4-Wire Overview

MCU Literature (.pdf) 
MCU1 Manual (.pdf) 
MCU3 Manual (.pdf) 

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Model 266 Terminal Bridge Specs (.pdf) 

Model 266 Terminal Bridge Hook Up (.pdf) 
Model 266 Universal Bridge Dipswitch Settings (.pdf)

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Model 404 Universal Bridge Hook Up (.pdf)

Model 404 Universal Bridge Jumper Settings 
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Model 276 Autocoupler Bridge Hook Up (.pdf)

Often referred to as "Hoot and Holler" or "Shout Down" phone systems, 4-wire phones continue to offer highly reliable private network communications over short and long distances. They are primarily used in urgent conference briefings, varying from small to large in scale. 4-wire communication is utilized where quality audible communications is essential.

Comlabs' current 4-wire offerings include telephones, bridges, routers, automated testing controllers and speakers. The systems support both DTMF and SS4 signalling.

Currently used in the White House, in national and regional U.S. Department of Homeland Security (DHS) and Federal Emergency Management (FEMA) offices, National Oceanic and Atmospheric Administration (NOAA) offices, and in every state and county Emergency Operations Center (EOC), Comlabs' 4-wire phones serve the needs of both the U.S. National Warning System (NAWAS) and the West and East coast Tsunami Warning Systems. Additional customers include the Federal Aviation Administration along with many of the world's leading financial institutions. Nuclear energy companies also employ Communications Laboratories' 4-wire products to provide emergency audio links to local EOC's and law enforcement agencies.

4-Wire Telephones
Comlabs offers three standard telephones that satisfy demand for most traditional 4-wire installations. As a firm, we also provides an assortment of custom telephones to meet specific needs.

Basic: The basic telephone is ideally suited to "hoot and holler" type arrangements, where users listen to traffic on the circuit over the built-in or accessory speaker, and pick up the handset when they wish to speak to others on the circuit. No backroom equipment is required to create the circuit. See Picture

Alert: Similar to the basic phone, the alert phone includes an audible and visual alert, which is activated when another phone (typically an MCU capable of transmitting an alert signal) sends an alert signal. See Picture

MCU (Multipoint Control Unit): Similar to a typical telephone, the Comlabs MCU 4-wire telephone features a full keypad and is suitable for individual, group and all call capabilities. Two, three and four digit station addressing (DTMF) and SS4 signalling are supported. MCU options include the capability of enabling a relay during an ALERT condition, and a telephone recorder interface.  See Picture

The MCU3 telephone has 3 new features which have been added to better meet our customers needs.   These include a handsfree Speakerphone, a 4 line x 20 character LCD, and an Ethernet connection which allows for serially reporting and/or programming the Telephone remotely.  See Picture_1    Picture_2    Picture_3   Call the office if you would like more info about these features.

4-Wire Bridges
Comlabs offers the following enclosed standalone and rack mount bridges:

Universal Bridge Assembly: The Universal Bridge Assembly is used to connect up to five 4-wire telephones to one circuit, and can also be used to bridge 4-wire circuits. It features level and impedance matching, and enclosure.  See Picture

Universal Bridge Card: The Universal Bridge Card is used to connect up to five 4-wire telephones to one circuit, and can also be used to bridge circuits themselves. It features level and impedance matching, and mounts for use in our Universal Bridge Rack.  See Picture

Universal Bridge Card Rack: The Universal Bridge Card Rack is a 19" rack mount assembly that can house and power up to 16 Universal Bridge Cards.  Picture 1  Picture 2

4-Wire Interfaces
We also offer several 4-wire interfaces to other communications systems:

CIU/SIU (Console Interface Unit /Switch Interface Unit Assembly): Our CIU/SIU allows dispatchers to access critical circuits from their dispatch consoles, providing the ability to access 4-wire circuits through standard PBX platforms. See Picture

VOX/AGC (Voice Operated Switch /Automatic Gain Control): Our VOX/AGC can be used to serve many functions, but are most commonly used to connect a Comlabs 4-wire circuit to a 2-way radio system.

RDTMFB (Remote Activated DTMF Bridge): The Remote Activated DTMF Bridge allows the user to selectively activate each port of the bridge from a remote location using a Comlabs MCU terminal. Individual ports can be turned on or off with confirmation of activation supplied.  See Picture

Speakers, etc.

The Model 216 communications speaker is designed to save space on your operator's console. It is only 3.6 inches square and capable of a high level of audio power with low distortion. It also has a front panel activity indicator that allows for easy identification when monitoring multiple circuits.  Picture 1  Picture 2

One Version of the Communication Speaker is the Model 375 which can decode certain preassigned DTMF tones and provide an Audible ALERT "warble" for 8-10 seconds.  We call this the "Addressable" or "SMART" speaker and it is currently deployed on the NAWAS system.

 ITC (Integrated Test Controller): When connected to an MCU circuit, the Integrated Test Controller can perform automated testing of each station connected to the network to ensure that all stations are operational and that audio levels have the correct attenuation. This computer software/hardware offering can be programmed for daily, weekly, and monthly testing as well as reporting.   Picture 1

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