S1 downlink coordination and interference mitigation
Folks,
Coincidentally at the Symposium, Graham Shirville spent some time coordinating proposed frequencies to some satellites, including Eagle, and after a suggestion I had from from Drew KO4MA, I reiterated to Graham that it may be advantageous to propose S1 frequencies right down at the bottom 1MHz of the 2.4GHz satellite allocation.
802.11 specifies a 1MHz guard band at 2400 to 2401MHz for regulatory OOB emission reasons. Signals +/-11MHz from the centre must be at least 30dB down from the carrier. Channel 1 is at 2412MHz.
Taking into account Doppler, the recommended S1 coordinated frequencies will be at the bootom end of 2400MHz without the possibility of OOB emissions on Earth due to Doppler.
73, Howard G6LVB
Howard et al
The linear transponder on ESEO will also be 'as close to 2400 as possible'. Given that the orbits of ESEO and Eagle are planned to be fairly similar (low inclination GTOs AFAIK) I would assume that the downlinks won't overlap, as there will be times when both satellites will cover the same footprint?
regards
Grant
Howard Long wrote:
Folks,
Coincidentally at the Symposium, Graham Shirville spent some time coordinating proposed frequencies to some satellites, including Eagle, and after a suggestion I had from from Drew KO4MA, I reiterated to Graham that it may be advantageous to propose S1 frequencies right down at the bottom 1MHz of the 2.4GHz satellite allocation.
802.11 specifies a 1MHz guard band at 2400 to 2401MHz for regulatory OOB emission reasons. Signals +/-11MHz from the centre must be at least 30dB down from the carrier. Channel 1 is at 2412MHz.
Taking into account Doppler, the recommended S1 coordinated frequencies will be at the bootom end of 2400MHz without the possibility of OOB emissions on Earth due to Doppler.
73, Howard G6LVB
Via the Eagle mailing list courtesy of AMSAT-NA Eagle@amsat.org http://amsat.org/mailman/listinfo/eagle
Hi Grant
The linear transponder on ESEO will also be 'as close to 2400 as possible'. Given that the orbits of ESEO and Eagle are planned to be fairly similar (low inclination GTOs AFAIK) I would assume that the downlinks won't overlap, as there will be times when both satellites will cover the same footprint?
I am sure that this will be taken into account, including the possibility of Doppler overlap expecially if one is approaching and the other receding. Perhaps a few more kHz too for crystal instability.
I originally raised this point of using the WiFi guard band really because it's a way of mitigating at least somewhat against interference, so that if anyone had any further comments I thought raising it here was as good as any. As I understand it, Eagle frequencies are definitely not set in stone, and paperwork needs to be formally submitted from AMSAT-NA/Eagle for IARU coordination. As the Eagle proposals are now ratified by the BoD, it was useful for Graham Shirville to be able to put it in the mix for other known S1 requirements, including ESEO and P3E, prior to a formal request.
73 Howard, G6LVB
participants (2)
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Grant Hodgson -
Howard Long