A method to measure the 1090 MHz interference environment

The 1090 MHz aviation surveillance frequency band is being used by a growing number of aircraft, applications and equipment types. The band is expected to soon reach critical interference levels. The frequency is used by aircraft transponders responding to interrogations from ground radar and from other aircraft. It is also shared by aircraft transmitting Automatic Dependent Surveillance - Broadcast (ADS-B) information, and by ground stations transmitting traffic information and cross-link ADS-B rebroadcasts. In the current protocols, information is transmitted asynchronously. Loss of information due to overlapping messages or garbling is acceptable in all protocols to a certain degree, but there is concern that this performance loss will soon become unacceptable as message densities increase. In order to quantify the problem, analyses and simulations are used, and they must make assumptions about the details of the interference environment. Therefore there is a strong need for measurements in the field to verify the models. This paper presents a new approach to measuring the 1090 MHz interference environment.