GPS World

Tag: GPS reliance

  • GPS could be deemed ‘less reliable’ if FCC’s Ligado decision stands

    GPS could be deemed ‘less reliable’ if FCC’s Ligado decision stands

    Photo: Logan Scott
    Logan Scott

    Spectrum regulation is much like land-use zoning: certain services are kept separate to avoid disturbing the neighbors. The U.S. Federal Communications Commission (FCC) has in effect allowed Ligado to build an outdoor concert venue next to a monastery, and by way of compensation, they offer free earplugs.

    GPS/GNSS signals are extremely weak and the receivers are extremely sensitive. To give some perspective, by the time they get to the GPS receiver, GPS signals are about a factor of 20 less powerful than cosmic background noise. Ligado’s spectrum was licensed for mobile satellite services (MSS) and so was not likely to interfere with GPS.

    “The U.S. Federal Communications Commission (FCC) has in effect allowed Ligado to build an outdoor concert venue next to a monastery, and by way of compensation, they offer free earplugs.”

    With its new, and much more valuable license, Ligado now has a legal right to build a terrestrial cellular service. Exhaustive testing over the past 10 years has repeatedly demonstrated that such a system will interfere with high-precision GPS/GNSS receivers used in surveying, timing and Earth observation. The Department of Defense (DOD) has also made strong claims that such a system will cause harm to its systems. In all cases, the effect is much like riding a bicycle at night. You can see fine until someone comes around the corner with the high beams on and blinds you.

    In its earlier filings, Ligado had asked for permission to transmit at a power level of 1500 Watts. In an amazing piece of legerdemain, they convinced the FCC, but not the Department of Transportation (DOT) or DOD, that by reducing transmit powers to 10 Watts, there would be no harm. This is a stunningly erroneous claim. As you lower the transmit power, you need many more cellular base stations to cover a given area. To use an analogy from my backyard, I can install one high-flow sprinkler head to cover the entire yard or a bunch of low-flow heads, each covering a small portion. Either way, the grass doesn’t care about anything other than inches of water, and I’m going to get wet if I run across the yard. Ligado’s core argument is equally wet. Nonetheless, it has great appeal to people who don’t understand how cellular systems work.

    So, moving forward and assuming the license stands, interference events will become more prevalent and GPS will be deemed “less reliable.” Because interference sources are largely untraceable, blame will rarely attach to Ligado. I expect that GNSS receiver vendors will incorporate improved filters into receivers and pass the cost along to buyers. Ligado, or more likely whoever it sells the spectrum to, will quickly move to petition for increased transmit powers to lower capital costs; after all, more base stations cost more. And so, the Visigoths have arrived, 4G in hand with a 5G label.

    Logan Scott is founder and owner of Logan Scott Consulting, www.gpsexpert.net.

  • First Fix: The PNT enterprise is real

    First Fix: The PNT enterprise is real

    Jules McNeff
    Jules McNeff

    Guest column by Jules McNeff
    Consultant and GPS World Editorial Advisory Board member

    GPS World publications are evolving, as this new column confirms. And the PNT world itself is evolving, first with the emergence of GPS in the 1990s, next with its universal adoption and duplication by others, and now with its foundational role in PNT-enabled applications for technologies of the 2020s and beyond.

    Millions of people have grown up in a world where GPS-enabled PNT applications pervade their daily lives, and mostly for the better. But GPS is no longer the only face of PNT around the world, though it is still the best known even as other space-based systems from international providers have joined the party.

    From its infancy, GPS was married with inertial systems and clocks. For a short time, GPS emergence stymied the commercial development of both, but as the viability of the marriage was validated, development turned toward miniaturization of the combination and adding more pieces as well.

    It is now clear that GPS was the spark, and a multi-faceted PNT enterprise is the new reality.

    Because of its free availability, GPS has been the foundational element in most of these integrated applications, and without GPS, many will not work as well — or at all. Consequently, dependence on GPS for efficient operation of many PNT-related activities has become a de facto reality. GPS timing is at the heart of interoperable telecommunications and data networks (most notably the internet) and of modern power grids. GPS positioning was the catalyst for adoption of the U.S. National Grid as a federal spatial interoperability standard for search-and-rescue and emergency response and by the SAE as a standard for commercial land mobility as well.

    However, dependencies create vulnerabilities, and over-reliance on GPS has been cited as a potential Achilles heel for both national security and economic critical infrastructure. Efforts have been under way for several years by the U.S. Air Force to strengthen all aspects of GPS and, more recently, much attention has focused on making use of complementary technologies to increase the resilience and performance of integrated PNT devices.

    Smartphone and autonomous vehicle developers have used such techniques for years to augment GPS for their applications. The awareness of value from ubiquitous access to precise position and time that was awakened by GPS in 1995 has now evolved into an understanding that diverse services from a broader PNT enterprise are necessary to preserve that access with assurance into the future.

    Congress and the DoD have recognized that reality, with Congress directing and DoD implementing a DoD PNT Enterprise Oversight Council to manage future acquisition of PNT capabilities for the military. In August, the Department of Defense (DoD) also released a public version of its Strategy for the DoD PNT Enterprise, highlighting the processes it has created to implement resilient PNT for the Joint Force. Congress and the White House both have also recognized that the imperative for resilient PNT must be extended to domestic critical infrastructure, and this has resulted in direction to civil federal agencies to both strengthen and back up GPS use for their constituencies. It is now clear that GPS was the spark, and a multi-faceted PNT enterprise is the new reality.

  • Is reliance on GPS making us lose our mapping minds?

    cozzens_tracy_4_130By Tracy Cozzens
    Managing Editor

    I love maps. As a child, I was my family’s designated navigator on car trips (or my parents indulged me!).

    I studied our roadmaps, searching out each legend icon on the map and finding icons to look up on the legend. I would use the map’s indicators to determine the distance between points and interesting landmarks. I was such a map fanatic, that I spent time one summer recreating in a large size a map of the Ancient Roman Empire. My father asked why. I had no real answer, except that I love history and maps.

    Today, some experts are warning that our ability to read and interpret maps might be in jeopardy because of our reliance on GPS devices. Some GPS-reliant drivers make massive blunders, such as a Syrian truck driver who ended up in Gibraltar Point, England, rather than Gibraltar on the south coast of Spain.

    Former president of the Royal Institute of Navigation Roger McKinlay told Vox reporter Brad Plumer that our reliance on GPS might be causing our innate navigational capabilities to atrophy over time, which is a problem when our smartphones will only ever be as “smart” as the humans using them.

    “Neuroscientists have discovered that our brains have two different specialized systems for navigation,” Plumer writes. “In one system, located in our hippocampus, we create spatial maps of the world around us, understanding how different streets and routes fit together. In the second, located in the caudate nucleus, we make a mental list of the different landmarks we encounter every day.”

    By not figuring out routes using maps, and relying solely on turn-by-turn directions, our ability to work out spatial maps and determine our place in the natural world seems to worsen.

    “McKinlay argues that schools should teach students map-reading and navigation as a critical life skill,” writes Plumer. “He also suggests that researchers start looking at whether there are ways to design GPS systems so that they help us learn about our environment rather than making us unaware of the world around us. (It’s unclear what exactly this would look like, but what if, as a default, these systems always walked us through the spatial map of where we were going?)”

    This map lover is all for it.