
GPS 2.0: Aerospace Corp. Launches Second Draft of GPS - hackuser
http://breakingdefense.com/2016/04/gps-2-0-aerospace-corp-launches-second-draft-of-gps-exclusive/
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nxzero
Nextgen GPS is this:
[https://en.m.wikipedia.org/wiki/GPS_Block_IIIA](https://en.m.wikipedia.org/wiki/GPS_Block_IIIA)

(GPS 2.0 appears to just be a term made up by the author.)

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wyager
More interesting than this is
[https://en.m.wikipedia.org/wiki/Real_Time_Kinematic](https://en.m.wikipedia.org/wiki/Real_Time_Kinematic)
, which uses no extra transmit hardware compared to normal GPS, but can
provide mm accuracy. (In practice, it often requires multiple cooperating
receivers, but current research is finding ways to make this work practically
in single-receiver handheld devices like phones.)

This technique has gotten thousands of times cheaper in recent years (now
around $150 for a receiver, according to a talk I recently attended) and
should soon be cheap enough for consumer electronics.

This works anywhere and doesn't require supplementary external hardware like
Wi-Fi.

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Animats
No, it doesn't work anywhere. It only works where you have line of sight to at
least 4 satellites, preferably 5. Indoor positions and positions in urban
canyons will not be anywhere near that good.

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mr337
And you still need the carrier grade corrections, withing 10 to 25km of the
rover receiver.

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zo1
There are growing amounts of free/open correction points/towers. If you're
lucky, you might be within 25km of one.

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lucb1e
Can anyone find where they got "[GPS had] its most accurate day ever last
week" from? All sites about GPS accuracy seem to be down and I can find no
news sources mentioning a most accurate day at any point in time.

Edit: a bit further on they mention it in more detail: "It had its “best day
ever” on Monday, generating signals with an an average global accuracy of .38
meters." but once again no source.

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kbaker
I'm not sure, I did find some other cool graphs though...

Real-time GPS SPS (Standard Positioning Service) PDOP (Position Dilution of
Precision): currently shows 1-2 meters precision worldwide -
[http://www.nstb.tc.faa.gov/RT_SPSPDOP.htm](http://www.nstb.tc.faa.gov/RT_SPSPDOP.htm)

24 Hr Max PDOP:
[http://www.nstb.tc.faa.gov/24Hr_MaxPDOP.htm](http://www.nstb.tc.faa.gov/24Hr_MaxPDOP.htm)

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Redoubts
This page is showing up completely blank for me.

Cache:
[http://webcache.googleusercontent.com/search?q=cache:tsK9lnR...](http://webcache.googleusercontent.com/search?q=cache:tsK9lnRv8H0J:breakingdefense.com/2016/04/gps-2-0-aerospace-
corp-launches-second-draft-of-gps-exclusive/)

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mp3geek
Adblock issue, I've fixed.

[https://hg.adblockplus.org/easylist/rev/3594df2e77f5](https://hg.adblockplus.org/easylist/rev/3594df2e77f5)

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Redoubts
Cool, thanks!

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chrispeel
I think this is a great proposal. Even so, I'm curious why there needs to be a
formal process for the use of many sources in localization. It seems to me
that anyone making a localization device (i.e. Apple or Samsung making phones)
could add inertial information, cell tower locations, and more to give great
location info.

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Redoubts
I was a little underwhelmed, myself. Apple absolutely does a bit of this now.

    
    
      Depending on your device and available services, Location Services
      uses a combination of cellular, Wi-Fi, Bluetooth, and GPS to determine
      your location. If you're not within a clear line of sight to GPS
      satellites, your device can determine your location using crowd-
      sourced Wi-Fi and cell tower locations or iBeacons.
    

[https://support.apple.com/en-us/HT203033](https://support.apple.com/en-
us/HT203033)

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davidjade
On the surface this sounds good until you realize that there is a pretty big
group of people that started using iPads, etc. with boating navigation and
charting app. Pilots too I think. Used to be you could tell when you had a
location fix using a GPS, especially when I wifi was turned off. Now my iPad
magically gets a location fix even when in airplane mode and I have no idea
how or if I can trust it enough for something critical. This all started
changing in iOS 8 or 9. Really wish Apple would expose more details to app
developers on what type of fix an iDevice was using.

