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Australia Microair Avionics +61 7 4155 3048 www.microair.com.au Germany Air Avionics +49 6224 98 96 999 www.air-avionics.com Spain Indra +34 914 805 000 www.indracompany.com UK BAE Systems - www.baesystems.com Trig Avionics +44 (0)131 449 8810 www.trig-avionics.com USA Avidyne +1 781 402 7400 www.avidyne.com BAE Systems - www.baesystems.com Harris Corporation +1 321 727 9100 www.harris.com Micro Systems +1 850 244 2332 www.kratos-msi.com NextGen UAS Transponders - www.nextgenuastransponders.com Northrop Grumman +1 847 259 9600 www.northropgrumman.com Raytheon +1 781 522 3000 www.raytheon.com Sagetech +1 509 493 2185 www.sagetechcorp.com Sierra Nevada Corporation +1 775 331 0222 www.sncorp.com Thales +1 240 864 7000 www.thalesdsi.com Urban Canyon +1 206 372 9032 www.ucflight.com Some examples of transponder manufacturers and suppliers 75 Unmanned Systems Technology | Summer 2015 radars, the military uses transponder codes to determine the identity of an aircraft, but here it is performed via Identification Friend or Foe (IFF) interrogation and response. Like a civilian SSR, military air surveillance radars use an IFF antenna that transmits a coded message to the aircraft’s transponder, which recognises it as ‘friendly’ and then in turn transmits encrypted details of the aircraft’s identity. IFF has an obvious purpose – to avoid aircraft being shot down by their own side. Mode-5 is an IFF protocol that is being introduced throughout NATO. Conceived in the mid-1990s as the result of a requirement from the US Joint Chiefs of Staff, the initiative was aimed at developing an IFF protocol to replace Mode-4. In 2002, NATO adopted Standardisation Agreement (STANAG) 4193, which mandated Mode-5 for all NATO and US military aircraft. STANAGs are NATO agreements stipulating the technical requirements and specifications for military and technical equipment and processes across the alliance. Their intention is to create a high degree of standardisation across NATO to make it easier for member nations to train and fight together. Mode-5 effectively transmits the same information as Mode-S in terms of an aircraft’s identify, its flight characteristics and its GPS position, but Mode-5 does so in a cryptographically secure fashion. Mode-5 has implications beyond NATO though, given that military operations such as those in Iraq, Afghanistan and Libya are performed not only by NATO members but by allied nations too. For this reason, many non-NATO members will need to ensure Mode-5 compatibility. Looking forward in terms of UAV transponder design, such equipment will therefore not only need to be capable of meeting the requirements of the Mode-S and ADS-B protocols, but ensure they can meet Mode-5 IFF requirements if they are to participate in future NATO- or US-led military operations effectively. Acknowledgements The author would like to thank Bill Banfi at BAE Systems, Antonio Tovar at Indra, Jim Davis at Sagetech, Jon Roper at Trig Avionics, Maynard Factor at Micro Systems and Emmanuelle Le Fol at Thales for their invaluable input into this article.