Digital Interference Mitigation Technique for the Interoperability of two Airborne two SatCom Systems for Small Aircraft

The Inmarsat and Iridium systems and signals share the same upper and lower frequency limit on the 1626.5 MHz frequency, affecting its interoperability and simultaneous full dual usage. For this reason, the two systems cannot be used simultaneously, especially in small/medium aircraft, since the Inmarsat transmitter power density affects the Iridium receiver in certain circumstances and configurations. This paper proposes the modeling and development, based on Software Defined Radio, of a digital interference mitigation technique in order to make possible the integration and deployment of the two systems in a reduced space without degrading the global performance of both systems under their operation. For this, we use a digital notch filter in order to reject the Inmarsat interference signal in the reception RF path of the Iridium system. Results in laboratory show the feasibility of the technique as a possible solution for Inmarsat/Iridium interoperability for dual onboard SatCom in small aircrafts opening the door for its usage on drones, in the near future.