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John Merrill is an electronics engineer emeritus of the Naval Underwater Weapons Center at New London, CT. He is a frequent contributor to the REVIEW.

[Author’s Acknowledgement: This paper is heavily dependent on many sources. However, special note is made of Evolution of Naval Radio-Electronics and Contributions of the Naval Research Laboratory by Louis A. Gebhard. This book helped to clarify the many technical developments at NRL that improved submarine radio communications.]

In the winter of 1896-97, John P. Holland’s sixth submarine, which would become USS HOLLAND (SS 1) on April 11, 1900, began to take shape at Nixon’s Crescent Shipyard, Elizabeth, New Jersey.

At the same time 24 year old Guglielmo Marconi, recently from Italy, was in England demonstrating his wireless equipment and taking out his first patent. Returning to Italy in June 1897, Marconi established wireless communications from land to Italian warships located at distances of up to some 10 miles. By 1902, on the United States liner PHILADELPHIA en route to the United States, he was receiving wireless messages at distances of 700 miles during the day and 1500 miles at night. Customers for his system of wireless telegraphy included various navies and armies as well as the commercial sector. These achievements in wireless telegraphy led to his Nobel Prize for Physics in 1909.

Naval Communications 1896

Communication between ships at sea was considered a knotty problem in 1896 when Marconi was demonstrating bis early wireless communication in England. Later in 1922, a retired United States Navy captain relating the history and development of radio or wireless telegraphy looked back to his time at the Naval War College in 1896 and summarized ship communication then.

“Outside the use of carrier pigeons, the sense of sight and bearing only were under consideration, that is, visual or audible communications between ships in extended formation … searchlight reflection on clouds at night … 30 mile communication sent and answered. A signal gun was estimated to be audible at 10 miles if conditions were favorable.”

The captain went on to note that by 1901-02 (after the Spanish War), Marconi’s concept of wireless communication between naval vessels up to SO miles apart was achieved.

On 21 January 1900, the New York Herald reported .. the day of flag and lamp signaling system in the Navy is drawing to a close”. At this time, Navy Board considerations included the advisability of discontinuing the homing pigeons service and evaluating wireless radio. The Navy board reported favorably for the wireless. The next year, 1901, the Bureau of Equipment bought duplicate wireless sets from France, Germany, Britain, and from the DeForest Company in the United States. Two years later 45 more sets were procured.

With wireless transmitting ranges of the order of 74 miles, the Royal Navy by 1900 had 26 ships equipped with wireless and six coast stations constructed. The British were the first to equip submarines with wireless telegraphy. The British submarine HOLLAND I, laid down in February 1901 with sea trials in April 1902, had a wireless compartment.

Military application in wartime quickly followed. During one of the final sea engagements between Russia and Japan in the northern Pacific on May 27, 1905, in a lifting fog at 3:30 AM the captain of the armed merchant cruiser SHINANO MARU used wireless radio to his advantage. He sighted the Russian fleet and, using the wireless, within 90 minutes was able to bring four of Japan’s finest battleships on a course to intercept the Russians and successfully destroy the opposing fleet. Without relay, the Japanese were generally able to communicate to ranges of about 60 miles.

General use of radio by the United States Navy in 1906 finds 57 equipped ships, 39 shore stations, and a transmit-receive capability between surface ships of about 640 miles. The primary wireless use at this time was for fleet reporting and ship-to-shore and vice versa, with additional support on land by use of the telegraph. Visual communication methods were still somewhat preferred. During this period, good operating discipline among naval wireless operators was generally lacking; this did not contribute to a broad acceptance of wireless.

Radio communications with submarines remained operationally unsatisfactory for several more decades. Space available in the submarine for radio equipment was limited, the power capability of the available transmitters was low, and the small antennas were too short for the low radio frequencies and equipments available through the 1920s.

