81–90 of 129 posts
Earlier quoted context omitted.
Note that countries have not succeeded in stopping satellite phone users within their borders... for example, the Taliban in Afghanistan use satellite phones extensively.
Are those phone companies breaking the law when they let the call on to their network?
Earlier quoted context omitted.
The speed of light is faster in space than it is in optical fibre. Could you elaborate? Thanks
My understanding of it is that when light passes through a medium, it does not do so in a straight line. So, while the actual speed of light remains constant, it takes longer to get from one end to the other.
Earlier quoted context omitted.
Isn't the internet by very definition a grid?
By which definition? http://en.wikipedia.org/wiki/Off-the-grid
More than that though, conceptually "off-the-grid" means not accepting a utility serivce from a provider but rather catering for that yourself. An internet connection is arguably a utility, and you'd be accepting it from an ISP. That goes against the concept, which would suggest you should maintain your own isolated network of computers and not connect with the outside world.
Earlier quoted context omitted.
> With low orbit devices I would imagine the latency should be better, I am guessing, but how much better. Your satellite's 22,000 miles above the earth. If you were directly under it, round trip latency would be 236ms. If these satellites are 684 miles up, and you were directly under one, round trip latency would be just 7ms. The distance between satellites, and between the satellites and whatever ground stations ac…
FEC and interleaving induced latency will likely become the dominant term for LEOs.
Shorter distance + faster signal thru air can amount up to 30-50% lower latency.
Musk claims to want to launch 4,000 or so satellites. The Goddard Space Flight Center indicates that there are 2,271 satellites in orbit now. I'm wondering to what degree this would make it more likely to have a negative feedback loop of satellite destruction in the case of a satellite being hit by space junk.
I believe they would be low enough that if they failed they would pretty quickly fall back into the atmosphere, and be replaced on the fly. I'm pretty sure I heard this in his talk about it in Washington on youtube.
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.
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.
Earlier quoted context omitted.
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.
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.
Earlier quoted context omitted.
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.
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.
Earlier quoted context omitted.
The speed of light is faster in space than it is in optical fibre. Could you elaborate? Thanks
http://www.rpi.edu/dept/phys/Dept2/APPhys1/optics/optics/nod... Speed of light in vacuum > speed of light in optical fiber. Same reason high frequency traders are using microwave between Chicago and New York instead of a fiber connection.