Inmarsat had previously decided to offer a free tier of their existing satellite data service to allow ADB-C (Contract) where position, velocity, intent, and meteorological data are sent based on events, schedules or requests <a href="http://www.inmarsat.com/press-release/inmarsat-provide-free-global-airline-tracking-service/" rel="nofollow">http://www.inmarsat.com/press-release/inmarsat-provide-free-...</a> <a href="http://code7700.com/ads-c.html" rel="nofollow">http://code7700.com/ads-c.html</a><p>ADS-B (Broadcast) instead is broadcasting continuously on 1090MHz for reception by other aircraft and ground stations.<p>Globalstar require an additional piece of hardware to be added to each plane to then rebroadcast these signals onto their network <a href="http://www.globalstar.com/en/index.php?cid=6300" rel="nofollow">http://www.globalstar.com/en/index.php?cid=6300</a><p>On the other hand, Aireon is going for the most ambitious option and the one this radio spectrum agreement relates to - launch new space based hardware on the Iridium NEXT satellites <a href="http://aireon.com/services/global-air-traffic-surveillance/" rel="nofollow">http://aireon.com/services/global-air-traffic-surveillance/</a>