Have you tried navigating around an unfamiliar city without a digital map? Maybe you arrive in a foreign destination and cannot get cell service right away. Unless you anticipated your predicament by downloading an offline map, and GPS is working, and your battery holds out, you may very well not know where you are and how to get to any destination. GNSS is the broader term for this technology, as there are multiple national Positioning, Timing and Navigation (PNT) constellations above us now: Navstar (aka GPS), Glonass, BeiDou, Galileo and the regional systems of Japan and India.
We are among an online digital map generation who has never owned a paper road map, nor stopped to ask directions, nor developed orientation skills based on nature. Imagine a war breaks out; in standard tactics, one or more warring party will block or confuse all GNSS signals in the area; your phone’s GPS is useless, and the local cell network may be misbehaving as it no longer has reliable time signals. Without a GNSS fix, you see no re-assuring blue dot on the map to place you in the digital map of the world. You now need to know where you are by reference to what you can see and identify.
This predicament may seem an amusing what-if until you actually experience the scenario. People tend to underestimate disaster risks when they live in nations far from conflict and disaster zones. Check out the data at the University of Louvain EM-DAT database; the Earth’s human population experiences one disaster a day globally — of natural or human cause. A tsunami in Indonesia wipes out the cell network, an earthquake in Kathmandu wipes out streets and cell towers, a large scale war in a region.
In well resourced nations, COWS emerge from protected locations to address damaged networks — Cell-towers on Wheels. Cell phones get a positional fix from the available satellite networks above but cannot tell the difference between fake signals and real signals. Planes too are equipped with GNSS equipment that can be spoofed. Civilian aircraft navigation was the main reason for the opening up of GNSS for civilian use after the shooting down of a Korean airliner over Russia, apparently due to that craft being off course due to poor inertial navigation technology of that time.
What technologies exist that might get around the lack of access to GNSS? One of the biggest vulnerabilities of the modern world is our dependency on GNSS timing data but that topic deserves a whole article unto itself. Cell towers get the precise time from GNSS satellites, and use that to ensure that signals in the network don’t interfere with each other — precise collision avoidance between each of the neighboring towers. Putting aside the chaos that might ensue from lack of timing data as the clocks in various computers drift out of synchronization, here’s a few of the technologies that exist today which do not rely on GNSS being present.
Visual Positioning System — if you can observe buildings and other landmarks while you do have precise GNSS data and record those positions, then observing that same building through a camera when GNSS is compromised, makes it possible to compute where you are as the observer with some precision. It’s photogrammetry and trigonometry wizardry (sometimes referred to as VIO, or visual odometry); this technology works very well. Sailors, trained to use dead-reckoning methods when in sight of land, would see VPS as a fancy version of finding two or more identifiable landmarks on the shore and then using a chart and compass to determine their vessels position at sea.
But would a military or disaster relief organization rely upon such VPS technology; it’s a qualified maybe. A city in conflict or post — tsunami may be unrecognizable due to damage and obscuration by water and mud. It is more likely that a well-financed military will use infrared signals (seeing objects and shapes by temperature) from a combined array of space, drone and terrestrial vehicles to match up to former infrared, visual and SAR maps of the territory and city. Persistent elements of cities that tend to survive disasters and conflict include thermally-visible features like sewers and power infrastructure.
As an individual, what older technology, and navigation skills might be of help if GNSS was not reliable or available? This is not a bug-out motivated list but just food for thought about life skills and dealing with risk mitigation if traveling into remote or disaster prone areas:
- There remains global, radio-broadcast precision timing signals. Clocks, watches and other devices still exist to receive this data. e.g. WWVB. GNSS too is synchronized to these terrestrial super-precise clocks.
- Buy a good quality compass and learn how to use it. Maybe buy two, and a permanent magnet, to enable you to make more.
- Buy paper maps and learn how to use them — both ordnance survey style maps used by hikers and orienteerers, and road network maps. Maps printed on waterproof pseudo-paper are particularly durable.
- Assuming you can power a cellphone, they contain compass sensors, which can be used to navigate the old fashioned way, using offline maps stored on the phone. This requires no data plan nor cellphone coverage at the time you are navigating. Likewise, a GNSS position fix by your phone requires no data connection. Should the phone not be able to tell you where it is via GNSS, you can move the ‘you are here’ marker on the offline map, and start to navigate from there.
- VPS will function if you have data access and the service is available in your country, and the landmark items remain recognizable.
- Train your memory and mind on orientation by avoiding the use of digital maps for some journeys. Commit the journey to memory and the destination direction, and try to complete the journey by dead reckoning and seeking simpler persistent landmarks e.g. tall buildings, distant mountain peaks, petrol stations. Navigation by named and identifiable landmark is a de facto, pre-digital method in many countries.
- Read and learn about how to navigate using non-technological or low-technology methods. Example — The Lost Art of Finding Our Way.
- Just for fun: reconsider the value of homing pigeons, used as recently as WWII, and featured in the plots of historical novels, such as James Clavell’s Shōgun.
