Remote Speaker Microphone


L3Harris offers a line of incredibly tough voice radios for firefighters; the XL Extreme. They represent a never-before-seen level of ruggedness: impervious to high temperatures, submersion, and extreme impacts.


The XL Extreme Speaker Mic, or ESM, taps into the critical controls and features of the fire radio (also engineered by Porticos) with commensurate high standards for audio quality.

Porticos created an architecture to translate the raw output from a MEMS microphone to a signal that could be packaged for USB streaming. The audio conversion challenged the limits of available processor resources, so Porticos optimized signal processing tasks to work within those limitations.

Generic Flex Circuit
Generic flex circuit.

The controls on the ESM are densely packaged, so Porticos made extensive use of flexible printed circuits (FPC). This simplified assembly, reduced the volume of wires inside the device, and allowed sensitive signals to be shielded without the use of bulky wire.

The ESM is powered by a host radio, meaning power consumption must be strictly limited. Porticos developed a sophisticated calculator that estimated the power consumed and projected dynamic component efficiencies.


The XL Extreme Speaker Microphone is the first and only device of its kind to be fully compliant with National Fire Protection Association (NFPA) testing. Porticos engineers met or exceeded all requirements for audio quality, size, ruggedness, and battery life.

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