[amsat-bb] Re: Galileo interference on L band

[John B. Stephensen]

The 1215-1240 MHz portion of our 23 cm band was deleted to protect GPS, so 
it could happen again.

73,

John
KD6OZH

----- Original Message ----- 
From: "i8cvs" <domenico.i8cvs at tin.it>
To: "John B. Stephensen" <kd6ozh at comcast.net>; "Marc Franco" 
<lu6dw at yahoo.com>; <amsat-bb at amsat.org>
Sent: Thursday, September 21, 2006 04:15 UTC
Subject: Re: [amsat-bb] Re: Galileo interference on L band


> ----- Original Message -----
> From: "John B. Stephensen" <kd6ozh at comcast.net>
> To: "Marc Franco" <lu6dw at yahoo.com>; <amsat-bb at amsat.org>
> Sent: Wednesday, September 20, 2006 10:13 PM
> Subject: [amsat-bb] Re: Galileo interference on L band
>
>
>> The article predicts that there may be limitations on the amateur 
>> service.
>> The biggest problem is sidelobes from the antenna that can be of either
>> polarization sense. A 16 kW EIRP uplink can easily generate 500 W EIRP
>> sidelobes (15 dB down) within the Galileo receiver passband and,
> replicating
>> the calculations outlined in the article, they can cause interference 
>> from
>> 42 km away.
>>
>> 73,
>>
>> John
>> KD6OZH
>
> Hi John, KD6OZH
>
> Does this imply that all 23 cm EME stations including G3LTF will have to
> move away from 1296 MHz ?
>
> 73" de
>
> i8CVS Domenico
>
>
>> ----- Original Message -----
>> From: "Marc Franco" <lu6dw at yahoo.com>
>> To: <amsat-bb at amsat.org>
>> Sent: Wednesday, September 20, 2006 19:03 UTC
>> Subject: [amsat-bb] Galileo interference on L band
>>
>>
>> > John,
>> >
>> > Galileo is circularly polarized, so using the opposite
>> > polarization sense will help.
>> >
>> > An excellent paper on Galileo interference was written
>> > by Peter Blair, G3LTF, a well known moonbounce
>> > authority and outstanding engineer. The paper can be
>> > found following this link:
>> >
>> > http://www.southgatearc.org/articles/galileo.htm
>> >
>> >
>> > 73, Marc N2UO
>> >
>> >
>> > --- "John B. Stephensen" <kd6ozh at comcast.net> wrote:
>> >
>> >> Unfortunately, the Gaileo downlink covers 1258-1299
>> >> MHz, the first satellite
>> >> has been lanched and the satellites in the
>> >> constellation will be on over the
>> >> entire world. Our uplink antennas have sidelobes
>> >> that are 10-20 dB down, so
>> >> a 1 kW EIRP SSB uplink results in 10-100 W radiated
>> >> towards terrestrial
>> >> receivers. A 256 kbps uplink would require 16 kW
>> >> EIRP and be 0.5-1 MHz wide.
>> >>
>> >> P3E has a second L receiver tuned to a null in the
>> >> Galileo signal (there is
>> >> only one null in the 1260-1270 MHz band) but no one
>> >> knows if this will help.
>> >> SSB users can move to the U uplink if L is a
>> >> problem. However, this only
>> >> works for narrowband signals. A wideband uplink
>> >> won't fit in the null and
>> >> can't move down in frequency.
>> >>
>> >> 73,
>> >>
>> >> John
>> >> KD6OZH
>
>