[HN Gopher] Official U.S. government information about the Globa...
___________________________________________________________________
Official U.S. government information about the Global Positioning
System (GPS)
Author : waterheater
Score : 99 points
Date : 2023-09-29 14:14 UTC (8 hours ago)
(HTM) web link (www.gps.gov)
(TXT) w3m dump (www.gps.gov)
| franky47 wrote:
| For a video form of this topic, Scott Manley did a review of how
| GPS actually performed better than initially designed:
|
| https://www.youtube.com/watch?v=qJ7ZAUjsycY
| throw0101c wrote:
| See also "Phasing Out GPS Reliance in U.S. Military Operations:
| An Imperative in the Face of Emerging Threats":
|
| > _Global Navigation Satellite Systems (GNSS), such as the
| American GPS, Europe 's GALILEO, China's BEIDOU, and Russia's
| GLONASS, play an essential role in modern warfare. Despite their
| different technical specifications--like frequencies and orbits--
| these systems are designed to be compatible, allowing for greater
| positional accuracy. However, their signals are susceptible to
| various forms of interference, such as jamming and spoofing.
| While there are security measures like anti-spoofing in place,
| these are not foolproof._
|
| * https://www.realcleardefense.com/articles/2023/09/26/phasing...
| londons_explore wrote:
| There are plenty of techniques the military could use to make
| jamming or spoofing almost impossible.
|
| For example, use a signal encrypted with a key not known to the
| enemy. That prevents spoofing.
|
| Jamming can be pretty much eliminated by using phased array
| antennas. They can reject signals coming from the wrong
| direction. To fully block a military unit receiving GPS, the
| enemy would need to have ~30 planes in the sky over the unit,
| between the unit and each GPS satellite, broadcasting the
| jamming signal. Pretty infeasible for them.
|
| There are other ways to make jamming far far harder. For
| example, if you are happy for your GPS receiver to be always on
| and have an atomic clock, you can make a new signal that
| replaces the 1024 bit PRN codes with multi-gigabyte codes which
| are secret. That effectively means rather than the enemy
| needing to overpower the real signal, the enemy needs to be
| billions of times stronger than the real signal to prevent you
| decoding it.
| wil421 wrote:
| Even with a key you can drown out the signal by blasting
| enough RF waves at the receiver or area. I've heard a Growler
| pilot describe what they do as shining a spot light in your
| face to blind you.
| sennight wrote:
| Continuing that analogy, in the case where a sky facing
| directional antenna is being used: the pilot is crouched
| under a sewer grate, shining a light at the soles of your
| feet, as you stare up into the night sky. If you are
| pumping enough power to overcome a directional antenna,
| than you are more in the realm of a directed energy weapon
| - which requires an insane amount of power (see inverse-
| square law).
| jabart wrote:
| Yes but you would have to do that from top down. You can't
| shine a spot light on the back of a person's head to blind
| them. Not to mention the tricks they use to make RF signals
| directional to both send and receive.
| TeMPOraL wrote:
| > _You can 't shine a spot light on the back of a
| person's head to blind them._
|
| You can, if the spot light is _strong enough_ , and the
| person in question isn't floating in deep space. Just
| keep adding power until the light reflected by the
| person's surroundings is strong enough to blind them.
|
| > _Not to mention the tricks they use to make RF signals
| directional to both send and receive._
|
| Makes me wonder if there's an RF equivalent of getting
| permanently blinded by laser light scattering off random
| objects in your line of sight.
| Hello71 wrote:
| that's called jamming and was addressed by the comment. if
| you wear very narrow blinders and point your face right at
| where you want to look, then the enemy needs to install
| their spotlight right ahead of you instead of just anywhere
| in front.
| throw0101c wrote:
| It is a mitigation that may help, but not foolproof:
| someone can jam or spoof from the sky.
|
| Current areas where jamming is being detecting.
|
| * https://gpsjam.org
| jhugo wrote:
| This jamming isn't from the sky though.
|
| Incidentally, there has been a recent escalation in this:
| over Iraq commercial airline pilots have been reporting
| increasingly successful GPS _spoofing_ , with GPS
| positions being shifted by tens or hundreds of nm, the
| clock being shifted, etc. In some cases this has exposed
| bugs in aircraft software where it has not successfully
| recovered the GPS position even after leaving the
| affected area, leaving them with degraded navigation all
| the way to the destination.
|
| This is not as dire as it might sound, as there are
| plenty of other ways for an aircraft to determine its
| position, though it certainly reduces the margins for
| error in some cases. But it's interesting because such
| spoofing _should_ be extremely difficult to carry out
| successfully, especially on a moving target like an
| airliner.
| throw0101c wrote:
| > _This jamming isn't from the sky though._
|
| In that particular instance, but:
|
| * https://en.wikipedia.org/wiki/Electronic-
| warfare_aircraft
|
| Waiting for drones:
|
| * https://apps.dtic.mil/sti/citations/ADA508909
| wil421 wrote:
| Encryption still won't stop it. You will need many
| blinders to get a fix on enough satellites.
| TeMPOraL wrote:
| Or make a stronger spotlight and point it at whatever is
| directly in front of you, to blind you with reflected
| light.
