[OT] Re: [vox-tech] recording telephone speech using dialogic

[Jeff Newmiller]

On Tue, 20 May 2003, joel pinto wrote:

> I am using Intel Dialogic card to record telephone
> speech. i am running it on windows.

There's your problem. ;)

> The speech data collected has a peculiar problem.
> Wheneve there is no speech ( silence after the
> utterance ), there seems to be a DC value to it. ( ie
> no zero crossings => totally above/below the zero
> axis).
> 
> I am wondering whether it is bcos of the AGC (
> automatic gain control) in the Dialogic OR is it a
> problem with the sound card.
> 
> the extreme case of the actual signal from telephone
> line having DC is ruled out bcos this is observed only
> in silence after the utterance.

Maybe you are feeding a current output into a capacitively-coupled voltage
input.  If so, you probably need to add some load (resistor to ground)
comparable to the impedance of the normal load for that output (speaker?).

---------------------------------------------------------------------------
Jeff Newmiller                        The     .....       .....  Go Live...
DCN:<jdnewmil@dcn.davis.ca.us>        Basics: ##.#.       ##.#.  Live Go...
                                      Live:   OO#.. Dead: OO#..  Playing
Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
/Software/Embedded Controllers)               .OO#.       .OO#.  rocks...2k
---------------------------------------------------------------------------