Internet speeds: bit vs. byte

[Boomhauer]

First TechIMO rules!
I’m trying to get the whole issue of internet speeds straightened out in my mind. With most cable ISP’s they advertise 1.5M download and 128K uploads. And DSL is usually offered starting at 256k download and 128k upload and for higher monthly rates that can be increased. I’ve heard that these broadband ISPs try to be a little misleading or prey on people’s lack of knowledge about the actual speeds. Is it correct that with Mb vs. MB and Kb vs. KB that the capitol and small B’s respectively refer to bytes and bits? Is there any difference between K and k? (forgive me for using caps vs. small incorrectly throughout this post; this is the issue I am trying to clear up) I understand that there are 8 bits in a byte so I’ve assuming that in real life that you would be transferring about 1/8 the info per given time frame using bits rather than bytes. I guess while I’m at it I am confused about 56k dial-up speeds. Is it really 56Kb, 56KB, 56kB or 56kb?
Where I’m confused is: how do you really figure out what kind of transfer rates you will have. (Let’s assume that with cable that you are the only user on and getting the full 1.5xx upload speed.) With 56k dial-up it’s been my experience that 5Kb/KB is a damn good transfer speed; usually one is in the 3 – 4 K/sec speed. Does that mean with a DSL 256k that you would get roughly 5 times that speed (25KB/Kb/sec)? What about the download transfer rate of 1.5M with cable?

Next, uploading…. Are the advertised speeds bit or byte? If bit than am I correct in assuming the actual transfer rate is really really slow? Does upload speed on cable go down as the number of users increase like it does with downloading?

Small business question: Since cable broadband appears to have extremely slow upload speeds would this be a poor choice for a small home based business? Is going DSL the only (affordable) way to get faster upload speeds? How and why do DSL providers charge so much more to give you faster uploads…. What is really changed in your service that allows the faster uploads? Is it wiring to your house or hardware or is it just that they can configure your system for a price so they do it?

This is getting pretty lengthy and rambling. I’ll post and then ask more specific questions as you help me with your answers.
Thanks!!

You are right about the b's and B's.

56K=56KB not 56Kb.

Dunno about the other business related use. But cable (which comes in with your TV signal) is generally faster than DSL.

[J-Excel]

I think its 56kb (kilo bits per second). And the max speed of 56kb is about 53kb because of phone line quality. There are 8 bits in a byte. So a 56k connection can move around 6.625 kilobytes per second max.

Cable and DSL advertisers say 50 times dialup, but they are using 28.8 for the dialup.

[DoctorReno]

Ok, we have one who says it's bits and one who says it's bytes for dial-up. Which member is right here?

[sixf00t4]

56k=56Kb=56kilobits

[DoctorReno]

Oh and just FYI J-Excel, the 53 limit is not a phone line quality issue. 53.3K(b?B?) is the maximum limit mandated by the FCC for dial-up although the modem may be 56K.

[J-Excel]

Whatever. Point is it's not true 56k in the US. I never get better than 50k so for me it is line quality.

[muno]

Haha j-excel

While the line speed in bytes (eg.256kb) is theoretically 32kBs, the maximum is something like 27,6kBs.

With some companies, both the speed go down (downstream and upstream) when more and more people use it. With some other companies they advertise the minimum the connection speed will ever be. All lines get shared somewhere.

The advertised speeds are always in kilo/megabits.

With modern internet connections, no cabling is required in-house. Cable comes from cable, and dsl from phone line.
If you don't really need fast upload, don't get it.
-M

[Urban_Squrill]

Good Thread!
Welcome to TechIMO.

[OuTpaTienT]

Here's an explaination from this thread.

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I find it easiest to just remember we got 2 seperate ways to measure transfer speed. Maybe like you could express the length of a football field in more than one way. Everyone knows it's 100 yards long. But it's also 300 feet long. And if you didn't know exactly what yards and feet were or how they related to each other, you might be fooled into thinking a 300 foot long field is longer than a 100 yard field.

So just like feet & yards, we got two different size units to make measurements with. We have bits and bytes. And just like a yard = 3 feet, a byte = 8 bits. The standard abbreviation for bits is a lower case "b". And for bytes it's a capital "B".

b = bit (nothing smaller than a bit. A bit is a 1 or 0 in binary.)
Kb = Kilobit, 1,000 bits (often seen Kbps when measuring speed. Kb per second.)
Mb = Megabit, 1,000 Kilobits, 1,000,000 bits (often Mbps - sometimes also seen as Mbit/sec or similar)

B = byte (a single byte is made of 8 bits. Just like a yard is made of 3 feet.)
KB = Kilobytes, 1,000 bytes ( KBps = KB per second)
MB = Megabyte, 1,000 Kilobytes, 1,000,000 bytes (and thus it also equals 8,000,000 bits)

Most of us are more familiar with the terms bytes and Kilobytes and Megabytes and Gigabytes because that is what we deal with for the standard measurement of file size, and HD size and memory size, etc.

So if we're talking about a connect speed of 1.5Mbps (Megabits per second) and we'd like to think of it in our more familiar term, "bytes", then all you do is divide it by 8.

1.5Mb = 1,500,000 bits

(convert it to bytes by dividing by 8)

1,500,000 / 8 = 187,500

187,500 bytes = 187.5 Kilobytes

So 1.5Mbps is the same as 187.5KBps


Of couse this is all approximate and you have to allow some give'n'take when converting these numbers. When you get really techinical you discover that things like error correction and/or the TCP/IP protocal take their own little bites out of the transfer speed, but it's usually so small that it's not worth trying to factor it into any calculations.
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