| throw0101c wrote:
| > _There are plenty of techniques the military could use to
| make jamming or spoofing almost impossible._
|
| The US DOD is not as confident as you are, as they looking at
| backups/alternatives:
|
| > _DOD primarily relies on GPS for accurate PNT data, which
| is essential to effective military operations. However,
| multiple threats can render GPS data unavailable or
| inaccurate. DOD recognizes the threats to GPS and is taking
| steps to address them by developing more robust GPS
| capabilities and alternative PNT technologies. GAO was asked
| to review DOD 's acquisition of alternative PNT
| technologies._
|
| * https://www.gao.gov/products/gao-22-106010
|
| > _To fully block a military unit receiving GPS, the enemy
| would need to have ~30 planes in the sky over the unit,
| between the unit and each GPS satellite, broadcasting the
| jamming signal. Pretty infeasible for them._
|
| All GNSS signals live on a finite number of frequency bands:
| L5/E5, L2, E6, L1/E1:
|
| * https://gssc.esa.int/navipedia/index.php?title=GNSS_signal
|
| * https://www.geospatialworld.net/blogs/gnss-frequency-
| bands-f...
|
| * https://www.tallysman.com/gnss-constellations-radio-
| frequenc...
|
| * https://en.wikipedia.org/wiki/Satellite_navigation#Frequenc
| y...
|
| > _The ITU have allocated the following L-band frequencies to
| GNSS (bold are aeronautically used):_
|
| > * _GPS, the centre frequencies are 1575.42 MHz (L1), 1227.6
| MHz (L2) and 1176.45 MHz (L5)._
|
| > * _GLONASS operates as frequency divisional multiple access
| (FDMA) and there are two operational centre frequencies 1602
| MHz (L1) and 1246 MHz (L2) and at 1207.14 MHz (L3). GLONASS
| over this decade will also introduce Code Divisional Multiple
| Access (CDMA) similar to GPS._
|
| > * _GALILEO has a range of frequencies assigned in the
| L-band as follows:_
|
| > ** _E2 - L1 - E1 - Centre frequency 1575.42 MHz (band from
| 1559MHz - 1591MHz)._
|
| > ** _E5A - Centre frequency 1176.45 MHz (band from 1164 MHz
| - 1188 MHz)._
|
| > ** _E5B - Centre frequency 1207.14 MHz (band from 1188 MHz
| - 1215 MHz)._
|
| > ** _E6 - Centre frequency 1278,75 MHz (band from 1260 MHz -
| 1300 MHz)._
|
| * https://pbnportal.eu/epbn/main/Overview-of-PBN/PBN-
| Concept--...
|
| A handful of planes (or drones) focussing on those few
| frequency ranges can do a lot of mischief.
|
| And this is not theoretical, but observed events:
|
| > _Russia has been thwarting US-made mobile rocket systems in
| Ukraine more frequently in recent months, using electronic
| jammers to throw off its GPS guided targeting system to cause
| rockets to miss their targets, multiple people briefed on the
| matter told CNN._
|
| * https://www.cnn.com/2023/05/05/politics/russia-jamming-
| himar...
| londons_explore wrote:
| GPS guided missiles are a unique case, because there is a
| good chance the enemy gets hold of the electronics.
| Therefore, you don't want to put your military GPS
| encryption keys in there, because if the enemy got hold of
| those keys, they could spoof your satellites.
| throw0101c wrote:
| > _Therefore, you don 't want to put your military GPS
| encryption keys in there, because if the enemy got hold
| of those keys, they could spoof your satellites._
|
| IIRC, I remember reading that the NSA has cipher(s) where
| the decryption 'algorithm' is completely than the one for
| encryption, _i.e._ , just because you have the decryption
| code doesn't mean you can encrypt.
| m4rtink wrote:
| So normal public key cryptography? ;-)
| throw0101c wrote:
| No, this is for symmetrical encryption.
|
| So think something like AES, but where the 'distributor'
| encrypts something, gives you a key and an algorithm, and
| you can decrypt it. But you cannot use the same algorithm
| to encrypt to send back anything.
|
| For the life of me I can't remember where I read it
| (which book), so have never been able to dig into it
| more.
| DoctorOetker wrote:
| How feasible would you estimate passive positioning systems?
|
| For example consider solar radio noise at frequencies that
| are partially reflected, partially transmitted by the
| ionosphere.
|
| Do you consider it possible for an SDR to geolocate by
| comparing multiple antenna signals say:
|
| 1: "direct signal" : sun -DOWN-> partial transmitted through
| ionosphere -DOWN-> antenna 1 aimed at sun
|
| 2: "geography / terrain fingerprinted signal" : sun -DOWN->
| partially transmitted through ionosphere -DOWN-> reflection
| on Earth -UP-> partial reflection from ionosphere -DOWN->
| antenna 2
|
| Or any suggested variations? (reflection from moon for
| example).
|
| https://commons.wikimedia.org/wiki/File:Ionospheric_layers_f.
| ..
|
| i.e. can Western _citizens_ prepare to still have
| geopositioning in case of an adversarial (successful) first
| strike against GPS and Galileo where the citizen refuses to
| rely on adversary positioning systems.
| kube-system wrote:
| check this out: https://en.wikipedia.org/wiki/Pulsar-
| based_navigation
| DoctorOetker wrote:
| this is interesting, thanks for the reference, but it
| doesn't seem affordable for average citizens:
|
| "The main error sources that impact the instrument design
| are the number of collected photons (related to the
| detector size and the integration time) and the timing
| accuracy."
|
| Detecting and filtering for appropriate X-rays would seem
| to require a large and thus expensive detector.
|
| Being able to self-locate during aerobraking (as
| described in following URL) is a very neat application
| though...
