|Jack Ganssle's Blog
This is Jack's outlet for thoughts about designing and programming embedded systems. It's a complement to my bi-weekly newsletter The Embedded Muse. Contact me at firstname.lastname@example.org. I'm an old-timer engineer who still finds the field endlessly fascinating (bio).
For novel ideas about building embedded systems (both hardware and firmware), join the 40,000+ engineers who subscribe to The Embedded Muse, a free biweekly newsletter. The Muse has no hype and no vendor PR. Click here to subscribe.
Over-Reliance on GPS
March 15, 2021
Scott and I were aboard my sailboat Voyager approaching Bermuda. On a small boat the island is a week's sail from Norfolk. If your course is off even a single degree you'll miss it, so navigation is critical. We've sailed there many times in the past, but on this passage decided to leave the GPS turned off, relying on celestial instead. (With celestial you measure the angle of the sun or other object over the horizon using a sextant, and then can compute your position). We got within five miles of Gibb's Hill and could easily make out the lighthouse. I turned the GPS on to be super careful navigating the reefs.
It told us we were on the other side of the island, 20 miles away.
Bermuda Harbor Radio told us the US Navy was conducting some sort of GPS jamming drills. Had we relied on that system we could have lost the boat.
I get the weekly notice to mariners and it's rare there's an issue which does not detail some planned GPS jamming, at times generating expected errors of 50 or more miles.
A recent NY Times article details tens of thousands of GPS incidents of this nature. Yet our entire infrastructure is dependent on the system. Even ATMs will fail to function if they can't get timing info from the satellites. An IEEE Spectrum article describes how airliners are facing problems when the military purposely degrades or jams the signals.
It is the DoD's baby, after all. I guess if they want to mess with it, that's their right. However, we have become so dependent on the system that purposeful jamming, which can drive airlines miles off course, seems criminal.
Cheap jammers are available on eBay. Malevolent actors can cause much disruption.
The problem really isn't GPS or the jammers. It's that we've become entirely dependent on the system. Sure, there are other satellite-based navigation aids, but their signal levels simply invite bad actors. GPS can be -150 dBm or lower; it doesn't take much to wipe that signal out.
The oldest rule of navigation is to never depend in a single aid to navigation. That buoy might have drifted off course. The radio beacon could be out. Not long ago we sailors had many electronic aids. There was Loran, which transmitted strong signals long distances. Many lighthouses broadcast morse code beacons that we could triangulate on. These are all gone. We're left with satellite navigation which, when it works, is breathtaking in its accuracy and ease-of-use. But that's about it. There's talk of enhanced Loran, but that seems to be more talk than action.
Me, I'll continue to carry a sextant at sea.
With a sextant there's a lot of plotting to get a position. This is typical over a three day period.
Feel free to email me with comments.
Back to Jack's blog index page.
If you'd like to post a comment without logging in, click in the "Name" box under "Or sign up with Disqus" and click on "I'd rather post as a guest."
Recent blog postings:
- Non Compos Mentis - Thoughts on dementia.
- Solution to the Automotive Chip Shortage - why use an MCU when a Core I7 would work?
- The WIRECARE - A nice circuit tester
- Marvelous Magnetic Machines - A cool book about making motors
- Over-Reliance on GPS - It's a great system but is a single point of failure
- Spies in Our Email - Email abuse from our trusted friends
- A Canticle for Leibowitz - One of my favorite books.
- A 72123 beats per minute heart rate - Is it possible?
- Networking Did Not Start With The IoT! - Despite what the marketing folks claim
- In-Circuit Emulators - Does anyone remember ICEs?
- My GP-8E Computer - About my first (working!) computer
- Humility - On The Death of Expertise and what this means for engineering
- On Checklists - Relying on memory is a fool's errand. Effective people use checklists.
- Why Does Software Cost So Much? - An exploration of this nagging question.
- Is the Future All Linux and Raspberry Pi? - Will we stop slinging bits and diddling registers?
