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US Navy’s new unhackable GPS alternative.
https://www.popularmechanics.com/mil...al-navigation/
The Navy’s Automated Celestial Navigation System would replace manual shipboard measurements with something more accurate, while Special Operations Command experts are developing a handheld device for commandos. Both pieces of tech are aiming for GPS-level precision. “The best accuracy for celestial navigation with certainty is within a couple of meters,” says Benjamin Lane of the Advanced Position, Navigation & Timing Instrumentation unit at Draper Laboratory in Cambridge, Massachusetts. “In practice, we are within a factor of a few of that.” SPOOFING, HACKING, OR DESTROYING THE STARS? NOT HAPPENING. The new systems use infrared rather than visible light for locating stars, allowing daytime navigation. The stars shine just as brightly in the day sky as they do at night, but their light is masked by sunlight scattered by the atmosphere. The scattering is strongest at short wavelengths. If you’ve ever glimpsed the sky, you know that blue light is scattered the most. But glimpse that same sky with a filter that allows only infrared light, and the sky suddenly becomes dark—and filled with stars. “Twenty years ago, these infrared sensors were quite expensive,” says George Kaplan, a consultant for the U.S. Naval Observatory. “Since then, costs have been going down and the pixel count is getting higher.” The rise of celestial navigation is also helped along with another piece of tech called a “phased optical array,” which does not need to be pointed at a section of the sky like a telescope does. This type of sensor does not have a lens to focus, but instead has an array of tiny meta-material antennas to capture light. A processing unit can phase-shift the signal from each antenna to achieve the same effect as a movable, focusing lens. |
Every thing old is new again, SR-71 used a star tracker as its prime means of navigation.
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Originally Posted by megan
(Post 11038876)
Every thing old is new again, SR-71 used a star tracker as its prime means of navigation.
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And with several civil alternatives, the Pentagon's GPS decommissioning is in the future
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Originally Posted by flighthappens
(Post 11038879)
Depending on who you believe, 3 blokes did that a little over 2000 years ago!
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How BIG is the device?
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This is what the SR-71 had.
https://timeandnavigation.si.edu/mul...igation-system 90 Meters precision at Mach 3+ is not that bad. This device is said to have inspired the "character" R2D2 from Star Wars. |
Defeated by cloud though, que the enemy developing weather control.
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Clouds at FL850?
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Originally Posted by Less Hair
(Post 11039175)
Clouds at FL850?
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Clouds at FL850? |
Originally Posted by Less Hair
(Post 11039008)
This is what the SR-71 had.
https://timeandnavigation.si.edu/mul...igation-system 90 Meters precision at Mach 3+ is not that bad. This device is said to have inspired the "character" R2D2 from Star Wars. Thanks - needs a bit of work to fit on my wrist I think........... but then the original GPS units wouldn't fit on my kitchen table |
It is using stars. Celestial navigation. Data fed into the aircraft nav system. The SR-71 was meant to be used for Post-SIOP reconnaissance when no working satellite or nav-emitter would exist anymore.
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US Army I think still use the DAGR which has anti-spoofing technology, they did a while back anyhow when I worked for them, although have not ever heard of a case of spoofing a GPS in theatre - nobody I spoke to about it seemed too worried, and many folk carried/wore a consumer Foretrex 401, which seemed to do the job at least as well (using MGRS setting, civilian satellites, and for 1/10th of the price).
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Royal Navy still teaches the use of a sextant. The US Navy has only in recent years re-introduced teaching it.
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Be nice to get a system that alos doesn't lose accuracy in the event of a major solar storm heating the ionosphere and changing the signal path for the GPS signals.
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Originally Posted by flash8
(Post 11039347)
US Army I think still use the DAGR which has anti-spoofing technology, they did a while back anyhow when I worked for them, although have not ever heard of a case of spoofing a GPS in theatre - nobody I spoke to about it seemed too worried, and many folk carried/wore a consumer Foretrex 401, which seemed to do the job at least as well (using MGRS setting, civilian satellites, and for 1/10th of the price).
https://www.voanews.com/silicon-vall...gps-disruption https://www.defensenews.com/global/e...ng-nato-drill/ |
Salute!