|
| https://web.archive.org/web/20170316044511/http://gsp.esa
| .in...
|
| I wonder what materials withstand the heat and plasma
| during aerobraking, yet are transparent enough for
| X-rays?
| londons_explore wrote:
| With a clock and a telescope, you can get super precise
| positioning the same as the 16th century way... Atomic
| clocks are now good enough to make those positions really
| good.
|
| You can do the same with radio frequencies and a phased
| array antenna if you like.
|
| I'm not sure if other approaches would perform better.
| DoctorOetker wrote:
| I mean without a clock, the reference being the direct
| path of noise from the sun.
|
| Telescopes are impeded by clouds.
|
| During night there is no line of sight to the sun, so I
| concede my rudimentary idea or question has similar
| drawbacks.
| DoctorOetker wrote:
| It would be interesting if precise time could be derived
| from imaging the night sky, so that the synchronized
| clock becomes unnecessary.
| amalcon wrote:
| I've actually heard of research into putting celestial
| navigation in guided missiles (from people who've worked
| on it -- so the idea that this is possible seems to not
| be a secret). Cameras and optics have become good enough
| to make this plausible with those kind of constraints.
|
| I don't know if it's been deployed, but I would not be
| surprised.
| nradov wrote:
| Some ballistic missiles have already been using celestial
| navigation operationally for decades. That is used
| primarily during the mid-course phase, and then they
| switch over to inertial (or maybe radar in a few cases)
| for the terminal phase.
| KaiserPro wrote:
| > How feasible would you estimate passive positioning
| systems?
|
| Totally feasible. DECCA and LORAN-C basically work on the
| same principle. have a number of transmitters at known
| locations and measure the phase/interference to get
| location.
|
| However, there are other ways. Visual navigation is totally
| possible (think SLAM, but with a pre-computed map)
| DoctorOetker wrote:
| DECCA and LORAN-C are not passive but rely on second
| parties maintaining transmitters.
|
| I may be wrong, but I would hazard SLAM would require an
| enormous amount of data
| 13of40 wrote:
| I was reading the specs for the GPS satellites vs. the
| GLONASS ones a while back, and it seemed like they transmit
| on a similar frequency but with a different modulation scheme
| and protocol. Pure speculation, but you could imagine a Tom-
| Clancy-esque scenario where their secondary role is to jam
| GPS when they need to.
| londons_explore wrote:
| To jam something, you ideally jam the same frequency, PRN
| code, and direction.
|
| If you don't know frequency, you need to jam a wide range
| of frequencies. Defences like frequency hopping make use of
| this. Bluetooth uses this for example, to prevent
| inadvertent jamming. In GPS, frequencies aren't secret.
|
| If you don't know the code, you need to jam with as much
| power as the benefit of the code. For GPS, thats a 10x 1024
| bit code, which provides 43 dB of processing gain. This can
| be increased almost without limit, _as long as you don 't
| plan to move much during the code period_. There are clever
| methods to make encryption keys double-up as PRN codes that
| the enemy doesn't know.
|
| For direction, it depends on the receiver. Your phone has
| an omnidirectional receiver, so the attacker is 'on par
| with' the real signal. A military directional phased array
| system might have 200 elements, and therefore 30db of gain.
|
| Add that up, and the enemy needs to use far far more signal
| power than the real signal to 'outshine' it. Turns out
| that's pretty much impossible - and if they get near to
| doing that, your biggest problem is probably being cooked
| by their jammer.
| KaiserPro wrote:
| > Jamming can be pretty much eliminated by using phased array
| antennas.
|
| citation needed there. GPS typical signal strength is
| -125dBm.
|
| For ground based stuff, its pretty simple to overpower the
| band so that nothing can hear it.
| sennight wrote:
| This has been a solved problem for a very long time. The
| nice thing about GPS satellites is that you know where they
| should be, and where they shouldn't, so long as your RTC is
| properly set and you've got a compass.
|
| A GPS Digital Phased Array Antenna and Receiver (2000):
| https://apps.dtic.mil/sti/tr/pdf/ADA452307.pdf
| KaiserPro wrote:
| yes, phased arrays, especially if you have a tight beam,
| can give you an extra 40db of SNR (see figure 9
| https://www.analog.com/en/analog-
| dialogue/articles/phased-ar..., also in the charts on
| your link)
|
| but thats still like -70dbm at best. That's about the
| level of being a few meters away from a wifi AP level of
| power.
|
| a 1 watt(RF) jammer is going to cast a large cone of non-
| GPS even with a phased array antenna.
| sennight wrote:
| You are forgetting about the phased nulling. Military GPS
| has been including jammer detection in the firmware for a
| long time. I remember my handheld unit constantly
| annoying me anytime the IED jammer (which was waaaay more
| than 1 watt of rf) went active... 2005ish - it would
| simply mask the signal coming from that direction and
| continue to provide positioning data.
| londons_explore wrote:
| Add in coding gain over 1 second (a code 10 million chips
| long), and that gives you an extra 70dB. Now it's getting
| hard to jam.
|
| Downside: This only works if your movement over the 1
| second period is predictable, to a small part of a
| wavelength. If you're moving unpredictably, you'll have
| to give up a few db's of coding gain.
| hiatus wrote:
| > To fully block a military unit receiving GPS, the enemy
| would need to have ~30 planes in the sky over the unit,
| between the unit and each GPS satellite, broadcasting the
| jamming signal. Pretty infeasible for them.
