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CML Micro signaling IC suits FRS, PMR446 radios

Posted: 09 Jul 2003 ?? ?Print Version ?Bookmark and Share

Keywords:cmx882? cml microcircuits? signalling processor IC?

The CMX882 device from CML Microcircuits is a full-function half-duplex audio and signaling processor IC for FRS and PMR446 type facilities. Under the control of the host ?C, all voiceband requirements such as Voiceband and sub-audio filtering, pre/de-emphasis, and compression and expansion are catered for.

The combination of new and standard signaling functions in the CMX882 offers, under software control, increased functionality, versatility, and privacy. Standard Extended-Code CTCSS and DCS functions are integrated with the XTCSS code implementation. The XTCSS signaling format employs both sub-audio (CTCSS) and in-band (XTC) signaling concurrently, which offers more than twice as many privacy codes as standard CTCSS operation.

The IC facilitates GPS by providing, in the Tx path, a 1.2Kbps or 2.4Kbps MSK data packet encoder that incorporates interleaving, FEC, CRC, and data scrambling. In the Rx path a 1.2Kbps or 2.4Kbps data packet decoder with automatic bit-rate recognition, 16-bit frame-sync detector, error correction, data descrambling, and packet disassembly is available.

Transmissions using the All Call Code will be heard by all radios with CMX882 regardless of their selected CTCSS code. The selection of the All Codes Monitor mode at the receiver enables all transmissions that are using a CTCSS tone to be heard, and the tone number to be reported. Open channel noise or calls lacking coding will go unheard. This method of channel monitoring allows miscoded calls from conventional CTCSS-party radios to be heard and directly responded to.

With low-power requirements and graduated powersave, the product requires a smaller ?C than existing FRS/PMR446 solutions, and is available in SSOP and TSSOP packages.

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