Patrick Murphy wrote:

> Okay, I will. She did say something about proprietary compression
> algorithms, but I'll ask her about milliseconds, next time. Lower
> latency should result in faster uploading and downloading, if a large
> file was being sent, right? So I could ask each ISP how long it should
> take to send, say a 100 MB file?

Latency refers to the amount of time between when a character or 
packet of data leaves your network, travels up through the satellite 
and back to Earth and is put back on the rest of the public Internet 
by the satellite service provider. You will probably notice longer 
latencies more in situations where many smaller packets are sent like 
checking email, filling out web forms, etc. Note that if you are doing 
something where you get a result it takes at least 2 x latency--one 
for your mouse click, etc. and the other for your result to be returned.

The compression algorithms used are usually more effective when 
sending big blocks of data like files. There's a certain amount of 
"overhead" bytes associated with each packet of data sent. If the 
packet contains only a few characters or a single mouse click there's 
not much to compress. Most humans feel that they have received an 
instantaneous response from a machine or system if they get some form 
of feedback or result in under 100mS. Longer than that and the delay 
begins to become perceptable without actual measurement.

I would stick to asking for an actual time in milliseconds as well as 
information on how they arrived at the figure. In my opinion the more 
open and forthright they are about their benchmark information the 
higher the probability you would be pleased with the results.

On our Direcway system no sophisticated measurements are required to 
tell that it is much slower for certain applications like checking 
email. When your connection is through a terestrial network 
downloading a hundred emails appears like a continuous stream where 
they come one after another. Through the satellite connection it's 
readiliy apparent that each one is being received and acknowledged 
individually.

None of this means you should not use any satellite based system. I 
would look carefully at any claims of my satellite is significantly 
faster than brand X.

Tim
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