June 2015 - AMSAT-BB - mailman.amsat.org

PSAT digipeater is ON
by Robert Bruninga 01 Jun '15

01 Jun '15

I just turned on the PSAT digipeater. You will notice that its callsign in this mode is just “PSAT” and not PSAT-1 when it is in SAFE mode. The ALIASes supported are ARISS and APRSAT. The PSK-31 transponder also remains in AUTO mode meaning it will come up whenever there are PSK31 signals on the 28.120 + frequency. Bob, WB4APR

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Re: [amsat-bb] PSAT key to success
by Robert Bruninga 01 Jun '15

01 Jun '15

Until we get authors adding Full duplex and AFC to their PSK31, here is a scheme that will work. Focus on the OVERHEAD pass. Horizon to Horizon. Because during these passes, the satellite is coming right at you for the first 5 minutes, and directly away from you for the next 5 minutes. This means the Doppler is nearly constant high during the first 5 minutes and then a rapid shift to a constant LOW for the last 5 minutes. And horribly shifting for the middle 1 minute. Your signal will have very little Doppler on the downlink and most anyone with any kind of PSK31 decoder will decode you fine. Don't do any frequency transmitteirn shift on the uplink or as KO6TZ says, you will cause people to lose lock.. When the satellite crosses overhead, you can then shift your TX frequency UP by 1.15 KHz and people will see you more or less back where you started... maybe. Bob, Wb4aPR -----Original Message----- From: AMSAT-BB [mailto:[email protected]] On Behalf Of KO6TZ Bob Sent: Sunday, May 31, 2015 4:39 PM To: amsat-bb(a)amsat.org Subject: Re: [amsat-bb] PSAT 1925 pass >Some of the traces I watched were pretty horribly Doppler shifted and not sure if MixW is able to decode that >coming up from ten meters and drifting like the ones I sw. From me experience on DO-64 and FO-29 using PSK31/63, I found adjusting for Doppler on the SSB up-link is a double edged sword. When the frequency is updated for Doppler, you loose sync for a few characters. If you don't correct the frequency, you will exceed the AFC limit of most programs, except WINPSK. WINPSK doesn't support multi line copy. Also using DigiPan in "munti" mode, there is no AFC. The s/w just creates another line. Pick your poison..... KO6TZ Bob _______________________________________________ Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb

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UT1FG
by Nicholas Mahr 01 Jun '15

01 Jun '15

Hey all, Just wanted to know, is Yuri still on his expedition? Or is he done now?

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LightSail identified
by Nico Janssen 01 Jun '15

01 Jun '15

All, Using detailed doppler shift measurements, I find that LightSail is object 90726, ULTRASat 7, without any doubt. This means that LightSail is actually object 40658, 2015-025H in the JSpOC catalog. The preliminary initial assignments in the JSpOC catalog for the objects in this launch will need to be corrected: PSAT = 90720 = ULTRASat 1 = 40652 = 2015-025B LightSail = 90726 = ULTRASat 7 = 40658 = 2015-025H BRICSat = 90729 = ULTRASat 10 = 40661 = 2015-025L 73, Nico PA0DLO

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