Do not diss those folks at Draper and other places that developed and fielded nav gear that used the stars to help their inertial systems. I worked with the Draper folks and the USN to develop ways to check on the guidance systems of the Trident missiles. Parts were hard to get because many vendors had gone outta business. Meanwhile, the subs were cruising about with all those missiles and the USN wanted to make sure their guidance systems still worked as advertised. Our company was hired to help with a test program that verified the specified accuracy of the missile's guidance system. . During the Reagan years, many documents about the Trident missile were put on the street. Was like us "catch us if you can" challenge. The basics were well known, but nobody else could come close to making such a system work. Lemme put this into perspective...... the sub could launch a missile from 3,000 or 4,000 miles away and it would hit inside a futbol field. The thing that amazed me was the guidance unit had an optical component that was programmed to look for a star during mid-flight and correct the inertial system. A series of holes in the gimbal housings would line up and find the star and then correct the inertial and then.... Remember, these folks were the ones that developed and fielded the Apollo guidance units, and we know what they did. I like the idea of using stars versus satellites. A bad guy could seriously wreck havok on the sats, but how could they move the stars? I have always wondered about depending too much on the sats. And I helped with the original JDAM mission planning efforts. Gums sends... |
The U.K. has been working on a “quantum compass” (far more accurate INAS) for years.
First example is large and only suitable for boats (new Trident subs?). But compare the size of the very first INAS unit (USS Nautilus) and recent commercial INAS units..... https://www.imperial.ac.uk/news/1889...ation-without/ https://www.zdnet.com/article/gps-ki...ee-navigation/ https://cimg8.ibsrv.net/gimg/pprune....795a05282.jpeg https://insideunmannedsystems.com/wo...now-available/ https://cimg2.ibsrv.net/gimg/pprune....cc2bfc02c.jpeg |
Originally Posted by Less Hair
(Post 11039175)
Clouds at FL850?
https://weather.com/science/weather-...ates-june-2019 |
Seen them a few times - always worth looking after dusk or before dawn if it's really clear - quite ethereal
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IIRC, an F84 with some sort of Astro/sun/star tracker under a glass dome in the nose crossed the Atlantic decades ago.
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First electro-optical astro-inertial system was developed for the Northrop SM-62 Snark, starting in the late 1940s. Airborne star acquisition and tracking was demonstrated around 1952. Snark of course was cancelled but Northrop built the Blackbird's system and that for the B-2. Kollsman developed an astro-tracker integrated into the B-58's NAS, and the Skybolt missile had one built into the pylon to update the INS immediately before launch. There is a Snark system in the Udvar-Hazy.
https://cimg9.ibsrv.net/gimg/pprune....6dff23c2f6.jpg |
Astrotrackers
Originally Posted by LowObservable
(Post 11040563)
First electro-optical astro-inertial system was developed for the Northrop SM-62 Snark, starting in the late 1940s. Airborne star acquisition and tracking was demonstrated around 1952. Snark of course was cancelled but Northrop built the Blackbird's system and that for the B-2. Kollsman developed an astro-tracker integrated into the B-58's NAS, and the Skybolt missile had one built into the pylon to update the INS immediately before launch. There is a Snark system in the Udvar-Hazy.
https://cimg9.ibsrv.net/gimg/pprune....6dff23c2f6.jpg Perhaps advances in inertial platforms and solid state electronics has enabled improved accuracy, reliability and maintenance costs. |
Salute!
Where have you flown recently, Global? The inertial platforms since the late 70's have demonstrated a mile per hour drift on high performance fighters that introduce many more gees and turn rates and... than your basic 747 cruising level for 10 hours. So a good position update can really help things. The Trident system had super inertial sensors, but the big thing was the mid course position update using a star. The clever Draper folks used that for basic position, but also to calibrate the inertial. The system did not need constant updates or signals from a GPS sat. If the Navy or Draper says a system can find a star in broad daylight, I tend to believe them. I agree that heavy clouds and such are a biggie, so a system they are talking about should not be the most inportant nav system for ultimate mission success. One thing you can do nowadays that was not possible 50 years ago is reset your strapdown or RLG inertial at last known position, then apply corrections to the inertial sensors. I like the idea of a system that is independent of the sats. I might also add that one platform I flew long ago used a doppler system to "help" the inertial. There may be fairly simple sensors to help a good inertial provide very accurate positional and body rates. Gums sends... |
If the Navy or Draper says a system can find a star in broad daylight, I tend to believe them |
Salute!
Thank you, Megan. I only know two Blackbird pilots, so I cannot confirm their astrotracking doofer. The "newer" systems I worked with a bit over twenty years ago watered my eyes. The strapdown inertial for AMRAAM aligned in seconds and could get you within a hundred yards in one minute of manuevering flight. I really like the idea of using something beside the GPS stuff. Gums sends... |
The FB-111 had an astrotracker.
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"The strapdown inertial for AMRAAM aligned in seconds and could get you within a hundred yards in one minute of manuevering flight."
