Branch Education
2 HN recommenders · recommended in 4 months, 2022–2024
28:09 · 9.9M views · Aug 19, 2022
Branch Education explains how Starlink works, from the ground dish and satellites to phased-array beam steering and data routing. Animations cover how a beam stays connected to a satellite moving at 27,000 km/h.
Recommended for its detailed and clear look at Starlink hardware and beamforming.
4 comments from Hacker News
>But wouldn't it be cool if, using software plus magic, you could use multiple antennas to create "virtual directionality" and re-aim a "beam" automatically as the client device moves around? [...] We're left with the simple (ha ha) matter of making sure that the receiver is in an area of maximum constructive interference at all times. To make a long story short, we do this by adjusting the phase between the otherwise-identical signals coming from the different antennas. There's a good Youtube video that illustrates the idea of deliberate constructive/destructive interference to "aim" antennas. Deep link: this video The video is about Starklink phased-arrays instead of wifi pointy antennas but it illustrates the same idea.
While on the topic of Starlink, I wanted to share this cool Youtube video [1] I watched tonight on how it works (PCBA design, beam forming, orbital velocity, up/downlink bandwidth as a result...etc). It's a bit long but has some good details! [1] this video
The satellite side isn't nearly as power constrained as a cell phone so they don't have to get it that precise. But every dB counts. They hit multiple subscribers at once with the sat side footprint but if an area is nearly empty I don't see why they couldn't keep a particular phone in the centroid (such as in emergency services to uninhabited areas). Likely they will differentiate between populated and less populated areas by allocating more time to a spot to service all of the customers. [LINK] Of course the gain wouldn't be as nice as when both sides can do the phased array trick but cell phones don't have the same kind of antenna capabilities that Starlink's dish has. This is the relevant bit: this video I suspect the reason it is text service and not voice is that the phone antenna constraint results in severe bandwidth limitations. And with all that tech working for them I still think it is a small miracle they got this to work.
How Starlink works: this video Its nearest ground station bounced off nearest satellite, or some inter-satellite links, using lasers, to the user. It's optimized to be shortest route, just like routers with the internet. If you stream a movie, that request goes to in a short path from the server to you. You streaming doesn't slow down someone in China, because the data never approaches any equipment in China. Same with Starlink.