COMMUNICATIONS-ELECTRONICS IN VIETNAM
 

Excerpts from Vietnam Studies, Communications-Electronics 1962-1970 by Maj. Gen. Thomas Rienzi.

There is an old Army maxim: "The communicators are the first ones in, and the last ones out."

The 39th Signal Battalion was the first regular U.S. Army ground unit to enter Vietnam. From this modest beginning there followed a steady buildup of Signal troops to match the initially slow but later accelerated growth of U.S. Army forces in Vietnam.

In 1962, U.S. Army Signalmen in South Vietnam began operating tropospheric scatter radio relay sets capable of providing numerous voice communications channels over extended ranges--the first use of that type of advanced equipment in a combat environment.

By 1964, U. S. Army Signalmen were operating a new satellite ground station which provided communications service between Saigon and Hawaii through a single satellite--the first use of satellite communications in combat.

And by 1968, U.S. Signalmen in South Vietnam had begun to operate fully automatic digital message and data switches, another first in a combat zone.
 

EARLY DAYS, 1951-1962

As early as 1951, U.S. Army Signal troops were providing a small U.S. advisory group in Vietnam with communications that linked into the Army's worldwide network.

By the time the U.S. Military Assistance Command, Vietnam (MACV) was established, high-frequency radio circuits operated by the Strategic Army Communications station in Vietnam were providing communications from Saigon to San Miguel in the Philippines, to Fort Buckner--a large Army logistics base in Okinawa--and to Bang Pla near Bangkok in Thailand. These radio links provided a few telephone and message circuits.

In addition to its high-frequency radio circuits, the station operated an overseas telephone switchboard and a manual message relay in Saigon.  Messages were relayed manually at a teletypewriter relay station by taking an incoming message off the receiving equipment in the form of punched tape and inserting the same tape at the appropriate send positions to transmit the message on to its destination.

The advisors, scattered up and down  the more than 500-mile long country, had to rely on the low capacity Vietnamese military communications networks and on a high-frequency radio network they operated themselves to pass messages and provide telephone service

As the U.S. effort in Vietnam expanded, the very limited communications available could not support the U.S. helicopter units, tactical aircraft and additional advisors being deployed throughout the land.

During 1961 and 1962 the joint staff of the Commander in Chief Pacific, pushed to modernize communications facilities in South Vietnam with two objectives: first, to create a communications system to meet the needs of the South Vietnamese in their counterinsurgency operations, and, second, to build it in such a way that it could be expanded to furnish the minimum needs in support of U.S. forces.

The increased tempo of counterinsurgency operations in Vietnam and the buildup of U.S. assistance to the Vietnamese had created an urgent requirement for a modern, reliable, large-capacity communications system that could provide high quality telephone and message circuits between key locations in Vietnam.

In January 1962, Secretary of Defense Robert McNamara approved establishment of a "backbone" communications system. The system, code-named BACK PORCH, would utilize tropospheric scatter radio trunks capable of providing numerous circuits between locations more than 200 miles apart.

These tropospheric scatter trunks would be advantageous since, unlike conventional microwave, which needs a line-of- sight between sets, they would pass over the vast distances of underpopulated, enemy-infested terrain to connect the major operations and population centers in Vietnam north of Saigon.

Line-of-sight microwave relay links are limited to much shorter distances, averaging about twenty to thirty miles.

From Saigon south to the Delta region, long-lines service would be provided by a commercial microwave system funded by the Agency for International Development (AID).

The U.S. Air Force was charged with responsibility for building and funding the BACK PORCH system; the U.S. Army would operate the system after completion.

The links of the system would extend from the U.S. Army's Saigon station at Phu Lam to Nha Trang; from Nha Trang to Qui Nhon; from Qui Nhon to Da Nang in the north; from Nha Trang to Pleiku in the Central Highlands; and west from Pleiku to a terminal in Ubon, Thailand.

Although these large tropospheric terminals, each of which was mounted in three large semitrailers, were designed for transportable operation, their 30-foot antennas could not be used due to the long path distances.

More effective and permanent were the 60-foot antennas, set in concrete and resembling billboards.

The system began service in Sept. 1962 when the BACK PORCH link between Saigon and Nha Trang was completed. At that time, the 39th Signal Battalion, headquartered at Tan Son Nhut, assumed responsibility for operation of the system.

During 1963 and early 1964, U.S. Army Signalmen continued to operate and improve the communications system. An additional mobile troposcatter link was installed, connecting Ban Me Thuot in the Central Highlands to the small town of Gia Nghia in west central Vietnam near the famous Duc Lap special forces camp. By mid-1964, a similar link was established between Gia Nghia and Saigon. Thus 25 channels were available for communications.

A major improvement in the capability to relay messages into and out of the Dept. of Defense's worldwide network was made in January 1964 upon activation of a 50-line message relay facility operated by Strategic Army Communications Station, Vietnam, personnel at Phu Lam. In January 1962, the station processed over 35,000 messages. The total increased to 117,000 in October 1963 and to 185,000 by mid-1964.

