
Look out for the second 2019 GPS week number rollover - weinzierl
https://rachelbythebay.com/w/2019/10/03/roll/
======
nippoo
This might be mildly annoying for car navigation systems. But nothing compared
to the potential danger for aviation: several published instrument approaches
are now GPS-only!

Reminds me of how NASA wouldn't fly the Shuttle over New Year's day to avoid
rollover issues: [https://www.newscientist.com/article/dn10459-y2k-like-
fears-...](https://www.newscientist.com/article/dn10459-y2k-like-fears-create-
shuttle-scheduling-crunch/)

~~~
toxican
I would really hope that something as critical as aviation instruments have
the capacity to be updated to account for this and that it's been treated like
a mini-Y2K with lots of fixes made ahead of time. But I guess we'll see...

~~~
ryandrake
You would hope that it would have happened ahead of time:
[https://arstechnica.com/information-
technology/2019/04/gps-r...](https://arstechnica.com/information-
technology/2019/04/gps-rollover-apparently-cause-of-multiple-flight-delays-
groundings/)

------
_trampeltier
The "fancy" sound driver on my companys HP ZBook does use 500MB Ram but a few
bytes for a correct date are still to expensive ...

~~~
tialaramex
The data stream doesn't move very many bits per second, and it needs to keep
saying the week number, so every extra bit you decide you want for that week
number means that for pure GPS units (which don't have the Internet to go get
the GPS metadata from, an Internet which also knows perfectly well which week
this is) the time from power on to first fix is proportionally slowed as they
wade through all those extra bits you just felt sure they needed.

"On the downside this will take 40 minutes to tell us where we are, on the
upside trampeltier feels better about it"

Also your driver probably doesn't use 500MB of RAM, more likely it wants 500MB
of address space, and address space is basically free on 64-bit systems anyway
so who cares?

~~~
est31
There's plenty of reserved bits in the old protocol to give more bits that the
10 the WN (week number) already has:
[https://i.imgur.com/QuJDwmb.png](https://i.imgur.com/QuJDwmb.png)

Source: Figure 20-1 in [https://www.gps.gov/technical/icwg/IS-
GPS-200K.pdf](https://www.gps.gov/technical/icwg/IS-GPS-200K.pdf)

Your argument that the space is sparse _is_ true though in the new protocol
which has still a message of 300 bytes but no reserved space any more:
[https://i.imgur.com/xyxCxIi.png](https://i.imgur.com/xyxCxIi.png)

Source: [https://www.gps.gov/technical/icwg/IS-
GPS-705F.pdf](https://www.gps.gov/technical/icwg/IS-GPS-705F.pdf)

It gives 13 bit to the message at least, making the counters roll over every
157 years instead of every 20. It's still a bit too little IMO. Date counters
should either be so short that engineers _must_ design rollovers into the
devices (e.g. 1 year) or longer than human lifespans by several orders of
magnitude (e.g. 1000 years).

------
donquichotte
> certain LTE chipsets have an OFFSET WEEK... and they haven't hit 1023 yet.
> Oh no. According to what I've managed to dig up, they're going to hit it
> 2019-11-02 at 23:59:42Z.

Any sources? What is an OFFSET WEEK? Why do you call it "GPS week number
rollover" when it is affecting LTE chipsets?

~~~
kkwtfeliz
GPS is integrated in LTE chips, so you don't need another one just for GPS.

~~~
Mediterraneo10
Do LTE chips also support GLONASS and BeiDou, or do phone makers have to
install a separate chip for those systems that Android phones commonly drawn
on?

~~~
cnvogel
[https://www.qualcomm.com/products/qualcomm-9205-lte-
modem](https://www.qualcomm.com/products/qualcomm-9205-lte-modem)

The Qualcomm® 9205 LTE modem is our next-generation ...

Qualcomm 9205 uses the latest generation (gen9) Qualcomm® GNSS engine ...

Location

Satellite Systems Support: GPS, GLONASS, Beidou, Galileo ...

------
saagarjha
If you're looking for another source, Apple released iOS 9.3.6 and iOS 10.3.4
to fix the same bug: [https://support.apple.com/en-
us/HT210239](https://support.apple.com/en-us/HT210239), which will stop
working correctly on November 3rd if not patched.

------
ilogik
My understanding is that the only bad thing that will happen is that the GPS
will show the wrong date (I think the time will still be correct?)

The coordinates will still be correct.

~~~
molmalo
From my experience (we had to change/fix a couple thousand devices in my
company), some gps modules simply stopped reporting valid positions, returning
just all zeroed.

------
throwaway_bad
I was recently trying to set a cookie to "never" expire.

Apparently there's no good way to do this other than pick a date that's far
enough out in the future.

A stackover answer gave an example setting it for 10 years. I thought I would
be defensive and set it to 20 years.

But then it will immediately break because 32 bit dates wrap around in 2038!

~~~
onion2k
It's bad enough supporting browsers from 10 years ago now. If we get to 2038
and I still need to support browsers from 2019 I'm going to be very sad
indeed.

~~~
bluGill
What is your target? I work in embedded systems: I fully expect software I
write today to run for the next 100 years. This is based on experience, we
have customers still using 75 year old machines to do real work (that is not
collectors) and I like to think engineering has learning something about
making better machines since then. I think that computers will forever be able
to drop back to 10baseT ethernet, ipv4 and html 1.0.

Of course I don't expect everybody will be able to support those
configurations. There are currently unknown security holes someplace in out
old equipment so nobody sane will connect our old stuff to the public
internet. Thus most developers are safe depending on users having something
fairly new. However a few will target behind the firewall customers and they
will be stuck supporting whatever that old machines supports.

~~~
devtul
After watching a few Def Con talks, I' am sure there is a good chance of a
very dedicated asshole out there trying to target those old systems.

~~~
bluGill
This has kept me awake at nights for years... It is now keeping boards of
directors up at nights unlike a few years ago when I was told not to worry.

No solution is in sight, but things are getting better.