|
| How did you arrive at this number?
| uoaei wrote:
| It's approximately the number of GPS satellites in the sky
| from a given location on the ground. One plane per
| satellite. Of course this varies due to geography, orbits,
| etc. but is a good rule of thumb.
| jabart wrote:
| Number is a bit high but may be counting GPS, and EU GPS
| satellites you would have to block. You can "see" 4-12 GPS
| satellites at a time for one system. Assuming the EU system
| has the same style layout.
| Jtsummers wrote:
| You don't need to block line-of-sight to the GPS
| satellites to create a GPS jamming attack. You just need
| a more powerful emitter near enough your intended target.
| No need for 30 planes trying to interpose themselves
| between the target and satellites.
| londons_explore wrote:
| You do if the victim uses a phased array antenna.
|
| And any decent military receiver will do that, precisely
| to prevent jamming.
| orangepurple wrote:
| Such a powerful jamming emitter is also a wonderful
| automatic target for loitering munitions
| Jtsummers wrote:
| If it's within a region that can be attacked and the
| opponent has those capabilities, yes.
| hef19898 wrote:
| If you ask "the internet", the answer is drones.
| Regardless of the question being asked...
| orangepurple wrote:
| Recently huge drone swarms have been launched recently to
| increase the chance of mission success.
| XorNot wrote:
| And to hope your enemy doesn't just launch a couple of
| anti-radiation missiles at your most powerful radiation
| source nearby.
| Jtsummers wrote:
| Assuming they possess that capability, that is a risk,
| yes.
| XorNot wrote:
| "home on jam" capability is being rolled out into smaller
| drone systems right now (it's not complicated per se,
| just somewhat risky since it could target friendlies).
| throw0101c wrote:
| > _Number is a bit high but may be counting GPS, and EU
| GPS satellites you would have to block._
|
| All of which transmit on the same 3-4 frequencies:
|
| * https://gssc.esa.int/navipedia/index.php?title=GNSS_sig
| nal
|
| so you'd only have to have high-power transmitters on
| those and you can block things.
|
| * https://gpsjam.org
|
| Do it from a plane, or drone, and directional antennas
| become less effective as the jamming is coming from the
| same direction as the real signal (the sky).
| londons_explore wrote:
| Phased arrays can have a beamwidth of 1 degree... Which
| means the enemy has to get their jamming signal within 1
| degree of the victim and the satellite.
|
| And now you need to do that 30 times when there are 30
| visible satellites.
| throw0101c wrote:
| A phased array can transmit to with-in a small angle, but
| how does that help the receiver? It is still coming from
| "the sky", so if you have an airborne jammer (EW fighter,
| drone), how will the receiver what's signal and what's
| noise?
|
| I am aware of the spot beam functionality, which has
| higher power, which could help with overcoming noise:
|
| * https://en.wikipedia.org/wiki/GPS_Block_III#Military_(M
| -code...
|
| The biggest recent help against jamming was the
| introduction of the L2C signal on a different frequency
| with the Block IIR-M satellites, and then the more
| powerful L5 signal on Block IIF.
| londons_explore wrote:
| A phased array antenna can both transmit and receive
| within a small beam angle.
| hef19898 wrote:
| So, basically back to old school, "manual" stuff? Should be
| doable, if less convenient.
| throw0101c wrote:
| The US Navy brought back celestial navigation (with sextants)
| as a backup:
|
| * https://www.usni.org/magazines/proceedings/2021/december/br
| i...
|
| * https://skyandtelescope.org/astronomy-news/u-s-navy-
| resumes-...
| hef19898 wrote:
| And all the other, old school stuff is still available
| anyway. Still, without GNSS, things are complicated.
| supertrope wrote:
| Cell phone towers depend on GPS for timing and frequency
| precision. A lot of processes depend on GPS availability.
| hef19898 wrote:
| Military navigation doesn't so. Sure, GPS makes things a
| ton easier but it is perfectly possible without it.
| burkaman wrote:
| Linked from this page: https://www.navcen.uscg.gov/gps-problem-
| report-status
|
| About 500 reports from people saying "GPS on my phone isn't
| working" and the US Coast Guard and Department of Homeland
| Security replying that "perhaps your phone is broken".
| throw0101c wrote:
| A bit of development history at "GPS Almost Ended Before it
| Began":
|
| > _The death struggle: NRL wanted a two-dimensional system, and
| Parkinson and the Air Force wanted three dimensions plus time.
| The NRL patent called for atomic clocks in the user equipment,
| which would have made them prohibitively expensive. Parkinson and
| the Air Force wanted atomic clocks on the satellites instead,
| which would greatly simplify the GPS user receiver if atomic
| clocks could be modified to fly in the high-radiation environment
| of space. It wasn't going to be easy to do, but space-qualifying
| atomic clocks turned out to be possible. NRL had tried to orbit a
| laboratory atomic clock, but it had quickly failed under the
| intensity of space radiation._
|
| > _With these modified concepts all defined, Parkinson spent the
| next three months trying to, at least, convince the key players
| in DoD not to say no. In December 1973, the Defense System
| Acquisition Review Council reconvened and voted yes. It was not
| that everyone in the military liked what they saw. Many
| navigation officials in the services liked the systems they had
| such as TACAN, VOR, DME, LORAN, etc. The Air Force was
| particularly opposed to GPS and no doubt preferred more
| airplanes._
|
| * Embedded PDF:
| http://www.brightcopy.net/allen/avne/60-9/index.php#/p/20
|
| * https://en.wikipedia.org/wiki/Bradford_Parkinson
| [deleted]
| nradov wrote:
| It makes you wonder what other proposals actually were killed
| at an early stage that would have succeeded brilliantly had
| they been funded.
