PSAT2 is doing great!
PSK31 and SSTV transponder have been on since launch.
SSTV downlinks are looking good.
See Gallery: http://www.urel.feec.vutbr.cz/esl/psat2/sstv/
Still waiting for first report of user PSK31 contacts.
But I have not said much about the VHF modes… because we have had difficulty commanding. This is because the PSAT2 VHF uplink uses an inexpensive narrowband XCVR module which is intolerant of overdeviated signals, exactly what you get with +/- 3 kHz of Doppler.
ANYWAY, we can now consistently command if we set the Kenwood to narrowband NFM and do it right in the middle of the pass. Plus, we can extend that a bit (1.25 KHz after center) by then changing the radio step size to 6.25 Khz where the channel raster ups the channel by 1.25 KHz).
So, we now have command again! You may have seen that we have turned on Sun vector S#... telemetry and can easily see by plotting the 1 minute xyz xyz xyz vector triplets that it is smoothly tumbling at about 1.3 RPM for nice battery charging and good thermal management.
The downlink is live on FINDU:
http://www.findu.com/cgi-bin/raw.cgi?call=psat2-1&time=1
Background:
This last 6 days of crisis was complicated by the fact that I am operating in a temporary dungeon while the building is being renovated and all my 27 years of lab stuff is in 200 boxes surrounding me. I installed a temporary ground station on the top floor and modest antennas and a TV rotator and the contractor let me drill a hole through the wall that they can seal up later. But the big problem is the 8 flights of stairs from my PC and internet connectivity in the dungeon up to the radio 6 times a day for passes with only a few hours sleep and all kinds of what-if-dead-ends. And with passes from 10 PM to 2 AM.
But we are back in the saddle again!
And this good news reprieve is only an hour old, so it will take a while to decide what we want to do next. In any case, the Brno University PSK31 and SSTV transponder has all the power for now, so enjoy.
Uplink USB on 29.4815 and downlink on 435.350 +/- Doppler. The transponder only comes up if there is a user in the uplink with PSK31.
Bob, WB4APR
Glad to hear all the positive news, Bob! Thanks for keeping everyone informed.
Regarding TLE, how sure are we that PSAT-2 is Object 44357 as indicated in:
https://www.celestrak.com/NORAD/elements/tle-new.txt
... at the suggestion of JA0CAW, a very accomplished amateur in Japan, on tonight's passes I attempted to determine whether PSAT-2's downlinks on 145.825 & 435.350 might be stronger by tracking Object 44355 (2019-036S). And, while you can't reach any conclusion from only two passes (nor at such low elevations), by eye & ear the downlinks seemed stronger when tracking 44355.
Of course, any number of factors could skew my result and tonight's observation was subjective at best. But I wanted to put this on the mailing list in case anyone else would like to do any similar tests.
FYI, just like last night I saw short snippets of PSK31 streams around the 280Hz & 375Hz marks but unfortunately still no sign of my 10m PSK31 uplink. I also got a few seconds of clear SSTV audio again tonight. The 70cm downlink is looking great! Just need a little more elevation for my modest setup and location (Virginia).
Thanks!
-Scott, K4KDR
===================
On Mon, Jul 1, 2019 at 9:03 PM Robert Bruninga via AMSAT-BB < amsat-bb@amsat.org> wrote:
PSAT2 is doing great!
PSK31 and SSTV transponder have been on since launch.
SSTV downlinks are looking good.
See Gallery: http://www.urel.feec.vutbr.cz/esl/psat2/sstv/
Still waiting for first report of user PSK31 contacts.
But I have not said much about the VHF modes… because we have had difficulty commanding. This is because the PSAT2 VHF uplink uses an inexpensive narrowband XCVR module which is intolerant of overdeviated signals, exactly what you get with +/- 3 kHz of Doppler.
ANYWAY, we can now consistently command if we set the Kenwood to narrowband NFM and do it right in the middle of the pass. Plus, we can extend that a bit (1.25 KHz after center) by then changing the radio step size to 6.25 Khz where the channel raster ups the channel by 1.25 KHz).
So, we now have command again! You may have seen that we have turned on Sun vector S#... telemetry and can easily see by plotting the 1 minute xyz xyz xyz vector triplets that it is smoothly tumbling at about 1.3 RPM for nice battery charging and good thermal management.
The downlink is live on FINDU:
http://www.findu.com/cgi-bin/raw.cgi?call=psat2-1&time=1
Background:
This last 6 days of crisis was complicated by the fact that I am operating in a temporary dungeon while the building is being renovated and all my 27 years of lab stuff is in 200 boxes surrounding me. I installed a temporary ground station on the top floor and modest antennas and a TV rotator and the contractor let me drill a hole through the wall that they can seal up later. But the big problem is the 8 flights of stairs from my PC and internet connectivity in the dungeon up to the radio 6 times a day for passes with only a few hours sleep and all kinds of what-if-dead-ends. And with passes from 10 PM to 2 AM.
But we are back in the saddle again!
And this good news reprieve is only an hour old, so it will take a while to decide what we want to do next. In any case, the Brno University PSK31 and SSTV transponder has all the power for now, so enjoy.
Uplink USB on 29.4815 and downlink on 435.350 +/- Doppler. The transponder only comes up if there is a user in the uplink with PSK31.
Bob, WB4APR
participants (2)
-
Robert Bruninga -
Scott