Satellite Communications

Hughes Satellite Antennae Meter

Found this in the shrubbery outside my daughter's house. Those are coax connectors sticking out of the sides at the top, so it appears to be some kind of meter for use with satellite TV of some sort. Turns out it used to align satellite dishes when they are being installed. This kind of scheme works with geosynchronous satellites, you know, the ones that are way out there, like 20,000 odd miles.

You can probably use some more conventional test equipment to do the same job, but this was designed for use by people installing satellite dishes when that was all the fad. Just Google Hughes Satellite Antennae Meter. Apparently HughesNet still offers internet via satellite. 

Talking to Marc yesterday and he tells us he was in Alvord desert last week, on vacation, but working, which isn't really a vacation, but what do I know about working anyway? Anyway he's got a Starlink satellite communicator. Starlink satellites are in Low Earth Orbit, about 350 miles up, about three times the altitude of the International Space Station. As such, they are moving across the sky, they are not stationary like the broadcast satellites.

When you are camping power is always an issue. You can always start your car to get juice to charge your batteries, but you really don't want to be doing that. The whole point of camping is to get away from running engines. OK, maybe not the whole point, but a major attraction.

Starlink Satellite Constellation
Currently 3,000 satellites

A Starlink antennae doesn't use a whole lot of power, but Michael tells us that when you first fire up Starlink it sucks about 80 watts of power for like 20 or 30 minutes and then it drops down to about half that. During that first 30 minutes it is downloading the ephemeris, which is a bunch of data that tells it where the satellites can be found. It needs this because it has to constantly adjust the antennae's aim. I think they use to actually move the antennae, but the current version uses a phased array antenna where aiming is controlled by adjusting the phase of the signal sent to each of the component elements.

Phased Array Antenna

Quora has a bunch of information about aiming satellite antennaes. I mean, how do you aim to hit something 20,000 miles away? Forget about doing anything like adjusting the sights on your rifle. At that distance you aren't even going to be able to see it. You would need something like a 5,000 power telescope to see them.