John - a PS,
Maybe I was reading too much into Rick Hambly's response yesterday when he stated that "we now have a band pan" without referring to L Band being in the plan, digital or analog. Hopefully, that was just a minor oversight on his part.
Regards...Bill - N6GHz
-----Original Message----- From: John B. Stephensen [mailto:kd6ozh@comcast.net] Sent: Sunday, September 10, 2006 11:18 PM To: Bill Ress; jules@g0nzo.co.uk; amsat-bb@amsat.org Subject: Re: [amsat-bb] Re: 10mtr and Galileo
Its not NIH but conservatism. With no secondary receiver, we need to be certain that there will be no problems in the future. If we were certain that there will be no government intrusion, then L band would be better as there are more high-power amplifiers avalable off-the-shelf today.
73,
John KD6OZH
----- Original Message ----- From: "Bill Ress" bill@hsmicrowave.com To: "John B. Stephensen" kd6ozh@comcast.net; jules@g0nzo.co.uk; amsat-bb@amsat.org Sent: Monday, September 11, 2006 06:02 UTC Subject: RE: [amsat-bb] Re: 10mtr and Galileo
Hi John,
Consider this.
- Galileo operating frequencies are already co-located with existing
ground
ATC radar systems. It has been indicated that the Galileo receivers will need to consider these and other interference issues (like us) and build
in
anti-jamming capabilities. Our GPS system upgrades are already working further in this direction.
- Amateur L-Band satellite transmissions from a single operator would
typically occur for short periods of time. A moving vehicle (car or plane) with a Galileo receiver would quickly be moving itself away from an
Amateur
transmission site. So statistically the chances for interference between a fixed Amateur transmission and a plane or car have to be very, very small and then only for a very short period. I've seen AMSAT comments about the possibility of an Amateur L-Band satellite transmission bringing down a
747.
Don't think so.
- I understand that interference could cause loss of acquisition lock but
that code reception would "free-wheel" until lock is restored. In other words, already there appears to be a way of handling momentary
interference.
- Galileo, when (if) built out will employ 27 active satellites in a
medium
earth orbit (23,616 km). I'm not sure how many satellites will be in view
at
any one time but one must consider that not all visible satellites signals will be interfered by an Amateur L-Band satellite transmission which will
be
using rather directional antennas.
- I understand that the P3E folks have already worked out a solution by
locating their L-Band operations in what will be a Galileo spectrum null.
If
that is the case, then the P3E folks are really using some good "science"
to
develop their satellite L-Band operations. Good for them!!
Hey - I'm not in the thick of it - but it seems there are some serious
gaps
in communication between AMSAT-DL and AMSAT-NA even though we read about glimpses of real technical exchange. I hope we're not falling for the NIH (Not-Invented-Here) syndrome.
Regards...Bill - N6GHz
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org]On Behalf Of John B. Stephensen Sent: Sunday, September 10, 2006 7:47 PM To: jules@g0nzo.co.uk; amsat-bb@amsat.org Subject: [amsat-bb] Re: 10mtr and Galileo
What bothered people is the fact that we need high power L-band uplinks
and
the statement in the report that "there is the potential for most amateur
23
cm transmissions to interfere with Galileo unless the Galileo receivers
are
designed and built to withstand it".
73,
John KD6OZH
----- Original Message ----- From: jules@g0nzo.co.uk To: amsat-bb@amsat.org Sent: Sunday, September 10, 2006 23:37 UTC Subject: [amsat-bb] Re: 10mtr and Galileo
Just for the record, the first Galileo satellite has already been
launched:
http://news.bbc.co.uk/2/hi/science/nature/4566264.stm
Also there was a study made by the UK microwave group (the body
representing
UK amateur interests above 1GHz), which makes interesting reading. It suggests that the signals from Galileo would have little impact on terrestrial/EME 23cms opperation. Obviously the conclusions woule
require
a
little re-interpretation, with respect to satellite based reception. But
as
Galileo transmissions will presumably be aimed at the earth, so that any amatuer satellite will receive signals greater than that on earth, for a minute part of it's orbit, I would think that the conclusions drawn
would
still be valid. It's an interesting read: http://www.microwavers.org/papers/iaru/C5-13_Galileo.pdf
Jules G0NZO
Speaking of allocations being taken away, I just can't fathom the AMSAT decision to drop L-Band up because of the "Galileo Affair." Now that's
a
decision based on "crystal ball engineering" and not fact. I've even
read
that if Galileo ever was launched - and that appears in the latest
press
to
be questionable" the US "would has threatened to shoot them down!"
Regards...Bill - N6GHz
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Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb