56k modem = How Fast?

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Ok, this has been bugging me for a while.Most people who still use modems to access the internet use a 56k modem, I believe.  And 56k modems go how fast?  56 kilobits per second, right?  Ok.

In my area, I have a friend who claims to have connected at 57,000 bits per second.  Seems a little fast but I figured out that that's only about 55.6 kilobits per second so its still ok, even though that's really fast for those things.

But recently another one of my friends has been connecting to CompuServe and its been saying that his speed is 100,000 bits per second or more, seems a lot fast for a 56k modem, I can only get about 44,000.  Not only that, but his download speeds support this too.

So I was wondering if anyone knows something about 56k modems that I don't  because I dunno how one can go that fast.

Ok that was a bit too long maybe.
 
Maybe your freinds are on Idsn or something. 44000 is normal and I think by law it can only connect at 54000(God knows why. Something with the power I think). Those modems can usually only reach 56k in lab conditions.
 
I'm using 56K modem. Usually I am able to connect at 50667 bps, but sometimes I connect st 52000 bps. It gives me download speed about 6.0 - 6.4 kB/s (from fast servers and using download accelerators like getright or netants). Hmm... when you're using isdn your nominal connection speed is 115200 bps (probly noone has reach it, it works usually at about 98 - 100k). When your motherboard has new version of serial pot (this that supports 230kbps speed) your connection speed may be even 128000 kbps (see above - 98 - 100k).
 
Oh, connection speed depends on few factor. Generally how far is from your modem to central, how noised is your line and which type of line end is using your operator (analog - usually about 48000, digitall - up to 54000).
 
Also your friend may have duel modems - 2 modems on 2 different lines sharing the same connection giving you the same speed as isdn although its not widely supported
 
A 56K modem can only connect at a theoretical maximum of 56K, usually less unless you live RIGHT next to the telephone exchange. What can happen with some modem drivers is that instead of reporting the connection speed on the modem, they report the connection speed on the COM port the modem is using ... which is up to 115K.Or - if you're talking about download speeds - compression can account for that. 56K is a theoretical maximum of 7KB/sec download speed, but on text files (HTML, TXT) mine can reach up to 10KB/sec due to hardware compression. Obviously can't help me with already compressed files like ZIPs, but it's a nice feature anyway.
 
There should be a program that converts everything to text files to allow modem compression to download it faster. Although I have this strange theory that that might not work too well.
 
You're right that might not work well. The problem is not that file has or not txt extension (or is using ansi or other characters). The problem is that zip file is already compressed and it can't be compressed more. (check on your computer using zip rar or whatever else). Text files haven't compressed parts. So the compression ratio may be about 90% (when i download html pages from fast servers i'm able to reach 20 kB/s!)
 
Ok well about my friend's modem.
I don't think he has two modems.  Unless its some wierd two-in-one kinda modem thing.  But that would still use two phone lines?  He only has one phone line, I know that for a fact.Also, it's not ISDN - I have ISDN and I get 128000 kbps connection (ALWAYS - it's really nice).


A 56K modem can only connect at a theoretical maximum of 56K, usually less unless you live RIGHT next to the telephone exchange. What can happen with some modem drivers is that instead of reporting the connection speed on the modem, they report the connection speed on the COM port the modem is using ... which is up to 115K.
Click to expand...
I bet its something like that.  115k sounds like what he told me he got.

The thing is, this only started happening after he downloaded a new version of CompuServe, so it might be some kind of software glitch that accounts for that.  Anyway, his downloads haven't gone above like 6k.  6k is just a lot faster than he got before.
 
Also... two modems on two lines wouldn't give you the same speed as ISDN... as ISDN gives you 64k per line (128k total) while the modems would give you probably 44-50k maybe per line (100k total) and that's GOOD... around here we get about 33k on our modems.
 
You got it i bet.. After running with several different ispz i found out that some do report that way.. the only true way to know you speed is to check it with a utility.. i think c-net.com can do it too... for example... A crappy ISP reported that i connected at like 115000 and it wuz bogus  :).. i usually connect around mid to high 40k..
 
Because I work for an ISP I can gave you the stright dope on what goes into an internet connection, and what's happening or this side.First of all you cannot get a 56K connetion on a normal phone line. The max is 53.3 but even that is really iffy. The reason why there is a 53.3K barrior is a little difficult to explain. I'll try my best.

You you transmit data on a phone line it a square pulse fequency wave. The higher the fequency, the faster the data can go. But also it reqires more voltage. You can only safely pump out data at 53.3K before you start blowing switches out.

Now the second thing that can make your connection slower is voltage loss on the copper line itself. When electricity goes through the line some energy is converted into heat and there is a small loss of power. Also the passing through the phyical switches at the relay points also cause loss. So the further away you are from the CO the slower the connection. Also if the main trunk is full of calls, you data has to route a longer distance through more switches to get from point A to point B.

Finaly I ask, what speed are you talking about anyway. Ire you talking about the absoulute maximum speed you can possably attain or data throughput. Both are defferant, but are related. Let us say you are connected to the internet, but sitting idle reading a page. Even though you are connected, you are not loading anything, therefore your throughput is at zero. (No data movement) So your speed is also zero. Throughput is best mesured on a graph over time as it can change. Now the maximum speed can also change as the modem can re-sync durung the connection. When you see that inital connection spped when you connect. Half the time that's not even correct and when the modem re-syncs the speed isn't updatded. It's a bug in DUN. Youre best just getting a throughput graph display for maximum speed display.

I hope that answers some questions.

-Halkun
 
also in the USA there are data limits on the data bandwidth available on a phone line. corrections: 8bits equal 1Byte, but in serial modems: 10bits = 1 bit (8 data bits+ 1 stop & 1 start bits)
ADSL= 2MBits/s = 200 Kbytes/s
Cable/NTL= 512KBits/s = 51.2KBytes/s
ISDN= 128KBits/s = 12.8KBytes/s
56KBPS modem (Dial up)= 56.6KBits/s = 5.7KBytes/s
36.6KBPS modem ....
etc etc
but these are rough figures, compression increases this bandwidth (eg: dial up is about 6-8KBytes /s)
ok?
 
And don't forget about error correction. It requires extra bits to be sent. (i don't know how this works but its propably something like checksum? or maybe not, I don't know)
 
IIRC, the error correction is just the final bit in a byte. If the last bit is 0 then the total no. of 1 bits in the byte should be even and if the last bit is 1 then the total no. of 1 bits in the byte should be odd. At least that's what I remember..
 
Depends how the error correction's been done. You've described parity, which is a simple way to do error checking. I suspect CRC is more likely using TCP/IP. Though of course, it might do parity too.
 
Just one thing to add about ISDN lines. They can be either 64K or 128K (like Ant said, 64K for each line). The important thing to note is that not all ISDN users have 2 ISDN lines. Some only have one (so they only have a 64K connection). If they have a dual connection (2 lines) then heck yeah, sure they can connect at 128K. In fact, I happen to have a dual ISDN line, and I can choose to connect at either 64K (using only one line) or 128K (both). What I like about it is that the line quality is so much more stable when compared to your average phone line. Is this true for DSL/Cable as well?EDIT: Poor wording.

[This message has been edited by Srethron Askvelhtnod (edited May 12, 2001).]
 
dsl is chaeper than ISDN cos its down the same line as the telephone class, and is very unpredictable (my exchange was down for 2!!! days).
 
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