MARC (Multi-Agency Radio Communications)

Land Mobile Radio (or LMR) has traditionally been used by companies, government agencies, and branches of the military to provide wireless communications between mobile personnel in the field and centralized dispatching and control centers. As the costs associated with purchasing and deploying radio systems have come down, it has become commonplace to see radios in use in general business environments such as retail, customer service, car rental, and construction.
The MARC server integrates with radio systems, extending the reach of your LMR communications over your IP infrastructure.

How does The MARC Server integrate with LMR?

To the MARC Server powered by MARC LMR, a radio is simply another endpoint in the communications infrastructure that may (or may not) require specialized processing to make communication possible. Let’s examine this statement in detail, starting with receiving audio from radios.
For MARC LMR to receive radio transmissions, those transmissions need to be converted into Voice-over-IP packets and placed onto the network using the industry standard Real-Time Protocol (RTP). A further requirement is that the audio must be encoded using a codec supported by the MARC LMR such as G.711, G.728, G.726, GSM, G.729, etc.
Sending audio to a radio is the inverse of the above process, requiring a conversion from Voice-over-IP packets into a format acceptable to the radio. The only additional requirement is that the audio transmission from MARC LMR may need to be accompanied by signaling required to “key” the radio. (We’ll discuss signaling in the next section.)
In most situations, the easiest way to connect the radio to the network, and to establish the bi-directional audio flow, is to use a device such as a simple router or VoIP gateway that connects to the radio through an analog interface such as E&M, FXS, or FXO.
P25 Digital Radio interfacing are available by some radio manufactures as well and are supported with MAR LMR. Support for analog interfaces varies across radio manufacturers so it’s worthwhile to find out what’s best suited to your environment.
Once this step is accomplished, all transmissions from the radio are placed on the network and received and processed by other MARC LMR endpoints. Audio from these other endpoints is received by the connecting device and relayed to the radio. This generic approach allows the MARC Server to integrate with practically any radio system available and allows agencies to add interconnectivity to the MARC Server in the shortest possible timeframe.