receivers aboard vessels or aircraft. Basically, a Loran-C fix 

 is determined just as in Loran-A. The significant features of 

 Loran-C are its high degree of accuracy and extended range. It is 

 useable twenty-four hours a day during all weather conditions. Its 

 precision is obtained by matching the Loran-C pulses for a rough 

 measurennent and matching the phases of the carrier frequency 

 within the pulse for fine measiirement. While Loran-A master 

 and slave stations maintain synchronization of one or two micro- 

 seconds, in Loran-C it is maintained to two-tenths of a micro- 

 second. The extended range of Loran-C results from a lower 

 transmission frequency of 100 kc. Loran-C will provide positional 

 information of one -quarter -mile accuracy within the limit of 

 groundwave coverage, approximately 1,200 nautical miles. Sky- 

 wave information, which is available both day and night, has an 

 accuracy of two miles at ranges up to about 2, 000 nautical miles. 



Loran-C receivers presently cost from $30,000 to $60,000. 

 These receivers weigh approximately 75 pounds and are about two 

 cubic feet in size. A production cost of approximately $10, 000 per 

 receiver is believed possible on quantity orders. These costs are 

 for instruments capable of realizing the full accuracy of the Loran- 

 C system. Receivers using modified techniques and supplying 

 accuracies of one to two miles can be produced at reduced costs. 



Present Loran-C coverage is confined to the Northern Hemi- 

 sphere, and all five of the operational chains in use today are 

 maintained by the Coast Guard. These chains, comprised of 

 seventeen transmitting stations, provide extensive coverage over 

 the Mediterranean Sea, Norwegian Sea, east coast of the United 

 States, and the Hawaiian and Aleutian Island areas. The latter 

 coverage is presently being used by the Coast and Geodetic Survey 

 Vessel Pioneer for oceanographic survey work. Preliminary 

 results have been very favorable. Additional chains could be 

 constructed at a cost of about ten million dollars per triad. 



Of all the aids discussed thus far, Loran-C appears to more 

 closely meet the ideal characteristics. However, because of its 

 range, it does not have the capability to provide suitable coverage 

 to some of the vast ocean areas of the Southern Hemisphere. 



There is, however, a shore-based electronic system which 

 may have the potential to provide this coverage. The OMEGA 

 System has been under active development for many years. 



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