71–80 of 92 posts
I'm taking the liberty of reworking their "plain language summary." I aimed for maintaining accuracy with relaxed precision, but please correct me if I've lost too much of either in the process. I corrected a specific bit of imprecision in language in the source's plaintext summary not clearly distinguishing between vertical/y v. vertical/z, something the technical abstract clarified by stating "vertical altitude." -…
Is '~1 m' meters or miles?
Can this cause any other issues other than GPS errors? Lines like It is followed by ionospheric hole (plasma depletions) due to rapid chemical reactions of rocket exhaust plumes and ionospheric plasma. sound concerning but that's most likely because I only understand half the words, and have even less of an understanding when they're strung together in that manner!
It is followed by ionospheric hole (should be It was... holes ) A ~900km wide patch of the ion blanket around the earth became thinner. Probably in the density sense, not the size sense: there was less plasma there than normal. (The abstract measures this in terms of how many electrons they counted in that area.) due to rapid chemical reactions of rocket exhaust plumes and ionospheric plasma. They think the thin patc…
Is the altitude stable enough to predict it accurately for a given launch?
Even plainer language: Rocket exhaust can have impact with atmosphere, we need to study it more on short and long term effects.
Saying "can" also implies "might not".
"Need" needs to come with "in order to do X". I don't need to breathe, but if I want to stay alive I do. So do I need to breather or not? It's either.
Every time somebody else burns a hole in the ozone layer I wonder if they did it over their home or over mine . Somehow I don't expect to be pleased by the answer.
Did anyone try downloading the actual paper? My browser opened and then closed a tab. Kind of odd.
The paper is behind a paywall. It probably went back to the abstract page because the login / buy panel is on the right side of that page. Maybe see if your local library or university has an institutional subscription you can use to access the paper?
I'm taking the liberty of reworking their "plain language summary." I aimed for maintaining accuracy with relaxed precision, but please correct me if I've lost too much of either in the process. I corrected a specific bit of imprecision in language in the source's plaintext summary not clearly distinguishing between vertical/y v. vertical/z, something the technical abstract clarified by stating "vertical altitude." -…
I'm taking the liberty of reworking their "plain language summary." I aimed for maintaining accuracy with relaxed precision, but please correct me if I've lost too much of either in the process. I corrected a specific bit of imprecision in language in the source's plaintext summary not clearly distinguishing between vertical/y v. vertical/z, something the technical abstract clarified by stating "vertical altitude." -…
Now, can this launch profile tell us anything about the mission?
Earlier quoted context omitted.
I don't have firsthand knowledge, but I'd be surprised if mission critical military gear uses GPS for more than a secondary / corrective role. I can't imagine the signals play that well in a heavily-jammed environment. High probability rough GPS fix + radar / optical terrain comparison & dead reckoning for terminal guidance seems more likely.
Military GPS devices have access to more frequencies and channels that consumer devices don't have. These frequencies use anti-jamming techniques (frequency hopping using pseudo-random patterns, etc). They also have much better accuracy available to them than the consumer devices. Typical dumb jamming systems aren't really going to do much against military anti-jamming techniques and if it really is hurting comms the…
I know they turned off Selective Availability ( https://en.m.wikipedia.org/wiki/Error_analysis_for_the_Globa... ) in 2000, so not sure if it's been true since then.
From what I was reading, it seems like semi-codeless approaches to the P(y) (aka military) signal offer approximately similar accuracy to actually being in possession of the key.
Furthermore, the P(y) signal uses the same L1 and L2 frequencies as civilian devices. Which makes sense when you're designing a system with 1970s broadcast technology.
From Wikipedia, it seems like the soon-to-be-launched Block IIIA satellites are the first that will incorporate the ability to spot-beam at higher power ( https://en.m.wikipedia.org/wiki/GPS_Block_IIIA#New_navigatio... ).