Sigtronics MRIM-2 Cellular Interface - Manual

SYSTEM DESCRIPTION
This system consists of a Sigtronics Emergency Inter-
com (either Ultrasound or EAI) with headsets and PTT
switches, a cellular phone with Hands-Free-Mode
interfaced through a MRIM-2, and as many 3PDT switch
boxes as there are stations that need to use the phone.
The two modes available on these switch boxes are ICS
(intercom and radio) and PHONE.
OPERATION
With all switch boxes in the ICS mode, everyone will
hear and be able to participate in the intercom con-
versations, talk and listen on the radio, and hear the
phone ring.
When the phone ringer is heard, the person sitting at
the phone controls sets the phone in hands free mode
and switches his switch box to the PHONE mode. He
can hear and talk on the phone, but everyone else on
the intercom cannot hear them, and he cannot hear
the intercom.
If the system is installed for more than one person with
cell phone access and the call is for someone else in the
vehicle, he switches back to the ICS mode to tell the
other person to switch over to PHONE mode. When the
other person is through with the call, he will go back
to ICS mode and tell the one at the phone controls to
terminate the call.
If two people select the PHONE mode at once, they will
both hear the phone but may not both be able to talk.
Only one at a time should be switched to the PHONE
mode.
If a person who is in the PHONE mode pushes his PTT
switch (if he has one), the radio will go into transmit
but no voice will be transmitted, and the intercom will
be muted. While in the PHONE mode, the PTT switch
should not be pushed.
To place an outgoing call, the person at the phone
controls would set his switch box to PHONE mode,
activate the phone, dial, and establish contact. He then
will switch over to ICS mode to announce to the other
person that the call is set up and waiting.
WIRING
Each intercom headset station that is to use the phone
will have a switch with three sets of contacts (3PDT)
wired as follows:
HEADPHONE & MIC CONTACTS - The mic and head-
phone of the headset shall be connected to the Wiper
of first two sets of contacts (A & B) such that in the
ICS position, their headphone and mic are connected
to their normal intercom connections. In the PHONE
position, the headphone and mic will be connected
to the MRIM-2. Note that, if more than one headset is
switched to the PHONE position, their headphones will
all be in parallel (which is not a problem), but the mics
will also all be in parallel. Electret mics may not reliably
work if paralleled.
RINGING CONTACT - The third contact (C) is wired so
that the MRIM-2 Cell phone receive audio (Blue Wire)
runs through a 100 ohm resistor to the common Inter-
com Headphone buss (also a Blue wire). This way when
the switch is set to ICS, everyone on the intercom will
hear the Cell phone ring during an incoming call. If
there will be more than one headset position wired for
phone use, the third contact is wired in a loop fashion
through all switches so that when any of the switches
are set to PHONE this loop is broken and Cell phone
conversation becomes private to the selected posi-
tion.
The Green and Red wires of the MRIM-2 must be
connected directly to the Green and Red wires of the
intercom to avoid alternator whine or similar interfer-
ence. The Black and PTT wires of the intercom will not
be connected to the switch(es). The Gray wire of the
MRIM-2 ties to the Black wire of the Intercom.
Instructions for using a Sigtronics Intercom System and a Cell Phone
Switching individual Headsets from Intercom and
Radio to a Cell phone interfaced through a MRIM-2
Specialists in “SOUND” Management
178 East Arrow Highway, San Dimas, CA 91773 ( 909 ) 305-9399
Made in the U.S.A.