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Broadband From The Sky In 2002?
Krendle writes: "A company named ISky is claiming that they will deliver high speed (2mbps down, 1/2mbps up) 2-way satellite Internet access by the end of 2001. One issue I've seen raised in newsgroups (in reference to satellite internet in general) is that of lag. With Internet applications like telephony and online gaming, etc., gaining popularity this is an important issue. 2Mbps from the sky still sounds cool to me, especially where we can't even get cable TV. What do you guys think -- will latency be a problem?" I'd be happy to "settle" for always-on wireless access faster than dial-up and cheap as DSL, but the iSKY Q&A page is short on price details. But it does say "iSKY is planning on being able to support all platforms including Macintosh, Linux, Solaris and Windows."
I'm on the end of a 1 meg satellite link right now, between the US and Australiam with RTT's of around 460ms. We can definately use this whole connection with multiple streams, but latency prevents the downloads from coming in at faster than 20Kbytes/second.
That seems like a reasonable figure. It still beats the 4.1KB/s I can get from dialup or the 14.4KB/s I could see from IDSL. I'd say it's not for everybody, but when other high speed options don't exist, it's a good thing.
I'm not sure about the details and the implementation has to be really messy but while the latencies will still be kind of long you can stream data quickly and sort of do tricks to cut down some latencies.
I just took a job with Echostar and we are partnered with both iSky and Gilat, I'll send more details to slashdot when I can get them. The customer set we are really aiming at (I believe) are the out lying customers who can't get a DSL connection.
We pump tons of energy into the air all day long, with pagers, cell phones, tv, radio, broadband... I just have to wonder - is there really no physiological effect?
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I recall a long time ago on slashdot (yeah, rob.. you reposted, heh) somebody stated the laws of physics dictate latencies of atleast 300ms.
I don't have many details, but it will be in by fall of this year if I remember correctly.
The problem with iSky is that the satellites will be in geosynchronous orbit. Given someone else here posted that it takes 0.25 seconds for data to travel from a ground transceiver to the satellite itself (a sum total of 0.5 seconds for data to travel from transmitter to satellite to a receiver), that's way too much data lag for many purposes.
The better solution is the upcoming Teledesic system that should be operational by 2004. Unlike iSky, Teledesic will have a constellation of satellites orbiting from 850 miles up, so the transmission time from the ground to the sats will be far, far shorter. This means wireless data transmission rates at T3 line speeds (45 megabits per second) from anywhere in the world. This is perhaps the solution for people who need broadband Internet access but live too far away for cable or ADSL modem access.
Raymond in Mountain View, CA
That's why the Teledesic system is such a great idea. Because they will use 844 satellites orbiting at 850 miles altitude, you'll have a LOT less data lag (I've read that Teledesic satellites can offer at least 45 megabits per second data transfer rates anywhere in the world). That's the equivalent of a T3 data line.
This is the best solution that will cure our "digital divide" problem of getting broadband Internet access to rural areas far beyond the reach of cable and ADSL modems. I'm sure that when the system becomes operational the first places that will get Teledesic transceivers will be Indian reservations, most of which are FAR beyond the reach of even normal telephone lines.
Raymond in Mountain View, CA
They don't mention any details on the upstream. Is everyone going to have a 20GHz broadcaster in their backyard? I wonder how they will work out issues of crosstalk between neighbors, I guess if this is only rolled out in low population areas it wouldn't be hard to distribute frequency so Abe's upload won't disturb Betty's download.
I wouldn't mind having a Long Fat Pipe (respect in the locker room) but I could always hi-jack a couple of neighbors DSL lines. I wonder if it would be possible to set up a communal DSL pool. A bunch of neighbors get DSL, and timeshare using all of them at once. So for 12 hours a week you get to use the full bandwidth of 30 DSL lines. Is there a router or something that can multiplex lines like that?
Scuttlemonkey is a troll
>Satellites at any altitude take *no* fuel to stay in orbit
Actually no. Theoretically yes. But earth's atmosphere actually extends way way up there.
...As was clearly stated in my previous post. However, orbital decay due to atmospheric friction even in low orbit takes years or decades - the atmosphere's density drops off exponentially (not as one exponential, but as a piecewise-exponential curve). It's extremely tenuous and gets even more so as you go up.
Let's use figures from the ionosphere data you cite for density - about 1.0e12 particles per cubic metre at the most dense layer. Let's also assume low earth orbit, which has an orbit length of about 4.0e7 metres. This gives collisions with 4.0e19 particles per square metre per orbit.
By comparison, water has about 3.3e28 particles (molecules) per cubic metre. Air has about 2.4e25 particles per cubic metre at one atmosphere of pressure. Much, much denser.
