Could we live without GPS? , Now this sounds like a bit of a daft question, I mean what
is the worst that could happen, maybe we would all have to learn to use a map again.
But seriously, the GPS service which was launched in 1978 for the US military and fully available
to the world since 1994 is now so embedded into our infrastructure it's being called
the worlds utility service so what might happen if it stopped working.
This video is sponsored by Stührling – For the Time of your Life!
Now whilst most people think that the GPS system is just there to act as a navigation
aid to find your way around in a car, it’s also found its way into virtually everything
that moves and other vital areas like the electrical power grid, banking, trading and
mobile communications This is where a failure of the system be that
by natural causes like a solar storm or deliberate sabotage could have effects that would be
far more profound than just having to dig out you old maps once more.
In a recent report sponsored by the US government, it was estimated that a GPS outage would cost
the US alone about $1 Billion per day with the effect getting worse as time goes by until
backups or new procedures are put in place. The report also found that since 1984, GPS
has created about $1.4 Trillion in economic benefits, most of that since 2010, so you
can see just how big it has become. At the heart of this is time. All the GPS
systems, be that the original US version or the Russian GLONASS, the European Unions Galileo,
China’s Beidou and the other proposed national systems all work on the same principle and
are in essence, extremely accurate syncronised clocks in constellations of satellites spread
around the globe sending out timing signals which are picked up by GPS receivers like
the ones in your smartphone or Satnav. It’s the accuracy of these timing signals
which is key and makes it all so very useful for so many applications.
The original US GPS system has at the moment 30 operational satellites in orbits of approximately
20,200km above the earth. Each one of these satellites has an atomic clock onboard which
is synchronised to the master clock at the United States Naval Observatory in Washing
DC to within 10 nanoseconds or 10 billionths of a second.
Each satellite broadcasts a continuous signal which gives its position in space and a timestamp.
Each is also is resynchronized every day to the master clock in Washington to take into
account any drift in the satellite's clock that might have built up in the past 24 hours
and for special relativity, because changes in the earth's gravity would affect the clocks
time to an outside observer especially when we are dealing with nanosecond timing.
To give you an idea of how critical this timing is, if there was a timing error of 1 microsecond
or 1 millionth of a second, your satnav could have an error in the region of 330km or 200
miles. Because of how important GPS now is, the Schriever
airforce base were the Master control station is located, is heavily guarded and is amongst
the largest concentration of classified areas in the airforce.
Where ever you are on earth and because of their numbers and positioning, the are always
between 6 and 10 GPS satellites in line of sight but the signal from 20,000km in space
is very weak and can be affected by the ionosphere. The GPS receiver searches for the 4 strongest
satellite signals and uses the satellites location information and the delay in the
time it takes for the signal to arrive at the receiver from each satellite to calculate
it’s position anywhere on the earth, the more accurate the timing, more accurate will
be the position. Because the GPST or GSP Time is linked to
one of the most accurate atomic clocks in the world and is completely free for anyone
to use, it is by default the most accurate clock available worldwide and much cheaper
than operating your own atomic clock. So how does this affect things like the power
grid. Well, in the old day's power grids were separate entities operated by different companies
in different states or even countries. As the requirement for power grew, grids had
to become connected. To do this, the electricity which is sent
as alternating current at normally 50 or 60 hertz has to match the frequency and phase
of a connecting grid or they could cause serious damage to each other. A system called SCADA
or Supervisory Control And Data Acquisition was developed used to monitor the electrical
supply and synchronise the different grids but it could take up to 30 seconds between
the measurement and the transmission of the data and this led to regular blackouts as
grids overloaded when they became out of sync with each other.
In the 1980’s synchrophasors began to be used, these systems gathered data once every
second and instantly transmitted it to the control rooms allowing much tighter control
of power from many different sources but they had to be synchronised together to work.
