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Milestone-Proposal:LORAN

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Loran consist of three components: 1.  a chain of radio transmitters creating an electronic lattice or grid upon the surface of the earth.  2. a loran receiver-indicator, something like  an electronic timer with a cathode ray tube and  3. loran nautical and aeronautical charts or tables published, for example,  by the US Navy Hydrographic Office.  
 
Loran consist of three components: 1.  a chain of radio transmitters creating an electronic lattice or grid upon the surface of the earth.  2. a loran receiver-indicator, something like  an electronic timer with a cathode ray tube and  3. loran nautical and aeronautical charts or tables published, for example,  by the US Navy Hydrographic Office.  
 
A simple explanation of how a navigator used loran in the 1940s to determine his position or fix  follows next: first the  line of position was established by measuring the relative time of arrival of two pulses which were known to have left two separate transmitters at times differing by a known interval. The time difference was noted in microseconds. With this information, charts and compasses, the navigator could plot a series of points on a chart plotting a line of position. But hold on; no fix point yet. A loran network with only two stations cannot provide meaningful navigation information as the 2-dimensional position of the receiver cannot be fixed without additional information to find the fix position. He may use a second pair of loran stations to determine a new line of position.  Crossing of these two lines of position is the loran fix.  For those wanting more details on hyperbolic system of navigation, see Chapter X111 of  Bowditch's American Practical Navigator.
 
A simple explanation of how a navigator used loran in the 1940s to determine his position or fix  follows next: first the  line of position was established by measuring the relative time of arrival of two pulses which were known to have left two separate transmitters at times differing by a known interval. The time difference was noted in microseconds. With this information, charts and compasses, the navigator could plot a series of points on a chart plotting a line of position. But hold on; no fix point yet. A loran network with only two stations cannot provide meaningful navigation information as the 2-dimensional position of the receiver cannot be fixed without additional information to find the fix position. He may use a second pair of loran stations to determine a new line of position.  Crossing of these two lines of position is the loran fix.  For those wanting more details on hyperbolic system of navigation, see Chapter X111 of  Bowditch's American Practical Navigator.
Today's loran operates on one of several frequencies between1700 and 2000 kHz. It enjoys propagation characteristics determined primarily by soil conductivity and ionospheric conditions. Both ground wave and sky waves can be used to provide coverage over an  extensive area with few stations.  Usually. stations of a pairs are located 200 to 400 miles or more. At one time, several station pairs were separated by 1000 to 1400 miles apart.  Transmitters now in use radiate about 100kw and give a ground-wave range oversea water of about 700 nautical miles in the daytime. The day time range over land is seldom more than 250 miles even for high-flying aircraft and is scarcely 100miles at the surface of the earth. At night the ground-wave range oversea water is reduced to about 500 miles by the increase in atmospheric noise, but sky waves, which are almost completely absorbed by day,become effective and increase the reliable night range to about 1400miles. Generally,, a number of stations are located so as to form a chain, with all but the end station in the group being double pulsing. In most parts of the world,, signaals can be received from at least two pairs of stations  making it possible to determine a fix using loran alone.  
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Today's loran operates on one of several frequencies between1700 and 2000 kHz. It enjoys propagation characteristics determined primarily by soil conductivity and ionospheric conditions. Both ground wave and sky waves can be used to provide coverage over an  extensive area with few stations.  Usually. stations of a pairs are located 200 to 400 miles or more. At one time, several station pairs were separated by 1000 to 1400 miles apart.  Transmitters now in use radiate about 100kw and give a ground-wave range oversea water of about 700 nautical miles in the daytime. The day time range over land is seldom more than 250 miles even for high-flying aircraft and is scarcely 100miles at the surface of the earth. At night the ground-wave range oversea water is reduced to about 500 miles by the increase in atmospheric noise, but sky waves, which are almost completely absorbed by day,become effective and increase the reliable night range to about 1400miles. Generally, a number of stations are located so as to form a chain, with all but the end station in the group being double pulsing. In most parts of the world, signals can be received from at least two pairs of stations  making it possible for a mariner to determine a fix using loran alone.  
 
