Redundant Navigation Systems Are Crucial When Satellite Interference Problems Occur　

　　Before satellite-based navigation became a thing, we had all kinds of radio navigation beacons. Before radio navigation, we navigated with stars and markers. A lighthouse is a navigational sign, and so is a road sign. Then we have the inertial navigation system, but they can only measure changes in position, and they need some way to set a reference point. Interest in these old technologies is growing as satellite navigation interference becomes a problem.

　　GPS satellite navigation and tracking have become a key link in the fast-growing logistics and freight ecosystem in the world. The company uses the global positioning system to track trucks and ensure their punctuality and the safety of goods.

　　Navigation by inertial sensors should be trivial enough as these sensors already exist in phones, for knowing to wake up when moved and for tracking motion in AR/VR games. I don‘t know if vehicle navigation systems have inertial sensors but they appear to have the means to detect motion from video cameras, cameras already in cars for looking behind them when backing up. Again, this won‘t tell a vehicle or phone where they are, only how they move, but with something to set a reference point we have systems that can navigate by these sensors with high enough precision and accuracy for getting people and cars from point A to point B.

　　Little wonder, then, that criminals are turning to cheap GPS jamming devices to ransack the cargo on roads and at sea, a problem that‘s getting worse but may be ameliorated with a new generation of safety technology designed to overcome threats from jamming.

　　For decades, we have had automated celestial navigation. This is a tool used by military forces before the advent of satellite navigation, and it is still used as a backup of GPS today. Now that video sensors and computing power are so cheap, the cost of adding them to mobile phones and car navigation should quickly approach zero. As pattern recognition improves, we can let the system navigate by identifying road signs, or by identifying buildings and other landmarks.

　　We have a terrestrial radio navigation system. One is VORFDME, and the other is LORAN. Both use radio transmitters that are more powerful than anything on a satellite. One problem may be the size of the antenna needed. The VOR / DME uses the VHF frequency, so the antenna may be too large for things in the pocket, but not for cars. Cars already have VHF receivers, we just call them FM radios. Rowland uses much lower frequencies, so an efficient antenna would be large even for cars, but not for building ships and planes that are big enough. Roland is not very accurate. Its purpose is to let people find coastal ports, not street addresses when they travel long distances by sea. Things like Lauret can be combined with sensors and software to pinpoint where a vehicle is moving. We now see that using this method, GPS computers can calculate position errors by comparing past positions with the motion detected by accelerometers.

　　In Mexico,GPS jammers are used in about 85 percent of truck thefts. In the United States, statistics are difficult to obtain, but there is no doubt that this kind of equipment is very common and widely used. Russia is currently using this technology to interfere with Ukrainian commercial aircraft.

　　If GPS jamming becomes a big enough issue then I expect demand for accurate backup systems to come up, and then once one manufacturer attempts to fill this demand then others should follow. We are concerned about the loss of VOR/DME beacons because of their value to aircraft that have experienced GPS interference. I believe LORAN is history now with stations closed long enough that they‘d have fallen into disrepair or been dismantled, but something like it could be built again. For / DME is considered redundant because of GPS, which leads to an effort to turn off the beacon as a cost-saving measure. Having redundant navigation systems could be seen as vital if there are people successfully jamming and spoofing one system for the purpose of theft and other criminal behavior.