DOT Pitched Multiple GPS PNT Backup Systems

Looking for information on alternatives to GPS-provided positioning, navigation and timing (PNT) capabilities, the Department of Transportation received input on a variety of systems that supposedly could fit that bill. Comments were due Monday at Regulations.gov. Globalstar and Echo Ridge said they're ready to do a field demonstration of PNT capability that could back up or complement GPS, operate independently of other global navigation satellite systems and require no new infrastructure. They said its augmented positioning system uses 24 low earth orbit Globalstar satellites and a series of its earth stations. Skyhook said its Wi-Fi-based system could provide hybrid location in populated areas that also use crowdsourcing to monitor GPS performance trends. Locata said its terrestrially based non-GPS system could cover all the traditional GPS functions needed for PNT services. Seven Solutions said its timing-only solution, using disparately located global navigation satellite system receiver sites, "would render local jamming and spoofing activities moot." Multiple filings weren't made public because of confidential business information. GPS is the best technology for precision navigation and timing requirements, and the industry supports looking at complementary technologies as long as they offer equivalent capabilities and performance, the GPS Innovation Alliance said. GPSIA said given the costs to develop those alternatives and potential limitations, federal resources should still be principally be directed at maintaining and improving the existing GPS system. Some possible alternatives came under fire. GPSIA said one possible complementary technology, eLoran, isn't accurate enough in navigation opposition data for many PNT functions like high-precision agriculture, surveying and intelligent transportation. Qualcomm said eLoran has problems -- its 10-inch square antennas are tough to house in mobile handsets and mobile devices generate high levels of low frequency noise in the 100 KHz rate in which eLoran operates. It said another possible approach, metropolitan beacon systems, would be limited to urban areas and need extensive network buildout and ongoing maintenance. DOT should keep in mind the wireless industry's network rerouting, device-based navigation and timing and cloud-based application capabilities to continue voice and data transmissions in the case of GPS outages when deciding the scope of need for GPS backup when it comes to wireless communications, CTIA said. It said any terrestrial backup will require substantial antenna deployments on U.S. wireless infrastructure, and DOT should be talking with tower company owners and operators about tower space availability and operational issues.