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NO GPS, What would you do?

NO GPS, What would you do?

by Capt Major » Tue Nov 09, 2010 9:10 pm

No GPS? No Problem
Aviation Week's DTI | David Hambling | November 08, 2010
This article first appeared in Defense Technology International.
Navigation via Global Positioning System is ubiquitous. Soldiers, vehicles and even artillery rounds are guided by satellite navigation, as long as the service is accessible.

But what happens when it isn't? GPS jamming has always been a concern and much effort has been expended in making the system jam-proof. GPS, however, may be unavailable for other reasons: Obstructions can block signals; satellites may be attacked; and a software glitch such as the one that brought down several thousand U.S. Air Force GPS units earlier this year is a possibility.

A market in GPS-alternative technologies is developing, and these may emerge as redundant safeguards.

One approach uses a series of radio beacons that act as an alternative to satellite-based transmitters. The Ranger from Ensco Inc., for example, employs beacons that transmit signals over a broad spectrum. Users access the system with handheld radios that calculate an individual's location based on the distance to each beacon.

The U.S. Defense Advanced Research Projects Agency (Darpa) is using the same principle on a larger scale for its Robust Surface Navigation (RSN) program. RSN will use any available signal augmented by additional radio beacons. New hardware will be required for RSN, in this case software-defined radios. Some elements of the program will transition to the U.S. Navy and Air Force in Fiscal 2011.

Another approach involves portable inertial measurement units (IMUs), miniature versions of the systems in aircraft and other platforms. One example is the matchbox-sized Dead Reckoning Module (DRM) from Honeywell. This has gyroscopes and accelerometers that calculate a user's position from his cumulative movement. The technical challenge is to compensate for the uneven motion of walking, which varies with each individual. Specially developed algorithms address this issue.

A more advanced version in the offing is Darpa's Microscale Ring Integrating Gyro program, which uses a vibrating structure in place of a spinning gyroscope to calculate location. Inertia keeps the gyro device vibrating in the same plane as it is rotated. Darpa plans to make its gyro small enough for integration on a chip-scale unit. If successful, this could replace GPS for ground users, and in munitions, drones and other applications.

IMUs tend to lose accuracy over time. Honeywell's DRM is claimed to have an accuracy rate within 2% of distance traveled, which is adequate for short missions on foot. Every IMU needs to be recalibrated at intervals with a correct location verified by other means including the stars. Stellar or celestial navigation requires accurate timing, which is not a problem with modern electronics. Millisecond accuracy will pinpoint a location to within 5 meters (16 ft.). The limit is the precision with which stars can be located. The Navy's Stella navigation system is reportedly accurate to 30 meters, while the NAS-26 system on the B-2 bomber is said to be so accurate that GPS is virtually redundant.

A recent Air Force Research Laboratory presentation on MQ-X Predator unmanned aerial vehicles (UAVs) describes a future craft equipped with star-tracking systems and IMUs as well as GPS, terrestrial radio navigation and terrain-matching capabilities.

Modern stellar navigation systems have evolved from the gimbaled telescope on the B-2, which swivels to locate stars. Size and weight are at a premium in air and space platforms, of course, and current units use solid-state devices with a wide field of view to locate several stars at once. They are tiny -- the Miniature Star Tracker from Comtech AeroAstro weighs less than 1 lb.

Adapting this technology for terrestrial use involves challenges, such as locating stars in daylight. Trex Enterprises developed a system for the Navy that tracks 6.3-magnitude stars at sea level in daytime. Such stars are barely visible to the eye at night.

A terrestrial user may wait days to get a stellar fix because of clouds. Predator UAVs or other aircraft with stellar-inertial navigation and radio beacons could act as GPS for users below, as part of a system such as the RSN. Even occasional passes by such aircraft would ensure that IMUs are kept updated and accurate.

Putting the hardware in place will take time and money. But in principle, the loss of GPS need not prevent soldiers and others from having precision navigation at their fingertips.

Credit:, Today in the military
Capt Major
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Re: NO GPS, What would you do?

by SV THIRD DAY » Wed Nov 10, 2010 11:48 am

Maybe I'm either old fashoned or a bozo...but am I the only one who has paper charts aboard the boat and actually USES them even with GPS knowing it could crash at the worst possible time? :?: Forget the question...I am a Bozo for sure.
Rich Boren
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Re: NO GPS, What would you do?

by svrocinante » Wed Nov 10, 2010 11:59 am

SV THIRD DAY wrote:Maybe I'm either old fashoned or a bozo...but am I the only one who has paper charts aboard the boat and actually USES them even with GPS knowing it could crash at the worst possible time? :?: Forget the question...I am a Bozo for sure.

Then add me to the Bozo list!
We carry paper charts on Rocinante and use them religiously.. they've paid off twice already!

We lost our chart plotter / GPS on a stormy overnight run down the NJ coast and finished the trip from around Atlantic City to Cape May running a compass course and our paper charts. Yes, I know we could have done it without any charts, but still, the confidence of knowing where we were removed a lot of the stress!

