Position line
As state line (English line of position, LOP) is in the classic navigation an approximately straight line marked on the surface of the earth, on which must be located according to a measurement of the position of the observer.
The general case of a state line is a locus, that is a curve lying on the all points for which the measured value is met. On the globe, these are mainly large circles, small circles or hyperbolic curves approximate to an air or sea chart straight at a sounding too deep lines.
The simplest case of a leased line provision is the bearing, that is, a magnetic or geographic direction measurement. It belongs to the group of methods of terrestrial navigation and is usually graphically - for example, on the chart - evaluated.
Directional or Peilstandlinie
If one included on the chart target point (called a landmark ) by rule - for example, at an angle P = 135 ° (southeast ) - one obtains the direction or Peilstandlinie by a brushing from the target point is precisely in the opposite direction, ie, P 180 ° = 315 ° (NW ). Is the measurement and the compass error-free ¹), the own location must lie on this line. The bearing of a second landmark ( cross-bearing ) yields the own position in the intersection of the two state lines.
Bearings may refer to the magnetic north relate (miss True North, with further references ) or on astronomical north, so the true meridian ( true north, RWN ). In English, it is called true north (TN) and the related bearing true bearing (TB). In contrast, the driven bzw.geflogene course true course ( TC) is called.
The definition of a directional state line can be done except with the compass or the Peilscheibe also by so-called Deckpeilung (often at harbor entrances ) or by a direction finding navigational transmitter ( radio line of position ). The status line can then also be transferred to the card or be directly compared with the target price of the ship. Similarly, the localization of aircraft is possible, but this is usually already automated ( see VOR or TACAN ).
¹) Otherwise, a correction (charging ) to be attached to the measured value.
Q- key aviation
The true direction of the plotted point to the aircraft or vessel complies with the QTE in the international Q key. For the calculation of the LOP ( QTE ) the True bearing (TB, on German true bearing ) must be known:
LOP = TB 180 ° or LOP = TB - 180 °, if the amount is more than 360 °.
In contrast to this classical bearing almost all courses and bearings of the radio and air navigation refer to miss True North ( engl. magnetic north, MN) Accordingly, the radio line of position - in contrast to the above definition - encoded as QDR.
Other forms of state lines
General can be a level line (LOP ) defined as the totality of all points ( " geographic location " ) on which the observer can be located due to its measurement:
The aforementioned cases apply strictly only on a level surface or on the sea. If the measured distances of the inclined circular arc ( 2 and 3) is a spherical portion, and three-dimensional positioning is more geometric loci result in space, such as
- When measuring the air pressure, the so-called PLOP (pressure line of position )
- In aviation a lateral displacement caused by spray drift - see also Single Heading Flight
- For measurements to GPS or other satellite system of a distance ball to the respective earth satellites.
Generally not enough to determine the location a level line ( a single measurement ) because the location can be anywhere on the LOP. This requires at least two LOPs are required. Only the intersection of two position lines (or three in 3D space ) gives the exact location ( engl. position or fixed).
For the purposes of elementary geometry position lines are geometric loci. The astronomical position line method was discovered in 1837 by the Boston Captain Thomas Sumner, by a fortunate and first used. According to him, such a position lines are sometimes referred to as the Sumner line.