[VoIP] New Question - Problem Solved

[Paul Wills]

I didn't make the "fix" permanent yet but I found two problems.

Putting an inductor in series with the tone source filtered out the high 
frequency stuff that was preventing the FXO card from working properly.  I 
was still getting a "break" in the middle of the tone burst though.

That turned out to be caused by an inductive "kick" caused by the chime 
relay opening.  Although there is no direct path to the audio circuit, I can 
see it coupling through the cable plant or power feed supplying the code 
call unit.  A little Western Electric RC network did the job there.  All is 
well.

I will permanently install the components tonight.  In the mean time, 
there's always clip leads.

Sheesh!  You would think that Automatic Electric would anticipate such 
problems when they designed their stuff back in the 1920's.  ;-)

PDW

----- Original Message ----- 
From: "Paul Wills" <pdwills at cedarknolltelephone.com>
To: "ikjtel" <ikj1234i at yahoo.com>; "Voice Over IP Tandem for Analog 
Switches" <voip at ckts.info>
Sent: Saturday, December 02, 2006 8:03 AM
Subject: Re: [VoIP] New Question


> Max, et al;
>
> The tone level *sounds* low but I'm starting to suspect that there are 
> some
> high frequency harmonics that are messing things up.  (After all, the tone
> source is a buzzer.)  I am going to play with some filtering later today 
> to
> see if that helps.
>
> PDW
>
>
> ----- Original Message ----- 
> From: "ikjtel" <ikj1234i at yahoo.com>
> To: "Voice Over IP Tandem for Analog Switches" <voip at ckts.info>; "Paul
> Wills" <pdwills at cedarknolltelephone.com>
> Sent: Friday, December 01, 2006 10:45 PM
> Subject: Re: [VoIP] New Question
>
>
>>
>> Paul
>>
>> I'm still skeptical that the echo cancellation stuff
>> has anything to do with the audio problem...
>>
>> First, the audio in question wouldn't get suppressed
>> in the first place, because it's flowing in the
>> opposite direction from which the canceller is in
>> effect!
>>
>> Second, cancellation is rarely perfect, yet you
>> reported "silence", not "attenuated"...
>>
>> Third, cancellation would be all-or-nothing and
>> wouldn't selectively affect only the "first syllable"
>> like that...
>>
>> How hard would it be to try lowering the tone level?
>>
>> Max
>>
>>