Positions is the 3rd Decimal necessary?

[B27]

They use the transits and do it by eye. All explained very well in this video.

Of course they do.
The senile service has no secrets from youtube...
Or maybe not?

 

[Sandy]

Raises an interesting question. As we know, mobile phones and Marine GNSS likely have GPS, GLONASS, Beidou and Galeleio combined on the same chip. That must result in a more accurate, faster and reliable fix than any individual network.

One of the RIN talks I attended on GPS hinted at there is a lot more to military GPS than civilian.

If you recall when we left the EU we were locked out some of the Galileo secret stuff.

 

[lustyd]

Raises an interesting question. As we know, mobile phones and Marine GNSS likely have GPS, GLONASS, Beidou and Galeleio combined on the same chip. That must result in a more accurate, faster and reliable fix than any individual network.

There's no permanant SA any more.

So... Does a NATO Aircraft Carrier use Russian and Chinese GNSS in addition to GPS and Galileo? ...and if, as I suspect, not, is my phone more accurate than the GNSS on a Warship?

I guess the question is, is very clever/sensitive Antenna/Hardware on one or two networks more effective than multiple networks combined?

Military GPS has access to more data in the code and also additional frequencies which AIUI help correct for atmospheric effects etc.

No, there's no SA but there is an additional encrypted signal giving greater accuracy (and trust!) available to military and paying commercial customers. Multi-band is now available to consumers, I have it in my wrist watch from Garmin and yes, it produces a far better fix either in atmospheric conditions or canyon conditions. I believe additional frequencies are available over and above what we get as civilians.
As I understand it, multi-GNSS fixes aren't as simple as just adding more satellites, even in consumer gear. I suspect on military vessels they will have the ability to consume all systems either independently or in aggregate, but UK ships would probably stick to GPS and Galileo for obvious reasons.
In good conditions, especially at sea, a single GNSS will produce an identical fix to multiple GNSS. I've tested this one and the results bear this out. At sea you'll pretty well always have enough satelites from any one constellation to get the best fix, and using multi-band it'll be even better. In very bad conditions, and especially in canyon conditions where only a portion of sky is visible, then combining fixes might give better results since more satellites and signals can be seen. The algorithms for combining vary, sometimes combining satellites and sometimes combining fixes. From what I know of military and safety critical systems I imagine they would go with the simpler approach of combining fixes selectively.

Opencpn can show the AIS target actual size

As do most plotters, my B&G units certainly do.

 

[lustyd]

If you recall when we left the EU we were locked out some of the Galileo secret stuff.

Oh turns out we don't use Galileo for military at all, that seems like an own goal after over £1.2Bn invested! Let's hope the US election goes well
UK involvement in the EU Space Programme

 

[Sandy]

Oh turns out we don't use Galileo for military at all, that seems like an own goal after over £1.2Bn invested! Let's hope the US election goes well
UK involvement in the EU Space Programme

The gift that keeps on giving.