On Sun, 11 May 2008 22:05:06 +0200
Michelle Konzack wrote:

> Am 2008-05-05 21:33:35, schrieb web at work:
> > The total for the file is about 130 meg.
> > If your speed is 56K then lets do the math.
> > 
> > 56k = 0.056 m/sec         though it could be faster line 128k =
> > 0.128 m/sec
> 
> 56k = 57344 kBit or 5734 Baud = 0.0054 MByte/sec
> 

56kb = 56000 bits per second. As serial data it is not 1024 bits per k
but 1000. It is also a maximum theoretical limit never usually attained
in real world situations. Using 50kb in an urban environment is often
much nearer the real world truth, distance from the exchange and line
interference tend to be the two most common losses. Note that expecially
in windows reported connection speed is the speed that was originally
connected at and it can drop over time. Very few modems negotiate higher
speeds again if line noise clears. For a long download you could then
guess at around 45kb average for a 56k modem in an urban environment,
much worse in a rural area.

http://en.wikipedia.org/wiki/Gross_bit_rate
Note the table on the right. Kilobit per second = 10^3 versus kibibit
per second = 2^10.

45000 / 8 = 5625 Bytes per second

> > 130 meg / 0.056 = 2322 seconds (rounded up)
> 

130MB = 130 * 1024 * 1024 = 136 314 880


> 130 MByte / 0.0054 MByte/sec = 24074 sec
> 

136314880/5625 = 24233 seconds.

> > 2322 sec = 38.7 minutes.
> 
> 24074 sec = 6 h 41 m 14 s
> 
> Since the OOo archive is already compresses,  the  Hardware 
> compression does not take effect and should be deactivated.
> 

Hardware compression works at the packet level whereas zip works at the
file level so V90 compression may still have a useful impact (not my
field of knowledge, so i cannot say how much).

> Idealy, with compression,  a  56kBit  V.90  Modem  can  transfer  up 
> to 35 MByte per second and an 64 kBit ISDN line up to 50 MByte per
> second.

WTF? per second? If you are sending a file that contains 10^9 identical
bytes precompressed into a 5k zip file perhaps otherwise this statement
is a bit misleading.

-- 
Michael

All shall be well, and all shall be well, and all manner of things shall
be well

 - Julian of Norwich 1342 - 1416

---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]

Reply via email to