LinuxSA Mailing list archives

  From: Adam Hawes <adam_hawes@dingoblue.net.au>
  To  : Linux SA <linuxsa@linuxsa.org.au>
  Date: Mon, 06 Nov 2000 20:51:38 +1030

Re: LT Winmodem!!!!! EEK!

> > You bandwidth pig! :-)  The rest of us spend far less time online.
> 
> Ah.  Point taken.  Mind you, I do spend 24x7 online, but mostly
> because that's the nature of my job(s).

In regards to the constant carrier, it is being generated while the
modem is active... If you start trying to do things like play streaming
video/audio then those valuable CPU cycles are off generating the
modem's data carrier and not decoding your video stream.  Add to that
the OS overhead and whatever other processes that may require CPU time
and you've lost a buttload of cycles.

Don't also forget that a serial bytestream is low bandwidth.  The
digital data used on the modem is pretty high-bandwidth digital audio
sampled at about 8kHz at probably 10-12 bits.  Work this out and it's a
pretty hefty load on the PCI bus if you're doing other stuff too.

I wouldn't buy a Winmodem on a matter of principle.  I've spend far too
much time working on high speed DSPs trying to get them to generate and
receive RS232 bitstreams by bit toggling while performing image
processing.  The result at the end of the day was that while I can
guarantee sending a character OK, I cannot guarantee receiving a
character, as the first bit is usually lost, or the timing of the stream
gets all out.  A similar scenario occurs within your PC, and as a
result, Winmodems will drop carrier far more than standard (hardware/DSP
based) ones.

Cheers,
Adam

-- 
Adam Hawes

Web:       http://overfiend.iwarp.com
Email:     adam_hawes@dingoblue.com.au
ICQ:       2492016

Voicemail: +61 (08) 8219-3238
Fax:       +61 (08) 8219-3238

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