I don't understand this article. If the GPS signals are jammed, what purpose does it serve to have an atomic clock on board your plane? You still need accurate signals with time data to measure against.
Am I missing something?
Am I missing something?
Now suppose someone is spoofing your GNSS signals, it's pretty hard to replace a constellation with another one whilst maintaining time consistency for you. One way to detect spoofing is comparing what a local clock is saying to whatever the GNSS is giving. A local, unfudgeable, stable, accurate clock is a good reference for this.
Assume you want it even super accurate.
Great, 3k for an SA65 https://www.microchip.com/en-us/products/clock-and-timing/co...
Holdover would be fine for even a very long flight.
Hell, even a good rubidium oscillator doing 1PPS will stay within 200 nanoseconds over 12 hours.
If you are trying to do navigation while jammed, none of these help you.
You still need good reckoning, which is the hard part
We done solved the clock problem enough already :)
I'm happy to learn this is not the case for every good oscillator. TIL.
But when they speaking about near zero temperatures, looks like they talking about something like Rydberg atoms - extremely sensitive matter, which could be considered as nuclear scale gyroscopes, or quantum gyroscopes, or read more about quantum accelerometer.
And current inertial navigation could be used to calculate relative coordinates like automobile odometer, but from integrating accelerations. But classic accelerometer is just not fine enough, and at this place appear quantum accelerometer and quantum gyroscope.
And I agree, article is terrible. I don't know why they use so abstract language, when could just say, navy already tested quantum navigation.
Planes flights are much more lengthy than rockets - I think, typical ~40 minutes or more (most long I hear 20 hours), so INS could integrate huge mistake.
And civilian education now close to forgot star navigation, but navy still train people to navigate with stars and learn Morse code.
Detect semi-surfaced submarine at night is really hard, if don't have intelligence data that it will surface on some non-random position.
From experience of Ukrainian war, my country have success with eliminating surface military ships, because have constantly monitoring their moves with satellites, but I cannot remember any case when semi-surfaced submarine was hit.
At a guess, Ukraine probably can't deploy naval assets with powerful radar close enough to where Russian subs are operating. But an adversary with a more powerful navy might be able to.
In these words you hit bull eye.
During WWII, submarines was just very special type of boat. You could check wikipedia about German u-boats - exist about TEN subtypes, from which only latest types have really significant underwater range, but all others was extremely limited in underwater activity.
But, surface ships of that time was even more limited, many could not achieve even half of surface speed of u-boat, so become easy prey.
But if you will try to find some artificial object on sea surface, that is really hard question. Just because sea is huge, so you need to check extremely large space in short time.
Radars are better to spot artificial object on sea surface than visual, just because radar easier to automate. But nothing more. Radar is also have problem of square distance, very similar to visual. So, as it is hard to spot partially surfaced submarine visually, it also hard to spot such sub with radar, because much less part will be on surface, so radar will have much less signal to detect.
Periscope size is nearly undetectable on surface, if it used carefully, just outside detection range of radar.
So, to conclude, Ukraine problem is, we cannot detect partially surfaced submarines on open sea, but they could fire missiles. Fortunately, Russians have very few submarines on Black sea, and after they was hit at harbors, their usage become very limited.
Agree with most of what you said, but U-boats generally had top surface speeds under 20 knots and were thus slower on the surface than most naval vessels of the time. They could certainly move faster than most convoys, but they couldn’t outrun pursuing destroyers or corvettes.
That is point. I'm not agree about most, but will be agree if you say about many.
> they couldn’t outrun pursuing destroyers or corvettes
But problem was, navy have so huge deficit of ships, so some convoys was run without naval support.
Sure, if all convoys was supported with fastest ships with best commands, u-boats will be no problem anymore, and as I understand, once this was happen.
Ballistic missile submarines are a completely different story. They aren't chasing anyone. Their entire goal is to be unpredictable and stay hidden, so if there's anyone with a radar around they are just going to keep quiet and move somewhere else.
Finding a sub prowling a shipping route is quite doable. Finding a sub in the middle of the Pacific Ocean? Not a chance.
When Ukraine got enough weapons to force Russian ships to stay at distance, situation changed dramatically, so export was unblocked.
I think, very similar things happen during WWII.
This is not about only submarines, this is about superiority.
They are, if you can get your radar on top of the periscope, e.g. mounted on a plane that flies above the sea.
https://en.wikipedia.org/wiki/LORAN
Before LORAN, used radio beacon navigation and star navigation (from Newton time), and good human navigator could achieve about 50km precision.
You could easy see signs of star navigation on good preserved old planes - they all have some sort of fully glass dome, or blister, to provide good near semi-sphere view. And sure, all those before-GPS era planes have separate navigator job position, sometimes shared with mechanic.
https://www.reddit.com/r/WWIIplanes/comments/59xfkz/pby_wais...
You could ask, how planes could fly with 50km precision? Answer is easy - at all plane routes built ground structures easy seen from air and last mile navigation become essentially visual flight, nothing more, nothing less.
On some places ground navigation structures preserved now, for examples:
https://en.wikipedia.org/wiki/Airway_beacon
https://en.wikipedia.org/wiki/Transcontinental_Airway_System
Perhaps in general aviation, but I can't think of any modern commercial airliner without an INS via the air data inertial reference unit.
The INS unit is separate and often has its own set of gyros and has to be connected as separate input to FMS or other navigational computers, same as connecting GPSes or other radio nav components.
For example the current model of popular Universal Avionics UNS1 series of NCU (navigational computer part of FMS) come with built-in augmented GPS receiversz but do not mention INS functionality at all even in extended models. Don't have access to manuals at the moment, but I'd expect to see INS as optional to connect over one of the external connectors on the MCU, as it was on the older models without integrated GPS
I had assumed that the ADIRU’s inertial reference data from its gyroscopes and accelerometers would feed into the FMS to provide INS capabilities in case GNSS was unavailable.
GNSS becoming "reasonably easy" to add meant that there was way less push to integrate INS after early use in transoceanic flights
Daily rotation is 360°/23.934h, so 0,25°/min, which is acutally quite a lot if you want to use a device to track your orientation.
Better are quantum navigation systems, using quantum matter as sensor, but they was too bulky to be used on planes, only last years appear more compact systems, sized like common home fridge.
Minor FYI: the earth rotates daily, but it revolves around the sun yearly.
revolve /rĭ-vŏlv′/
intransitive verb
To orbit a central point.
"The planets revolve around the sun."This is the principle gyrocompasses work on; when left running for a while they align themselves with true north; the axis of Earths rotation.