First Lightsquared Interference Meeting

http://www.gpsworld.com/gnss-system/gps-modernization/news/first-lightsquaredgps-working-group-meeting-held-11197

They couldn't agree on what constitutes an acceptable level of
interference. What's so difficult? Let's start with something like
this:

'The accuracy of a GNSS receiver shall not be degraded when operating
outside the near field of the LTE station antenna'

Let's say 10 wavelengths defines the near/far field boundary. We can
argue about specific definitions and conduct of testing from there.

Lightsquared isn't allowed to turn on an actual base station for field
testing? Nonsense .. set one up at a remote test site and issue a
Notice of Testing. Conduct Working Group defined testing and then set
aside a block of time granting anyone who engineers, designs or
manufactures GNSS devices access to the test site.

Well, this is not what the FCC wants to hear.

--- CHAS

I wonder what the situation is for military devices. Are they effected?
Given that GPS is essentially a military system, I would sort of expect the
military to have reserved a sufficient guard band to avoid interference or
otherwise, the right to block any installation that would interfere with
their equipement.

(Some time ago, the Dutch military just blocked the use of 3.5 GHz for Wimax
in a large part of .nl because it would interfere with some military
installation)
--
That was it. Done. The faulty Monk was turned out into the desert where it
could believe what it liked, including the idea that it had been hard done
by. It was allowed to keep its horse, since horses were so cheap to make.
        -- Douglas Adams in Dirk Gently's Holistic Detective Agency

On Thu, 10 Mar 2011 13:56:46 +0100, Philip Homburg wrote:

Yes, they're affected.


The military has some pretty strict "hands off the home soil" rules to
follow.



--
Christian Biblical literalists are trusting themselves to an archaic
English translation of a Latin translation of (help me here) Greek?
Aramaic? source. I wouldn't even trust a VCR manual to make it through
that intact. - Dr. Dee

From what I understand that applies to military operations. Then can't
go out shooting bullets anybody outside of their bases. Its much like
NY police would be in trouble if they arrested someone in LA without
having an LA cop alongside.
But that in no way shape of form prevents the Air Force from sending
military personnel or contractors with military GPS receivers to test
their stuff wherever lightsquare testing takes place. That would be a
technical activity.
L1M should be hit hard. The hardest.
But L1M isn't being used at all today, just for testing. Need to
launch another 10 IIF satellites before M-Code is officially useable,
plus OCX needs to be in place to monitor the M-Code signal integrity.
But Aviation in general will be hit just as hard. Doppler effect at
jet speeds aren't insignificant, that pushes aviation receivers to
look a little farther out. An F22 high speed cruise is about twice the
cruise speed of business jets, so twice the Doppler effect.
At the same time, I'm surprised people talk about 1000 Watts. All
modern telecom stuff irradiates just a few Watts. The last 20 years
huge advancements in electronics allowed receiver sensitivity to
improve in an astonishing pace. I don't know of any modern wireless
systems that irradiates more than 5W.
But 1 Watt of irradiated power is a LOT of power. Its enough for the
signal to be detectable hundreds of miles away in line of sight (at
high altitude for instance).

Correction I don't know any modern telecom wireless systems that
irradiate more than 5W. Of course there are tons of FM/AM radio
stations in the 100-1000W range. As well as Loran towers had tens of
thousands of Watts of transmitted power, but those are far lower
frequencies that are all far, far away from GPS. But cell phone,
WiMax, WiFi, point to point links, point to multi point systems, they
all transmit signals around 1 Watt.