Hey HN community!

I've recently fallen down the rabbit hole of ham radio and antennas/satellites. While experimenting with a handheld directional YAGI antenna, I realized there must have been a better way than pulling out my compass app and continuously checking to make sure I was getting the right angle. So I built STAR! It uses your device's built-in motion sensors and location to precisely align your antenna with any satellite orbiting around Earth.

Honestly, I didn't know you could access a device's motion data from the web so that was super fun to play around with. I've been able to get some great images from NOAA weather satellites and learn about some fun math that makes this all work.

PSA: You can build your own YAGI antenna for about $10 in materials. Just look up a "tape measurer antenna" and thank me later for the fun project :)

Would be great to have a few links to popular satellites on the homepage for people who don't know any NORAD IDs.

Good point, just added a link to a demo using the ISS id. Thx!

came here to say that.

ISS = 25544

Neat. Needs a search box for satellite name -> norad id, or a link to n2yo

Thx! Will add a search box this weekend

This is awesome. Many years ago I tried making an Android app for uni that would help you point your phone at the star you selected. The maths for that was insane and way over my head, I can only imagine that satellites would be much harder.

Such a cool use of everyday tech!

It might actually be easier since they have know trajectories and velocities with a easy to calculate schedules.

giantg2 is right! The position and velocities are already known in the form of a Two-line element set (TLE). That makes it quite easy to calculate its current location using orbit propagation algorithms.

If you want to go down a fun path I suggest reading more into TLE data. They are currently in the process of adapting the standard to allow for more satellites since in its current form it can only track 99,999 satellites

There are libraries built with all of this math done for you already.

Astropy, orekit are two I recall from memory, but there are more

Seems to work well, thanks. Bookmarked for sure. Much better than screwing with the level and compass apps while trying to aim an antenna!

Haha that was the goal!! Glad you like it

This appears to be similar to Google Sky. What are you doing that Google Sky isn't?

Well, for one, this exists, and Google Sky doesn’t any more.