h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

i have an old-fashioned 56k modem.... what i want to know is what is the delay between putting info in and actually receiving say a reply over the net... i reckon it is somewhere between 30 + 100 secs... are there figures for this? just plain curiousity .. but i would really appreciate a sensible answer...

p.s. i dont mean ping... know all about that...

There is no simple answer, but it is possible to estimate a minimum.
First, 56k is the maximum speed of the modem in Baud (bits per second), but your connection speed depends on prevailing line conditions: I usually get 44k or so, if I get 20k or less I go offline and try again. When you go online, your machine tests the line for bandwidth and noise, and chooses the fastest connection speed that is likely to be reliable.

Text will usually be sent as one byte per character, so 56k/8=7k chars/sec. In addition, data is sent in packets, and each packet carries an address and some error correcting codes. This gives you some idea of the maximum speed you can send or receive, but at every node in the system each packet must be stored, read, and re-routed, which causes some delay. There is no way to predict how many nodes a packet will pass through, as each node will choose the least busy route at the moment, and successive packets may travel by different routes and arrive in the wrong order at the destination.

This is where the greatest delay occurs, the server at the receiving end has to store the packets, put them in the right order, ask for retransmission of any corrupted packets, wait for them, then put together a reply and send it.

The short answer is, it all depends.
Sorry you asked?

JR

Additionally, at busy times, you may well have to wait for the server's attention, in which case your message will be queued by the server, and we all know what that feels like.

JR

30-100 secs sounds like a very long time to me, on most sites I get a reply in 1-5 secs, if it takes more than 20 I tend to get bored and give up, unless I really want the info.

Pictures and sound contain huge amounts of data, and take that much longer to load. Check your connection speed, and if all else fails, go for text only(much faster).

JR

tks jr... i understand much better now... i usually operate at 44... but it finally explains what is stored at the server... i reckon about 30sec plus worth.... agree normally it appears instant if ping ok.... if u check radio against net reception....delayed...

Net radio is heavily compressed, and contains lots of error correcting codes, encoding and decoding causes most of the delay, even without the line in between.

JR

ps... it is probably much less... cos what does not seem instant seems ages...

Digital radio is similarly compressed, and several seconds late even without the net. (I have a freeview box)

JR

You can time net radio delay fairly precisely by watching your computer clock while listening to the pips. (the last pip is the hour, and make sure your clock is right).

JR

Dulcie, here's a practical online test of your connection speed: http://promos.mcafee.com/speedometer/

I think I can guarantee that you will be seriously disappointed!

Doc.

thanks doc... i was really more interested in what hangs in there... i have observed it with a couple of applications... ping i know varies depending... but i will give it a go for the heck of it... noisy phonelines are another break on the system..

cheers

Dulcie. Just found this one that I tend to believe more: http://www.pcpitstop.com/internet/Bandwidth.asp

Several tests and some explanation.