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
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2-line TLE
NORAD ID: 40661U
International code: 2015-025L
Current LightSail TLE being used on sail.planetary.org/missioncontrol
(best fit is ULTRASat8 - not confirmed)
1 40661U 15025L 15150.55115000 +.00017130 +00000-0 +45788-3 0 00150
2 40661 055.0112 297.1659 0249189 205.9605 230.4519 15.12499718001507
===
w9gb
Sent from iPad Air
31-5-2015 21:33 UTC
2:Fm PSAT-1 To APOFF Via ARISS <UI R Pid=F0 Len=34> [18:33:48R]
T#820,850,070,743,685,810,00011100
73s de LW8EXS
Mercedes ( Buenos Aires ) Argentina
Hi all,
Tried listening for PSAT for the first time, and had a really nice
pass. I don't have the 10m uplink side configured, and this was all
manually tuned. So I still have a bit of work to do, but the results
exceeded my expectations. Signal peaked at S6 or so, full quieting.
I think the Keps (object 90721 Epoch 150.54728009) were a little ahead
of reality, maybe 30 seconds to a minute. There was some QSB, but it
could also have been my coarse antenna rotation and manual tuning.
Radio was a Yaesu FT-847, 2x16 element beam, and with FLDIGI on my Linux
box, using the internal (motherboard) sound card.
Greg KO6TH
W3ADO-5 beacon B 019 43 25 800 260 +10
W3ADO-5 beacon B 020 18 23 797 260 +12
W3ADO-5 beacon B 021 31 23 806 260 +1c
W3ADO-5 beacon B 000 43 26 802 249 +11
W3ADO-5 beacon B 002 99 35 796 251 +15
W3ADO-5 beacon B 003 65 30 800 252 +16
W3ADO-5 beacon B 004 99 32 802 252 +17
W3ADO-5 beacon B 007 93 42 796 252 +19
W3ADO-5 beacon B 008 87 23 796 252 +19
tuning (er, clicking) around, found...
CQ CQ PSAT KO6TZ KO6TZ
CQ CQ PSAT KO6TZ KO6TZ
These seemed pretty solid, doppler-wise, but later I couldn't quite lock
on to the subsequent QSO (doppler shift slightly too much for FLDIGI)
back to the beacon...
W3ADO-5 beacon B 011 31 42 798 249 +18
W3ADO-5 beacon B 000 40 31 802 248 +17
W3ADO-5 beacon B 001 81 42 795 251 +19
W3ADO-5 beacon B 002 34 31 799 251 +20
W3ADO-5 beacon B 003 87 37 800 252 +21
W3ADO-5 beacon B 006 68 38 792 251 +22
W3ADO-5 beacon B 007 87 23 792 252 +22
W3ADO-5 beacon B 008 46 43 791 250 +22
W3ADO-5 beacon B 006 37 28 817 250 +23
I have for sale a Cushcraft 214 two meter beam. This beam covers 144-146mhz
and has 15 elements on a 15 foot boom, 15.5 dB forward gain and a 24 DB F/B
radio. Good condition it just needs a boom to mast clamp, something you
can probably make up yourself.
This would make a nice uplink antenna for Mode J, or Mode B receiving
antenna. I am asking $60 plus shipping for it. Pickup is also possible in
SW Oklahoma area. I can take paypal/check/MO.
73 John AF5CC
I have for sale a set of 4 10 element 70cm antennas. These have 6 1/2 foot
booms and are end mounted. With these antennas comes the H frame stacking
framework with mounting brackets. The stacking distance is 3 feet by 4
feet. It also comes with the power divider for the 4 yagis. Everything
you need to get the 4 bay system going is there. The antennas are homebrew
but very well made, resembling M2 yagis. This system has been used for
70cm EME with good results. The 4 antennas have a common horizontal cross
boom to mount in an elevation rotor if desired.
I would prefer a face to face deal but shipping is possible if you are
willing to pay shipping. I can meet someone in the OKC area, around the
Dallas/Fort Worth area, SW Oklahoma or North Texas. You can come to
Lawton, OK and pick them up also. It might be possible to deliver this
setup to Central States conference in July as well.
I am not sure exactly what these are worth, but will entertain offers.
This setup will give you a big signal on mode B, or great reception on Mode
J, that is for sure.
73 John AF5CC
I've been observing that with the current keps the Downlink frequency of the
PSK31 beacon is about 2Khz low.
A good US pass over the US at about 1936.
What I have been doing is decoding the entire 3 KHz with DM780's
Supersweeper or Fldigi and fixing TX at about 600Hz.
That way I catch everybody and there is no need to match frequencies.
I've been trying to TX below 1KHz to minimize interfering with folks
operating normal 10m PSK.
Dave W0DHB