The second time, we where in South Carolina (ICW) and we lost all our electronics... everything!
Fortunately, we had just finished marking our location on the chart and maria was able to keep us on course and out of trouble while I tracked down the problem... don't know what we would have done if we didn't have our paper charts with us.
Carlos & Maria
S/V Rocinante may not be able to control the wind,
but you can adjust your sails..._/)
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Re: NO GPS, What would you do?

by ka4wja » Wed Nov 10, 2010 1:37 pm

1) First off....
SV THIRD DAY wrote:Maybe I'm either old fashoned or a bozo...but am I the only one who has paper charts aboard the boat and actually USES them.....

You're certainly NOT the only one!!!!
Since I do the same....

I use paper charts as my primary charting, plot my course on the charts, follow those courses with my two Ritchie steering compasses as my primary "heading indicators", and use GPS (along with DR, and/or coastal plots, and/or celestial) as my position fixing......and I engage my autopilot on the particular course I desire, it does NOT follow a "route" from a chartplotter, nor head to a "waypoint", but only steers the course I desire.....(this is one of my peeves.....sailors that have the pilots follow a "route" from their chartplotters....ahh, don't get me started!!!)
Been doing all of the above for many years.....and if you eliminated the "GPS" from the above, this is how I've been doing it since a kid in the mid-1960's.....and used DR and celestial exclusively on my first Atlantic crossing in the pre-GPS days, 30 some years ago....

These statements above may seem odd to anyone that has a look at my Nav station, but they are true!!! (my paper charts being actively used are in the chart table, or at the helm.....and long=term storage is secured in multiple "portfolio-type" in the aft cabin....)

2) Secondly, as to Capt Major's posting of what DARPA has been working on, as well as the capabilities of the B-2......I find it heartening....
{I have a friend that was (is?) a senior engineer, handling the design and reprogramming of the B-2's software defined radios.....and while he couldn't be specific, he did mention their multiple SDR's that work with the NAV system, and the B-2's NAV system allows the B-2 to navigate "in the blind" during/thru multiple nuclear explosions (both on ground and in space).....nice to know that these guys will make it home safe.....}

Further, I've seen miniature laser-ring gyros, and wondered how long before they're small / cheap enough to install in every handheld radio as a compliment to GPS.....and now it seems they (DARPA) may have an even better solution????

And, I the only one who notices these proposed "beacon-type" unit's similarity to LORAN????

Oh well, our wonderful tax dollars at work!!!!

But, I guess I'm a Bozo, along with Rich!!!!

Fair winds...
John, KA4WJA
s/v Annie Laurie, WDB6927
MMSI# 366933110

(currently lying, Sewall's Point, FL)

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Re: NO GPS, What would you do?

by Delezynski » Wed Nov 10, 2010 3:00 pm

Add another Bozo here :lol: !

Unless we are on a VERY short hop and close enough to see land and the anchorage with no chance of fog. We use our plotter, BUT ALSO USE our Yeoman chart plotter. It uses the GPS to allow us to plot on our PAPER charts at the same time. I mark the chart every 30 min. (minimum). If the GPS goes down and out, I just carry on...................

Greg & Jill Delezynski
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Re: NO GPS, What would you do?

by ughmo2000 » Wed Nov 10, 2010 4:10 pm

Hello. I'm a Bozo and have been for many years.
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Re: NO GPS, What would you do?

by Louis Riel » Wed Nov 10, 2010 5:40 pm

When I began crossing oceans, GPS meant Gray Plastic Sextant. Amazing how dependent some have become, in such a short time.
System failure will eliminate the non bozos, and leave the oceans a bozo only place. Not a bad thing for us bozos.
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Re: NO GPS, What would you do?

by brentswain » Tue Sep 12, 2017 3:18 pm

I met a cruiser in Shearwater last summer who had reserved time in Glacier Bay . His electronic charts had crashed, and he was desperately looking for paper, so he could make his reservation time.
Best not rely on electronics so much.
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Re: NO GPS, What would you do?

by RBEmerson » Tue Sep 12, 2017 10:19 pm

We're all just a battery failure away from The Age of Sail.

Paper inshore, sextant offshore. And, yes, I do sights to stay current with sight reduction.
Eat more moose, 17,000 wolves can't be wrong...
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Re: NO GPS, What would you do?

by robertkowalski » Wed Sep 27, 2017 3:21 pm

I follow the jet trails I generally know my compass course as a rule on passage I check gps once a day don't really get worried until I see land. funny thing is the two times I ran aground I was using a chart plotter.
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Re: NO GPS, What would you do?

by robertmackie » Mon Oct 02, 2017 7:58 am

I still do a bit of contract flying, couple of months a year. Anyhow, the "new" pilots that I end up flying with have no idea how to navigate without their GPS. Hell, they don't even teach them "bearings" in school anymore.

A few years ago there was an outage when we were up on Lake Huron (currently in Panama) and 80% of the boats would not move without their GPS....

The world will come to a screeching halt if the Internet and/or GPS ever goes down for an extended time.
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Re: NO GPS, What would you do?

by Scott Berg » Mon Oct 02, 2017 8:14 am

it's fun when an old (but good) thread comes back to life! Any sailor (and I include those who sail trawlers and motor-yachts just as the Navy does) over the age of 50 learned before the days of GPS and many of us before LoRaN and SatNav (Transit). It was Piloting, DR, Celestial, and our friend the RDF once you were close enough. GPS is nice but wholly unnecessary; good charts, a good compass, and good pair of binoculars are all you need for coastal navigation; add GREAT DR and/or a sextant, watch, almanac, and tables for offshore....
Scott Berg WA0LSS
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