Lets assume that you have a satellite with a mass of one tonne and a cross-sectional area of 5 square metres (solar panels and all). Assume it's in LEO with an orbital period of about 90 minutes. How long will it take before it loses 0.5% of its orbital velocity (enough to lower its orbit by about 70 km)?
Let's assume that all collisions are inelastic - that is, mass that the spacecraft collides with sticks and accretes. This will give an approximately correct answer and is easy to calculate.
The spacecraft's mass needs to increase by about 0.5% for inelastic collisions to lower its velocity by 0.5%. It needs to collide with about 5 kg of matter to do this. With an area of 5 square metres, that means 1 kg of matter per square metre.
Let's assume that air has a density of around 1.1 kg/m^3 at one atmosphere (I may be off by 0.1 or so, but that's close enough for these purposes). This gives a mass of 1.1 kg * (4.0e19 / 2.4e25) = 1.8e-6 kg per orbit.
At 90 minutes per orbit, this means 4.9e7 minutes for orbital velocity to be reduced by 0.5%, or about 90 years. That's considerably longer than the expected lifetime of the satellite's electronics.
In summary, for anything placed in LEO or higher, it will be something other than orbital decay that determines satellite lifetime.
However, don't expect satellites to replace cable any time soon. There are difficulties when you try to scale up to the silly bandwidth levels required:
Your satellite is at least 300km up, and making microwave beams really parallel is tricky (unless you want to use a huge dish, which adds weight and cost to the satellite). This means that, even pulling tricks like having multiple fairly-narrow-angle transcievers per satellite, you still get everyone within a few tens of kilometres sharing the same uplink. Fine for low-density areas, but not for cities.
Microwave beams have a data bandwidth comparable to their frequency - a few Gbits/sec. at most. This is the maximum _shared_ bandwidth per uplink region, and the maximum bandwidth of the pipes between the satellites. Bump the frequency up to get more bandwidth, and you start getting blocked by light cloud cover and thin walls (and ceilings). While you could do something like have an optical link from satellite to satellite, your uplink/downlink bandwidth is going to be pretty crummy compared to, say, a fiber backbone serving the same area.
I'm not trying to bash satellite data services - as mentioned above, they do have their uses. I'm just trying to stave off the inevitable flood of "Wow! Now everyone in the city can get cable bandwidth from their palm-pilots!" messages.
To cause damage to animal or plant tissue, electromagnetic radiation needs to either cook it by raising its temperature (lots of watts, like in a microwave or a solar reflector), or have ENOUGH ENERGY PER PHOTON to ionize it. Radio wave and microwave photons don't have enough energy to ionize or break chemical bonds in living tissue. They're less dangerous than infrared radiation (heat). UV, X-rays, and Gamma rays have enough energy per photon to ionize or break chemical bonds in living tissue.
Yes, let's talk photons. It turns out the situation is not as simple as it first seems. The energy from a microwave photon eventually ends up as heat, but you could easily argue that for every other form of EM radiation as well. The question is, what happens in the interval between the time the energy is adsorbed, and the time it ends up as waste heat?
Basically, microwaves set up a rapidly oscillating electric field in the material they pass through. Polar molecules (Such as water) experience a torque that aligns them in the direction of the elctric field, and which changes direction each time the field reverses direction. What makes water an especially good adsorber of microwaves is their network of hydrogen bonds, some of which must be broken to allow the molecules the freedom to rotate with the field (Note--hydrogen bonds break and reform all the time, it's one of the properties that allows water to flow).
Now, what happens to biological molecules is something that is not understood well. We do know, though, that polar molecules will experience forces that unlike those from normal thermal agitation, in that the forces are non-random.
In vitro, microwave energy can cause subtle but repeatable changes in gene expression and protein activity (Such of those like heat shock proteins) in ways that differ from those observed with simply application of heat. Go to PubMed and search for the term "Microwave Exposure", you'll find there is actually quite a bit of research on the subject.
Their web site says their satellites are in geosynchronous orbits.
Geosynchronous orbit is 37500 km. This translates into a minimum roundtrip speed-of-light latency of 250ms.
Any netrek player will tell you that that amount of latency is too high for effective gaming!
Actually, it depends on the size of the dish they give you.
An 18 inch dish, like is used with DirecTV and Dish Network are really the absolute minimum size that is useable. It takes a really big thick cloud to knock out the signal you receive when you have one of these dishes.
However, you can use (and DirecTV/Dish have them available) 24 inch dishes. They give you a lot better signal reception and the nasty storm cloud effect is all but fixed (unless it is a really really really big cloud).
Transmitting, on the other hand is a bit different story. I am assuming this thing is going to be pretty low power - it would have to be unless this outfit wants to have a lot of it's customers burned by RF when they stand in front of the dish, which would be very very awful. Trust me, RF burns are not fun at all.
