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Re: L-Band



Well I am not sure what is intended to be on the L5 frequency in terms of
power/link budget from the satellites but someone should tell the DOD etc
that here in Europe at least there are many ( ie tens of ) civilian air
traffic control radars
on and around 1250 MHz.

Their peak powers are in the gigawatt range and although the highly
directional dishes
tend to point upwards a bit, they radiate lots towards the horizon.

Also it should be noted that many of them are not located at airports but on
tops of hills/
mountains to give area coverage.

Not the sought of RF environment that would suit weak signal handheld GPS
receivers running
on a couple of AA batteries with a patch antenna IMHO!

BTW before anyone else brings it up I have to declare a non AMSAT  interest
in these frequencies-
I am also involved in planning ATV repeaters in the UK and most of these
have inputs around the
1245-1250 frequencies. - and yes we do co-exist with the radars!

The 1250 possibility first came to my notice at the IARU Region 1 Conference
in Tel Aviv in '97 but
I had not been able to find out any further information up to just now.

If any more detailed information is available/emerges I would be most
interested in it!

73's to all


Graham G3VZV



-----Original Message-----
From: Santillo, John <SANTILLOJ@pcmail.systems.gec.com>
To: AMSAT BB <amsat-bb@AMSAT.org>
Date: 14 April 1998 16:23
Subject: L-Band


>Hello all.  The below information came out of the Hudson Division
>Loop newsletter.  Althought it doesn't impact satellite uplink
>frequencies directly, I thought it might be of interest to the group.
>
>
>
> *** From "The ARRL Letter" 4/10/98:  The ARRL has learned that
>the second civilian frequency for the Global Positioning System
>(GPS) could wind up within Amateur Radio's secondary allocation
>at 1.2 GHz.  A decision on whether the new, second frequency will
>be 1205 or 1250 MHz is expected to be made in August.  An
>allocation at 1250 MHz could mean the end of Amateur Radio in the
>band 1240 to 1260 MHz.  The Amateur 23-cm band runs from 1240 to
>1300 MHz.
>     In February 1997, the Departments of Transportation (DOT)
>and Defense (DOD) announced an agreement assuring civilian GPS
>users of a second frequency--referred to as L5 and considered
>essential for critical civilian GPS uses.  According to a DOD
>news release, the White House Commission on Aviation Safety and
>Security, chaired by Vice President Al Gore, "called for the
>establishment of a second civil frequency as part of a broader
>program to maintain US leadership in aviation and satellite
>technology."  For more information, see
>http://www.defenselink.mil/news/Feb1997/b022797_bt095-97.html.




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