Subject: From: Date:

Phone/Intercom & SR LEC1964.aol.com Sun, 17 Oct 1999 16:58:12 EDT

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ECS Users Group
     I have been using a cordless phone (Casio CP-850) for over a year now as 
my voice communications for speech recognition (SR). All audio both to and 
from the Soundblaster goes through the cordless "base" and to and from 
cordless handset. In addition pressing the "intercom" button on the handset 
wakes up or puts to sleep SR and an ECS control point can place the "base" 
on-hook or off-hook which allows outside phone access to SR. I use my cell 
phone with its unique caller ID for SR access.
     This required an audio pair from the 'base" speaker to the Soundblaster 
mic input. An audio pair from the soundblaster speaker output to the "base" 
mic input. An opto-isolation emitter/detector bridged across the "base 
intercom" LED with the detector output wired to an ECS digital input point 
for SR sleep/wake control and dry contact from an ECS digital control point 
to place the "base" on or off-hook.
     Phone circuits (pairs) are balanced. If either conductor has a path to 
ground 60 cycle hum becomes a problem. Therefore, all external "single ended" 
connections should have isolation. For the audio circuits this is done 
through audio transformers. I used RadioShacks 1:1 phone isolation 
transformer PN 273-1374. They easily went inside the "base" enclosure and 
perform very well. The other two connections to the base are isolated by 
using the opto-isolation and the dry contact.
     Initially I wired the audio circuits directly with no transformer 
isolation and background noise was reasonably good but with the addition of 
the LED circuit that I had wired directly to an analog input point noise 
levels became excessive. So I went back and added the isolation. For those 
that have experienced hum problems with a direct audio connection you might 
want to try an isolation transformer.
     The overall performance of this conversion along with the newer version 
of Microsofts SR is very good. I would have to say easily a 98+ hit rate. 
Although I still use the other interactive resources (Maxi-Controllers, 
PalmPads, pendants, and IR remotes) I am now strongly commited to SR. I have 
just under 300 SR "commands". That number grows rather rapidly once you 
realize how easily more control or data retreaval commands can be added to 
your system.
     A comment about using the cordless "base" to answer an incoming call. 
The "base" has a speakerphone feature which is controlled by a pushbutton. 
Basically when the speakerphone is active the base is off-hook and phone line 
audio is available to the Soundblaster. I bridged an ECS digital output relay 
contact across this pushbutton. Using the Zoom modem ring detection or its 
caller ID ECS can selectively answer incoming calls by using ECS to "press" 
the speakerphone pushbutton. This gives the caller access to SR with complete 
two-way audio. You can also use the speakerphone as part of an ECS initiated 
call. This is done by having both the modem and the speakerphone go off-hook 
with the modem providing DTMF dialing, ringback detection, and "call 
answered". Now the called party will have access to SR. Unlike the 
experiences I have had with modem audio, the Soundblaster audio out (TTS) is 
unaltered and very understandable.

Larry C.

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