AVR-Chat

On Sep 29, 2005, at 8:13 PM, Farzlina Ab.Hadi wrote:

> hi everyone!
>
> i am doing a modem communication for a telephony design. we decided  
> to use the v.22bis protocol for modem comm. on my observation, when  
> working at 2400b/s, after handshake , there will be stream of  
> garbage seen on the hyper terminal. so my tx and rx is definitely  
> out. but very clean when doing 1200b/s. tx and rx of data is ok.
>
> may be it is something to do with the telephony board design.it  
> must have created some noise that would interfere the comm at 2400b/ 
> s. because when i test from ext. modem to another ext. modem, it is  
> ok at 2400b/s.
>
> hopefully someone could give some input or ideas. thank you very  
> much for any reply!

About the time of 2400 baud telephone modems there were other tricks  
being performed in attempt to do data compression and network-like  
error detection and correction. "MNP-5" comes to mind. Is possible  
you see extra garbage from an external modem talking to your modem  
when the external is trying to detect extra protocol layers.

--
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.