| syncsynchalt wrote:
| I firmly believe that the GPS we got is the best option we
| could have picked.
|
| I've read a lot of the design papers from the 60s and 70s
| that formed GPS. The initial design was a 3-satellite
| constellation that would only cover Viet Nam. Options
| considered [1] included a receiver broadcasting to the
| satellite (wouldn't scale infinitely) or having an atomic
| clock in each receiver (high cost and weight). The
| expectation would be that there were about 100 GPS receivers
| worldwide: those installed in USAF and USN planes, and
| possibly some in USN ships or US Army tanks.
|
| One constraint they eventually settled on was that a receiver
| should be portable (less than 50kg) and inexpensive (less
| than $500k adjusted)[2]. It just goes to show how far we've
| come from what was at the time considered ambitious in its
| size and cost goals.
|
| [1] https://www.xyht.com/wp-
| content/uploads/2016/07/3-5-redacted... page 57
|
| [2] https://www.xyht.com/wp-
| content/uploads/2016/07/3-5-redacted... page 73
| Rebelgecko wrote:
| The original Woodford & Nakamura TOR has a really cool hand
| drawn table showing all of the alternatives and their
| pros/cons. It was definitely for the best that they went with
| the most technically challenging option (inventing atomic
| clocks that are small enough to go to space) since that choice
| is responsible for a lot of the neat aspects of GPS (users
| don't need to be near ground stations, they don't need their
| own synchronized clocks, and GPS receivers really are receive-
| only)
|
| Edit: just scrolled down and saw that my comment is a bit
| redundant with syncsynchalt's :)
| abeppu wrote:
| Relevant this week:
|
| - GPS costs around $2B/yr to continue operating
|
| - Most of this comes from the defense budget
|
| - This year, because of shenanigans, the NDAA has _not_ yet been
| passed b/c there are significant and controversial amendments in
| the House version
|
| - We're careening towards a government shutdown
|
| I'm not saying this _will_ happen, or _should_ happen ... but if
| GPS went off with the rest of the government, would Congress
| reach a resolution faster?
|
| https://www.gps.gov/policy/funding/
| wkat4242 wrote:
| GPS is far from the only GNSS now. This whole shutdown business
| justifies our EU decision to develop GALILEO despite the cost
| and the Americans not being too happy about it.
| 1-6 wrote:
| [flagged]
| abeppu wrote:
| No, by shenanigans, I mean the NDAA amendments that put in
| stuff about abortion and transgender policies in an effort to
| make even basic continued national security part of the
| culture wars.
|
| https://www.politico.com/news/2023/07/14/house-passes-
| defens...
| orangepurple wrote:
| EU Galileo, RU GLONASS, and CN BeiDou constellations all
| continue to operate but GPS receivers are not allowed to
| receive their broadcasts within the United States for political
| reasons only.
| mukara wrote:
| Signals from Galileo, GLONASS, and BeiDou (and other semi-
| regional navigation satellite constellations) can be received
| in the US. Any decent GNSS receiver you can purchase in the
| US will be able to receive all 4 major global constellations.
| I know this cause I work with them everyday.
|
| Even the typical "premium" cellphone will receive all 4. (I
| know some Android manufacturers disable the used of BeiDou,
| but they can still receive it.) The iPhone 15 Pro's tech
| specs mention "Precision dual-frequency GPS (GPS, GLONASS,
| Galileo, QZSS, BeiDou, and NavIC)".
| joecool1029 wrote:
| > Any decent GNSS receiver you can purchase in the US will
| be able to receive all 4 major global constellations. I
| know this cause I work with them everyday.
|
| All common handset devices used in CONUS (every iphone,
| android phone, etc) will ignore BeiDou signals. Would love
| if someone hacked the GNSS firmware to make it usable, but
| haven't seen it happen yet. If you travel outside the CONUS
| geofence these signals will show on the device, but FCC has
| some mandate requesting a block, so it's blocked.
| mukara wrote:
| >All common handset devices used in CONUS (every iphone,
| android phone, etc) will ignore BeiDou signals.
|
| This is correct for smartphones and the likes (all
| handsets??), though not entirely correct for all GNSS
| receivers. For example, I regularly use receivers with
| uBlox F9P chipsets with BeiDou enabled from factory [0].
|
| >Would love if someone hacked the GNSS firmware to make
| it usable, but haven't seen it happen yet.
|
| If we ask the Broadcom or Qualcomm engineers nicely, they
| might tell us how to unblock them for their smartphone
| chipsets in the US. I might've seen it before :)
|
| [0]
| https://www.digikey.com/en/products/detail/ardusimple/AS-
| RTK...
| [deleted]
| smachiz wrote:
| I think technically they should only receive for Galileo in
| the US - unless any of the others have also received
| exceptions from the FCC.
|
| While in other countries, presumably your phone turns on
| the additional sources.
| jonah wrote:
| My - few years old, mid-range - Android phone shows that
| it is using 5 of the 6 GLONASS satellites in view as part
| of its fix. (In California, USA.)
|
| Edit: Using GPS Test: https://play.google.com/store/apps/
| details?id=com.chartcross...
