Navigation

[capnsensible]

Exactly. But the discussion and original link was specifically about eLoran, which is a radio wave solution with all of the same issues as GNSS

OK how about this?

For IATA director general Willie Walsh, "we need coordinated collection and sharing of GNSS safety data; universal procedural GNSS incident guidance from aircraft manufacturers; a commitment from States to retain traditional navigation systems as backup in cases where GNSS are spoofed or jammed."

Those systems include beacons or transmitters on the ground emitting radio signals that help planes to triangulate their position.

So IATA are advocating a land based alternative.

For those who remember DECCA, hands up all those that used to call it Desmond?

 

[billskip]

Oh, I took some people out for a brisk sail for a couple of hours. No gps was used during this exercise and we survived.

Mind you, slight overcast fab viz and scorchio. Makes sailing a bit easier.

Damn, and there was I thinking I was in control

 

[lustyd]

So IATA are advocating a land based alternative.

But those will also be radio based and subject to the same attacks. We're back to asking what problem they're solving.

Unfortunately the aerospace industry (among others) has a habit of using maths rather than common sense to mitigate risk. The idea is that a second system will halve the risk because that's how risk maths works. If you ignore that both systems are likely going to fail for the same reason at the same time then it makes sense. I had to do such things for air traffic systems at one point and unless you understand the failure modes it's a pointless exercise.

 

[oldmanofthehills]

I think for a yacht the problem if it exists, os trivial. Provided GPS is live then any spoofing would likely to be so short lived before countermeasures that the boat would be only a few miles further before correct info used. Might be very different for an aircraft or missile as seconds could then count

And i think it unlikely that anyone would spoof the position of say the rocks approaching LAberwrach just I approached on a cloudy night

 

[rogerthebodger]

If any new form of navigation system will not use the radio spectrum if that is what you are saying, there must be a system on board the tracks the movement of my boat from its start position.

This seems to be something to inertial navigation system on older aircraft that was replaced by GPS.

That would be fine for missiles where accuracy is imperative but for me using GPS to get to close to my point of destination and than to use Mk1 eyeball to navigate into the harbour and on to my mooring.

If the Mk1 eyeball cannot be used due to fog, you can just wait until Mk1 eyeball can be used

This seems to me more scaremongering

 

[capnsensible]

Inertial navigation systems have been around since the 1950's. But were subject to drift over time.

Question. From what I'm now reading, it's relatively easy to mess about with the very weak gps signals, especially the time bit at the heart of it.

Jamming radio waves, from the little I remember from a while back, require much more sophisticated machines close to the transmitter? Well closer than a satellite in orbit.

 

[lustyd]

Inertial navigation systems have been around since the 1950's. But were subject to drift over time.

Question. From what I'm now reading, it's relatively easy to mess about with the very weak gps signals, especially the time bit at the heart of it.

Jamming radio waves, from the little I remember from a while back, require much more sophisticated machines close to the transmitter? Well closer than a satellite in orbit.

You don't have to "jam" a GNSS signal because it's very weak, you just have to overpower it. Because the ground station is so much closer it's trivial to overpower the signal from space and you don't need to be anywhere near the transmitter unless someone had shielded from some directions. Planes could shield 180 degrees below the plane, for instance. This is one place where eLoran has an advantage since the ground station may be 100W so you'd need a lot of either power or directionality to overpower it. Unfortunately either approach is easy enough for bad actors. GNSS suffers a bit more because morons can buy a kit on Ebay for $20 to achieve the same.

 

[rogerthebodger]

You don't have to "jam" a GNSS signal because it's very weak, you just have to overpower it. Because the ground station is so much closer it's trivial to overpower the signal from space and you don't need to be anywhere near the transmitter unless someone had shielded from some directions. Planes could shield 180 degrees below the plane, for instance. This is one place where eLoran has an advantage since the ground station may be 100W so you'd need a lot of either power or directionality to overpower it. Unfortunately either approach is easy enough for bad actors. GNSS suffers a bit more because morons can buy a kit on Ebay for $20 to achieve the same.

From what I remember GPS is line of site so the signal would need to be quite close to the receiver my GPS device to overpower my receiver.

Not easy when I am out at sea close to land maybe but that when Mk1 eyeball comes in

 

[capnsensible]

You don't have to "jam" a GNSS signal because it's very weak, you just have to overpower it. Because the ground station is so much closer it's trivial to overpower the signal from space and you don't need to be anywhere near the transmitter unless someone had shielded from some directions. Planes could shield 180 degrees below the plane, for instance. This is one place where eLoran has an advantage since the ground station may be 100W so you'd need a lot of either power or directionality to overpower it. Unfortunately either approach is easy enough for bad actors. GNSS suffers a bit more because morons can buy a kit on Ebay for $20 to achieve the same.

OK get that. But it's certainly a big game of measure/ countermeasure by the actors on the world stage....

 

[Buck Turgidson]

IRS is still very much alive and well and you will find 2 or 3 on every commercial aircraft. Normally the Honeywell micro laser ref which is the industry standard. The problem is they still drift due to maths and the standard architecture for the last 20 years is to continuously update them with yes you guessed it GNSS position