An Early 1907 View or the Submarine and Wireless Telegraphy

In 1907, Cyprian Bridge, an officer in the Royal Navy (later Admiral Sir Cyprian Bridge), wrote “Why do we want submarine boats? To do with increasing of invisibility, but otherwise under greater difficulties the same work as torpedo-boats, viz, to sink or injure an enemy’s ships.” Regarding radio-telegraphy, Bridge observed, “It permits between an observer and his chief, scores and perhaps hundreds of miles apart, the exchange of question and answer … the range of direct communication has already been increased to twenty times its former amount, if not still more.”

To assure better wireless equipment performance from the manufacturers, the Navy established the U.S. Naval Radio Telegraphic Laboratories in the fall of 1908 under the Navy’s Bureau of Equipment. Working space and facilities were made available at the National Bureau of Standards in Washington, DC. Further performance needs led the Navy by 1915 to develop radio equipment in house. The Washington Navy Yard was assigned the development of radio receivers and wave meters. Naval Laboratories at various locations such as Great Lakes, Illinois and the Naval Air Station at Washington (Anacostia), DC addressed research and development aspects of the Navy’s radio needs during and immediately after World War I. The efforts included radio broadcasting, radio detection and aircraft radio.

At the time Bridge was making his observations, both the United States and Great Britain bad already accepted the notion of the submarine primarily for coastal defense. In 1908, British D- boats appeared with radio masts, the first for a British submarine. Cage type antennas were slung from the masts.

By 1910, the number of German submarines began noticeably to increase. Starting with the outfitting of the U-5 in June 1910, all further U-boats were fitted with radio telegraphy. On the U-5, two aerial masts could be lowered from inside the submarine. The wireless system communication distances achieved were about 50-62 nautical miles between ships and U-boats and distances of about 30 nautical miles between U-boats. British submarine radio distance performance matched that of the U-boats.

With the beginning of World War I hostilities, 45 U-boats were ready for service or in construction. The Royal Navy submarine fleet was the largest in the world with 74 boats, 31 under construction and 14 more either on order or projected.

In the last pre-war British maneuvers of 1913, the submarine was perceived by some as having greater possibilities than those of harbor defense. Two distinct roles for the submarine began to evolve: those of a submarine killer and of a fast long range cruiser-like underwater support of the line of battle.

Communications with and among military ships at sea through the centuries has always been a continuing unwieldy problem. Even with all the current technological advances at the start of the 20th century, surface ship wireless communications were only embryonic in view of the progress in wireless communications which the new century would bring. Although the 1901 annual report of Secretary of the Navy John D. Long referred to the advisability of discontinuing the homing pigeon service and substituting for it some system of wireless, World War I would still see the use of this mode to pass information from a submarine to the shore base.

An often encountered story of that period tells of a British E class submarine operating off Heligoland, the German North Sea Gibraltar-like naval base. The need arose for the submarine to send an urgent message to Harwich, a homeport for destroyer and submarine flotillas on the east coast of England 140 miles from the submarine. The submarine’s wireless telegraph range was 50 miles. The submarine captain at 4 AM ordered four pigeons, each carrying identical words, to be dispatched in a moderate wind for Harwich in a west-south-westerly direction. The message arrived at about 3:30 in the afternoon. This took place almost 20 years after Marconi’s development. Communications were certainly among the submariner’s problems.

The need for enhanced submarine communications would soon be apparent, but the technologies to achieve this would only slowly evolve. The surface ship’s communication dilemma by the mid- 1920s would be under reasonable control. The solutions to submarine wireless communication problems through and beyond World War I would lag. Reasons for the lag stemmed in part from the immediate environment and proximity of the sea to the submarine and its appurtenances. Through the years, submarine antenna problems due to temperature (from the tropics to the Arctic regions), pressure as the submarine went deeper, drag forces as it moved faster, wave slap, and high sea states always ranked high. Adding to these primarily mechanical challenges, the sea around the submarine is generally opaque to the radio waves. Notwithstanding these realities, the submarine gradually became electromagnetically connected although sometimes the pace was imperceptible. In retrospect, the slowness was due to a combination of shortfalls in understanding, technological developments, and fiscal allocations.

