[Asterisk-Users] Chaining more than one zap echo canceller?

Henry Devito hdevito at qwest.net
Wed Oct 13 19:32:25 MST 2004


A transformer would not work correctly on a phone line due to talk path
being a DC voltage.  1:1 transformers only work with AC voltage.  

-----Original Message-----
From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Chad Scott
Sent: Wednesday, October 13, 2004 9:22 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [Asterisk-Users] Chaining more than one zap echo canceller?

I'm not aware of anyone making something like this for telephone 
systems... all the ones I've seen are RF matching networks for 
transmitters and receivers.  You'd likely have to build it.

On Oct 13, 2004, at 7:43 AM, Jayson Vantuyl wrote:

> On Wed, Oct 13, 2004 at 07:12:12AM -0700, Chad Scott wrote:
>> If you wanted to fix an impedance mismatch the "right" way, you'd use 
>> a
>> matching network.  In it's simplest form, you could use a transformer
>> to convert the 150 ohms impedance at the jack to 600 ohms for the
>> equipment.  You could also use a dynamic matching network with 
>> variable
>> capacitors and inductors to create just about any impedance you want.
> Can I buy something like this or do I have to build it?
>
> -- 
> Jayson Vantuyl
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