Submarine Navigation in a GPS-Denied Environment

The Iridium satellite constellation consists of 66 low-Earth orbit (LEO) satellites, primarily used for global data and voice communications. The satellites transmit in the L-Band at carrier frequencies from 1616MHz to 1626.5MHz. Using one of the Iridium satellite?s paging channels to broadcast time and frequency measurements, a ground receiver can collect these measurements for computing position fixes. Unlike GPS satellites, Iridium satellites use spot beams to focus their transmissions on a relatively small geographic area. Each satellite supports 48 spot beams. The Iridium satellite spot beams provide a unique mechanism that is extremely difficult to spoof or jam. NAL Research proposes to develop an Iridium position navigation and time (PNT) receiver to collect Iridium signals for geolocation determination. The receiver will have similar form-factor as a commercial GPS receiver or a SAASM GPS receiver. It will provide ocean platforms an alternate method for truly global (pole-to-pole) geo-positioning.