As time has gone by it become easier to use GPS time as the timing source for the synchrophasors
because this is a worldwide standard and allowed larger and larger grid configurations spanning
multiple countries. However, GPS is a 1970’s technology which
was never intended for such critical infrastructure control, not because it doesn’t work, on
the contrary, it works very well, the problem is security because even on the military side
it is using standards which are decades old. The signal is also weak signal its also very
easy to jam completely or spoof it, that is override it with a fake signal with fake timing
information. This is something which in the beginning was only thought possible by other
advanced nation-states but with the advancement of technology, almost anyone can now buy the
equipment to do this. There have been instances when people have
been using GPS jamming devices on trucks so as not the be tracked at work but the side
effect was to block all the GPS signals for few kilometres around them. This might be
an inconvenience to other GPS users on the road but when they came to an airport it caused
major issues for tracking and guidance of smaller planes and vehicles using it.
In 2011, Its thought that a drone operated by the CIA over the city Kashmar in Iran was
brought down by spoofing one of its GPS receivers, something which was later proven in 2012 in
tests in the US. If the GPS timing of a grid synchrophasor
was spoofed and off by more than 26.5 microseconds it would compromise the integrity of the grid
that could backout entire regions. But while GPS timing of synchrophasors is
still a limited but rapidly growing area, financial trading is almost completely reliant
GPS timing for high frequency automated trading. The trading systems work by taking advantage
of the market before the effect of news becomes apparent.
In this time, Millions of transactions can trade billions of dollars in seconds and this
requires sub-microsecond timing with the trading computers often co-located in the network
centres to avoid delays, even the position in the room and the exact length of cable
used to connect them to the network becomes critical.
Some network providers hire out the use their own atomic clocks as a source of timing but
many smaller traders use the GPS timing because there can still be a sub-microsecond delay
as the private clocks sync up to the national standard used by the GPS at midnight and as
they say time is money and in this case that is very true as billions could be traded in
the wrong way because of a microsecond timing error
Another area of concern is mobile communications. Mobile phone towers use the GPS timing to
synchronise their internal clocks which are used to multiplex calls into a digital data
stream and pass them from tower to tower before re-assembling them and sending them to the
correct phone. If the timing is out between the towers then the calls would be scrambled
and lost. It's estimated that after a 30 day GPS outage,
the communications network functionality would be between 60% and zero depending on how quickly
the towers went out of sync. It not just spoofing and jamming which causes
concern, space weather and in particular, the radio noise created by solar storms can
cause the weak GPS signals to be lost and in the worst-case scenario a massive solar
storm on the same order of magnitude as the Carrington event of 1859 could even wipe out
most of the GPS satellites, though if that were to happen now, losing the GPS signal
might be the least of our problems. There is also concern that the US military
is far more reliant on GPS than either Russian or Chinese and any attack on the system be
that directly on the satellites or by uploading false data could have an adverse effect on
the US. For this reason, the US now holds military exercises in which the GPS receivers
are turned off and alternative methods are used.
In 2018 the GPS Block III upgrade started and will of consist of 10 new satellites by
2023. These will have greater signal power and new secure coding for the military signals
and an additional frequency for the civilian one, which will allow compatible receivers
to remove the delaying effects of the ionosphere. Other GPS systems like the EU’s galileo
can work with the US GPS to create a larger more available GPS signal.
So is there anything we could do if we lost the GPS system. Well, there are other older
land-based radio navigation systems which are still in use, one in particular called
LORAN dates back to WW2. In recent years it has been updated to eLORAN and because it
is basically a timing service it could be used as a substitute for GPS.
Being land-based means that the signal is over million times stronger than GPS and therefore
much more difficult to jam or spoof but it only covers areas were eLORAN transmitters
are placed so it's not a worldwide service. The UK now uses eLORAN for navigation control
thru the straights of Dover in the English Channel, the busiest waterway in the world
because of fear that a GPS system could be knocked out by a spoofer on either side of
the channel So could we survive without GPS, yes we could
but as we have never lived in a world where it suddenly disappeared, it’s loss on a
worldwide basis is still unknown, but one thing is for sure, the more time goes by and
the more integrated GPS becomes into our way of life the bigger and more profound the effect
will be.
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