Jamming and spoofing GPS

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DH and I used to fly our Cessna 150 and 177 cross-country, to Canada and the Caribbean during the 1990s. The FAA thoughtfully provided thousands of VORs (Variable Omnidirectional Radar) all around the U.S. While DH flew, I held a detailed large paper chart that covered a specific area. As we flew, I would adjust our radio receiver to the local VOR to make sure we were on the beam. DH had a large nylon pack containing all the contiguous charts for our route.

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When Garmin released its first commercial GPS for use in general aviation aircraft I bought it for DH as a gift. It cost hundreds of dollars and provoked envy in other general aviation pilots. I still used the charts but using GPS was a game changer. I like the charts because they show all the little airports along the way which could be a landing spot if needed. The FAA still maintains VORs but is planning to cut way back since commercial airliners all use GPS.

Nowadays, every teenager has a mobile phone equipped with GPS. Many drivers can’t even read a map as their GPS-equipped cars give them directions to their destinations. (Assuming these aren’t driverless cars.)

Remembering what the world was like before GPS is like remembering the world before telephones or radio. We all take GPS totally for granted. The U.S. GPS system is world-wide.

Weapons systems all use GPS, including missiles and drones. But what happens if GPS is jammed or spoofed? This can mess up the weapon – and also collateral civilian GPS.

GPS jamming is emerging as an increasingly prevalent — and troubling — weapon of war

By Katie Hunt, CNN Science, Updated Mar 6, 2026

Within 24 hours of the first US-Israeli strikes on Iran, ships in the region’s waters found their navigation systems had gone haywire, erroneously indicating that the vessels were at airports, a nuclear power plant and on Iranian land.

The location confusion was a result of widespread jamming and spoofing of signals from global positioning satellite systems. Used by all sides in conflict zones to disrupt the paths of drones and missiles, the process involves militaries and affiliated groups intentionally broadcasting high-intensity radio signals in the same frequency bands used by navigation tools. Jamming results in the disruption of a vehicle’s satellite-based positioning while spoofing leads to navigation systems reporting a false location. …

There are multiple global navigation satellite systems, with the US-run Global Positioning System, or GPS, being the best-known and most used. The EU operates a parallel system called Galileo, China has its own BeiDou satellites and Russia has a system known as GLONASS…

On highly automated, modern ships, GPS interference can be hard to detect. And while it’s perfectly possible to navigate using alternative tools, including radar, inertial systems such as accelerometers and gyroscopes, visual watchkeeping, and celestial navigation, younger mariners are often less familiar with these techniques and tools. … [end quote]

The article is packed with lots of examples.

I can’t help wondering whether it would be more cost-effective to base a missile (or drone) defense system on GPS jamming rather than interceptor missiles.

Wendy

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Back in the day navigating with charts was called dead reckoning.

The Captain

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You would think those jamming antennas would be easy targets for drones.

Wasn’t it the Yom Kipper war when Israel sent model airplanes over the battlefield to get Egypt? to light up its radar so they could be identifed and attacked?

With so much electronics out there the modern battlefield must light up like a Christmas tree. How do you distinguish friend from foe?

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If I remember correctly, the Dead of dead reckoning does not refer to fate or mortality, but is an alliterated spelling of the contraction of the phrase Duration Direction = D.D. reckoning.

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I never thought about it. Let’s see what AI can come up with:

Google AI:

The claim that “dead reckoning” is an abbreviation for “Duration Direction” (D.D.) is a common, but incorrect, piece of maritime folklore. The term does not refer to a contraction of a “D.D.” phrase.
Wikipedia

Here is the accurate breakdown of the origin and meaning of dead reckoning:

  • Original Meaning: It is a method of navigation used to calculate a current position based on a previously known position, speed, and direction, without relying on external observations like stars or GPS.

  • Etymology: It is believed to be a shortened form of “deduced reckoning,” which was often abbreviated to “ded.” in old ship logs and later evolved into “dead”.

  • Earliest Use: Evidence for the term appears in written works as early as 1613, notes the Oxford English Dictionary.

  • Alternative Theory: Another common interpretation is that “dead” refers to calculating position while “dead in the water” (stationary) or is used in the sense of “dead” as “absolute” or “direct” (e.g., “dead on,” “dead straight”).

  • “Deduced” Misconception: While “deduced” is the most likely origin, some historical arguments suggest that “ded” was not commonly used in the earliest logs. However, the “Duration Direction” contraction (D.D.) is not generally supported by historical evidence.
    Oxford English Dictionary

Conclusion: Dead reckoning is a technical, nautical term representing “deduced reckoning”—a calculation of position based on speed and direction since the last known fix—not a contraction for “Duration Direction.”

AI has a serious error in stating “without relying on external observations like stars or GPS.” Everything visible was fair game and the Sun, the Moon, and the stars were very much in use. This is beautifully explained in We, the Navigators: The Ancient Art of Landfinding in the Pacific by David Lewis.The book explained many of the things I had seen on the water but never understood their meaning, wave patterns, birds, clouds and more.

Sadly Polynesian navigation is dying, overtaken by modern technology.

The Captain

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Younger everythings struggle when technology breaks down. Many surveyors are dead in the water when their equipment breaks down. They often don’t know how to set control with a compass and tape.

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There are four worldwide GPS systems, the US, EU, Russia, and China.

It’s obvious why a major power would want its own, you can’t launch missiles at Washington and not have them change the coordinates to have the missile land harmlessly at sea while it’s in flight.

That said, why wouldn’t the military just use multiple GPS systems, including hacked Russian and Chinese, rather than rely on the one that we know is going to be spoofed in time of war?

I must be missing something.

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The corruption involved with government contracts. Especially in dictatorships.

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Maybe what you’re missing is that this is probably being done…but hasn’t been publicized, for obvious reasons.

Wendy

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