Don't throw away your paper charts! - GPS failings to come

[Luckless]

If you have a sensitive enough receiver, then you can pick up the back wash signal from another receiver. That is, the field echo produced by a receiver picking up the original field.

With the right gear, you can pin point a GPS unit a few miles away. It is funny as such technology was actually far easier and more reliable around the Second World War than it is today. Why? Because now we have massive signal pollution, and it has become harder and harder to detect against the massive amounts of interference.

[Frosty]

Is it April the 1st today?

[Luckless]

It is all based on EM fields.
What is a transmitter? Current run through a wire to produce and EM field.

What is a receiver? Current running through a wire, produced by an EM field.

When you pick up a signal, you also produce a slight back echo, a greatly reduced, and slightly distorted signal of what you have picked up. With the right gear you can detect this second signal and track it, but because it is so weak, you have to be fairly close to pick it up, and the original signal has to be fairly powerful to have much chance of detecting it easily.

[Zed]

Originally Posted by Luckless

If you have a sensitive enough receiver, then you can pick up the back wash signal from another receiver. That is, the field echo produced by a receiver picking up the original field.

Yeah OK I buy that if you are the only guy in the desert with a GPS unit and they are just over the ridge looking for you, but from space and, as you say, from among 10's, 100's... 1000's of units operating in any given area where none of them has a unique signature. Nah... where is my tinfoil hat!... I can't say I'm signing on for that one!

[mydauphin]

Originally Posted by Zed

Yeah OK I buy that if you are the only guy in the desert with a GPS unit and they are just over the ridge looking for you, but from space and, as you say, from among 10's, 100's... 1000's of units operating in any given area where none of them has a unique signature. Nah... where is my tinfoil hat!... I can't say I'm signing on for that one!

It can be done, that is why other countries want to develop their own systems. The US controls gps, and unfortunately is very dependent on it. It is a great system but it was not meant to survive an attack. As a matter a fact it is easy to knock it out at a local level. Of course you might get an HARM missile sent your way .... Yes, it is much easier to jam than track.

I can't tell you much more but there is much more. The NSA and other agencies has capabilities that go beyond what you think. They didn't spend billions to guess at things. They just don't share info. They know where a VHF receiver is without you transmitting, that is old technology, the German developed it during WWII.

[marshmat]

I hope I'm not unique here in not owning a GPS. For what I do (inland lakes, rivers and canals), the only effective means of navigation is a chart and your eyes. (On many of these lakes, there aren't even charts.) The next boat will have one, but more for updating the DSC VHF than as a primary navigation system.

LORAN is still going strong here in Canada; the LORAN charts are still available and the Coast Guard publishes the ASF corrections in the Radio Aids every year. So many commercial ships and fishing boats still use it that they can't shut it down yet. The receivers are hard to find, though.

Tracking down all sorts of radio devices from a distance is quite possible with the right equipment. I recall hearing that this was one of the major flaws of the USCG's Project Deepwater retrofits- a heap of improperly shielded wiring in what should have been high-security comm systems ended up radiating so much EM noise that you could intercept supposedly encrypted communications with nothing more than a directional antenna and a properly tuned receiver.

The selective availability feature of the NAVSTAR GPS system has been disabled since 2000, but the US military reserves the right to turn it back on at any time (although many other departments are strongly opposed to any attempt to do so). When active, SA introduces small distortions in the timing of some of the GPS signals according to a complex cryptographic algorithm, seeded by a numeric key that changes daily. Having a military receiver is not enough to eliminate the SA distortion; you also need that day's secret key. (The US government says that all new NAVSTAR GPS satellites will not be fitted with SA hardware.)

Alternative satellite navigation systems:
- Russia's GLONASS system is supposedly in the process of being restored to full operation, with some help from India.
- China is building a global system, COMPASS, expected to be operational around 2015.
- The EU's Galileo system is scheduled for worldwide coverage by 2013, with sub-metre resolution and no selective availability system.

