Today was another ARISS Practice Session for the RF-Crew, plus our first opportunity to do walkthroughs with the kids asking their questions.

From beginning to end, all the inside RF gear took 31 minutes for one person to set up, which meant that things were ready to go about 15 minutes before a 10:03 AM pass. The primary and backup doppler computers were set up as the Doppler and Tracking PC. That worked well, the only glitch, which we have seen before, is that the Green Heron middleware tracking software (listens to the SatPC32 DDE Server and talks to the USB ports) had to be shut down and restarted to have it start sending commands to the rotor box, even though it was already communicating with the rotor controller.

We had 100% packet coverage for 6.5 minutes of the pass (47 degree max elevation — about what we can expect next Friday).  That corresponded to a 20 degree elevation when rising, and 8 degree elevation when setting.  But we could tell the ISS was hearing us (much more ERP on our end) pretty much from horizon to horizon.  Since packet requires a higher S/N level, I suspect this means we will have about 8 minutes of good quality audio next Friday.

We did some testing of the antenna array polarity switch and found that no current was being drawn, initially feeling that indicated the switch or cable wasn’t working.  However it dawned on us that an isolated power supply was being used, and it was not tied to the power supply running the radio.  Therefore there was no ground return through the coax. This Saturday we will power it from the radio supply.

The photo above shows the gear in use.  From left to right:  Green Heron Az/El Rotor Controller, Laptop controlling rotor, Icom IC-9100 Transceiver, SCS DR-7400 packet modem (on top of rig), Laptop controlling Doppler.

From about 10:30 AM on, the focus switched to a live walkthrough with the kids asking their questions using the on-air mic and PTT switch.  Things went very well with that, and there was the time to cycle all the kids through twice.  If we were lucky enough have horizon to horizon communication, I am sure we would get through all the questions, but no doubt some of the kids won’t get a chance to ask their questions before the pass window closes.

ASA Student asks “How do you cut your hair and nails in space”

The RF Crew met at ASA today from about 10 AM until 2 PM for another on-air practice session using the ISS Packet Robot. Executive summary:  things went very well for both passes — still some gremlins, but nothing that wasn’t overcome before either pass.

The computer used for Doppler and Packet was still suffering from being introduced to the Rotor Controller this past Thursday, which necessitated a reinstall of the software to stop the obscure german error messages.  But that gave us a great opportunity to practice manual Doppler correction (preprogrammed channels in the IC-9100) which worked fine for the first pass.  The install was completed between the two passes, and things worked great on the 2nd pass.

The Rotor Control laptop was back and working fine.  It’s always a test of faith to wait for the clicking of relays and changing displays that doesn’t happen until until the ISS is about 5 degrees above the horizon.  I would suggest moving the array by manual control to be pointing in the right general direction.  The TLE file was about 10 days old (pre-boost) and that caused it to start tracking about 5 minute early. We corrected that for the second pass.  Updating TLEs and verifying PC clocks is on the checklist for the event day.

We tried the antenna polarity switch during the second pass — it did not appear to make any difference with either the RX levels or the SWR on transmit.  We will measure current next saturday to be sure that the relay is actually being energized.

The egg beater was installed after drying it out and sealing things up. The SWR was 1:1 at 144 MHz, rising slowly to 1.2:1 at 146 MHz. During the last 3 minutes of the second pass we tried it on air.  The reality is it will not be very effective — we could hear the ISS Packet Robot faintly in the background (not at all without the preamp on).  And it was obvious that the packet robot was not hearing us at all.  Of course the ISS was only about 10 degrees above the eastern horizon and sinking fast.

Some of the packets from ASA that were reported on the global APRS network were:
12:51:48 EDT: N1ASA>CQ,RS0ISS*,FN41IM,ASA,qAR,N0AGI-1:hello wb3fkp
12:53:47 EDT: N1ASA>CQ,RS0ISS*,FN41IM,ASA,qAR,VA3ROM:>fn41IM -/
12:53:57 EDT: N1ASA>CQ,RS0ISS*,FN41IM,ASA,qAR,VA3ROM:Hello N2RRJ
12:54:18 EDT: N1ASA>CQ,RS0ISS*,FN41IM,ASA,qAR,VA3ROM:Hello
from all saints academy in rhode island