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<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;
mso-outline-level:1"><b><span
style="font-size:14.0pt;font-family:"Times New
Roman";
mso-font-kerning:18.0pt">From:<span style="mso-spacerun:yes">
</span>The
Register (British IT News Site)</span></b></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;
mso-outline-level:1"><b><span
style="font-size:14.0pt;font-family:"Times New
Roman";
mso-font-kerning:18.0pt"><a class="moz-txt-link-rfc2396E" href="https://www.theregister.co.uk/2019/02/12/current_gps_epoch_ends/"><https://www.theregister.co.uk/2019/02/12/current_gps_epoch_ends/></a></span></b></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;
mso-outline-level:1"><b><span
style="font-size:24.0pt;font-family:"Times New
Roman";
mso-font-kerning:18.0pt"><br>
</span></b></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;
mso-outline-level:1"><b><span
style="font-size:24.0pt;font-family:"Times New
Roman";
mso-font-kerning:18.0pt">Fun fact: GPS uses 10 bits to store
the week. That
means it runs out... oh heck – April 6, 2019</span></b></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;
mso-outline-level:2"><b><span
style="font-size:18.0pt;font-family:"Times New
Roman"">Nav
gadgets will be Gah, Properly Screwed if you don't or can't
update firmware</span></b></p>
<p class="MsoNormal"><span style="font-family:"Times New
Roman"">By <a
href="https://www.theregister.co.uk/Author/Shaun-Nichols"
title="Read more by this author">Shaun Nichols in San
Francisco</a> 12 Feb 2019 at 21:37
</span></p>
<p class="MsoNormal"><span style="font-family:"Times New
Roman""> </span></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-family:"Times New Roman"">Older satnavs
and such devices won't be
able to use America's
Global Positioning System properly after April 6 unless they've
been suitably
updated or designed to handle a looming epoch rollover.</span></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-family:"Times New Roman"">GPS signals from
satellites include a
timestamp, needed in part to calculate one's location, that
stores the week
number using ten binary bits. That means the week number can
have 2<sup>10</sup>
or 1,024 integer values, counting from zero to 1,023 in this
case. Every 1,024
weeks, or roughly every 20 years, the counter rolls over from
1,023 to zero.</span></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-family:"Times New Roman"">The first
Saturday in April will mark the
end of the 1,024th week, after which the counter will spill over
from 1,023 to
zero. The last time the week number overflowed like this was in
1999, nearly
two decades on from the first epoch in January 1980.</span></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-family:"Times New Roman"">You can see
where this is going. If
devices in use today are not designed or patched to handle this
latest
rollover, they will revert to an earlier year after that 1,024th
week in April,
causing attempts to calculate position to potentially fail.
System and
navigation data could even be corrupted, we're warned.</span></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-family:"Times New Roman"">"GPS devices
with a poorly
implemented GPS Time-to-UTC conversion algorithm may provide
incorrect UTC
following a week number rollover," US Homeland Security
explained in <a
href="https://ics-cert.us-cert.gov/sites/default/files/documents/Memorandum_on_GPS_2019.pdf"
target="_blank">its write-up</a> (PDF) of the issue this week.</span></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-family:"Times New Roman"">"Additionally,
some GPS devices that
calculate the week number value from a device-specific date
rather than the
start of the current GPS Time Epoch may provide incorrect UTC at
some other
device-specific date."</span></p>
<p class="MsoNormal"><span style="font-family:"Times New
Roman""><span style="mso-spacerun:yes"> </span>As the <i>Reg</i>
reader who tipped us off to
the shortcoming noted, this could be a significant headache for
data centers
that use GPS timing for synchronization.</span></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-family:"Times New Roman"">"Decent vendors
should have patches.
But who has been thinking about this?" our tipster told us.
"This
could be a low-key Y2K style bug all over again, but with
companies doing less
preparation."</span></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-family:"Times New Roman"">Fortunately,
devices on sale right now
should be prepared for this rollover and handle it gracefully.
Uncle Sam's GPS
nerve-center <a
href="https://www.gps.gov/cgsic/meetings/2017/powers.pdf"
target="_blank">GPS.gov says</a> (PDF) receivers that follow
the
ICD-200/IS-GPS-200 specification should be able to deal with the
week number
overflow. This basically means newer receivers built after, say,
2010 should be
fine, provided they follow the <a
href="https://www.navcen.uscg.gov/?pageName=gpsTechnicalReferences"
target="_blank">specs</a> and notice the rollover.</span></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-family:"Times New Roman"">To put it
another way, if your gadget
goes haywire in April, it's probably because of this. If it
works as normal:
brilliant, it's not affected. Consider yourself forewarned.</span></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-family:"Times New Roman"">GPS.gov also
notes that the new CNAV and
MNAV message formats will use a 13-bit week number to solve the
epoch migraine
right up until the planet becomes uninhabitable via climate
change or we all
blow ourselves up.</span></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-family:"Times New Roman"">For devices
unprepared for the counter
overflow, a firmware upgrade will be necessary to keep the
things working
properly. GPS.gov recommends those unsure about their readiness
for the
turnover, particularly enterprises, should consult the
manufacturer of their
equipment to make sure they have the proper updates in place. ®</span></p>
<p class="MsoNormal"> </p>
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