The success in the North Atlantic led to rapid expansion elsewhere. The Coast Guard had been involved with the development from the start so when the time came to provide trained personnel the Coast Guard found itself in the Loran business.
This would continue to be a Coast Guard responsibility after the war. The Pacific war showed the need for a Loran-like system that could be operated over much greater distances than Loran A could provide. The potential solution was to use lower frequencies so an experimental set of stations were set up.
The main result of these tests was to show that pulse envelope matching, as used in Loran A, was too inaccurate with the long pulses at the low frequencies required and that a phase comparison system would be required. With the end of the war these experiments were not followed up on. By the early s, the Department of Defense required a highly accurate long range radionavigation capability. The Sperry Company had proposed a navigation system which would use phase comparison and operated on two frequencies.
This was later reduced to one frequency and the Air Force tried to adapt it for tactical needs but had given up on it. They have averaged about fifteen men. As the stations had to be entirely self-sufficient, they had cooks, hospital corpsmen, in addition to the electronic technicians who operated and maintained the transmitters. Each station was commanded by a commissioned officer, usually a lieutenant, with a chief petty officer as second in command. Prospective commanding officers were given a short training course in loran and administration before assignment.
Many young men dreaded loran duty because of the isolation, but after it is over, nearly all of them felt it had been well worthwhile. At isolated stations, tours of duty were for one year. The great majority of loran stations were supplied with fuel, bulky spare parts, and large staple items by a Coast Guard supply ship, which called once or twice a year. Unless they were located near a large community, loran stations received mail; personnel, fresh stores, and emergency spare parts by Coast Guard airplane.
Most stations had their own airstrip. Training operators and navigators: A great number of radio operators and technicians from the US and other countries had to be trained on how to operate the new navigation transmitters. Additionally, navigators aboard ships and aircrafts had to learn a whole new way of doing things to find their fix. Loran was an entirely new system of radio navigation. Its unique achievement was the speed in which loran was developed and pressed into service during the war.
By , the extent of loran coverage available to navigators is illustrated in the accompanying figure. The North Atlantic Chain was given priority to allow ship convoys to find their way across treacherous waters. During wartime, Loran had the advantage of allowing ships to maintain radio silence. The system became operational in early , and late that year stations were established in Greenland, Iceland, the Faeroes and the Hebrides to complete the North Atlantic cover.
At the request of the RAF, another station was put into the Shetlands to cover Norway, and loran was eventually used by over aircraft of Coastal Command. By , the North Atlantic Chain consisted of the following loran stations.
The name of the organization operating the station is also identified. In the summer of , the USCG completed the first independent installation of loran transmitting stations in the Aleutian Island. The equipment in this case had been quickly fabricated in the shop in Cambridge, as Naval procurement had not yet come into effect. The Coast Guards continued the work and installed twenty-five stations in the Pacific, climaxing its efforts with stations at Jima and Okinawa, which were erected closely on the heels of the invading forces.
Of special significance in the Pacific warfare were stations in the Marianas, which provided very effective guidance for the 20th Air Force in its bombing of Japan. Loran made its greatest direct contribution to winning the war because distances in the Pacific Ocean are enormous. As American forces moved westward, airfields were built on many of the small islands. LORAN was declared obsolete in and decommissioned in High frequency operation, while providing higher performance, is largely more susceptible to jamming and hacking than lower frequency systems like LORAN.
In a low-frequency system, the signal integrity is much stronger, therefore requiring a more powerful transmitter to cause interference. GPS satellites, on the other hand, are easier to jam and are more prone to disruption from space weather, EMP electromagnetic pulse events, and can be blocked in areas with large buildings.
This new system, which is still in development, will be more self-sufficient than its predecessor, LORAN-C, as well as more accurate with longer range. While LORAN remained an integral part of maritime and arial navigation for many decades, it seems that the once antiquated technology is making a smart comeback.
With better technology that makes it more competitive with GPS, eLORAN provides a secure backup option for radio navigation both overseas and in the skies. You must be logged in to post a comment. To refine the signal and to make phase difference measurements possible, the carrier phase of selected pulses was reversed in a predetermined pattern. This pattern was different for each transmitter Master and Secondaries in a given chain and was repeated every two GRI's.
Simply stated, phase coding determined whether the first peak in the pulse was upwards or downwards. Loran-C receivers combined two different techniques, multilateration and phase shift resulting in the capability to produce a highly accurate fix.
The basic measurements made by Loran-C receivers was to determine the time difference of arrival TDOA between the Master signal and the signals from each of the Secondary stations of a chain. Each TDOA value was measured to a precision of about 0. As a rule of thumb, nanoseconds corresponds to about 30 metres.
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