Electronic ATON: Loran units can mean unusual duties

by Petty Officer 2nd Class John D. Miller

By the time you will have finished reading this sentence, Loran Station Carolina Beach will have transmitted its radionavigational signal 401 times. To human ears, the 8-pulse sequence sounds akin to a hyperactive, monotonous cricket. To a boat or airplane’s Loran receiver, though, the 650,000-watt transmission enables it to almost instantaneously identify its own location. Operating long range navigation, or Loran, is part of the Coast Guard’s responsibility to maintain the United States’

However, Loran Station Carolina Beach and its 23 sister stations are charged with sustaining an electronic signal. A singular task in and of itself, when added to the unusual experiences associated with being part of an extremely small unit, Loran station duty constitutes one of the more atypical assignments in the Coast Guard.

For instance, the station’s Engineering Petty Officer, Petty Officer First Class Amel Davis, begins his workday once a week by mowing the grass on part of the 212-acre station in southeastern North Carolina. On one hand, with only three other people assigned to the unit, the lowest ranking being an E-5, there is little room for delegation. On the other hand, maintaining the station’s grass at a reasonable height is one of the non-traditional collateral duties that the machinery technician is responsible for in order to ensure easy access to the station’s four 625-foot towers.

“There are so many things out here that I do that I could never have gone to school for,” explains Davis, whose previous duty assignments included tours aboard a 110-foot patrol boat and a buoy tender.

There is no training, for instance, on repairing four-wheelers, another item in the station’s inventory of non-standard issue equipment. The ATV allows the station’s crew to get quickly to their communication towers across the base’s vast, sandy, cactus-studded field. When repairs are needed to the towers–typically as a result of lightning strikes–one of the station’s 3 electronics technicians begins a long climb upward.

“At least the towers aren’t hot,” says Chief Petty Officer Michael Smith, referring to the fact that the looming towers are not energized. Instead, the station’s officer in charge explains that the towers elevate and support several cables between them that actually transmit their signal up and down the east coast and far out to sea.
The signal itself is generated in an unremarkable-looking, equipment-filled room divided by two rows of tall, gray metal cabinets. They emit a constant mechanical hum, punctuated by the electronic staccato of the Loran transmission. In the cabinets, fifty-six half-cycle generators amplify an electronic signal they receive from a computer called a Pulse Amplitude Timing Controller (or PATCO), which generates and shapes the signal into eight pulses 1000 microseconds apart. It is then sent from the room via a transmitter to a spidery antenna outside called the apex, and

In contrast to GPS, which uses satellites to determine geographic position, Loran relies upon the time differences between transmitted signals. Each Loran station outputs its pulsed signal at a precise interval, and a Loran receiver identifies its own position by comparing when it receives a signal from a chain’s master station with when it receives signals from a chain’s two secondary stations. The receiver generates numbers that correlate with a grid of colored time difference lines that cover nautical charts. Though not quite as precise as GPS, Loran is based on Universal Time Code and is better at repeatedly returning users to the same location.

The other comparative advantage of Loran is its low frequency band, which makes it less vulnerable to jamming than GPS. The World War II-era technology also has more safeguards in place than the satellite-based system and is not limited to line of sight reception like GPS.

“Our main priorities are staying on air, in tolerance and protecting the user,” says Smith, referring to the station’s microsecond-level margin of error relating to the signal, and how exceeding it can lead a boater or an aviator astray. “As a consequence, the stations have built-in redundancies. We’re set up to the point where if there are any problems with the signal, we can quickly switch equipment to remain on air.”

That is why there is two of everything at the station: two PATCOs, two timers, two output coupling networks and two backup diesel generators in case the electricity goes out. A continual schedule of preventative maintenance to both sets of equipment, though, seeks to limit the potential for error. Even something as seemingly inconsequential as an accumulation of dust could possibly affect the signal, explains Petty Officer Michael Leveille.

The Electronics Technician is prepared for such contingencies, though. After the morning’s routine maintenance–whether dusting, lawnmowing, or diesel generator testing–the station’s crew shifts into drills designed to hone their responses to equipment failures. Carolina Beach’s Executive Petty Officer, Electronics Technician First Class Brett Edgerly, pulls a non-critical fuse in a piece of the stand-by equipment in the transmitting room. He calls Leveille over to diagnose the red, furiously blinking lights. Working off a mental checklist, the latter methodically goes through potential problems until he locates the loose fuse and replaces it.

The routine of drills and preventative maintenance is broken up by the paperwork needed to document it all. So as to let his crew focus on their technical duties, Smith says he tries to do as much of it as possible.

“One of the advantages to life at a small unit is the opportunity for everyone to be more hands-on with training,” he explains. “It increases proficiency and makes the job more interesting.”

There are also benefits to the routineness of life at a Loran station. Albeit uneventful and relatively repetitive compared to duty on a cutter or at a small boat station, the consistency enables the crew to continue their education and allows for the rare luxury of lots of time at home with families.

“When I was on a patrol boat I couldn’t even tell my wife where I was, and when I was on a buoy tender, my schedule changed every day,” says Davis, whose family appreciates the respite from the chaotic routine of cutter life as much as he does. “Staying in the area and being able to come home every day at about the same time gives my wife a break raising our kids.”

A nice trade off, then, for time spent at the helm of the station’s lawnmower. Both are part of life when navigating the radio waves instead of those at sea.

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