Developnent of prototype DME/P transponder

Abstract

DME/P (Distance Measuring Equipment/Precise) is a ranging subsystem of MLS (Microwave Landing system). A prototype DME/P transponder was developed by ENRI in FY 1986. This paper describes the outline of the DME/P transponder equipment and the result of its test. The specifications of the equipment are based on the requirements of the accuracy standard 1 in ICAO ANNEX 10. In order to meet the requirements for FA (Final Approach) mode, the equipment has a DAC (Delay Attenuate and Compare) circuit, automatic system delay compensetion, and so forth.

The results of the transponder equipment test satisfy the accuracy of the standard 1 in the specified range of the interrogation signal level and environment temperature. The flight test of the transponder was carried out at ENRI in Tokyo using DME/P test interrogator. Though a ranging error due to garbling with TACAN signals of which frequency separated from the transponder by 3 channel was observed, it could be suppressed by a slew rate limiter of the DME/P interrogator. The system CMN using the slew rate limiter is 60% of the ICAO standerd at 5NM in FA mode.