[hristov]

Can someone with some experience in satellites tell us what is possible in terms of satellite internet. For example, I really doubt most individual people would be able to actually connect directly through satellites. If that is the case, a satellite radio would have to detect and distinguish millions of different simultaneous data streams. I doubt there is enough spectrum for this.

[artimaeis]

I'm only familiar with the basics of the networks capabilities per my former position as a technician for WildBlue/Exede. Connecting directly through satellite is certainly possible if more people were interested in it. Our satellite networks are still fairly basic primarily because there's not been a historical abundance of interest in the technology due to its limitations compared to terrestrial networking.

ViaSat-1 is (as far as I'm aware) the most capable satellite currently in orbit, with a rate of 140 Gbit/s. Its bandwidth capacity when launched larger than all of the other North American satellites combined.

I would be VERY surprised to learn that the fundamental issue with this would be spectrum capacity, as the K band satellites operate in is very wide.

The way current satellite technologies typically deal with concurrent data streams is to split up into 'beams' that cover a specific region. Currently VS1 uses 72 bands but they're spread all over Canada and the US. With more satellites and tighter beam placement it's certainly feasible to have millions of simultaneous connections.

I feel like I kind of rambled on there - if there's anything in particular you'd like me to expand upon I'd be happy to (and if someone notices I'm wrong about anything please let me know!).

[jacquesm]

> if there's anything in particular you'd like me to expand upon I'd be happy to

Since you asked :)

How much of this is relying on phased array antennae on the satellite and does that mean you won't have to aim a dish or will the downlink for residential require a tracking antenna or do those also work using phased arrays these days?

[artimaeis]

Wow! That's an excellent question that I only barely know about. I'll give as much of an explanation as I'm able to and I apologize to any enthusiasts who cringe at my response!

So I'm not sure where Musk's project is going to go - as schiffern stated below it seems they're going to go with a LOS phased array, and if they've actually got the price down that low with stable performance then they've really brought some incredible innovation to the field!

As I understand - ViaSat1 used a hybrid design antenna in space that allows them to do some pretty incredible things on the ground. Consumer internet is provided via traditional Ka-band ground antennae that have to be carefully positioned and installed. They also have services for Ku-band, S-band, and L-band antennae. These applications do generally use some form of phased array antennae so that they don't have to use any sort of mechanical tracking apparatus.

Needless to say, I'm mad excited for Musk pouring some funding and engineering efforts into such an awesome project!

[jacquesm]

Thank you for the answer. The first time I tried to get my head wrapped around phased array antennae I utterly failed, a bit better the second time around. That's some high-class voodoo, along the lines of 'indistinguishable from magic'.

Pretty curious what the consumer package will look like and what capabilities it will have.

[schiffern]

Musk says they'll use line-of-sight phased array ground receivers, in the $100-300 range.

https://www.youtube.com/watch?v=AHeZHyOnsm4

[dangrossman]

HughesNet has 600,000-some subscribers. WildBlue has over 300,000. They're satellite ISPs with 12-15mbps residential service.

[emcrazyone]

Back in the 90s I use to install 2 way Earth Stations for Hughes. An Earth station is basically a box that puts TCP/IP over Satellite. They are installed in many gas stations in the US. If you drive down the street and see a white dish on the roof, chances are my company did the install ;) These links handle credit card transactions for paying at the pump and they also handle lottery purchases.

The industry wasn't regulated very much until a situation in which some installers aiming dishes for EDJ (Edward Jones Financials) were knock things off line by aiming dishes at wrong satellites. I don't know much about how the technology works but it became apparent that aiming a dish at the wrong "bird" as we call them could interfere with others.

The EDJ thing was big news back in the day although a google search turns up nothing. It reportedly knocked Edward Jones off line for something close to a week while many were deployed to go and re-aim satellite dishes.

After this incident, the FCC got more involved and now to install a two way satellite dish, you have to take a course and pass it. My whole team was required to go through this training.

We also installed 2 way satellite internet for a company out of Canada that had a PCI card you plugged into your PC. The PCI card would then connect to the dish transmitter and LNB. The down speed was around 4-5Mb/s while the up speed was very slow at around 128Kb/s. I forget the name of the company but they had a proprietary driver for the PCI card that compressed the TCP packets in order to deal with the huge latency of traveling up to space and back down. They also had patents on a modified TCP/IP stack whereby they could locally ACK outbound TCP packets to improve throughput (as it was explained to me at the time).

[aptwebapps]

In the past such services have used geosynchronous satellites, at least far as I am aware. The problem with that is the great height of the satellites means a pretty serious lag. IIRC, about 250 ms, round trip. LEO satellites, however, would have a tiny amount of lag added.

[hristov]

Yeah, but can Hughes handle it if all 600 000 came from a small area? Or do they rely on people to be relatively dispersed?

[skj]

Generally satellite ISPs are dial-up for upload and use the satellite link only for download.

[artimaeis]

I can't speak for Hughes but I was a trained tech for WildBlue /Exede. Neither of their services have ever used dial-up for upload. While early generation WildBlue services were fairly slow on the upload, Exede was able to push 4+ mbit to the subscriber fairly constantly.

[ghshephard]

That was true 10 years ago. I'm on a 50 GB/month Satellite link that is many, many miles away from any type of alternative comms right now. Everything, upload and download, is through the GeoSynch Satellite. 600 ms latency, but data rate is pretty good - around 10 mbits/second.