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The latter include WAAS and the U.S. Coast Guard's network of LF marine navigation beacons. The accuracy of the corrections depends on the distance between the user and the DGPS receiver. As the distance increases, the errors at the two sites will not correlate as well, resulting in less precise differential corrections.
There are associated concepts, such as the DRMS (distance root mean square), which is the square root of the average squared distance error, a form of the standard deviation. Another is the R95, which is the radius of the circle where 95% of the values would fall, a 95% confidence interval .
One can also use the 1 in 60 rule to approximate distance from a VOR, by flying 90 degrees to a radial and timing how long it takes to fly 10 degrees (the limit of the course deviation indicator). The time in seconds divided by 10 is roughly equal to the time in minutes from the station, at the current ground speed .
With the wide adoption of satellite navigation systems, the term has come into much wider usage. Neglecting ionospheric [3] and tropospheric [4] effects, the signal from navigation satellites has a fixed precision. Therefore, the relative satellite-receiver geometry plays a major role in determining the precision of estimated positions and times.
In navigation, dead reckoning is the process of calculating the current position of a moving object by using a previously determined position, or fix, and incorporating estimates of speed, heading (or direction or course), and elapsed time.
In marine navigation, starboard bearings are 'green' and port bearings are 'red'. Thus, in ship navigation, a target directly off the starboard side would be 'Green090' or 'G090'. [7] This method is only used for a relative bearing. A navigator on watch does not always have a corrected compass available with which to give an accurate bearing.
The distance along the great circle will then be s 12 = Rσ 12, where R is the assumed radius of the Earth and σ 12 is expressed in radians. Using the mean Earth radius , R = R 1 ≈ 6,371 km (3,959 mi) yields results for the distance s 12 which are within 1% of the geodesic length for the WGS84 ellipsoid; see Geodesics on an ellipsoid for ...
True course is 120°, the Variation is 5° East and the Deviation is 1° East. T: 120° V: −5° M: 115° D: −1° C: 114° True course is 035°, the Variation is 4° West and the Deviation is 1° East. T: 035° V: +4° M: 039° D: −1° C: 038° True course is 306°, the Variation is 4° East and the Deviation is 11° West. T: 306° V: −4 ...