The Collins DME-40 Receiver-Transmitter is used in the Collins DME-40 Distance Measuring Equipment System to compute the slant range distance to an ILS-DME/VORTAC/VOR-DME ground station. The DME-40 System includes a DME-40 Receiver-Transmitter, antenna such as an ANT-42 or 237Z-1, control unit such as a CTL-30 or 313N-4D, indicator such as a 339F-12/12( ) or IND-40( )/41( ) and an UMT-13 or 390R-( ) mount. The DME-40 system determines the slant range distance to the ground station, the time to station and the aircraft velocity which is then supplied to the indicator with digital and analog data. The operating frequency is selected by a two-out-of-five frequency code VHF control unit from 252 available frequencies. The DME-40 has a transmit frequency range of 1025 to 1150 mHz.

The DME-40 is housed in an ARINC 1/2-ATR short case that is 4.875 inches wide, 3.50 inches high, 13.85 inches long and weighs 7.20 pounds. The DME-40 can be operated at an altitude of up to +45,000 feet but has a test altitude of +55,000 feet with a temperature range of -54°C to +55°C when in continuous use. The DME-40 has airflow holes on all sides for convection cooling. The DME-40 part number 622-1233-003 is for Military use.