CMX883(2002) 데이터 시트보기 (PDF) - CML Microsystems Plc

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CMX883
(Rev.:2002)

Baseband Processor for ‘Leisure Radios’

CML Microsystems Plc 

FRS Signalling Processor

CMX883

Signalling:

XTCSS

A state-of-the-art (squelch) signalling format, employing both sub-audio (CTCSS) and in-band (XTC)

signalling concurrently, which offers more than twice as many privacy codes as standard CTCSS

operation and completely eliminates interference caused by other traffic on the channel (quiet operation).

Additionally, the XTCSS signalling can be employed as an over-air control for such features as voice-

compression. XTCSS is fully compatible with both conventional and enhanced CTCSS signalling

operations and will implement the All Call Code function.

CTCSS

The CMX883 is pre-programmed with 39 standard CTCSS (+ Notone and DCS ‘turn-off’ code) and 12

additional ‘split-tone’ frequencies. Any one of these can be selected for reception or transmission.

Decoding is aided by the use of adjustable decode bandwidths and threshold levels. Decoding is carried

out rapidly thus avoiding the loss of the beginning of speech or data signals. A CTCSS configuration of

this product enables ‘Tone Cloning’.

Two unique features of this product are its CTCSS ‘All Call Code’ and ‘All Codes Monitor’ modes:

All Call Code – transmissions using this code will be heard by all CMX883 enhanced radios regardless of

their selected CTCSS code. This provides an important benefit to both safety and convenience.

All Codes Monitor – selection of this code 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 is a superior method of ‘channel monitoring’, which allows miscoded calls

from conventional CTCSS-party radios to be heard and directly responded to.

DCS

The DCS code is in NRZ format and is transmitted at 134.4b/s in either 23 or 24 bit patterns. The code,

for transmission or reception is programmed via the host µC with the ‘turn-off’ code being supplied from

the CTCSS facility. Decoding is carried out rapidly thus avoiding the loss of the beginning of speech or

data signals.

© 2002 CML Microsystems Plc

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D/883/2

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