Distance Measuring Equipment (DME)


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. The on-board equipment used to display the slant distance can vary from frequency selectors and radio magnetic indicator (RMI) instruments which display the paired frequently of both the DME and VOR/ILS, or standalone instruments which display information only from the DME.

Despite operating in different bands, DME and VOR or ILS frequencies are coupled before the request of the slant distance is made. This is completed manually using on-board equipment and displayed by the VOR or ILS’s frequency selection. Specifically, DMEs usually operate between 960 and 1215 MHz. DME systems work with certain types of navaids which include VOR-DME, VORTAC and ILS localisers.

Because DMEs measure slant distance, any terrain that blocks the line of sight between the DME station and the aircraft will impact both the DMEs range and ability to communicate with the on-board equipment.

Systems Interface as your DME Provider

We supply and install DME systems from world-leading ground-based navigation systems manufacturers including Moog Fernau, Indra Navia, and Selex. With our supporting services, we also provide servicing, commissioning and specialist training ensuring that all your DME equipment is always ready for use.

Meeting the requirements of both ICAO Annex 10 and FAA-E-2996, these DMEs can be controlled alongside a range of other navaids including VORs (DVOR and CVOR), ILS and NDB or independently and can operate with omnidirectional, unidirectional and bidirectional antennas.

DME Installation, Supply & System Training Projects

Recent installations include:

For more information about our Distance Measuring Equipment systems please get in contact and one of our team will be happy to discuss your requirements.

ISO Systems Interface is a fully
ISO 9001 : 2015 accredited organisation
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