Forums

DTMF in G.729

Started by Bob Tausworthe February 16, 2000
I am reading a spec that states that G.729 is capable of conveying
DTMF. Is this correct? I would have thought that G.711 would be required
to accurately code DTMF.

thanks in advance

Bob Tausworthe




Hi, Bob

My experience shows that is not generally correct. In the case of 50 ms
pulse interval duration and 50 ms tone off interval duration (that is
common in auto dial) DTMF detectors can't detect output of G.729
correctly even if one uses G.729E. But G.728 does this work. I think
that G.726 is capable to code transparently DTMF signals as well.

Ilya Pozdnov.

Bob Tausworthe wrote:
>
> I am reading a spec that states that G.729 is capable of conveying
> DTMF. Is this correct? I would have thought that G.711 would be required
> to accurately code DTMF.
>
> thanks in advance
>
> Bob Tausworthe >
>
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"bob tausworthe" <> wrote:
original article:http://www.egroups.com/group/speechcoding/?startb
> I am reading a spec that states that G.729 is capable of conveying
> DTMF. Is this correct?

I think yes.I have at hand the "IEEE Communications Magazine, Sept. 97"
open in page 44. There is a table on performance requirements,
objectives and results for G.729:

one parameter is capability to transmit signaling / information tones,
among the requirements is DTMF and the Objective is that the tones have
to be transmitted with distortion as low as possible. The result is
"Met requirements"

Regards,

Sara


Bob / Ilya:

I can say with certainty that G.729E passes DTMF perfectly in a
normal
POTS channel. By that, I mean that at signal levels between -3 and
-25
dBm with a clean (non-noisy) channel, G729E passed all DTMF digits
perfectly in extensive testing.

I can't state what happens in lines with poor S/N, poor frequency
response, etc. Chuck --- In , Ilya Pozdnov <pozdnov@i...> wrote:
> Hi, Bob
>
> My experience shows that is not generally correct. In the case of
50
ms
> pulse interval duration and 50 ms tone off interval duration (that
is
> common in auto dial) DTMF detectors can't detect output of G.729
> correctly even if one uses G.729E. But G.728 does this work. I think
> that G.726 is capable to code transparently DTMF signals as well.
>
> Ilya Pozdnov.
>
> Bob Tausworthe wrote:
> >
> > I am reading a spec that states that G.729 is capable of conveying
> > DTMF. Is this correct? I would have thought that G.711 would be
required
> > to accurately code DTMF.
> >
> > thanks in advance
> >
> > Bob Tausworthe
> >
> > tozz@c...
> >
> >
----------------------------------
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> > To Join: Send an email to
> >
> > To Post: Send email to
> >
> > To Leave: Send an email to
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> > To consult the archives: http://www.egroups.com/group/speechcoding
> >
> >
----------------------------------
--
> > *** Got Questions? Get Answers. Got Answers? Get Paid. ***
> > Sign up at Infomarco.com and you can win $30,000 cash or a trip
to
China.
> > http://click.egroups.com/1/1251/0/_/8885/_/950669111/
> >
> > -- Talk to your group with your own voice!
> > -- http://www.egroups.com/VoiceChatPage?listName=speechcoding&m=1