Weeknotes 5

  • Still an introvert
  • Had some people visiting in the building for the first time in over a year.
    They are an oil and gas company that is looking to use RIO in a monitoring application.
    Great guys, great company and great to brainstorm up a solution with face to face (mask to mask), but yeah, social interaction is still exhausting.

  • Geostationary satellite orbits
  • Still reading papers and stuff trying to get my head around orbital parameters.
    Mostly how much they drift and over what sort of period.
    Really interesting, really over my head.

  • 3D printed helix
  • The guy in Czechoslovakia that I have been chatting with on-line about satellite antennas has uploaded the lastest version of the 7 turn helix antenna that we have been building and using.
    You can see it on Thingverse here: https://www.thingiverse.com/thing:4834929
    There are 4 versions of the antenna, so be sure and select the right one for your application.
    Terry has printed one and if it builds and tests well it will be the one he prints in volume and the one that I build 7 or 8 of and sell to the guys that have been asking for one.

  • Dish focal point upgrade
  • Spent some time on Sunday confirming my main dish focal point (The 6 foot (2m) dish that tracks 98w 4F3).
    My dad came up with the idea to use al-foil to show the suns reflection and show me where the radio waves are focused on.

    The day started out overcast, so the foil is not doing much in this photo.
    It was really hard for me to get photos of the actual before and after since both axis were unlocked and the dish was moving all over the place.
    I also don’t have much room around it where it is in the upper garden.

    You get the idea.
    The before shot of the focal point was very large, about 2 feet in diameter at a guess. It was pretty clear, but just a lot larger than I expected.

    This is the focal point as it is now.
    I just had to shorten the arms to bring it in.

    Now when I moved the feed horn in an out of the ring I can see some difference to the signal. (Before the shortening, if I moved the horn all the way in, I was going the right way, but was still short of the focus).

    Bit of a busy screenshot, but this is the signal before (on the left) and after (on the right).
    The top half has the live signal as it comes from the satellite. You are looking at about 2 MHz of spectrum.
    The bottom is the history (or waterfall) of the signal, its hard to see in a photo, but the bottom waterfall falls like rain drops down a window.
    Its pretty handy as you can see the length and history of a data burst.
    Anyway, here is the thing… the after focal update is stronger. You can see, yes, I have more noise (the background speckle), but note that I am now getting some yellow in the signal.
    It goes from blue, to yellow to red. My goal is red of course, that will give the decoding software the best chance of getting the aircraft data out of the burst.
    Bottom line…. Due the moving around of everything, I need to do some more dish tracking re-calibration and tuning…. So yeah, more getting up at 2:30am.

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