| mukara wrote:
| Not sure about "technically" or what the legal situation
| is. In practice, I know consumer smartphones in the US
| use a combination of all 4 constellations for
| positioning. If you have Android, you can easily verify
| this using various apps. If you're on the west coast
| (California Bay Area, at least), you can even receive
| unreliable signals from one or two Japanese QZSS
| satellites, which are supposed to be regional over the
| Asia-Oceania region. You can even see a few SBAS
| satellites (mainly used in aviation.)
| ShakataGaNai wrote:
| Yea. Even if not officially approved by the FCC etc, the
| signals are still being broadcast. So there may be
| interference, but the signals are there and often
| receivable.
|
| The problem is really just that while premiums consumer
| devices support basically all GNSS providers, that's not
| true of a lot of devices. There is a lot of
| cheap/old/specialized systems out there that are still GPS
| only.
|
| In the case of a GPS shutdown, I'm not worried about my
| iPhone 15. However, what is currently in place and
| certified for flight in a 30 year old 757? Have they gotten
| around to generic GNSS support or is it just GPS? I
| honestly don't know and would rather we didn't have to find
| out the hard way.
| wkat4242 wrote:
| The "interference" is actually how GNSS systems work and
| it makes things better.
| hef19898 wrote:
| Plus, some receivers can work with signals coming from
| different cobstellations, e.g. one GPs, one GLoNAS and one
| Galileo, in order to provide a proper position.
| khuey wrote:
| It's been legal to use Galileo signals in the US for several
| years now. https://www.gps.gov/spectrum/foreign/
| joecool1029 wrote:
| I never could find where the US authorization was for
| GLONASS signals. I imagine it was included in some kind of
| bilateral treaty between US and Russia. The program to
| authorize later constellations (which Galileo went through)
| was not in place yet. It's like everything they issued
| since then ignores that we were using those signals since
| the 2000's.
| mikewarot wrote:
| I'm currently in a basement in the US, and my cheap phone GPS
| has acquired 6 US, 4 Russian and 4 European satellites in
| view.
| [deleted]
| ShakataGaNai wrote:
| > but if GPS went off with the rest of the government, would
| Congress reach a resolution faster?
|
| Oh hell yes. GPS is the basis of trillions of dollars of
| business globally. Just look at sea shipping and aviation
| alone. Would a lack of GPS ground every commercial plane?
| Maybe.. maybe not... but it certainly would be a huge
| disruption.
|
| The first time it happens everyone would just drive hard to
| making sure all "GPS" systems were actually multi-system GNSS
| systems. Which is already true of most consumer phones, but I
| imagine there are still plenty of GPS-Only stuff out there.
| After the first GPS shutdown and the time for retrofit,
| everyone would have support for Galileo etc... and the
| Europeans would be standing there going "SEE!!!! I told you we
| can't trust the Americans!". And they'd be right.
| hackernewds wrote:
| it wouldn't just disrupt planes, it would crash planes if
| this were not even planned as a contingency. as a senior
| operations manager for a global logistics company, I was
| actually not even aware of this being a possibility until TIL
| here
| rlpb wrote:
| > it wouldn't just disrupt planes, it would crash planes if
| this were not even planned as a contingency.
|
| It would not. Aircraft have other navigation systems they
| can use instead, such as inertial reference and ground-
| based VOR navigation. And where there's radar coverage,
| they can be vectored by controllers.
|
| This probably couldn't be used to keep up with the volume
| of air traffic today, but it would be enough to get
| existing flights down safely.
|
| For landing, ILS is still very common, and doesn't require
| GPS either. An aircraft planning to land at an airport
| without ILS will have no trouble finding a nearby diversion
| airport that does have it.
|
| Even as more ground-based navigation beacons are
| decommissioned, retaining enough for such an emergency
| remains an active consideration.
| thewataccount wrote:
| To my knowledge planes don't use the gps for very much, and
| AFAIK they use the barometric altimeter for maintaining
| their flight level. A controllable, plane that can maintain
| altitude is difficult to crash. The GPS stuff is mostly
| supplemental and is relatively new.
|
| And pilots can land with a visual approach and still have
| ILS.
|
| You would still have ADSB with your altitude, and I beleive
| heading and airspeed.
|
| Because of the existing requirement to be spotting traffic
| and being over 1000ft away from other planes, they should
| be fine.
|
| ATC should still have radar vectoring for their airspace.
|
| I assume planes use more then just GPS, and use galileo and
| the other networks like consumer GPS do.
| Iwan-Zotow wrote:
| I'm pretty sure all GPS receivers now are multisystem. So
| GLONASS and Baidu will continue to serve you
| dfxm12 wrote:
| The 2018 shutdown did not appear to affect GPS. Is this looming
| shut down different in some way?
| khuey wrote:
| No, it's not.
| rootusrootus wrote:
| There's a recent article I read (NPR, I think?) where Mick
| Mulvaney was interviewed about that shutdown. He made the
| point (and spun it to make him look especially noble, of
| course) that the effects of a shutdown are largely decided by
| the Office of Management and Budget. They can choose to
| soften the blow, or they can make it hurt.
|
| He argued that in 2013 under Obama, the OMB really turned the
| screws and hired contractors to fence off even national
| monuments which were otherwise unmanned anyway. Complete with
| signs announcing why they were fenced off. They wanted the
| public to feel the pain and associate it with Republicans
| (which seems to work, historically the GOP gets the majority
| of blame for shutdowns).
