On Sat, 7 Mar 2020 15:18:00 -0700
Bob Martin aphid1@comcast.net wrote:

Sorry, but there is too much fearmongering in there. We are not losing a
war. At least not the way this nice gentleman depicts it. Yes, China,
Russia and Iran are all upping their game. Yes, they employ it for military
gains as well. But, unless you actually plan to go to war with either
of them, this does not really matter. It seems like a lot of people in
the US are still stuck in the cold war mindset that war is inevitable
and that we should prepare to destroy or be destroyed. Luckily, the world
has changed quite a bit since 1962.

In terms of spoofing, that's has been adressed in many ways. One is
that the US military is replacing all its civilian receivers (which
it used because they were cheaper) by military ones. The new M-code
on the Block II-M and Block III satellites makes this also easier.
Another is that Galileo added capabilities to authenticate the signal
in order to ensure that safety critical systems are not being mislead.
GPS is expected to follow suit (beside the military signals, which
are already authenticated).

Additionally, all airports that offer GPS/Galileo for landing assist
(as far as I am aware of, there is no airport that allowes GPS/Galileo
only based landing) have signal quality monitoring and reporting. In
case the GPS/Galileo signal deviates from what it should be, either
by being jammed (which happens quite often btw) or by being spoofed,
it signals all air planes that they should disregard the GNSS signals.
I have heard of similar systems used at some harbors.

Currently, the only "critical" infrastructure that is kind of unprotected
are the cellphone base stations and DVB-T stations, both of which use
GPS/Galileo for synchronization and syntonisation. But, there an easy
remedy is available through network time distribution (ask Magnus for
details).

Another piece of infrastructure that depends on GNSS are monitoring stations
for the power grid. There it's a bit more difficult, as they don't have
an underlying network infrastructure that would allow them to synchronize.
But these are (currently) just for monitoring and thus are not vital to
the functioning of the power grid. There are discussions on how to mitigate
the risk, though. Luckily, they only need 100µs to 1ms level of accuracy,
so in worst case an OCXO could cover any jamming for a day or two.

If China goes through with their plans to put up another 120 LEO satellites,
that would make life quite a bit interesting, though. Currently, the biggest
problem all GNSS systems have is that the reception in dense urban jungle
(think about an old town in a European city or downtown New York) has only
very few satellites visible at any given point. There are companies that
try to change that using local navigation beacons (e.g. https://foam.space )
but the cost of doing that on ground is comparable to doing it in space.
Japan launched for this very reason the QZSS. It has been puzzling to me
that neither Galileo, nor GPS ever sought to replicate this over the major
centers in Europe and the US. It would definitely help. Now, if China
launches these 120 additional satellites, we will suddenly have a very dense
population up there, which will allow to navigate even between highrises.
This would bring Beidou, which most people currently only see as "just another
GNSS system" to become the major player in cities and with that, in the
largest GNSS market: cell phones.

		Attila Kinali

--
<JaberWorky> The bad part of Zurich is where the degenerates
throw DARK chocolate at you.

GPS gets “clobbered” at North American airports, occasionally.  It complicates the landing approach, but, pilots train for that scenario.

There are companies that offer GPS jammers, that truckers are known to use.  I know of one case, where GPS was jammed for many months at a airport.  The source was never found, but, a truck rental agency was right under the runway approach.  The USA FCC has a tiger team to track down GPS jamming for airports.

KR