Inside GNSS Media & Research

MAY-JUN 2018

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10 Inside GNSS M A Y / J U N E 2 0 1 8 I write this having just returned from the AUVSI XPONENTIAL trade show in Denver. Featur- ing autonomous and remotely piloted vehicles of incredible diversity, these vehicles are truly systems of systems of stunning sophistication and complex- ity. I was reminded of the spirit of innovation we had in the early days of GPS when we were willing to try anything and everything just to get it to work. "Crashes" were the norm, USAF Majors made launch decisions and painful failures were oen how we learned best. Fast forward 40 years and GNSS is a mature and sophisticated indus- try. Reliability, accountability and integrity are just some of the hallmarks of maturity whether we are talking about individuals or industries. Unfortunately, institutional rigidity and difficulty in adapting to new circumstances are also hallmarks of maturity. In recent years numerous attacks on GNSS have been developed and put into practice in the civil sec- tor. In the European Union (EU), the Strike3 effort has documented and classified more than 50,000 unique jamming incidents. Spoofing, both inten- tional and unintentional, has also been seen; deliber- ate spoofing in the Black Sea area and an uninten- tional spoofing incident in Portland come to mind. All this in spite of strong laws regulating the sale, import and use of civil jamming equipment in most nations. ese are good laws but they are not 100% effective. e simple truth is that while we can see interference, we usually can't find its source. GNSS receivers will need to comprehend an increasingly complex environment to avoid producing hazard- ously misleading information (HMI). e failure of many civil receivers to maintain situational awareness in interference is well docu- mented. In the NLV Pole Star tests conducted in the UK, the ship's GNSS thought it was flying at Mach 1 over Finland. More recently, in the Ligado-spon- sored NASCTN tests, one of the two high precision receivers tested gave clear evidence of locking onto the interference source rather than the GPS signals. e list goes on and on but the point is this: unless you test a receiver for the environment it is expected to operate in, you don't know how it will react. Exposure testing is fundamental to taking corrective action. e EU is taking a leadership position in this, both with its RED standards (ETSI EN 303 413) and with its dra standards for receiver testing against threats (available at ). When I first described and proposed receiver certifi- cation in 2011 to the US PNT advisory board, it was dismissed as being an inhibition to innovation. But as the threat has evolved, the advisory board seems to be evolving in their opinion as evidenced by their protect toughen & augment (PTA) mantra and some of the recent presentations by the Department of Homeland Security and the National Coordination Office. e caution though is that an overly complex test or specification really will inhibit innovation and will prove counterproductive. Rather than seek Federal Aviation Administration style 99.99999% confidences I would much rather see simple 95% style tests for basic situational awareness. Having more satellites to operate with is a tre- mendous boon to all nations and a failure to provide spectrum protections for all GNSS is in a word, stupid. Integrity monitoring is fundamental in not producing HMI and having lots of signals makes undetected spoofing all that much harder. If even a single signal goes uncaptured in the target receiver, RAIM techniques can raise a flag to alert the user to the possibility of HMI. Authenticatable signals pro- vide stronger hardening since such signals cannot be generated by a simple signal generator. e EU has passed laws requiring Galileo to transmit authen- ticatable civil signals (DECISION (EU) 2017/224 of 8 February 2017) and at least one manufacturer has given their endorsement (see Inside GNSS, Mar/April 2018, "Munich Hot Licks"). e caution though is that only adding navigation message authentica- tion (NMA) is tantamount to security theatre; true source authentication requires watermarking at the chip level. e US CHIMERA design for L1C is one way of doing this and it my fervent hope that the EU (and the US) adopts something equivalent in its civil protections. So back to the AUVSI XPONENTIAL trade show. Almost every vehicle I saw had GNSS as a critical and highly trusted component. So much so that numerous vehicles had three GNSS receivers and associated antennas on them. When I asked why, the answer was illuminating: "In case one of them gets spoofed, we can use the other two to continue operation". Our customers need a basis for selecting receivers that have been exposure tested for basic competency in challenged environments. THINKING ALLOWED What Does a Competent Receiver Look Like? LOGAN SCOTT FOR INSIDE GNSS "OUR CUSTOMERS NEED A BASIS FOR SELECTING RECEIVERS THAT HAVE BEEN EXPOSURE TESTED FOR BASIC COMPETENCY IN CHALLENGED ENVIRONMENTS."

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