- Will Coronavirus Spell the End of Open Offices - How can we continue to work in these sorts of conditions?
- Problems in Ramping Up Ventilator Production - It's not as easy as some think.
- Lessons from a Failure - what we can learn when a car wash goes wrong.
- Life in the Time of Coronavirus - how are you faring?
- Superintelligence - A review of Nick Bostrom's book on AI.
- A Lack of Forethought - Y2K redux
- How Projects Get Out of Control - Think requirements churn is only for software?
- 2019's Most Important Lesson. The 737 Max disasters should teach us one lesson.
- On Retiring - It's not quite that time, but slowing down makes sense. For me.
- On Discipline - The one thing I think many teams need...
- Data Seems to Have No Value - At least, that's the way people treat it.
- Apollo 11 and Navigation - In 1969 the astronauts used a sextant. Some of us still do.
- Definitions Part 2 - More fun definitions of embedded systems terms.
- Definitions - A list of (funny) definitions of embedded systems terms.
- On Meta-Politics - Where has thoughtful discourse gone?
- Millennials and Tools - It seems that many millennials are unable to fix anything.
- Crappy Tech Journalism - The trade press is suffering from so much cost-cutting that it does a poor job of educating engineers.
- Tech and Us - I worry that our technology is more than our human nature can manage.
- On Cataracts - Cataract surgery isn't as awful as it sounds.
- Can AI Replace Firmware - A thought: instead of writing code, is the future training AIs?
- Customer non-Support - How to tick off your customers in one easy lesson.
- Learn to Code in 3 Weeks! - Firmware is not simply about coding.
- We Shoot For The Moon - a new and interesting book about the Apollo moon program.
- On Expert Witness Work - Expert work is fascinating but can be quite the hassle.
- Married To The Team - Working in a team is a lot like marriage.
- Will We Ever Get Quantum Computers - Despite the hype, some feel quantum computing may never be practical.
- Apollo 11, The Movie - A review of a great new movie.
- Goto Considered Necessary - Edsger Dijkstra recants on his seminal paper
- GPS Will Fail - In April GPS will have its own Y2K problem. Unbelievable.
- LIDAR in Cars - Really? - Maybe there are better ideas.
- Why Did You Become an Engineer? - This is the best career ever.
- Software Process Improvement for Firmware - What goes on in an SPI audit?
- 50 Years of Ham Radio - 2019 marks 50 years of ham radio for me.
- Medical Device Lawsuits - They're on the rise, and firmware is part of the problem.
- A retrospective on 2018 - My marketing data for 2018, including web traffic and TEM information.
- Remembering Circuit Theory - Electronics is fun, and reviewing a textbook is pretty interesting.
- R vs D - Too many of us conflate research and development
- Engineer or Scientist? - Which are you? John Q. Public has a hard time telling the difference.
- A New, Low-Tech, Use for Computers - I never would have imagined this use for computers.
- NASA's Lost Software Engineering Lessons - Lessons learned, lessons lost.
- The Cost of Firmware - A Scary Story! - A hallowean story to terrify.
- A Review of First Man, the Movie - The book was great. The movie? Nope.
- A Review of The Overstory - One of the most remarkable novels I've read in a long time.
- What I Learned About Successful Consulting - Lessons learned about successful consulting.
- Low Power Mischief - Ultra-low power systems are trickier to design than most realize.
- Thoughts on Firmware Seminars - Better Firmware Faster resonates with a lot of people.
- On Evil - The Internet has brought the worst out in many.
- My Toothbrush has Modes - What! A lousy toothbrush has a UI?
- Review of SUNBURST and LUMINARY: An Apollo Memoir - A good book about the LM's code.
- Fun With Transmission Lines - Generating a step with no electronics.
- On N-Version Programming - Can we improve reliability through redundancy? Maybe not.
- On USB v. Bench Scopes - USB scopes are nice, but I'll stick with bench models.