Called NXDN, its common air interface (CAI) is a result of a joint development between Kenwood Corporation and ICOM Incorporated. NXDN digital radio equipment supports commercial Private Land Mobile Radio (PLMR/LMR) to serve light commercial, more demanding business and industry, and public safety applications, even on 6.25kHz channels. The technology satisfies the US Federal Communications Commission (FCC) Part 90 'narrowbanding' requirements; as of December 2009, 70,000 RF channel licenses were approved for NXDN operation. CML is committed to the promotion, support and development of this exciting new radio technology.
The CMX7131 and CMX7141 are digital PMR processors built on CML’s proprietary FirmASIC technology and are suitable for use in a number of digital radio systems now including NXDN. FirmASIC component technology enables on-chip sub-systems to be configured by a Function Image, a data file that is uploaded during device initialisation that defines the device's function and feature set. This technology provides the flexibility for the CMX7131 and CMX7141 to support dPMR, DCR and NXDN radios as well as analogue two-way radios.
The new Function Image developed by CML provides a number of features very important to NXDN design, including: a high performance 4FSK data pump supporting soft-decision coding mode (which improves the reliability of the data link) and integrated RRC filters; a high performance, autonomous AFSD that greatly simplifies host microcontroller development and risk, differentiating between frame sync cases, which can also reduce an NXDN receiver's average Rx power consumption; a voice codec (ADC and DAC) for microphone/speaker paths to complement an external AMBE-3000 vocoder device and integrated auxiliary functions that reduce total BOM cost and size.
As an aside, the Chairman of the NXDN Forum recently announced that the NXDN Forum and the dPMR MoU have agreed to collaborate on issues of common interest in the promotion of 6.25kHz FDMA technology. CML has made available, on it's website, a downloadable brochure describing ETSI's role in Digital Private Mobile Radio (dPMR) available in English, French, Italian and Spanish.