Interrogation Rate Measurements of Distance Measuring Equipment in Air Navigation System

Performance-based navigation is grounded on wide usage of a pair of Distance Measuring Equipment (DME) as one of the alternative positioning methods on-board of an airplane in case of primary system malfunction. The flight measurement system automatically detects the most optimal pair of ground equipment to support positioning with high performance. A variety of available algorithms of DME selection logic may increase workload of some elements of the navigational aids network, due to the limited capacity of each transponder. In the paper, we propose a passive system for interrogation rate measurements and statistical analysis of navigational aids ground network performance. The system includes two software defined radios. One of them is used for receiving and processing of interrogation signals with DME capacity estimation. Another one detects air traffic data by receiving and decoding messages under automatic dependent surveillance broadcast. The interrogation rate in channels of Ukrainian navigational aids network has been measured and reply efficiency was estimated.