So, the dish is probably going to increase in size to 36 inch (like Primestar had) or maybe even bigger.
They're planning on supporting all platforms.
I thought they should just support tcp/ip over ethernet, and be done with it..
Yes, lag is an important issue (inherent in the distances between earth and satellite combined with the speed of light), but its importance in a given application depends entirely on that application. If you're trying to play Quake, then you're SOL. If you're streaming audio from a shoutcast server (or downloading naughty pictures like most users), you won't take such a hit. But like with most of these technologies, it'll be embraced eagerly precisely by those who have no other choice, while the rest of us snicker with our T1s and cable modems.
"If one is really a superior person, the fact is likely to leak out without too much assistance" -- John Andrew Holmes
Even if latency is a huge problem, I won't be bothered. I'd much rather have slashdot come ripping down the airwaves at me at 2mbs after a 1 or 2 second lag than it slowly trickling down my modem connection at 56k.
Doing large amounts of downloading (basically all i do) won't be a problem with lag, now gaming is another issue, if you're a die-hard gamer, you can spare the expense of having a modem connection for games, and just use your satellite for downloading mp3s, or websurfing.
Hi, just figured I would ass my 2 here. /.ers to be) the latency shouldnt be a problem. Email, web, FTP, and say, CC authorization, and maybe even a small webserver would run fine over these connections. :)
I currently sit on a 2.4 GHz wireless lan (breezecom pro.11-D to be exact) which handles almosy 3mb on the wan and has a T1 to the net... the distance from point to point is ~2.5km and on the WAN I notice latency ~12ms and to the internet ~200ms. I am not a huge fan of Quake, but it seems to run fine, other games such as EverCrack run just fine... websites fly, and well.. I have no complaints. So on the subject of satalite connections, I think that for most home users, (not power users, which I find most
To address the problems of picking up a large area of signals making some satalites lagged if they fly over dnesly populated areas.. I can think the most simple solution to this is fly multiple satalites over an area and make them addressable, the internal bandwidth of these things could be 100's of gigabits, and they choose based on it's address which packets to then route to their land based internet feeds...see where I'm going? competeing cell phone companies do this kind of stuff.
Of course the other option is to have satalites opperating at diffrent frequencies over the same area, that woudl work too.
Anyways hope that adds to this
-Doug
Q. What's it take to get a story posted on
There are a couple of external factors involved in the pricing of digital satellite service. First, it has to compete with cable in areas where cable is available. I've compared the pricing. It looks like satellite services substitute a few more (non-local) channels in place of the local service they can't provide at very similar price points for their packages in our area at least.
Second, they have to build sufficient volume to keep the price at that level. The equipment that they have to maintain is different from cable. The cost per user scales quite differently. With cable, each new neighborhood needs its own lines. With satellite, the infrastructure is centralized or in space. It gets paid for in big chunks.
They'll be competing with cable modems, DSL, and for rural users, ordinary dial-up access. And they are comping in after those services have gotten a head start. They are going to have to sell an attractive package, or they won't generate the customer base they need to keep going.
The net will not be what we demand, but what we make it. Build it well.
The other thing I would add is that the 250ms latenncy is only the physical layer. If you add on the rest of the networking required for data to reach a wireless device, it won't be uncomon to see 500ms or more.
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Just wait until the new Lincoln Navigator comes with a Dish on the roof and a wireless basestation providing a net link within a 1000 ft radius.
OTOH "I'll give my presentation in just a minute, I have to move my vehicle to the front parking lot."
This sort of service could be really useful for the travelling salesman types who need full net access.
Then again it could really ruin your back to nature vacation when you are in the remotest part of Glacier Natl Park and some Net Phreak comes walking by with one of those friggin Satelite Backpacks and you can help yourself from asking him if you can check your e-mail/stocks etc.
Ahhh technology
no sig.
that this kind of service will have a place in the world... perhaps for mobile computing? I wouldn't want to use it for standard service from my desktop if DSL or Cable Modem is available. Not sure about telephone modem... it would depend on how badly I need the higher throughput.
Gonzo
So what about security? Anybody with a receiver would be picking up your download, your mail? And you'll also upload to these satellites? So how much power does that take? Is that even legal to broadcast radio waves? Will they make it legal? Will the service degrade with increasing usage? Can I use the receiver to decode TV signals ?;)
What if it gets cloudy? How bad a latency are we talking for a cycle?
(The RV idea is good though)
You can't handle the truth.
Don't ever plan on using it as a Quake server ... Sattelite is cool and all ... but they are going to have the exact same problems DirecTV has with their Web Access .... over 1 second ping time ... it's not so bad if you are running a BBS, FTP Server or even a Web Server ... where 1 second doesn't mean TOO much ... but again gaming would be horrible.... you'd be dead before you start!
DaiTengu
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Damage Inc. BBS