At the beginning of World War I in 1914, one would find both wireless and diesel engine for propulsion as innovations in the E class, the fifth evolution of U.S. Navy submarines.

A 1915 book regarding modem submarines and their role in naval warfare at that time prompted the comment that radio (day or night) means of signaling was first in a list of eight techniques or methods of signaling. That same year, author Frederick A. Talbot observed that German boats were using wireless telegraph to relay 150 miles to Berlin. In 1916, the U-20 (which had sunk the LUSITANIA the previous year) established a submarine distance wireless record of 770 miles, communicating with Germany. In March the following year after sinking a French battleship off Sardinia in the Mediterranean the U-64 reported that event that same night to a German cruiser operating off the coast of northwest Germany. This was accomplished with a transmitter power of about 1 Kw and telescopic aerial masts. U-boats operating against commerce west of the British Isles routinely were able to talk directly with stations in Germany and Belgium

The concept of a fleet submarine in support of the battle group grew. This was articulated in 1916 by Lieutenant (junior grade) F.A. Daubin in The Fleet Submarine, an article in the Naval Institute Proceedings. Daubin observed that by February 1916, 487 ships had been sunk by submarines. He discussed the characteristics of a fleet submarine and noted that the increased size of the fleet boat would allow for a radio plant of greater power than the limited space available in the then current coast defense submarines. This fleet concept persisted for the next several decades and heavily influenced submarine design. The evolving role of an independent offensive submarine brought the submarine further into the command and control radio communications needs. From 1915, anti submarine warfare was the primary submarine mission.

A 1917 book, Secrets of the Submarine, mentioned that the submarine wireless problem was one of antenna masts. At that time experiments with telescopic and folding masts, mounting and dismounting without crew on deck, had not been successful. The author also speculated that Germans off Great Britain were using wireless.

U.S. Navy World War I submarine missions occasioned many escapades of near disaster from hostile or near hostile action by friendly convoy and convoy escorts. Primarily as a result of lack of communications, four U.S. Navy submarines, N-3, N-4, 0-4, and 0-5, were inadvertently fired upon during the summer of 1918. Total disaster was only avoided at the last moment in each case.

The N-3, after being hit by fire from a British transport and taking water in the torpedo room, was nearly rammed by an American destroyer coming within 20 yards. As a result of the accidental skirmish, an unexploded British 7.S inch shell was found in the submarine’s forward superstructure.

The N-5, previously damaged by a collision, was fired upon by a British steamer while the submarine was slowly en route to New London.

Six days out of New York City, after completing convoy escort and inbound, the 0-4 was fired upon by a convoy steamer; but the shots fell short. Identification was then successfully established. There were procedures for recognition in place, but positive identification and reliable ways to communicate were not available. Friendly force action against submarines also occurred during World War II.

A 1920 Naval Institute Proceedings article on American submarine operations during the War commented on World War I submarine N-5’s radio communication posture. The N-5 was one of seven N class submarines constructed by the Electric Boat Company during 1917-18. During the last year of the War in order to receive radio communications the N-5 surfaced, raised the radio masts, and listened for further orders from the Navy shore radio stations at Arlington, Virginia (completed late in 1912) or at Siasconset on Nantucket off the coast of Massachusetts.

In the early post-World War I period, the establishment of the Radio Corporation of America and the start of the Naval Research Laboratory at about the same time significantly impacted Navy radio communications growth and effectiveness.

In October 1919, RCA was founded by the General Electric Company and included the holdings of the Marconi Wireless Telegraph Company of America, a subsidiary of a British owned company. The Marconi Company owned Navy-leased wireless equipments, both shore-and ship-based. This action provided a United States based radio equipment manufacturing source for the Navy that would always remain under American control. Lessons from World War I regarding potential problems in the event of foreign monopoly of some segment of the wireless industry led the Navy to look favorably at such a corporation.

Further, by consent, RCA had legal access to a number of radio and related patents stemming from a variety of sources. In the early 1920s, in addition to General Electric, Westinghouse and American Telephone and Telegraph Company were the original stockholders of RCA. These three companies accounted for more than half of the stock holdings. Radio related patents of the several companies were available to the new corporation.