A BRIEF HISTORY
 
A BRIEF HISTORY
The name loran is derived from long-range navigation, a name given by Lawrence M. Harding, a career officer of the United  States Coast Guard (USGC). Harding is one of the loran pioneers we should not forget.  Beginning in 1943, USCG played a key role in getting some twenty-five loran transmitter stations up and running in the Pacific.  Pierce gives credit to the USCG for loran stations in Iwo Jima and Okinawa,  erected closely upon the heels of the invading forces. Other loran stations in the Pacific helped guide the Air Force in its bombing campaign.  Until quite recently,  USGC crews have been manning loran stations in this part of the world for over 60 years.  The loran system in the United States was shut-down by the government on 8 February 2010. The nominator witnessed this great event, planting the seed for this milestone nomination.  
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The name loran is derived from long-range navigation, a name given by Lawrence M. Harding, a career officer of the United  States Coast Guard (USGC). Harding is one of the loran pioneers we should not forget.  Beginning in 1943, USCG played a key role in getting some twenty-five loran transmitter stations up and running in the Aleutian Islands and the Pacific.  Pierce gives credit to the USCG for loran stations in Iwo Jima and Okinawa,  erected "upon the heels of the invading forces". Other loran stations in the Pacific guided the air force in its bombing campaign.  Until quite recently,  USGC crews have been manning loran stations in this part of the world for over 60 years.  The United States loran system was replaced by GPS and shut-down on 8 February 2010. The nominator witnessed this great event, perhaps planting the seed for this milestone nomination.  
  
But other individuals should be mentioned:
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Other individuals should be mentioned:
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1941 - Melville Eastman of the Microwave Committee:  First  leader of a small group organized under the newly formed Radiation Laboratory of the Massachusetts Institute of Technology. This group was responsible for developing a new radio navigation system. CEO and founder of General Radio Corporation of Cambridge, Eastman had taken a leave of absence from his company during 1941 to 1943.
  
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Jack Pierce,  a senior research fellow at Harvard University, Cambridge, MA joined the team in 1941.  He would later receive the Medal For Engineering Excellence in 1990 for the design , teaching and advocacy of radio propagation, navigation and timing which led to the development of Loran,  Loran C and Omega. Pierce,  Eastman and a small group of radio experts soon began testing the United States' first hyperbolic radio aid to navigation, investigating  radio frequencies, wave patters, reflection, and so on. 
  
1941 - Melville Eastman of the Microwave Committee: first leader of the Rad Lab group or division assigned to develop radio navigation. In the spring of 1941, a small the founder of General Radio Corporation of Cambridge, was organized under the newly formed Radiation Laboratory of the Massachusetts Institute of Technology, from which it drew two or three key personnel, while other were recruited from outside sources. Further research and investigations were undertaken and soon indicated that changes in the basic design were necessary..
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radio frequency, patterns, wave reflection 
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When a grande long-lived engineered system like LORAN, .. this nomination milestone gives credit to those persons that worked  on the so-called Project 3 or C
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. The USCG had a permanent office working on this project. One person in particular that deserves mention is  Coast Guard Lt. Cmdr. L.M. Harding who provided supervision and  direction for the Pacific  Loran  ...
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n,  . . He was replaced by Jack Pierce of Harvard ..  was an authority
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Long lasting near global radio navigation system. Evolved from LORAN, SS-LORAN, LORAN-A, and LORAN-C  which was taken out of service recently.
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Period of interests: 1940 to 1946 when a new from of radio navigation is proposed, 1941 when R&D work begins, throughout  WW2, to 1946 when LORAN is a well established engineered system globally. LORAN's service to just recently is treayed in ..... .
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Timeline 1940 to about 1945. why limited .
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Rad Lab was able to step after loran was running on a firm fundation.
 
Rad Lab was able to step after loran was running on a firm fundation.
 
Rad Lab's  project involvement terminated when loran was on a solid foundation..  
 
Rad Lab's  project involvement terminated when loran was on a solid foundation..  
 
Jack Pierce's epic article published by the IEEE in 1946 is the prime source for the information here.  
 
Jack Pierce's epic article published by the IEEE in 1946 is the prime source for the information here.  
Who was he?
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John (Jack) A. Pierce,  a senior research fellow at Harvard University, Cambridge, Mass. was awarded the Medal For Engineering Excellence in 1990 for the "design , teaching and advocacy of radio propagation, navigation and timing which led to the development of Loran,  Loran C and Omega." In 1941, Pierce began working at the Massachusetts Institute of Technology's Radiation Laboratory which was testing the United States' first hyperbolic radio aid to navigation called Loran.  Later work produced Loran C which operated at a lower frequency of 100 kHz. After WWII, he was appointed senior research fellow in applied physics at Harvard and from 1950 to 1974 did work on low frequency navigation aids that lead to Omega.
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Among his many awards are a 1948 Presidential Certificate of Merit and the 1953 Morris Liebmann Prize of the Institute of Radio Engineers.  
 
Among his many awards are a 1948 Presidential Certificate of Merit and the 1953 Morris Liebmann Prize of the Institute of Radio Engineers.  
 
JA Pierce was . . .???/////
 
JA Pierce was . . .???/////

Revision as of 21:15, 10 December 2010

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