ICRI - Theory Of Operation

An ICRI is capable of bridging, or linking, the voice communications between several radios, and other voice sources. The sources may include:


  • Two-way radios ( portable, mobile, narrow band/wideband, convetional/trunked, encrypted, P25).
  • Telephone (land-line, cellular, satellite phones, Sprint or Verizon Push-To-Talk, STU or STE)
  • Voice Over Internet Protocol (VoIP)/Radio Over Internet Protocol(RoIP)
  • Handset/headset

 

An ICRI permits these sources to be linked in multiple nets/talk groups according to the operational requirements of the Incident Commander. The participation of each agency’s radio or other voice communications devices in a net/talk group is controlled by a rotary switch for each voice device connected to an ICRI.


The voice received from a remote voice source is utilized by an ICRI to “key” all other connected devices. As audio is received from the radio or other device, the other devices in that radio’s assigned net/talk group are “keyed” and the audio is released to these devices for transmission to users monitoring these devices.


  • An ICRI contains up to ten circuits that key the radios connected to an ICRI; these circuits are commonly referred to as “VOX” or “voice-activated switches.” An 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 an 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).

 

All radio connections/ports on an ICRI are “universal”; any radio can be connected to any port without special adjustment. Radio interconnect cables provided with an ICRI are engineered for the radio brands/models, and along with circuitry within an ICRI, adjust for the difference that may exist between radios.


Connection of mobile radios to an ICRI will not prevent the regular operation the mobile radio’s hand microphone and speaker. This capability is derived from the design of the C-AT-supplied, radio interface cables.


Initial connection of voice devices is aided by LED indicators for each connection/port. The LED is an indicator of audio input to an ICRI and is used to initially set the radio output level to an ICRI. This adjustment is made without meters or other instruments; an Automatic Level circuit in an ICRI, that requires no user involvement, aids in this.


Each net/talk group can be independently set for a trunking system or repeater that has an access delay. Generally, the setting of the delay by C-AT will never need to be adjusted.


An ICRI’s efficient circuit design permits a wide range of input voltages, 7-20V DC, will power an ICRI without degradation of its capabilities/function.

 

OPTION: An ICRI will broadcast on all nets/talk groups a unique unit identifier in plain English. The broadcast will occur in ten minute intervals. The broadcast will be delayed whenever there is voice communications initiated on any of an ICRI ports.

 

OPTION: One (up to eight) 250’ extension cables for radio interface may be supplied with this ICRI. The extension cable permits a radio to be placed at this distance from an ICRI. This may be 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 distance.

 

OPTION: An ICRI can be controlled remotely. DTMF tones from a radio equipped with a keypad can be used to (1) disengaged/reengage all radios in all nets/talk groups, effectively terminating or reterminating all interconnections/interoperability, (2) connect all ports into a single net/talk group---for all call announcements.

 

OPTION: Each Talk Group can be monitored through self-amplified, external speakers, when jacfks are added to an ICRI. These jacks can be installed on the left side of an ICRI. The jacks can also be used for recording the communications on each Talk Group. The audio level is optimized for the input to a digital recorder .

 

OPTION: An ICRI can optionally be equiped with Voice-over-Internet-Protocol "VoIP" or Radio-over-Internet-Protocol "RoIP" to communicate with other voice enabled devices across a network. Connection to an ICRI can be made directly through the device's IP address or indirectly though a SIP address. This circuit can be disabled, depending on situational needs. When enabled, the SIP Ethernet port is configured to announce an incoming “hand shake” request via an internal ringer and then “auto-answer” connecting the audio to the radios and handset connected to an ICRI.

 

OPTION: An ICRI can be configured for plug 'n' play compatibility with a BGAN Satellite gound station for long range radio communication.