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What is a Distance Measuring Equipment?
Distance Measuring Equipment simply refers to a tool used to measure slant range distance through propagation delay of very high frequency or ultra-high frequency radio signal timing. It is a radio navigation technology that is transponder-based.
The distance measuring equipment was invented by the Australian inventor, James Gerry Gerrand. When he was still under the process of inventing the equipment, he was supervised by Edward George Bowen of the Commonwealth Scientific and Industrial Research Organization.
The distance measuring equipment has been considered to have identical functions with the secondary surveillance radar.
The secondary surveillance radar is being utilized by the air traffic control. Its function is not purely for the detection and measurement of the aircraft’s position; it also provides information regarding the identity and altitude of the aircraft. The same with the distance measuring equipment, it is transponder-based.
The distance measuring equipment was a product of the World War II. Its distance measuring component was said to be similar to the tactical air navigation system – a navigation system used by a military aircraft.
Aircraft uses the distance measuring equipment in determining their distance from the transponder that is land-based. The equipment can send and receive pulse pairs with the help of the VHF Omni Directional Range.
VHF Omni Directional Radio Range is an aircraft’s short-range radio navigation system. It allows the aircraft to determine what their position is through a receiving unit. Also, it allows the aircraft to receive radio signals that are transmitted from the radio beacons’ network.
Accurate touchdown distance is made possible through the low-power distance measuring equipment. As long as it would be co-located with either the instrument landing system glideslope antenna installation or the instrument landing system marker beacons’.
Aside from it provides the distance from the land-based transponder and accurate touchdown distance, the distance measuring equipment also has a very crucial role when it comes to timing.
It enables the aircraft to communicate or interrogate the transponder located on the ground with a series of interrogations. The ground station with the ground transponder then replies with the same sequence of interrogations.
There should be less than 30 pulse-pairs every second. 30 is the maximum.
The distance measuring equipment also helps in calculating the aircraft’s distance. It takes at least 12.36 microseconds for a radio signal to travel one nautical mile for it to be able to reach the target. This is called the radar-mile.
The distance of the aircraft from the ground station of the distance measuring equipment is calculated through the formula, distance = rate * time.
From the term itself, distance measuring equipment, it provides information regarding the distance to 100 to 200 aircraft, one at a time.
This equipment has been considered as one of the most important pieces in the military, commercial aviation and private jet flights industry.