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puzzled kbps Kbps

Community Veteran
Posts: 1,817
Thanks: 11
Registered: 30-07-2007

puzzled kbps Kbps

My line syncs at 7500 Kbps.

what should I see in terms of kbps and Kbps when I download.

When I download from the likes of ATI I get 600Kbps and the file of 34 mb downlaods in 30 to 40 second is this correct or should my downlad speed be nearer the 7500Kbps.

cheers

A
7 REPLIES
N/A

puzzled kbps Kbps

Essentially, kbps/Kbps are the same thing. The only varying factor is the case of the b/B where b = bits and B = bytes, though sadly this is far less than often followed nowadays but that is how it should be. Also as far as being technically correct, K should always be capital because it represents Kilo.

Your line synced at 7500 kilobits per second in this case would (mathematically, with 8 bits per byte) work out to 937.5 KB/s... tho this is where my understanding of quite how line speeds are actually calculated comes to a crashing halt because it simply isn't true for any line speed when worked out that way. For some reason I still don't fully understand (and I haven't bothered researching because it isn't that important at the end of the day) you can just divide your line speed (Kbps) by 9.6 to give the maximum speed not including overheads.

That being the case the highest you can expect to see is 781.25 KB/s, though including overheads it probably wont go much over 760 +/- 10.

Still... at the end of the day, you are doing a lot better than most maxdsl users atm :p
Community Veteran
Posts: 14,469
Registered: 30-07-2007

puzzled kbps Kbps

Data is transmitted in packets and each packet has additional data, usually referred to as the overhead, added to ensure your data gets to the right destination, intact and in the correct order. The overhead is typically between 5 -> 10% of the data sent. Added to that the return acknowldgement packets and you see why you can never send data at the full sync speed. Also contention and packet fragmentation can further reduce the overall throughput you can get.

As a rough guide I just remove a 0 and use what's left as the KBs figure (much easier than deviding by 8 or 9.6 Wink ). So for 7500Kbs that becomes 750KBs, 2500Kbs becomes 250KBs, 1172Kbs becomes 117KBs.

Also for MaxDSL, your data throughput rate is determined by a table detailed here, for LLU, your throughput speed is your sync speed.
Community Veteran
Posts: 1,817
Thanks: 11
Registered: 30-07-2007

puzzled kbps Kbps

Cheers, I was close in my thinking. I just wanted to check after someone eslewhere had talked of download speeds going from 600 to 2900 something I guess they were talking Kbs not KBs.

A
N/A

puzzled kbps Kbps

Just a note about the K/k

k is the usual way of expressing kilo (x1000) but in computing K is used. K also means kilo but it is equal to x1024. Slightly different. However M is always used for Mega but in computing Mega is K x 1024 whereas anywhere else M = k x 1000. Similar with Giga (G) and Tera (T).

And yes B = Byte and b = bit.

JOHN
N/A

puzzled kbps Kbps

See this link

I was under the same impression as you but in the late 90's the definition for K and k was changed.
k can equal 10^3 or 2^10

So by this you must be 30+ Cheesy
polsapple
Grafter
Posts: 30
Registered: 15-09-2007

puzzled kbps Kbps

And for those interested...
4 bits is called a 'nibble'. Honest. It's half a byte.
Clever eh?

Cheesy
N/A

puzzled kbps Kbps

Ah right OK. Err well I'm just shy of 30 actually :lol:

Good old nibble. I've also seen this written as nybble.

Better defragment my winchester disc now.


JOHN