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kbps to kBps

I am reading an article and I think the author made a mistake. He wants to calculate the latency on the 56kbps WAN link. According to him 56kbps = 57344 bytes per second (56 * 1024). So the latency is 1538/57344 = 0.026820 seconds.
But isn't 56 kbps = 7168 bytes per second. Can somebody confirm that I am correct? Thanks
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netdoc01
Asked:
netdoc01
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andeporterCommented:
As far as I know (56*1024)/8=7168
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asianandrewCommented:
Typically, a lower case "b" is bits, and a capital "B" is bytes. There are 8 bits per byte, so:

(56 kilobits/second) * (1024 bits/kilobits) / (8 bits/Byte) = (7168 bytes/second)

So, you are correct
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netdoc01Author Commented:
1 byte = 8 bits and 1 kilobyte = 1024 bytes

56 kbps = 56000 bps. Doesn't it give us 56000 / 8 = 7000 bytes per second?
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asianandrewCommented:
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netdoc01Author Commented:
Sure but then when I do convert 56kbps to byte per second through Google, it gives me the same answer as yours, which is 7168 bytes per second. So I am a bit confused. Is it 7000 bytes per second or 7168 bytes per second because for the conversion of 10mbps to bytes per seconds, Google gave me 12,500,000 bytes per second (10,000,000 bps / 8), which I agree. Thx

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asianandrewCommented:
My guess would be that Google is taking common conversion from bits to kilobits (1024 bits/kilobits), but Wiki says under the Prefixes section that 1,000,000 bits/s = 1 Mbit/s.

In my opinion, the difference between 1024 and 1000 (2.4%) is far outweighed by actual transmission speeds, which from my experience never hit this advertised speed (for example, over a 100Mbps cable, I'll get 80-90Mbps which is 10%-20% off).
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netdoc01Author Commented:
It looks like Google took the same conversion approach as Wiki for 10mbps. But for 56kbps, it took the 56 * 1024 to get bytes per seconds.

I agree that the difference is small. But I just want to be able to explain why we use (56 * 1024)/8 instead of 56000/8 in the kbps to byte per second conversion.
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Tapan PattanaikSenior EngineerCommented:
HI netdoc01,
                 
                     http://www.beesky.com/newsite/bit_byte.htm

The calculations is based on:
In the cases when used to describe data storage bits/bytes are calculated as follows:

    * 1 byte = 8 bits
    * 1 kilobyte (K / Kb) = 2^10 bytes = 1,024 bytes
    * 1 megabyte (M / MB) = 2^20 bytes = 1,048,576 bytes
    * 1 gigabyte (G / GB) = 2^30 bytes = 1,073,741,824 bytes
    * 1 terabyte (T / TB) = 2^40 bytes = 1,099,511,627,776 bytes
    * 1 petabyte (P / PB) = 2^50 bytes = 1,125,899,906,842,624 bytes
    * 1 exabyte (E / EB) = 2^60 bytes = 1,152,921,504,606,846,976 bytes

According to the above link

56kbps = (56/8) kilobytes/second  = 7 kilobytes/second

7kilobytes/second= (7*1024)bytes/second  =  7168 bytes/second


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asianandrewCommented:
I just had a thought - It doesn't make sense for the conversion to be 1024 when dealing with time.

1024 is a bit to byte conversion relating to storage as tapanpattanaik said. However, when you're talking about transfer, there is no conversion. There's transmission. You transfer a bit (1 or 0, high or low, etc), and you can count those per second.

When it comes to storage, you count those too, but its based on the combination. For instance, if you have 2 bits, you have 4 possible combinations. Even if you wanted to represent the number 3, you'd still be required to have 2 bits (in binary, this would be 11). The number 4 would be represented as 100, and 5 would be 101.

So, I think the right answer is that 56 kbps = 56,000 bps.

I hope this makes sense.
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netdoc01Author Commented:
Yes. I am talking about transmission over a link.

tapanpattanaik,
Your calculation makes sense. You convert to KB then to bytes. Now how would you perform the calculation from 10mbps to bytes per second, based on the matrix in your reply.
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asianandrewCommented:
As I mentioned, I think since it is transmission, 10 Mbps = 10,000,000 bps

I believe transmission speeds are in SI units
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Tapan PattanaikSenior EngineerCommented:
When you are talking about transmission :

bps is for "bits per second"

The letters bps are short for bits per second. A byte (described earlier) is actually 8 bits. But that's not important. What's important is that unlike a byte, which is a measure of size, bps is a measure of speed. Simply stated, the higher the bps, the less time it takes. It's a lot like Miles Per Hour (MPH) in that sense. Think how long it would take to get from New York to California in a car going 55MPH. Now think how long that same trip would take in a jet going 700MPH. Simply stated, the higher the MPH (or bps), the less time it takes.

As a rule, we use bps as a measure of the speed of getting data from one computer to another across a network (including the Internet). And we use "K" for a thousand, "M" for a million, and "G" for a billion, as usual.  The rule-of-thumb is that an uppercase B always stands for "bytes" while a lowercase "b" always stands for "bits per second".

Abbreviation Spoken             Bits per Second        (English)        Alternative Abbreviations
Kbps        Kilobits                          1,000               Thousand          Kb or Kbits
Mbps        Megabits               1,000,000        Million                  Mb or Mbits
Gbps        Gigabits                   1,000,000,000      Billion                  Gb or Gbits

for more details check this below link:

http://www.coolnerds.com/Newbies/kBmBgB/SizeAndSpeed.htm

so 10 mbps =10*(1000000)= 10000000bits/second
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netdoc01Author Commented:
I understand exactly what you are saying. But I am a bit confused for the conversion from bps to Bps.
For 100mbps, we have 100,000,000 bps / 8 = 12,500,000 Bps.
For 56kbps, why can't we have 56,000 bps / 8 = 7000 Bps instead of (56*1024) / 8 = 7168 Bps?
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netdoc01Author Commented:
Any help with this?
"For 56kbps, why can't we have 56,000 bps / 8 = 7000 Bps instead of (56*1024) / 8 = 7168 Bps?"
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asianandrewCommented:
56 kbps = 56,000 bps = 7,000 Bps = 7 KBps

Since this is speed, there is no 1024 conversion.
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Tapan PattanaikSenior EngineerCommented:
HI asianandrew,

                 yes, when u calculating Telecommunications bit rates , you should take 1000,  not 1024 ( it is for storage).

check the below link.

http://innovationzen.com/blog/2006/07/28/the-broadband-speed-guide/

Read the below forum and some one has complained about the Google calculator.

http://www.google.com/support/forum/p/Web+Search/thread?tid=0f4d1b2d5701c4d4&hl=en

thanks
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