Ars Technica's Teardown of “Dishy McFlatface,” the SpaceX Starlink user terminal links to the YouTube video Starlink Teardown: DISHY DESTROYED! and a screenshot from there is shown below.

There are three 45 degree bevel gears; the two on each side connect to motors and the one in the center seems fixed relative to the mounting posts.

Question: I'm wondering how does this SpaceX Starlink ground station antenna's gear mechanism move it in both altitude and azimuth? By driving the substantial-looking motors in the same versus opposite direction could this kind of mechanisms both rotate around the shaft (azimuth) and point up and down (altitude or elevation)?

This answer to How should we point our SpaceX Starlink ground transceiver antennas? in Space Exploration SE confirms that even the current dishes move somehow but it's not specific. The antenna is not parabolic reflector like a "direct-TV"receiver, but instead is an array antenna. It seems that in order to maximize exposure at all angles they've decided to articulate the array mechanically for at least some of the satellite tracking, rather than use electronic phasing of each element alone. This way the antenna can always present near-maximum area to the StarLink satellites as they pass back and forth across the sky every few minutes.

screenshot from Starlink Teardown: DISHY DESTROYED!

click for larger view or watch the linked video

  • 1
    $\begingroup$ That's certainly what it looks like. My Google-fu couldn't produce a patent, though. $\endgroup$
    – Phil Sweet
    Mar 5, 2021 at 1:42
  • $\begingroup$ @PhilSweet thanks, I'm not particularly mechanically inclined; all I can think of is the differential on my Plymouth Satellite from the 70's (which looked exactly like this) and that thing wasn't supposed to move in altitude and azimuth at all! $\endgroup$
    – uhoh
    Mar 5, 2021 at 2:49
  • $\begingroup$ I'm having difficulty visualizing the effect on the dish - since the motors rotate in opposite directions, and appear to be bolted to the plate, What ends up moving (i.e. how does that not cause a torsion)? does the dish both move in Alt and in Az as the motors run? $\endgroup$ Mar 5, 2021 at 15:42
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    $\begingroup$ @CarlWitthoft that's a good point. When the person in this video lets the system rotate around the axis of the main mounting post I'll say that the motors are rotating in the same direction from the point of view of each motor. They are mounted pointed in opposite directions, but if they both turn clockwise in their own frame, the antenna rotates in azimuth. But I'm thinking that if one is instructed to turn cw and the other ccw, then the motors (mounted to the plate as you mention) will force the plate to tilt up and down (altitude or elevation). $\endgroup$
    – uhoh
    Mar 5, 2021 at 23:38
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    $\begingroup$ @Uhoh thanks for elaborating. My confusion was because I forgot that the gears could "stall" on the post and only the dish would move. $\endgroup$ Mar 8, 2021 at 12:32


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