|
| I think it's unlikely anybody is going to turn off GPS
| because the gov't "shutdown". I think the larger risk is that
| they will stop paying air traffic controllers, while
| expecting them to come to work anyway. That'll work for a
| while, but eventually some of those controllers may opt to
| stay home.
| dfxm12 wrote:
| Republicans don't get blamed for the government shutdowns
| because of signs or fences by national monuments. They get
| blamed because they are at fault, whether that's trying to
| cut the increasingly popular ACA purely out of spite to
| Obama in 2013, or party infighting like this year or 2018.
| mindslight wrote:
| The "blame" is exactly what Republican Party wants, to
| keep up their kayfabe marketing of "fiscal
| responsibility". Put interest rates around 7% for the
| next several decades, end the inflationary treadmill, let
| the everything bubble deflate, let the Wall Street
| debt/financialization cancer recede - and then it would
| make sense to talk about fiscal responsibility as a real
| thing. Until then any peanuts thrown to the plebs by the
| Democrats are really just mitigating the economic damage
| from the trough of overwhelming corporate welfare.
| throw0101a wrote:
| TIL:
|
| * https://en.wikipedia.org/wiki/Kayfabe
| jhoechtl wrote:
| There are a couple of german words which made it into
| mainstream english like angst, zeitgeist, abseil. Based
| on your comment I would suggest a new one: brandrede.
| Look it up, afaik there is no english equivalent.
| mindslight wrote:
| From a quick look the literal translation is "fire
| speech" which doesn't seem that hard to understand. So it
| would seem the significance is its place as a cultural
| touchstone, and cultures can certainly differ.
|
| As to your larger point, pointing out errors in the
| social consensus is intrinsically inflammatory, as it
| upsets _most everyone 's_ neat little boxes they
| conceptually pigeonhole things into. That's unfortunate,
| but I don't think I said anything unnecessarily
| inflammatory - rather just tying together concepts each
| claimed by the red and blue tribes that they mostly use
| to talk past each other.
| abeppu wrote:
| I'm sure there are _some_ discretionary choices made but
| ... what does a shutdown that doesn't hurt look like? At
| some level, the government is huge and expensive, and
| society is adapted to it continuing to operate. If we had a
| no-pain way to not spend all that money, we should do it.
| But I'm guessing that putting up some fences around a few
| monuments is pretty cheap (it's not like they put up a
| fence around the whole grand canyon or something) relative
| to the funds that are being stopped.
|
| I think the political showmanship here is that it's easy to
| have an above-the-fold image of a "closed due to shutdown"
| sign in front of the Lincoln memorial that's immediately
| comprehensible, but there's not a great pic to show more
| substantive but dry government work that doesn't happen or
| gets delayed. It's hard to visually instantly convey
| "you're still paying all your taxes but you're getting a
| whole lot less government right now."
| dylan604 wrote:
| If everyone's turn-by-turn navigation stopped working,
| there would be riots in the streets (if they could figure
| out how to get there).
|
| If you want to bring attention to the everyday person,
| turning off GPS would definitely get their immediate
| attention.
| yjftsjthsd-h wrote:
| Don't a lot of modern systems combine GPS with GLONASS
| and Galileo?
| jhoechtl wrote:
| Pretty much every smartphone younger than four years.
| antonjs wrote:
| Also most receivers for super economically important
| things like a avionics or marine navigation, but shutting
| off WAAS specifically (augmented accuracy data for GPS
| broadcasted using a much smaller set of satellites) would
| affect air traffic that need it to land in low visibility
| at an increasing number of airports.
|
| Though, to the OP's point about GPS, WAAS is operated by
| the FAA, so it isn't clear to me whether not passing the
| defense authorization would affect it in the near term.
| dylan604 wrote:
| If they stop paying the ATC controllers, there won't be
| any planes needing to land. So no problem! /s
| abeppu wrote:
| I don't actually expect GPS to be impacted in the coming
| week, but I think the big difference is that in the last
| partial shutdown, DoD funding had already been separately
| approved in September [2,3], and the shutdown started months
| later [1]. This cycle, b/c the NDAA has _not_ been passed,
| the DoD will be meaningfully impacted [4]:
|
| - service members will not be paid
|
| - some post and base services, commissaries and medical
| procedures may be stopped
|
| Note that legislation has been proposed but not adopted to
| make sure that military personnel are paid even during a
| government shutdown. Note also that key military
| promotions/confirmations have been blocked for months in the
| Senate. It really seems like Congress does is not currently
| taking the military and national security seriously.
|
| [1] https://en.wikipedia.org/wiki/2018%E2%80%932019_United_St
| ate...
|
| [2] https://www.congress.gov/bill/115th-congress/house-
| bill/5895
|
| [3] https://www.congress.gov/bill/115th-congress/house-
| bill/6157
|
| [4] https://www.npr.org/2023/09/27/1201956915/government-
| shutdow...
| Jtsummers wrote:
| > Note also that key military promotions/confirmations have
| been blocked for months in the Senate.
|
| One man in the Senate is responsible for this one.
|
| Non-essential civil service (a substantial part of DOD
| operations) will not be working come Monday (unless an
| agreement is reached by then) unless they are on multi-year
| funds. Program offices and large portions of logistics are
| largely staffed by civil service at this point so this
| could have huge impacts on military readiness.
| abeppu wrote:
| > One man in the Senate is responsible for this one.
|
| One man bears special responsibility, but as the recent
| confirmation of 3 top appointments shows, there are
| mechanisms that could be brought to bear. My (limited)
| understanding is that Senate holds can be ended with a
| cloture vote, so any 60 Senators could agree to move the
| nominations to consideration.
