Demodulating FSk encoded packet to extract CLI

[Mudassar Mehboob]

Hello

 I want to extract a Caller ID from FSK v.23 encoded signal acquired through a sound card. Please Help

Regards

[Travis_M.]

Hello,

I don’t have any experience with this, though, if you provide us with some additional details on what that particular standard is, and on some of the things you have tried I’d be happy to take a look at it……

Sorry I don’t have anything else though.

[Mudassar Mehboob]

HI

Right now i am acquring my signal through audio port of pc but finally i will do it using NI DAQ ( which has been ordered for but not recieved yet). The Caller  ID comes between the first and second ring period and it is fsk encoded. The information includes the caller ID of sender, time and date stamp , exchange code etc. If i know how to decode any fsk encoded signal i would be able to extract the required information.

Thanks for your reply

[rpursley8]

You only need two filters decode fsk.  Use two bandpass filters each centered at the frequencies used in the fsk.  Take the absolute value of each output and then measure the DC level.  Determine the appropriate threshold value for the DC level for both signal.  If there is a signal one one or the other that would be your zero or one.  If there is not a signal on either, then there is no data present.

Do you have a recording that you can post?

[Mudassar Mehboob]

Thanks for your tips i will definately try them

Here is the recorded audio. Listen it with windows media player and turn the scope on from the visualizations options in windows media player so that u would be able to see the wave form. The CLI packet arrives between the first and second ring. There are three rings in this recording.

Thanks for your help again

Message Edited by Mudassar Mehboob on 06-27-2006 03:42 AM

Message Edited by Mudassar Mehboob on 06-27-2006 03:50 AM