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 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
Loran-C. With the advent of
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,
are due to close in 2016.
Radio-Radar-Sonar in Naval Applications
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.
Fig. 1 - A radar-equipped PT boat.
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
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 and ordnance.
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.
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. 2 - A naval communication room at the
Cheltenham, Maryland, Naval Radio Station. In this installation
both manual equipment and the newer radioteletype units are
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.
Fig. 3 - Radar equipment in operation at
the Naval Research Lab.
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
Fig. 4 - Loran receiver indicator aboard
a Coast Guard vessel.
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 - The Loran timing sequences.
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
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 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.
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.
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
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 of range.
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.
Fig. 8 - A v.h.f. direction finder on an
aircraft carrier deck.
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. 9 - Typical radio compartment in a Navy
PBY patrol bomber.
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 infrared
Fig. 10 - A simple type viewer used by signalmen
to read messages sent with the otherwise invisible infrared
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.
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
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 October 15, 2015