[Mike Walker]

Actually Ctn, a great source of latency on satellite is the time that it takes for the data to be uplinked to, and downlinked from the satellite! We're talking a round trip of more than 30,000 miles.

 

[Russ Arcuri]

Mike -- Sounds like for your uses, satellite is a good choice. The latency is actually pretty terrible when compared with cable modem, dsl, or even dial-up. But it's wonderful for large transfers, of long duration -- like streaming audio & video.

As to the cause of the latency -- it has little to do with the fact that uploads are (usually) dial-up. Dial-up's latency is not too bad, actually. It's because packets from the host to your computer are travelling more than 22,000 miles from the earth's surface to a satellite, and then another 22,000 miles back to the earth's surface. On either end, there's equipment that must handle the packets just as you would with other technologies -- like DSL or cable would have, but without the 44,000 mile trip in the middle.

For two-way satellite systems, which don't involve dial-up for uploads, latency is even worse. This is because your uploads are also making a 44,000 mile trip.

The more complex a page is, and the more disparate sources for the given information on a page, the more long latency will affect page loading speeds. Fortunately most satellite providers will utilize various caching techniques to minimize latency for typical web pages. On the other hand, there are no good techniques for improving latency for online gaming, etc.

Satellite is often the only option for people, but there are those for whom it's the best option, even if others are available. Apparently you're one of them.

 

[Ctn]

Quote:

Originally posted by Mike Walker Actually Ctn, a great source of latency on satellite is the time that it takes for the data to be uplinked to, and downlinked from the satellite! We're talking a round trip of more than 30,000 miles.

Yap...isnt this what I said?
*scratches his head*

In short most of the latency is in the upstream till the time data is actually sent from the sat. I.e. time to get the request from you (from your dial up modem) to the time the sat sends the data you requested but time taken for the data from the sat to reach your sat dish (receiver) is really fast! no?

Im pretty sure this is the case...then again...correct me if im wrong.

 

[Ctn]

Quote:

For two-way satellite systems, which don't involve dial-up for uploads, latency is even worse. This is because your uploads are also making a 44,000 mile trip.

Does a ping via sat take more than 250ms? Im curious...

edit: I just did a search on the web...omg...shocking

Geostationary Earth Orbit(GEO)
In 1945 Arthur C. Clarke first studied the possibility of placing satellites in geostationary orbit : that is at a distance of 35,767 km above the equator. At this distance from earth the gravitational pull in exactly matches the centrifugal force out and thus the satellite remains stationary in relation to the earth. The so-called 'Clarke Belt' was the original orbit used for communication satellites. Typically they are placed at a distance of not less than 2 degrees one from the other to prevent signal interference from neighbouring satellites. At this great distance from earth the latency factor, the time it takes the signal to travel to and from the satellite, is significant (240 milli seconds ) and must be considered when developing computer systems. There are currently just over 220 geostationary satellites in operation, making this orbit completely full for spots above North America and very little available spots elsewhere.


Middle Earth Orbit (MEO)
is approximately 9,800- 20.500 km from the earth Its latency factor is .06 - .14seconds. It requires more satellites than the GEO models but fewer than the LEO's to cover the same footprint.

Low Earth Orbit(LEO)
is approximately 800- 2400 km from earth .Its latency factor is below .03seconds. Many more satellites are required to cover the same footprint as the geostationary models and the technology required to relay transmissions from one satellite to the next is new and more complex .

From what you are saying the sats would be classified as (MEO) and have a latency of about 60-140ms. So I guess I wouldnt say it would be much slower than dial up...worse case is about the speed of dial up....best case is still better than dial up...no?

 

[Tuberoller]

Well after EXITE! went under I was without my cable modem for a whole month.I now have ATT and it's super fast but is very erratic.I hate the mail functions and the user settings.

 

[Russ Arcuri]

Quote:

Originally posted by Ctn From what you are saying the sats would be classified as (MEO) and have a latency of about 60-140ms. So I guess I wouldnt say it would be much slower than dial up...worse case is about the speed of dial up....best case is still better than dial up...no?

No. At more than 22,000 miles, (35,000 km), these satellites would be considered geostationary. Latency is worse than dialup. But, as Mike pointed out, this isn't a big problem for some types of internet use.

 

[Audio-Me]

I want 1.5mbps bi-directional wireless damn it (no it's not satellite, transmitted through radio)! $70/mo for two computers hooked up. I'm gonna give the company a call today.

Wish me luck.

 

[Ctn]

Quote:

Originally posted by Russ Arcuri No. At more than 22,000 miles, (35,000 km), these satellites would be considered geostationary. Latency is worse than dialup. But, as Mike pointed out, this isn't a big problem for some types of internet use.

Ah okie dokie