• Tracking three DME stations at once provides accurate updates of aircraft position
• Built-in diagnostics simplify maintenance and reduce down time
• Station identifier automatically provides direct confirmation of information source
• For enhanced safety, Rockwell Collins' exclusive echo monitor circuits prevent display of erroneous data from multipath reflected signals
• Simple, yet solid mechanical construction plus greatly simplified electrical adjustments permit quick, easy maintenance
• Fewer parts, lower power dissipation and thermally sound construction provide a significant increase in reliability
• Three-channel coverage and a variety of input possibilities provide unprecedented flexibility and redundancy

The Pro Line II DME-42/442 Distance Measuring Equipment brings unprecedented DME capability to business and regional air carrier aircraft. Microprocessor technology provides complete information from up to three DME stations from a single receiver/transmitter and indicator. This multichannel operation offers the pilot more information from a single unit. It meets today's requirements for advanced navigation systems.

The DME-42/442 can provide complete DME information from three ground stations simultaneously.

The pilot controls the DME using a control head, flight management system or navigator. These provide serial digital commands to operate on one, two or three specific frequencies.

The receiver/transmitter performs a series of tasks for each frequency that are similar to those of single channel units, namely: interrogate, listen and process. This entire cycle of tasks takes only 12.5 ms.

After performing these tasks on one frequency, the program tunes to the second where the process is repeated, and finally, to the third frequency. All the frequencies were previously selected on the controls or by a navigation system.

This process repeats by using data previously stored for each channel as a starting point for additional processing. The complete multichannel cycle takes only 37.5 ms, so the DME samples each channel 27 times each second. Even when covering three channels at once, it can lock-on in less than one second.

Pro Line II DME systems provide a variety of input and output options that permit a wide range of systems applications.

The input ports of the DME-442 can be configured for Commercial Standard Data Bus (CSDB) or ARINC 429.

The DME-42 accepts conventional 2 x 5 parallel tuning and provides both analog and digital outputs. The DME-42 can directly replace a DME-40 in any installation that does not use the pulse-pair output with no changes required in aircraft wiring.

The tuning inputs and information outputs of Pro Line II units are completely independent of each other. This makes it possible to operate in a hybrid CSDB/ARINC 429 system with the DME-442 or to operate in a hybrid digital/conventional system with the DME-42.