What was the drift over a few hours GUMS? In my experience the advantage of GPS is no drift, nor worry about being able to see the stars, constant updates |
Talking to a Habu who was giving a talk on the jet, I asked how good the astrotracker was at aligning at Mildenhall under cloudy skies with East Anglian low stratus off the North Sea....
"Not very!" was his answer! But once R2D2 could sniff out the stars up at FL nosebleed even at Mach lots, it was VERY good! |
Salute!
Yeah, Astur, prolly a nm per hour or less. Of course, it only had to get the missile within x yards after 30 seconds, and it was being used for a cluster bomb guidance system on a new system. The reason I mentioned it was the technology advancements since the first large scale use of inertials and then the development of strapdown systems. The alignment times decreased by an order of magnitude. So way I see it is tonight I could lay my iPhone down next to me at the campsite and it would look at the stars and compare with my Starmap program and then compute. I just have bad waves about a major conflict where the other side could disable or degrade the existing GPS system enough to cause big problems. Gums sends... |
it would look at the stars and compare with my Starmap program and then compute. I agree that reliance on an active transmission is inherently a bad idea. |
Not sure if this all ties just into OneWeb or also the US PNT systems*……
http://bidstats.uk/tenders/2021/W13/747897237 https://www.gov.uk/guidance/space-based-pnt-programme https://www.cityam.com/oneweb-in-tal...-to-rival-gps/ * https://www.c4isrnet.com/battlefield...-of-september/ * https://www.militaryaerospace.com/se...natives-to-gps |
"the alignment times decreased by an order of magnitude. ""
I remember it well - and the nagging fear that the drift on YOUR unit was one of the outliers on the curve............ Of course the old methods were'nt foolproof. I know of someone who set off to cut a 50 km path through a rain forest and dialed in the magnetic deviation on their survey gear on the "wrong" side". Only found out when they arrived, several weeks later, on a river 50+ kms away - several kms off plan........... |
Of course the old methods were'nt foolproof. I know of someone who set off to cut a 50 km path through a rain forest and dialed in the magnetic deviation on their survey gear on the "wrong" side". Only found out when they arrived, several weeks later, on a river 50+ kms away - several kms off plan........... |
I've worked in West Irian and Kalimantan and that story doesn't surprise me at all - if you live in those god-forsaken forests you must develop skills us incomers have no idea of..................
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In Absence of GPS.....eLoran To The Rescue?
In this month's US Naval Institute monthly magazine is an article about the need for a ground based replacement for Space based GPS navigation and Time Signalling in the event of War breaking out.
The Russian doctrine assumes all Space based systems shall be made Combat In-effective and are taking measures to provide backup systems. Traditionally, the US Coast Guard provides navigational systems for the US DOD and ran the legacy LORAN-C system for Fifty Two Years before ending that program in 2010. There is a proposal for the creation of a new eLORAN system to be operated by the USCG among requirements that it be deployable to combat areas when needed to replace losses of GPS coverage. The article reports the Russians have used GPS disruption tactics in Syria and the US Military has also done similar actions at various times. If Western Militairs, including the RAF and RN along with the US Forces were to lose all use of GPS Navigation services and its knock on uses.....are we prepared for that contingency? Is eLORAN needed? Are the Russians and Chinese ahead of the West as stated in the Proceedings Article? |
Originally Posted by SASless
(Post 11054706)
In this month's US Naval Institute monthly magazine is an article about the need for a ground based replacement for Space based GPS navigation and Time Signalling in the event of War breaking out.
The Russian doctrine assumes all Space based systems shall be made Combat In-effective and are taking measures to provide backup systems. Traditionally, the US Coast Guard provides navigational systems for the US DOD and ran the legacy LORAN-C system for Fifty Two Years before ending that program in 2010. There is a proposal for the creation of a new eLORAN system to be operated by the USCG among requirements that it be deployable to combat areas when needed to replace losses of GPS coverage. The article reports the Russians have used GPS disruption tactics in Syria and the US Military has also done similar actions at various times. If Western Militairs, including the RAF and RN along with the US Forces were to lose all use of GPS Navigation services and its knock on uses.....are we prepared for that contingency? Is eLORAN needed? Are the Russians and Chinese ahead of the West as stated in the Proceedings Article? Where is the advantage? |
Along with eLORAN.....might we see a return of something called eDECCA?
or....CONSOL Radio Systems? |
Youngsters these days have no map reading skills. They rely on GPS to get where they are going, whether it is a satnav or more likely, their phone.
Admittedly they are very good at finding places using them, but going back to basics might prove a challenge for most of them. |
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