Scientific American of April 1920 reported Loop Aerials for Submarines. The article was based on a paper read before the American Physical Society and reported some results of experiments made aboard a submarine to determine radio communication performance. This successful antenna concept is sometimes called the clearing line loop. The clearing lines, cables located over the submarine from bow to stem, were used to keep off debris and prevent damage to the submarines when surfacing. The loop attached to the clearing lines consisted of two insulated wires connected (grounded) to the submarine hull at the bow and the stem. It was carried over suitable supports to the bridge and then through radio lead-ins to the receiving and transmitting apparatus. The submarine loop antenna out performed ordinary antennas. The maximum depth of submergence for receiving was found to be frequency dependent. At radio frequencies of the order of 30 kHz, signals could be received when the top of the loop was submerged 21 feet. Transmitting from the loop at a frequency of about 300 kHz, distances of 10 or 12 miles were obtained when the top of the loop was practically at the surface. The range was found to decrease to two or three miles when the top of the loop was eight or nine feet below the surface. It was also noted that the loop could be used as a direction finder, maximum signals being received when the submarine was pointing toward the transmitting station. Limitations of the clearing line loop included obstruction of firing from the deck guns and easier detection of a surface submarine by enemy aircraft.

These findings indicated modest progress and a growing understanding of the submarine’s needs and its environment. The requisite radio communication technologies making the submarine the ultimate war machine would only slowly evolve and begin to be available in the post-World War II era and beyond.

The submarine’s continuously broadening acceptance, increased numbers, propulsion enhancements, improved weapons and tactical value placed radio communications demands beyond the state-of- the-art of available radio communication equipment.

The Naval Research Laboratory (NRL) Begins

Early in World War I, Germany’s submarine effectiveness and the observed importance of science on warfare affirmed the need for a new Navy laboratory for experimental research, to be managed by civilians under the direction of a naval officer. In August 1916, an Act of Congress established and funded the new research laboratory under the direction of the Secretary of the Navy. NRL’s charter included a vast number of technical areas including radio. Lack of agreement on the location of the laboratory and the United States’ entrance into the War the following year delayed the construction of the laboratory until December 1920.

In early 1923, the first five buildings of NRL were completed. The site selected was at the Bellevue Arsenal on the Potomac River below Washington. They were augmented by the addition of the Naval Aircraft Laboratory, the Naval Radio Telegraphic Laboratory, and the Radio Test Shop from the Washington Navy Yard.

Some of the areas of NRL’s work which contributed to the effectiveness of submarine radio communications during the period between World War I and World War II included radio propagation studies, the Navy’s adoption of high frequencies {HF), high frequency equipment, intrafleet HF equipment, crystal frequency control, and submarine HF transmitters.

By 1924, the growing needs for commercial radio broadcasting led to the establishment of the broadcast band, 550-1550 kHz. Between 1900-1920, the Navy primarily used radio frequencies below 600 kHz; but the Navy bad plans to use what became the broadcast band for future intrafleet communications. This development led the Navy to consider frequencies above the broadcast band. Building on the experience of the radio amateurs who from 1912 had access to frequencies above 1500 kHz, NRL examined this part of the spectrum and developed propagation theory to predict performance at the high frequencies. For long range communications, HF provided improved performance. The equipment required less power and was more compact and lighter. The equipment cost was relatively lower; and, further, more channels were available to the Navy.

Interest in HF was further increased because the new Navy fleet organization made in 1922 created a need for more channels for radio circuits between the various fleet elements. Multiple frequency reception and transmission from the ships was also a requirement for consideration.

After several years of HF propagation studies, equipment development, and various experiments and tests, a definitive long range round-the-world HF test was conducted in 1926. Successful extensive long distance tests at HF were held between NRL and the USS SEATTLE operating in Melbourne, Australia. In late 1926 the Navy decided to include HF equipment in its Radio Modernization Plan, then undergoing revision. Planned HF installations were greatly extended beyond the earlier recommendations.

