Re: blind demodulation - sound card - lucent winmodem - new topics

[Evrim ULU <evrim () envy com tr>]

New additional information from my survey:

I've finally understood that my usual sb16 can be used to emulate a modem. 8Khz, 
8 bits are sufficient.

The most informative project on this topic done by Fabrice Bellard 
(http://fabrice.bellard.free.fr/linmodem.html). This project is a generic modem 
driver for linux and includes the source code. It has complete v34 
modulator,demodulator and a core v90 source but most of them are not working 
since it's unfinished. Also, source includes a pipe to sound card which uses 
linux oss driver to /dev/dsp. Readme states that two computers interconnected 
via sound card can trasfer v34 data but do not states how to do it.

Most of the stuff is ready like dft(discrete fourirer) and fft (fast fourirer).

Btw, i couldn't find enough info so, i'm going to pick Proakis Digital Comm. 
book from library and look for PCModulation explanation.

Also, i've got my phone line properties. 62.5DCvolts when offline. 23mA current. 
When rings, something like 113 DCVolts appear on line but this is not true i 
think since AC is sent to ring the phone. While connection 5DCvolts is seen.

Could anybody having enough knowledge on electronic circuits send me a circuit 
diagram so that i can connect my phone line to the line-in of my sound card? If 
i can do this, i would be very glad and continue to try to code the dsp stuff.

Thnx.
--
Evrim ULU
evrim () envy com tr / evrim () core gen tr
sysadm
http://www.core.gen.tr


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