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Musk files to provide Internet service from space

washingtonpost.com

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Re: Musk files to provide Internet service from space

#121

Post by dylanjermiah »

savage_platypus wrote: post #29
toomuchtodo wrote: post #17

Earlier quoted context omitted.

As opposed to current pipe dreams: * gigafactory under construction * freemont factory producing ~50K vehicles/year * spacex successfully, repeatedly delivering payloads to orbit (and successfully demonstrating their crew escape vehicle recently)

Just because something is being built with other people's money does not make something a success. None of the companies Elon has been involved with have ever actually generated a profit -- they have largely just taken advantage of speculative investors and their willingness to buy into his ideas.

SpaceX profitable for ~7+ years now. Tesla could be, but every cent is being pumped into growth, research and dev.

Re: Musk files to provide Internet service from space

#122

Post by dzhiurgis »

darkmighty wrote: post #89
dzhiurgis wrote: post #86

Earlier quoted context omitted.

Will it still need gyro mechanism? There are satellite (I think Ku band) dishes for larger (~50ft) boats nowadays. They are using gyroscope assisted motors that wouldn't suffice for compensating rolling motion of a smaller boat.

The laptop-sized antenna he mentioned doesn't need a gyro because it uses phased-array tech. Essentially you resolve signals in any direction (up to a resolution given by number of elements and array size) by carefully combining them with certain phase offsets such that signals from all but one direction cancel out. This adjustment is made on the fly to track a signal with changing direction.

I see.

Would something like pCell would be an improvement here?

Re: Musk files to provide Internet service from space

#123

Post by jokr004 »

dankohn1 wrote: post #67
Cherian wrote: post #48

Earlier quoted context omitted.

1. At the risk of sounding stupid, will governments allow something like this that can bypass gateways under control? 2. Can cellphone communication work this way on scale (like Iridium)? Bypassing providers like tmobile, sprint etc.

1. As an American-based company, SpaceX would be subject to CALEA [0], meaning that they would have to enable law enforcement intercept of communications with a warrant. This would likely be done by replicating the packet streams at the gateway. However, it's quite possible that you could use the system in a repressive country, without them knowing about it or having a way to stop you. 2) The purpose of the system (a…

"The purpose of the system (and the spectrum) will likely be broadband data, not hand-portable voice."

You're unlikely to get one without the other.. if down the road you can get an affordable internet connection on your phone without having to deal with cellular networks, I'd bet that you would see a huge shift to VOIP.

Edit: Whoops, looks like phones probably won't be able to receive this signal practically.

"I believe Musk is, like Teledesic, planning to use the Ka-band. That means the smallest antenna would be the size of a large laptop" [0]

[0] https://news.ycombinator.com/item?id=9689869

Re: Musk files to provide Internet service from space

#124

Post by nathan_long »

dankohn1 wrote: post #66
grecy wrote: post #20

Earlier quoted context omitted.

How will devices on the ground communicate with the satellites? i.e. do we still need fixed dishes, or are we looking at something new so an iPhone can get signal right from the satellite?

I believe Musk is, like Teledesic, planning to use the Ka-band. That means the smallest antenna would be the size of a large laptop (and that's only if phased arrays become cheap enough). So, it would work for a car, plane, boat, or house, but would be too big to use while walking.

But one could imagine a city where many shops have satellite internet and open WiFi, so that in effect you can walk around with a phone and use this.

Re: Musk files to provide Internet service from space

#125

Post by yincrash »

greglindahl wrote: post #12
yincrash wrote: post #10

Earlier quoted context omitted.

~250ms RT latency http://en.wikipedia.org/wiki/Satellite_Internet_access#Signa... Hubble is a pretty low orbit. Geostationary orbits are @ 36,000km

SpaceX is proposing putting them @ 1,100km. The speed of light is faster in space than it is in optical fibre.

so ~7ms RT. The satellites will be moving in the sky relative to the ground, so users will need to be able to switch satellites often?

Re: Musk files to provide Internet service from space

#126

Post by hotpockets »

dankohn1 wrote: post #66
grecy wrote: post #20

Earlier quoted context omitted.

How will devices on the ground communicate with the satellites? i.e. do we still need fixed dishes, or are we looking at something new so an iPhone can get signal right from the satellite?

I believe Musk is, like Teledesic, planning to use the Ka-band. That means the smallest antenna would be the size of a large laptop (and that's only if phased arrays become cheap enough). So, it would work for a car, plane, boat, or house, but would be too big to use while walking.

Not if I'm wearing my urban sombrero!

Re: Musk files to provide Internet service from space

#127

Post by darkmighty »

dzhiurgis wrote: post #122
darkmighty wrote: post #89

Earlier quoted context omitted.

The laptop-sized antenna he mentioned doesn't need a gyro because it uses phased-array tech. Essentially you resolve signals in any direction (up to a resolution given by number of elements and array size) by carefully combining them with certain phase offsets such that signals from all but one direction cancel out. This adjustment is made on the fly to track a signal with changing direction.

I see. Would something like pCell would be an improvement here?

pCell is just phased array technology.

Directionality and sectioning has been used since the beginning of cell technology: first with cell splitting and then with cell sectoring, and recently more aggressive splitting (smaller cells) -- it's an ongoing evolution. The kind of tracking this has required is very easy to do: once your signal is stronger in a competing sector for a significant amount of time, switch sectors. The same principle can be applied to phased arrays but the small number of sectors makes it much more tractable computationally and in terms of hardware.

A phased array in a city environment needs to track in real time the position of users, with enough feedback from them to make sure your prediction matches with their position well enough, and use this information to continuously adjust sub-nanosecond (depends on the freq/bandwidth) phase offsets to array elements. In principle it`s even possible to do multi-tower coherent communication. Needless to say, this tech is expensive right now, and I imagine hard to get to work reliably.

MIMO is also closely related, the difference being traditional MIMO actually adjusts amplitudes only (non-coherent) of multiple data streams to create channels (after a linear transformation at the receiver). This means the signals are still ominidirectional for your wi-fi MIMO. Being non-coherent means it's much cheaper.

Re: Musk files to provide Internet service from space

#129

Post by vignanv8 »

dankohn1 wrote: post #13

I was Director of Marketing with Teledesic, Craig McCaw and Bill Gates's Internet-in-the-Sky from 1995 to 2000. I'm a huge fan of what Musk is doing, with order of magnitude cheaper launch costs and satellite hardware. AMA.

Thank you for the AMA and the replies.

I have couple of questions.

1. Among the companies which have announced plans for space-based internet like SpaceX, OneWeb, LeoSat, Yalini etc which do you think can deliver good quality internet at the lowest costs.

2. What according to you is the most likely terrestrial delivery model to succeed. Partnering with local mobile operators/ISP's (like OneWeb) or creating an altogether new infrastructure/gateways/ground stations (like Yalini).

3. I couldn't find details of SpaceX's plans (like throughput, speed, latency, costs, delivery model etc.). Can you refer me to any publicly available information on this.

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