Omega, like Loran, is a hyperbolic navigational system em- 

 ploying synchronized master and slave stations. It differs from 

 Loran in that only phase difference between two transmitted signals 

 is measured rather than phase and envelope differences. Because 

 the Omega systenn utilizes radio frequencies in the 10-14 kc. band, 

 ranges up to 6,000 miles are possible during day and night. The 

 baselines between stations will be much longer than those of either 

 of the Loran systems. This will greatly reduce the geometrical 

 errors of the system. Three experimental Omega stations are pre- 

 sently in operation. For worldwide coverage the shore component 

 of the Omega systenn would consist of a synchronized chain of 

 approximately 10 stations, each costing about 12 million dollars. 

 Tests conducted to date indicate that line-of-position accuracies of 

 about 1 to 3 miles may be available on a baseline in the daytime. 

 This error will be slightly greater at night as the distance off the 

 baseline increases. Due to the long range of Omega, a correction 

 factor for the 4 to 5 hours duration of sixnset and sunrise on the 

 baselines will have to be determined if the system is to be useable 

 during these periods. It is estimated that an operational receiver in 

 quantity orders should cost about $10, 000 to $20, 000 each. The 

 receiver should not weigh more than 200 pounds nor be larger than 

 4 cubic feet. Receivers, which do not incorporate all the precise 

 accuracy features, may cost less. 



The Omega system has an ambiguity problem. Identical phase 

 comparison readings are obtained at locations a given distance 

 apart. With the 10.2 kc. equipment planned, these ambiguous 

 zones of operation occur approximately every 8 nautical miles. 

 Some other means must be available to position the vessel within 

 the correct 8-mile zone if synchronization is lost. Also, the re- 

 maining research and development required in Omega is the deter- 

 mination of whether or not propagation characteristics can be 

 accurately predicted over large areas. 



It is obvious that existing navigational systenn s do not fully 

 meet the requirements of the National Oceanographic Program. 

 No single navigational technique presently employed has all of the 

 ideal characteristics. Nevertheless, this does not mean that the 

 National Oceanographic Program must await development of a 

 single such aid. Rather, it appears likely that the required navi- 

 gational control can be achieved more reliably and economically 

 with a combination of techniques. Large areas of the Northern 

 Hemisphere are covered by precise Lorain-C signals. Loran-A, 

 with a lower acciiracy, fills in much of the remaining areas of 



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