| [deleted]
| hunglee2 wrote:
| GPS spoofing will be an excellent technique for false flag
| operations
| moate wrote:
| Building giant space lasers will be an excellent technique for
| holding the world ransom for ONE BILLION DOLLARS.
|
| (This is where we pitch one sentence villainous plots right?)
| hef19898 wrote:
| Don't forget the _sharks_! I want those!
| hunglee2 wrote:
| I make no recommendations! It is only observation of an
| imbalance of power that could be exploited by the dominant
| owners of satellite technology
| moate wrote:
| Water is wet. This statement is as useful as "The GPS's
| continued existence benefits systems built on the GPS" but
| with more fear implied. It doesn't really feel like a novel
| thought, more like one of the first 5 things you might
| throw up in the "cons" column when discussing it vs
| alternatives.
|
| Don't get me wrong, I have plenty of qualms with the US
| government, but walking into a discussion on say, foreign
| aid spending programs and saying "The Government will spend
| this money almost entirely in ways that advances its global
| agenda" is just sort of a Duh moment.
|
| I'm sorry, this is a very long way of saying "so what, who
| cares, what are you proposing?"
| KaiserPro wrote:
| I mean, that was the entire point of GPS in the first
| place. Allow the US to navigate quicker, more accurately so
| that they could get stuff where they needed to be quicker
| and more efficiently.
| throw0101c wrote:
| GPS spoofing, _not jamming_ , is causing issues around Iran-
| Iraq such that the FAA put out a notice:
|
| * https://www.ainonline.com/aviation-news/air-
| transport/2023-0...
|
| There was/is speculation that spoofing may have been used in
| the capture of a US drone:
|
| * https://en.wikipedia.org/wiki/Iran-U.S._RQ-170_incident
| OldGuyInTheClub wrote:
| The article on Consumer grade GPS receivers and their associated
| maps not being good enough for truckers was a surprise. That's
| something I had never thought about.
| supertrope wrote:
| Low bridges are a hazard for inexperienced truck drivers.
| https://www.youtube.com/@11foot8plus8
| OldGuyInTheClub wrote:
| This SoftStop barrier looks promising.
|
| https://www.laservision.com.au/portfolio/softstop/
| Thoreandan wrote:
| Relevant occurrence in GPS history:
| https://en.wikipedia.org/wiki/Korean_Air_Lines_Flight_007
| sheepybloke wrote:
| Fun fact I learned recently: The GPS reference epoch was moved
| from 2000 to 2001 due to an Alaskan earthquake in 2002. It's
| crazy how an event like that can change something like GPS!
|
| https://en.wikipedia.org/wiki/International_Terrestrial_Refe...
| y04nn wrote:
| > Is military GPS more accurate than civilian GPS?
|
| > The user range error (URE) of the GPS signals in space is
| actually the same for the civilian and military GPS services.
| However, most of today's civilian devices use only one GPS
| frequency, while military receivers use two.
|
| > Using two GPS frequencies improves accuracy by correcting
| signal distortions caused by Earth's atmosphere. Dual-frequency
| GPS equipment is commercially available for civilian use, but its
| cost and size has limited it to professional applications.
|
| > With augmentation systems, civilian users can actually receive
| better GPS accuracy than the military.
|
| Is it fully true ? So the only advantages of the military GPS is
| that the codes are unknown and that it is more jamming proof ?
| KaiserPro wrote:
| Civilian GPS signal can be selectively diluted in certain
| areas, which is useful for stopping most non-military and a
| large number of military navigation kit.
| smachiz wrote:
| they also have the ability to fuzz civilian GPS while not doing
| so for the military... so probably, until they don't want it to
| be true.
| y04nn wrote:
| They only need to change the CDMA codes of the civilian GPS
| to render it unusable. Also at the beginning of GPS they
| purposely added inaccuracies into the timing to make it less
| precise for civilian use, but because of the FAA and other
| needs (and methods that have been developed to counter the
| injected inaccuracies) they finally removed it in 2000.
|
| To respond to my question. With long term measurements and
| the help of the L5 band it is possible to obtain sub-
| millimeter accuracy [1]!
|
| [1]: https://en.wikipedia.org/wiki/Global_Positioning_System
| ck2 wrote:
| Fun fact: You know the "Hidden Figures" women who did the intense
| calculation for the military and space programs in the USA before
| computers were powerful enough?
|
| GPS was one of those systems needing intensely calculated orbits,
| Dr. Gladys West was responsible
|
| https://www.afspc.af.mil/News/Article-Display/Article/170746...
| Isamu wrote:
| This is interesting
|
| >The 2024 GPS Testing for Critical Infrastructure (GET-CI) event
| is set for the fall of 2024.
|
| >This event provides an opportunity for CI O&O and manufacturers
| of commercial GPS receivers used in critical infrastructure to
| perform equipment evaluations in a rarely available live-sky
| spoofing and jamming environment. For the 2024 GET-CI event, S&T
| will create a live-sky GPS environment primarily for fixed
| infrastructure applications but will also support some ground-
| based mobile applications.
| ksherlock wrote:
| My second favorite part about GPS is that it's a general
| relativity experiment, for anybody still on the fence. GPS
| satellites run 38 microseconds faster/day (from our perspective)
| due to the difference in gravity which works out to being off by
| ~6 miles/day.
| 64operator wrote:
| [dead]
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