There have been rumours of combined NAVSTAR/Galileo receivers in development that will be able to take signals from either or both systems. GPS III and Galileo are, at present, expected to be interoperable.

[Vettmech]

I say people driving around in cars dont need GPS so take them away. Too bad get a map, pull the blueberry out of your ear and blackberry out of your ass and learn how to read billboards road signs. Truckdrivers need GPS for an effiecency issue, boaters and aircraft for a safety issue. But those lost people driving around in circles because they will never know where they are anyways... they dont need GPS ..To them I say plan your car trip before yu leave the house...know where you are going...if you want to be "hightech" try "map quest" It works pretty good half the time...the other half of the time you will be lost and probably feeling like the good old days have returned.
my opinion thats all

[mydauphin]

I think a better question might be what are possible substitutes. Is Loran still around? What about using VHF radio direction beacons?... Are all these gone?

Is anyone making a intertial navigation system that wil fit in smaller boat?

[BeauVrolyk]

I have been reading through this forum for a while and I'm really confused. What's the deal? Why does anyone care what another person uses for navigations. Why does anyone say something like "pull the ___ out of your ass..." ?? What motivates that??

There may be some way that some government might "track" someone with a radio or GPS, but why does this elicit all this anger and all this bitching??

I must admit I am baffled. I had thought that sailors would use whatever technology was available and when it stopped working they'd move on. What's with this anger???

You guys need to go sailing more and spend less time on the net.

Just my opinion,

Beau

[BeauVrolyk]

Originally Posted by mydauphin

I think a better question might be what are possible substitutes. Is Loran still around? What about using VHF radio direction beacons?... Are all these gone?

Is anyone making a intertial navigation system that wil fit in smaller boat?

VHF works fine, you just need a chart that shows where the radio transmitters are located.

B

DGPS does send a signal.

[mydauphin]

Originally Posted by BeauVrolyk

I have been reading through this forum for a while and I'm really confused. What's the deal? Why does anyone care what another person uses for navigations. Why does anyone say something like "pull the ___ out of your ass..." ?? What motivates that??

There may be some way that some government might "track" someone with a radio or GPS, but why does this elicit all this anger and all this bitching??

I must admit I am baffled. I had thought that sailors would use whatever technology was available and when it stopped working they'd move on. What's with this anger???

You guys need to go sailing more and spend less time on the net.

Just my opinion,

Beau

Real Boaters are always looking for options in price, redundancy and just in case of nuclear or other disaster a fall back position. Just the same reasons I have flotation suits, life vest, several vhf, 3 gps, a sextant, etc...

Yes. I wish could spend more time boating and less on computer...

[BeauVrolyk]

Originally Posted by mydauphin

Real Boaters are always looking for options in price, redundancy and just in case of nuclear or other disaster a fall back position. Just the same reasons I have flotation suits, life vest, several vhf, 3 gps, a sextant, etc...

Yes. I wish could spend more time boating and less on computer...

Yup, one of our worst traits. When I got back from cruising last time I realized that I had hauled TWO sets of sight reduction tables along for 10,000 miles, along with TWO sextants, and never touched any of it. I really do think one spare would have been enough, as I had two GPS units.

We Americans in particular are far too concerned about dramatic disasters, like nuclear war etc... that you mentioned, and don't spend near enough time on the stuff that is most likely to happen.

Number of sailors lost at sea due to a failure of the GPS system - zero so far as I know.

Number of sailors lost at sea due to their own lack of practice sailing and the preparation of their boat - quite a large number.

We're are, as a group, talking about the wrong stuff - if one were actually worried about being safer.

Just my 2 cents.

[yipster]

Originally Posted by BeauVrolyk

"Anything worth doing is worth doing to excess"

sure you'r rite yet in this case i felt like mentioning your bottom line

[BeauVrolyk]

Originally Posted by yipster

sure you'r rite yet in this case i felt like mentioning your bottom line

Point taken B-))