode-ray tube indicator.
Fig. 5 shows how this information looks on the cathode-ray tube indicator.
By selecting increasingly faster sweep rates for the CR tube of the receiver-indicator,
the two pulses (master and slave) are measured first coarsely and then minutely
down to the last microsecond difference of the time of arrival. The received pulses
are first lined up on their respective pedestals. The master pulse is made to stop
on the stationary pedestal either at the left end or the beginning. The slave pulse
is then similarly lined up on the adjustable pedestal by means of an electronic
knob control. The unit is then switched to a faster sweep of the tube to magnify
the two pulses in question. The amplitude of one is increased or decreased as necessary
so that one is fully superimposed on the other. When they merge to resemble a single
pulse without overlap, the time difference is read directly in microseconds on a
veeder counter. By knowing which pair of stations was used (shown on the station
selector switch), for example, Pair 2, and the time difference (as shown on the
Veeder counter), for example, 1220 microseconds, the ship's line
of position may be established by referring to loran line of position 2-1220 on
the map. Experienced personnel can take such a reading in a matter of seconds. They
can also perform this operation continuously or as often as required.
Fig. 6 - The Loran line of position.
Fig. 7 - The atomic shock wave. A few seconds after the
"Able Day" bomb exploded at Bikini, a camera in the tower on the atoll recorded
the atomic pressure wave thusly.
Fig. 8 - A v.h.f. direction finder on an aircraft carrier
Fig. 9 - Typical radio compartment in a Navy PBY patrol
Fig. 10 - A simple type viewer used by signalmen to read
messages sent with the otherwise invisible infrared light.
Fig. 11 - A guided missile is launched at the pilotless
aircraft base of Naval Air Missile Test Center, Point Muqu, California. Guided missiles
are high on the research priority list.
Fig. 7 portrays one of the greatest and most important applications of electronics
in warfare - the atomic bomb. This weapon represents new frontiers in electronics
since every step of the bomb's development as well as its control involves the use
of electronic apparatus and techniques.
One heavy utilization of electronics is peculiar to the Navy. That is in the
field of underwater sound detection, known as sonar. Sonar utilizes both audible
(sonics) and inaudible sound (supersonics), chiefly the latter. This sonar equipment
is used to detect submarines and surface vessels by means of the sound waves they
set up in the water. It is the submarine's most useful electronic device when it
is submerged. A fathometer is also considered a sonar device but this equipment
operates only in a vertical plane. Sonar is comparable to radar inasmuch as it sends
out a pulse and waits for the pulse to return before sending out further pulses.
The time taken for the pulse to travel to its target and return is calculated and
calibrated on an indicating dial in terms of distance. This is approximately 5000
feet-per-second with corrections for sea water density, salinity, and temperature.
Sonar is also used in a modified form by aircraft in detecting submarines.
One example of this is the sonobuoy. An airplane drops a sonobuoy into the water
where it floats on the surface and releases a water-protected cable terminating
in a hydrophone (equivalent of a waterproof microphone) into the water for a depth
of several feet. The sounds picked up by the hydrophone modulate a radio transmitter
in the, sonobuoy which, in turn, radiates the information from the sonobuoy antenna.
This signal is picked up like radiotelephone signals by aircraft within ' horizon
The basic components of a shipboard sonar system include a driver unit to produce
the sound signal to be transmitted, a projector to transmit the signal to the water
and pick up the sound signals from the sea, a receiver-amplifier which amplifies
these signals, and indicating equipment which gives the range of the target which
reflected the outgoing signals. The bearing of such signals is determined by rotating
the projector back and forth for maximum indication. A dome protects the projector
and prevents water noise. Retracting gear hoists and lowers the projector as well
as trains or rotates it in order to determine the direction of the sound. The receiver-amplifier,
the indicating equipment, and controls are grouped together in an. assembly called
the "stack" which is located near the maneuvering controls of the vessel. Auxiliary
equipment such as the BDI (bearing deviation indicator and the attack plotter facilitate
the use of sonar information in tactical applications. The driver is located close
to the projector and retracting gear in order to keep the leads to the projector
short. It is remotely controlled from the "stack." The projector is, of course,
under water. When the projector is in operating position it extends beneath the
keel of the vessel so that the sound beams may be directed in any horizontal direction
without obstruction by the ship itself. Placing the projector a substantial distance
below the keel helps to avoid interference produced by the noises of the ship itself.
The retracting gear, mounted on a sea chest, is built into the hull of the ship.
It raises the dome into the sea chest for protection when there is danger of damage
by underwater obstructions or heavy seas. The motors for operating the retracting
gear can be controlled from either the stack location or from the lower sound room.
Extraordinary problems may arise from the fact that the projector dome protrudes
below the vessel. Often submerged objects or even large fish collide with the dome,
damaging it or putting it entirely out of commission.
Fig. 8 is a high frequency direction finder on an aircraft carrier. This
unit is used for locating the source of high frequency radio transmissions. It proved
particularly useful in pinpointing the exact location of any submarine using high
frequencies to transmit to other such craft. The information picked up by this equipment
is then used to dispatch ships and aircraft to the scene for appropriate action.
Other applications of' electronic equipment as used by the Navy include the radio
gear carried by a Navy PBY patrol bomber of the Catalina type. See Fig. 9.
Such craft did effective work in rescuing pilots and crews of other planes shot
down or forced into the sea by engine trouble. They were also used to good advantage
in patrolling missions and in flashing radio intelligence to other naval units.
Fig. 10 shows a simple infrared unit used for communication by means of
invisible light. Its ability to function with light waves that are invisible to
the naked eye (electromagnetic frequencies lower than 375,000,000 megacycles) permits
secret communication, particularly at night. This technique was used on most of
the major fleet units at the time of the Mariannas campaign in World War II. Subsequently
these units have been installed on all surface ships of the active fleet. Special
filters and hoods have been developed to convert the standard Navy blinker light
into an invisible light. These filters screen out all but the infrared component,
thus the transmission is invisible to any observers except those equipped with specially-designed
Fig. 11 is a photograph of the "Loon," one of the many guided missile whose
operation is dependent on electronics. The word "guided missile" is replacing the
term "pilotless aircraft." It is an aircraft without a human pilot whose function
have been replaced by electronics. In addition to not jeopardizing a human life,
the guided missile is faster in response than human endurance and reaction time
would otherwise permit.
Technical officers and enlisted technicians in our modern Navy are receiving
training and experience with all of these diversified types of electronic equipment.
The training they are getting would be virtually impossible to duplicate elsewhere
since the equipment on which they work is out of the range of most educational budgets.
Electronic technicians now receive training comparable to that given pilots when
the elaborateness of facilities and cost of the courses are taken into consideration.
This same thing applies to similar educational facilities offered by the Army and
Air Force and to some extent the Coast Guard and the Marine Corps. Very few of the
men who received such training will dispute its value in civilian life. There are
openings in the merchant marine, with civilian airlines, the CAA, and the various
branches of the FCC as well as industry for men who fully understand the operation
of such equipment.
In time of peace or demobilization, radio or electronic technicians with military
training enjoy excellent civilian employment opportunities. In time of national
emergency they insure national security. And when war comes, they enable our country
to substitute technology for human lives to win the only battle that really counts
- the "last one."
Posted July 14, 2022
(updated from original post on