51–60 of 243 posts
Whats really sad for aviation is there was already an extensive network of ground based navaids. As GPS has proliferated, they've slowly been decommissioned as they age out to save on cost. I'm specifically referring to VORs which provide azimuth and range to station. GPS is fantastic and as a primary source everyone loves the benefits it brings. However, in a century of aviation, everyone has kinda sorted out that y…
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VOR is extremely short range and requires an extraordinary number of transmitters to provide any volume of coverage. Additionally it cannot provide coverage over oceanic areas. We USED TO have a nearly global long-range land based navigation system called LORAN, which only required one master station and a few remote stations to provide continent-scale coverage. But it was decommissioned in a cost savings move after…
On VOR: It's also a PITA to use, and for inexperienced people, or someone who rarely uses it, they can confuse flying towards and away from the station.
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On VOR: It's also a PITA to use, and for inexperienced people, or someone who rarely uses it, they can confuse flying towards and away from the station.
If you are a general aviation goober like me, flying a 1960's propeller airplane, sure, that is true. However, in a modern commercial aircraft, all position sources including VOR-DMEs, GPS, and IRS are cross-compared by the flight management system and turned into a latitude, longitude, and circular error of probability. There is no TO/FROM flag to worry about in a 777, and no reverse sensing on the back side of a lo…
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On VOR: It's also a PITA to use, and for inexperienced people, or someone who rarely uses it, they can confuse flying towards and away from the station.
Time was, if you didn't understand how to use VORs, you couldn't really fly. We used them as primary en route nav, as well as for approaches, for many decades. As a CFI I think most of the confusion around VORs these days comes down to poor or inadequate training.
No worries in the long run; similar to the "energy crisis," new inventions and technology will mitigate the issue: Quantum Compass: https://en.wikipedia.org/wiki/Quantum_compass Also see: https://www.sandboxaq.com/post/sandboxaq-and-acubed-achieve-...
I'm sorry, but a multi-kilogram (at a guess), five-figure-priced (at a conservative guess) device with kilometer-scale error (per their actual press release) is not a substitute for a GPS. And you probably can't improve on many of those specs no matter how much "inventing" you do. There's just not that much information in magnetic fields, especially if you don't spend an infeasible amount of money on keeping maps up…
My "no worries" comment was a bit tongue-in-cheek. Who knows how far the tech will go or how cheap it will get.
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Not really. It uses 2MHz band, with the wavelength of around 160m. This means that it's easy to receive via a ferrite bar antenna but hard to transmit. You need an antenna of at least around 40m size for that to be efficient.
Even a 160m guy-wire tower is cheap. 40m.. my friend installed 32m one just to have better internets, not exactly out of pocket cash, but nothing compared to say swapping a car.
Meanwhile, GPS can be jammed or spoofed with a briefcase-sized device for a couple of kilometers around you.
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I would be curious on and interested in guidance from a GNSS expert on what the risk profile is when you're using jam resistant frequencies with a multi GNSS constellation chipset (GPS, Galileo, BeiDou), WAAS (GNSS corrections received via satellite), and when close enough to airports that support it, LAAS (GNSS corrections broadcast from airports). Follow up questions would be what countermeasures are available to b…
Because GPS and other GNSS have only a very weak signal strength there are no jam resistant frequencies, you can jam them all very efficiently, or you can jam them very efficiently in selective way (jam BeiDou, but not GPS). GPS was jammed even as early as Iraq war. "Coalition troops also got a glimpse of GPS’s greatest weakness during the Gulf War. Iraqi forces installed jammers, for example, on top of landmarks suc…
With all the man made EM emitters in the world, it seems like passively matching what can be “seen” to a database of known emitters (with signal profiles and locations) could be extremely accurate where people are (less helpful on the open ocean and remote wilderness). Similar to what’s already being done with Wi-Fi and Bluetooth but general purpose, perhaps?
Whats really sad for aviation is there was already an extensive network of ground based navaids. As GPS has proliferated, they've slowly been decommissioned as they age out to save on cost. I'm specifically referring to VORs which provide azimuth and range to station. GPS is fantastic and as a primary source everyone loves the benefits it brings. However, in a century of aviation, everyone has kinda sorted out that y…
Seems like we'd need a modern version that's less susceptible to jamming, otherwise aren't we just replacing one jammable service with another?
Received GNSS power is on the order of -130dBm (10e-16 W) - you can jam that with a 1W terrestrial source for hundreds of meters around. Way more if you're willing to scale the power from car USB power levels to bigger grid-connected supplies.
LORAN, from my quick googling, looks to be about 6-7 orders of magnitude higher received power.
Earlier quoted context omitted.
Because GPS and other GNSS have only a very weak signal strength there are no jam resistant frequencies, you can jam them all very efficiently, or you can jam them very efficiently in selective way (jam BeiDou, but not GPS). GPS was jammed even as early as Iraq war. "Coalition troops also got a glimpse of GPS’s greatest weakness during the Gulf War. Iraqi forces installed jammers, for example, on top of landmarks suc…
A lot of work is being done to make GPS more jam resistant, and - just as important - more spoof resistant. The latest batch of satellites has a whole raft of countermeasures to help a receiver to identify whether the received signal is genuine or whether it was spoofed. Receivers too can do a lot to detect spoofing by just observing the signal (for instance: unrealistic power levels on reception, impossible response…
What work is done to make GPS more jam resistant?