----- Original Message ----- From: "John B. Stephensen" kd6ozh@comcast.net To: "Marc Franco" lu6dw@yahoo.com; amsat-bb@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@yahoo.com To: amsat-bb@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@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