Ground DME

omnidirectional

Systems Interface is a provider of Distance Measuring Equipment systems for En Route or terminal navigation associated with an ILS or VOR and has unrivalled experience in the supply, installation and commissioning of these aviation systems. What are Distance Measuring Equipment? DME aviation systems provide an aircraft with slant-range distance tracking using ground-based and aircraft equipment. The ground-based DME transmitter, usually coupled with a VHF omnidirectional radio range (VOR, DVOR or CVOR), instrument landing system (ILS), non-directional beacon (NDB) or other instrument, calculates the aircraft's flight position from the transmitter and displays the measurement to the pilot within their onboard display. This distance is called the ‘slant range’ which is the line-of-sight distance between the aircraft and the DME transmitter which are positioned at different levels (altitudes). The slant-range distance enables the pilot to determine a time-to-station value which assists during the flight path, descent and landing. The Function of DME DMEs and navaids function using different frequencies. DMEs utilise ultra-high frequencies (UHF) whereas the co-located VORs and ILSs utilise very-high frequencies (VHF). When an aircraft requests the slant distance, it sends a signal called the interrogation pulse to the ground-based DME. The transmitter then responds, relaying a signal back to the onboard aircraft equipment. The duration of this UHF signal to and from the DME station is then used to calculate the distance of the straight line from craft to station.