We had another practice session today with two viable passes:
13:09L 17 degree max elevation (SW – N – E)
14:45L 66 degree max elevation (SW – S – SE)

The backup antenna was verified and was working as expected.  The primary antenna was also working fine.  The polarity switch was rewired and powered from the primary radio supply and worked fine.

A total of three PCs were verified as working correctly.  Only two are required to be working on event day.  The backup radio (another IC-9100) is now in-hand.

It appears that all we have to do is get SatPC running, then start the Green Heron tracking software, enable tracking/disable tracking, then enable it again to have things work correctly from the very beginning.

The antennas were pre-positioned prior to both passes which allowed us to hear a few packets prior to the ISS rising above the horizon.

The first pass was at 13:09L (17 degree max):
– First packet heard at 13:10:28 (5 degrees elevation)
– First packet repeat at 13:13:15 (10 degrees elevation)
– Last packet repeat at 13:18:54 (6 degrees elevation)
– Last packet heard at 13:19:30 (2 degrees elevation)

So a very low-long distance pass resulted in 5m39s of solid packet connectivity.  I suspect voice would have actually worked about 8 minutes of the pass.

The second pass at 14:45L (66 degree max):
– First packet heard at 14:46:35 (1 degree elevation)
– First packet repeat at 14:47:15 (4 degrees elevation)
– Last packet repeat at 14:55:03 (8 degrees elevation)
– Last packet heard at 14:56:30 (1 degree elevation)

So a much closer pass resulted in 7m48s of solid packet coverage. There was a rather pronounced fade toward the end of the pass, which prompted us to use the polarity switch.  The ISS immediately picked up about 5 S-units of signal strength, and we were able to continue packet exchanges until 14:56:00 — so solid packet coverage for 8m45 seconds by using the polarity switch.  I suspect voice would have worked for almost 9 minutes of the pass.

Bottom line:  Excellent session.  Everything worked correctly.

Next practice session on Thursday May 5.  RF Crew to report by 11 AM.  First pass at noon.  Second pass at 13:35.  NOTE:  second pass is almost identical to our event pass on Friday.  We expect to be working with the kids again on Thursday (so on-air mic tests).

ASA Student Practices Calling for the Space Station NA1SS

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”