| The possibility of using the Automatic Dependent Surveillance - Broadcast (ADS-B) system for monitoring air traffic from orbit is examined. Experimental work is described which successfully demonstrated reception using a stratospheric balloon of ADS-B signals sent over the 1090 MHz Extended Squitter system. A model is developed of the signal propagation from aircraft to satellites in various orbits, including atmospheric effects. The resulting power level at the orbital altitude is used to determine the net receiver gain needed to reliably detect the signals from orbit. A model of the effect on detectability of signal collisions is developed and resulting design parameters determined. ADS-B signals are concluded to be detectable with a gain of 0-5 dB from LEO and 30 dB from GEO orbits, for aircraft populations of up to 4000 in the sensor's field of view.;List of keywords: ADS-B, air traffic surveillance, Automatic Dependent Surveillance - Broadcast, aviation, Extended Squitter, high-altitude balloon, Mode S, satellite, signal propagation, space missions... |
