• Tracking three DME stations at once provides accurate updates of aircraft position
• Station identification recognition provides direct confirmation of information source
• For enhanced safety, the Collins exclusive echo monitor circuit prevents display of erroneous data from multipath reflected signals
• ARINC 429 and CSDB tuning and data outputs provide a variety of installation options
• Serial tuning and data output capabilities are compatible with the DME-442
• Single set of high-speed ARINC 429 I/O buses provides tuning, digital audio, navigation data, maintenance data and software data loading capability
• Interfaces with the RIU-4000 allow a concentrated radio interface to the rest of the aircraft
• Reduced size, weight and power set a new standard for business and regional aircraft avionics
• Meets latest DO-160D Change 1 environmental requirements
• Internal diagnostic capability minimizes time spent on fault diagnosis; fault code read out available on CTL or RTU
• Comprehensive maintenance software package works with aircraft maintenance computer and service center test software for improved maintainability

The DME-4000 Distance Measuring Equipment is a member of the Collins Pro Line 21 CNS family of products that feature state-of-the-art digital signal processing technology, digital audio, a consolidated tuning/data/audio bus, comprehensive maintenance software and software data loading. The Pro Line 21 CNS products set new standards for size, weight and power in the business and regional aircraft market. It retains the same form factor as the current Pro Line II and Pro Line 4 products (3.3 inches high, 14 inches long) but have reduced widths that allow size reductions of up to 50 percent and weight reductions of up to 35 percent. These products are also designed and tested to meet the more stringent DO-160D environmental requirements for helicopters and composite body aircraft.

The DME-4000 maintains the same serial data and analog audio interfaces as the Pro Line II and Pro Line 4 products, thus allowing it to fit into existing installations with a minimum of modification to the existing aircraft wiring. These legacy interfaces duplicate the operation of the Pro Line II and Pro Line 4 products. For new installations it provides high-speed I/O buses which interface with the Radio Interface Unit (RIU) allowing use of new features such as software data loading, enhanced maintenance reporting, digital audio, data communications management and data concentration.

The DME-4000 is a remote-mounted multichannel DME. It operates on 252 channels from 960 to 1215 MHz with both X and Y pulse-pair spacings with a transmitter output power of 300 watts minimum and a minimum receiver sensitivity of -85 dBm.

The DME-4000 provides information from up to three DME stations utilizing a single receiver/transmitter. The DME-4000 accepts up to three frequency assignments via an ARINC 429 serial digital tuning input from either the RIU or from an auxiliary tuning source. The microprocessor program within the receiver/transmitter (R/T) sequentially directs the unit through a series of tasks for each commanded frequency. The unit performs an interrogation cycle consisting of frequency tune, transmission, reception and processing every 12.5 milliseconds, thus allowing each station to be interrogated up to 26.7 times per second. Individual automatic gain control (AGC level), track status, distance, velocity and identity information for the selected channel are stored at the conclusion of each cycle and restored when that frequency is again sampled.

Station identifier is automatically processed for display as an adjunct to the audio identity signal to permit direct confirmation of the information source. Display of erroneous data from multipath reflected signals is prevented by continuously searching for returns occurring earlier than the indicated distance. Distance lock occurs within one second of initial tune to a new frequency and identity decode occurs within one minute. Internal diagnostics allow accurate isolation of a failed unit in the aircraft as well as isolation of faults to the functional element in the shop.

The DME is tuned via one of three ARINC 429 ports, one of which is connected to its own side radio tuning unit and one connected to the cross side radio tuning unit. Data for each of the three stations being tracked is output on each of two ARINC 429 ports.

The high-speed ARINC 429 buses interconnecting the unit with the RIU-4000 may be utilized to provide software data load capability when the unit is installed in the aircraft.