The Navy’s use of HF (2,000 to 18,100 kHz) made possible antennas smaller in size and reasonably compatible with the spaces available on a submarine. Further in 1927-28, NRL developed a new HF transmitter for submarine use.

To demonstrate the HF capability, two fleet submarines (V-1 and V-2, commissioned in 1924) had the new transmitters and antennas installed in June 1928 at San Francisco. The submarines conducted transmit and receive tests in the Pacific. They were able to communicate both day and night with NRL in Washington, DC from Hawaii. At the time, this was a long distance communication record for a submarine.

Other United States submarines were smaller than the V class and could not accommodate the HF transmitter. Therefore, in the following year (1929) NRL developed a second HF submarine transmitter suited to the smaller space available on the non-fleet type submarines. This new submarine transmitter was made in sections to fit the limitations of submarine hatch diameters and passageway constraints of the S class. Using higher radio frequencies (shorter wavelengths) also made it possible to use several different antenna configurations which were less constraining than the antenna needs for the previously-used lower frequencies. In particular, the success of HF made it possible to eliminate the cumbersome clearing line loop previously mentioned. Loop, flat top, and periscope-mounted antennas could be used with these new NRL transmitters.

November 1929 submarine patrol trials with the new NRL HF transmitters proved successful, establishing an HF range capability of about 575 miles. Under various limited and constrained conditions of submarine operating depth, ranges of the order of 90 miles were achieved.

During 1930 and 1932, 20 of NRL’s LF/HF transmitters were procured from industry. They were for use on some of the S class coastal submarines which operated with the larger V class submarines. Additional production of submarine transmitters occurred in 1933 and 1935. In the period 1930 1945, leading up to and including World War II, various versions of NRL’s transmitters provided the foundation for both the shipboard and shore station transmitters.

By 1930, submarine HF communications proved to be useful for scouting and screening submarines in support of the fleet. It was noted that submarines could be maneuvered by radio in a way not unlike visual communications.

To support the HF transmitters, NRL developed a tuned radio frequency HF receiver in the mid 1920s. A commercial procurement made the receiver available to various ships, shore stations, the Marine Corps, and the U.S. Coast Guard. A later receiver was produced in quantity, (about 1000) and provided throughout the naval service.

By 1934, NRL’s work toward developing a suitable Navy HF superbeterodyne receiver resulted in commercial procurement. This series of receivers was purchased in large numbers during World War II.

In 1940, after four decades of radio development, submarine communications had improved, but with continuing limitations. At the beginning of World War II, the submarine could receive message at long ranges of thousands of miles with a dependable very low frequency (VLF) one way link to shore. Messages were sent via the VLF Fox method (developed in 1914 during World War I), a no receipt transmission from a shore station on a four hour schedule with repeated messages to ensure reception. The submarine posture for reception was at that time typically at periscope depth with a loop receiving antenna aligned with the distant VLF transmitter. Receiving posture could require as long as an hour. Another factor in the time equation for message reception was the sea state and its impact on the submarine.

HF transmission and reception for the submarine was the other primary channel. At HF, an important adverse consideration during transmission was the vulnerability of the submarine from enemy direction finding techniques. These frequencies also required operation at periscope depth, a constraint similar to that of VLF.

Communication, an essential part of submarine operation, therefore presented a high risk aspect which had to be balanced with the submarine’s purpose or mission and its safety.

As the intensity of World War II deepened in 1940, the typical submarine was vastly different than HOLLAND’s 53 foot long craft with a crew of nine, a bow torpedo tube and three torpedoes. The wartime fleet type submarine was 300 feet long and had a cruising range of 11,000 miles. A crew of about 80 was average. Radio communication equipment, although not perfectly matched to this submarine much advanced from HOLLAND’s designs, did meet the needs of the time.

After World War II

Both ends of the electromagnetic spectrum were exploited to enhance submarine communications after World War II. Satellites, computers, and other new knowledge during the next half century alleviated some of the needs. But the oceans above and below the submarine do not easily submit to the submarine’s communication needs.


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