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THEORY OF OPERATION
In simplest terms, the ICRI performs several primary functions:
Distributes audio received from one two-way radio to other radios, telephone or recording device
connected to the ICRI.
Utilizes this same incoming audio to ―key‖ the other radios connected to the ICRI.
Permits the connected radios to be placed into one of two ―nets‖/talk groups. Talk group selection is
controlled by the switches on the reverse side of each ICRI radio jack.
May expand number of interconnected agency radios by a physical link between two units/ICRIs
This configuration of the ICRI is design to be quickly set-up, and operate for extended periods
without additional power sources or specialized support equipment.
The ICRI will operate for at least 6 hours on its internal battery or 24 hours, with 8 ―AA alkaline
batteries (somewhat less in cold weather). The ICRI can also be powered by an external battery
pack, a vehicle-supplied or other DC source, or AC.
Two, three, four, five radios can be linked together through the ICRI. Within each ―kit‖ are the
interconnect cables to link radios and telephones. Unencrypted radios can be link in one talk group
while encrypted can be linked in the second talk group. Talk group selection is controlled by the
switches about each radio ―port‖.
Up to five portable radios, and required interconnect cables will be supplied with the ―kit‖ (other
portable and mobile radios can also be connected).
A Sprint ‗phone in ―Direct Connect‖ mode can also be linked to the 2-way radio communications nets.
A land-line telephone can be connected to the radios; no special cable is required.
Unencrypted radios can be linked in one talk group, while encrypted can be linked in the second.
Military radios, and satellite ―phone‖ and voice-over-IP devices can be linked to the 2-way radios with
cables that can be supplied.
The ICRI will operate for 24+ hours, with 8 ―AA‖ alkaline batteries (somewhat less in cold weather).
It can also be powered by an external battery pack, vehicle-supplied or other DC source, or AC.
A 250‘ extension cable for radio interface may be supplied with this kit. The extension cable permits
a radio to be placed at this distance from the ICRI. This may useful when connecting to a satellite
antenna/radio or when a team enters a structure/tunnel. Multiple extension cable can be connected
for even greater distances.
An ICRI contains up to six circuits that key the radios connected to the ICRI; these circuits are
commonly referred to as ―VOX‖ or ―voice-activated switches.‖ The ICRI uses these circuits to
perform other controlling functions as well. Only the VOX directly connected to the incoming audio
is used to key each of the other radios simultaneously (all other are temporarily disabled, preventing
a second ―voice‖ from causing a disruption in initial voice being distributed).
There is no discrimination or evaluation of the incoming audio so that delays are not inserted into the
audio transfer or ―keying‖ processes. Radios, telephones and/or recording devices connected to the
ICRI are provided with the incoming essentially in real-time (an initial delay at keying to preserve
the first syllables of incoming audio as the transmitters [including wide area, repeater-based
―trunked‖ radio systems] are keyed up).
