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An example of slant range is the distance to an aircraft flying at high altitude with respect to that of the radar antenna. The slant range (1) is the hypotenuse of the triangle represented by the altitude of the aircraft and the distance between the radar antenna and the aircraft's ground track (point (3) on the earth directly below the aircraft).
Range information is functionally identical to the method provided by civilian DME: pairs of 3.5 microsecond (μs) pulses (measured edge-to-edge at 50% modulation strength) from an aircraft are repeated by the station being interrogated, using the round-trip time to calculate slant-range distance.
Range: Distance along the plane established by the horizon Slant Range: Distance along the true line of sight True: Angle in earth coordinates with true north as the reference Relative: Angle in deck-plane coordinates using vehicle heading as the reference Rectangular: Cartesian coordinates typically known as X, Y, and Z Spherical
Calculations for the "slant range" (range between the antenna's phase center and the point on the ground) are done for every azimuth time using coordinate transformations. Azimuth Compression is done after the previous step. Step 5 and 6 are repeated for every pixel, to cover every pixel, and conduct the procedure on every sub-aperture.
In aviation, distance measuring equipment (DME) is a radio navigation technology that measures the slant range (distance) between an aircraft and a ground station by timing the propagation delay of radio signals in the frequency band between 960 and 1215 megahertz (MHz). Line-of-visibility between the aircraft and ground station is required.
When more than three distances are involved, it may be called multilateration, for emphasis. The distances or ranges might be ordinary Euclidean distances (slant ranges) or spherical distances (scaled central angles), as in true-range multilateration; or biased distances (pseudo-ranges), as in pseudo-range multilateration.
The PRI, in turn, will limit the maximum continuous swath width in slant range, which is only slightly influenced by the uncompressed transmitted pulse length . The continuous time interval that the radar echo can be received is upper bounded by the time interval between the end of a transmitted pulse and the beginning of next one, say P R I ...
For distances up to a few miles and fixed locations, true-range can be measured manually. This has been done in surveying for several thousand years – e.g., using ropes and chains. For longer distances and/or moving vehicles, a radio/radar system is generally needed. This technology was first developed circa 1940 in conjunction with radar.