[GreenKeys] Acoustic Coupler

[Chris Elmquist]

On Saturday (10/15/2011 at 09:51PM -0500), Jim Haynes wrote:
> On Sat, 15 Oct 2011, Larry Tighe wrote:
> 
> > Howdy Experiend,
> >
> > I've fired up a Model 33ASR with the acoustic coupler on the right side.  It
> > has a "Carrier" lite, Originate and Answer along with full or half duplex
> > switches.  The handset lies in the proper recptacles...above the indicator
> > and switches.
> >
> > The Anderson Jacobsen modem is connected to the acoustic coupler.  I'm not
> > having much luck getting it to talk to a Telex machine.  So my question is,
> > were these for private line type operations or should they interact with a
> > standard dial up Telex machine?
> >
> I would not expect it to talk to a Telex machine.  These were made for
> calling in to computer time sharing services.  I don't even know what
> a "standard dial up Telex machine" is - the original Telex used a DC
> loop rather than a modem.  If you are talking about a TWX machine, there
> are some options that are different between the two.
> 
> There are two pairs of tones, either of which can be used for originate
> or answer, and then either of them independently can have the higher
> tone be mark or space.  So that allows for eight different mutually
> incompatible services.  One was TWX, one was DataPhone which is the
> computer time sharing service, one was for WADS (a service that did not
> get FCC approval) and there was to have been something called
> WADS-prime as well.

Right... the AJ modem in the M33 is a Bell 103 compatible *originate*
modem.  That means you need to dial in to a 103 *answer* modem.
The answer modem will have the tones reversed...  ie,  it will receive
1070/1270 Hz and transmit 2025/2225 while the originate modem does the
opposite, transmits 1070/1270 and receives 2025/2225.  So, you cannot
have two originate devices talk to each other nor two answer devices
talk to each other.  You need originate calling answer.

http://en.wikipedia.org/wiki/Bell_103_modem

If you have a "smart modem" for a PC, you can configure that to be a 103
answer modem.  You'll need to either have two phone lines so that you
can dial from one line to the other, with this smart modem on the line
receiving the call or you'll need a PBX or telephone line simulator
so that you can get a ring signal to the smart modem to simulate an
incoming call... or, you can gin up a telco loop and then manually
(with AT commands) force the smart modem to answer after you have gone
off-hook with the desk set you are putting into the acoustic coupler.

Chris N0JCF

-- 
Chris Elmquist