The station also activated modern high-powered high-frequency transmitter equipment at Phu Lam and receiver equipment at Ba Queo, both on the outskirts of Saigon, to replace older equipment which had provided radio trunks into the worldwide Defense Communications System.

A new Saigon overseas switchboard was installed at Phu Lam to improve long-distance telephone service. This manual switchboard had positions for four operators.
 

MILITARY ACTION INTENSIFIES

The Tonkin Gulf incidents of August 1964 marked the first direct engagements between North Vietnamese and U.S. forces. By December 1964, the North Vietnamese had infiltrated no less than 12,000 troops into South Vietnam. At the same time, a Viet Cong division had been organized and was engaged in combat operations.

In order to bolster the faltering South Vietnamese forces, the United States deployed additional advisors and support units.  By the end of 1964, U.S. troops in Vietnam numbered about 23,000.

Communications deficiencies within Vietnam became more apparent as the hard-pressed signalmen struggled to provide the communications service required by the new buildup.

As a result, the Commander in Chief Pacific had validated requirements to the Joint Chiefs of Staff for additional communications service. These requirements became known as Phase I of the Integrated Wireless Communications System. IWCS was described as "a communications system which provides numerous channels of communication on a highly reliable basis; included are multi-channel telephone cable, troposcatter and multi-channel line-of-sight radio systems such as microwave."

By the end of 1965, Army signalmen were being trained in the U.S. for deployment to Vietnam. They would be available in increasing numbers to upgrade and expand the improvised communication support then available in Vietnam.

In 1966, the Dept. of the Army organized the 1st Signal Brigade. Units were assigned to maintain the area communications systems throughout the country.

The Integrated Wireless Communications System was a microwave and tropospheric scatter communications web that eventually spanned the entire Republic of Vietnam and Thailand. The completed system became by far the largest communications complex the Army had ever undertaken, creating the equivalent of the Bell Telephone System for South Vietnam and Thailand. However, the system did not come into being quickly, easily or inexpensively.

Phase II was approved in January 1966 and scheduled for completion in October of that year. The primary purposes for Phase II were to expand both the major north-south backbone trunk system and the Saigon microwave complex, and to extend the system into new areas in support of combat. Sixteen new sites were to be added. In all the number of terminals was doubled and the circuit total was tripled.

In August 1966 Phase III of the Integrated Wireless Communications System was approved, which would provide support for 400,000 troops. The primary objective of this phase was to extend the wideband system into the Mekong Delta area in order to meet the needs of expanding combat operations there. The first link would not be completed until Dec. 1967. The remainder of Phase III would not be completed until much later in 1968.

Whereas the years from 1962 until 1967 were devoted to building the communications foundation in Vietnam, 1968 and 1969 were years of completion and sophistication. During that period, the huge IWCS was finished. For the first time, modern automatic switching equipment for voice and message traffic was introduced into a combat zone.

The last link of Phase III was accepted and put to traffic in January 1969. After four and a half years of effort, and at a cost of $235 million, the most massive undertaking in the history of the Army Signal Corps was finally finished.

 

THE MILITARY AFFILIATE RADIO SYSTEM IN VIETNAM

By Maj. Gen. Thomas Rienzi

The Military Affiliate Radio System or MARS as it is popularly known, is a worldwide network of military and designated civilian ham, or amateur, radio stations.

Its mission is to provide emergency backup and supplemental radio links for U.S. Department of Defense communications. MARS operators perform vital services for both the military and civilian population. Their services range from establishing rescue communications following an earthquake or tornado to allowing a combat soldier to talk via radiotelephone to his wife.

The MARS operation in Vietnam is definitely small when compared with all other Army communications services provided, but to hundreds of thousands of servicemen in Vietnam and their families back home, it is the most important service provided by the Signal Corps.

After receiving the approval of the government of the Republic of Vietnam, MARS began operation in Vietnam in late 1965, with all U.S. armed services participating. The Army MARS program in Vietnam started with just six stations. A personal radio and telephone hookup, or "phone patch," service began in February 1966 when the Department of the Army authorized the Vietnam MARS station to make contact with designated stations in the United States.

A U.S. contact station would then place a collect call to a designated home, and for five minutes a soldier in Vietnam, perhaps one just in from a jungle patrol, could talk to his folks, who were halfway around the world.

True, the reception was not always good due to ionospheric storms and weather disturbances. But who cared when an amateur radio operator in the United States was relaying to a soldier on a remote firebase in Vietnam the message "yes, she loves you and yes, she will marry you, over."

The U.S. Army, Vietnam, portion of the MARS program was completed in October 1969 with a total of forty seven MARS stations, operating in seven different nets. The number of contact stations in the states had grown to over a hundred.

In the spring of 1970, the number of phone patches and completed connections, from Vietnam to the United States, reached an all-time high, averaging over 42,000 each month.

At the conclusion of the MARS expansion program in Vietnam, soldiers in every American unit had access to a local MARS station.

The backbone of the MARS station in Vietnam was a commercially purchased, "off the shelf," single sideband radio, which was capable of spanning great distances.

It was not only the mainstay for the MARS stations, but also for several years was used constantly in Vietnam to meet combat requirements for a long-range radio.

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9TH INFANTRY DIVISION MARS STATIONS