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cheriot
I couldn't agree more that devices don't expose enough detail about a GPS
position. It sounds like you solved your problem, though. Airplane mode turns
off cell and wifi radios, but leaves GPS alone so it's the only thing left to
read position from.

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nxzero
Anyone able to compare GPS 2.0 to other systems used by China, Russia, etc.?

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MrUnderhill
The "GPS 2.0" label used in the article is a bit of a misnomer I think, and
possibly just something the author came up with. There is no radically new
satellite navigation system described, just some rather superficial mentions
of the need for alternative electronic navigation aids to augment satellite
navigation (Loran, inertial sensors etc), which are not limited, or directly
related, to GPS.

The closest thing to bear a "next gen" GPS label is the new block IIIA
satellites, sometimes (officially) referred to as GPS III.

For civilian users, the most notable change in block III is that there will be
a signal L2C available on the L2 frequency. With 2 frequencies, you can
calculate ionospheric delay, resulting in better accuracy and resilience.
Before this, L2 only carried the encrypted military Y code (but L2 could still
be used for carrier phase tracking, so industrial non-military GNSS receivers
could still make some use of it).

There will also eventually be an improved (backward-compatible) signal on the
L1 frequency, and even a 3rd signal on L5. There fundamental system remains
the same though, this is more of an evolution than a revolution. E.g, L2C is
already available on some block II satellites. For military uses, there are
some other interesting changes in block III, notably a new military signal M
with a spot-beam antenna that can target a limited area, which is pretty cool.

Russia's GLONASS satellites evolve similarly, with the new 3rd gen K
satellites getting more frequencies etc, and using CDMA just like GPS
(previously the GLONASS signals used FDMA, i.e. each visible satellite used a
different frequency slot). Galileo and BeiDou are also quite similar, but
BeiDou is notable for using geostationary and inclined geostationary
satellites in addition to regular medium earth orbit satellites (essentially
to get improved coverage in Asia). A possibly interesting feature of Galileo
is that there may be a "commercial service" signal, i.e. that non-navigational
data may be broadcast via the Galileo satellites.

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brandmeyer
I for one would like to take advantage of the slow deployment of L2C and L1C
to change the payload. The program delay is potentially an opportunity to add
cryptographically strong authentication to the signal structure. The greatest
near-term threat to GPS isn't jamming as mentioned in the article, its
spoofing. Strong authentication is the most promising antispoofing defense,
and the growing commercial drone industry is going to need it.

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dzhiurgis
You seem to know a lot about this and it always interested me.

How does current GPS prevent from spoofing. My understanding is that only
military GPS signals are encrypted. If so, how strong is the encryption? What
type it is?

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elfchief
It's not so much that the military signal (ranging code) is encrypted, per se,
but it uses a DRNG for which the parameters are kept secret.

To be able to spoof GPS, you need to be able to duplicate the ranging code for
a given satellite. This is easy for civilian GPS, where the code repeats ~1000
times/sec and the details are public; much harder for military code where it
repeats 1 time/week and the parameters are secret.

You can still jam either one, though, just by overwhelming appropriate
frequencies with noise. This is what the spot beam in newer satellites is for
-- getting more power to areas of conflict to make the signal harder to jam.

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brandmeyer
> but it uses a DRNG for which the parameters are kept secret

A standard block cipher running in CTR mode would provide the same
functionality. So I don't think its wrong to say that the signal is encrypted.

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elfchief
By this logic, crypt(3) creates encrypted (rather than hashed) passwords,
because it can be implemented with DES.

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buckhx
It mentions protecting against jamming, but I hope they also explicitly make
efforts against spoofing. I think that's the bigger security concern when your
receiver thinks it has the right position, but an attacker is providing the
signals and rerouting at their desire. Currently only tightly controlled
military receivers have anti spoofing security distributed via the P(Y) code.

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avar
How would this work while still retaining the ability to have e.g. indoor GPS
repeaters?[1].

1\. [http://www.gps-repeaters.com](http://www.gps-repeaters.com)

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buckhx
It's a tricky problem. I could see enterprise solutions for private GPS
networks that have signed messages similar to an asymmetric JWT signature.
That way the message can be passed around and the client can assert if the
message has been tampered with.

That approach requires the satellite networks to have knowledge of the key
pairs for each client. Not something you'd see the government provide, but a
possibility for commercial applications.

