. Electronic navigational aids; loran, radiobeacon, and radarbeacon systems and loran, radio-direction-finder, and radar ship equipment . LINE OF POSI- TION DETER- MINED FROM . "B" READING LINE OF POSI- TION DETER- MINED FROM "A" READING Figure 1-2. Navigator aboard Loran-equipped ship at S establislies "fix" by determining two lines of position, A and B by Loran measurements. Line of position A is found by measuring the time difference between signals received from transmitting stations Ai and Ag. Line of position B is found by measuring the time difference betwe
. Electronic navigational aids; loran, radiobeacon, and radarbeacon systems and loran, radio-direction-finder, and radar ship equipment . LINE OF POSI- TION DETER- MINED FROM . "B" READING LINE OF POSI- TION DETER- MINED FROM "A" READING Figure 1-2. Navigator aboard Loran-equipped ship at S establislies "fix" by determining two lines of position, A and B by Loran measurements. Line of position A is found by measuring the time difference between signals received from transmitting stations Ai and Ag. Line of position B is found by measuring the time difference between signals received from transmitting stations Bi and B2. The navigators fix is established at the point of intersection of the two lines of position. The latitude and longitude of the navigator's position is determined from the Loran data by using either the Loran charts or Loran tables. :(2) High order of positional accuracy attained. (3) Reliability of Loran under all kinds of weather conditions. Vessels and aircraft at sea may determine their position by means of Loran both day and night when they are within 750 nautical miles of the transmit- ting stations. This is based on the reception of "ground waves," which travel on the surface of the earth and are the most stable type of radio waves. At night, however, "sky waves" are received which are radio waves that travel outward from the transmitter until they "bounce" or are reflected from a region of the upper atmosphere known as the "ionosphere" and reach the navigator after reflection (fig. 1-4). The use of "sky waves" extends the range of Loran service at night up to a distance of 1,400 nautical miles from the transmitting stations. However, the positional data obtained by using "sky waves" Loran signals is somewhat less accurate than the information
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