CML Microcircuits
COMMUNICATION SEMICONDUCTORS
CMX883
Baseband Processor for
‘Leisure Radios’
Provisional Issue
D/883/7 March 2004
Full-Feature Audio-Processing and Signalling for
Half Duplex FRS, MURS, GMRS and PMR446 ‘Leisure’ Radios
Features
•
Automatic signal type scanning and IRQ on
detection of valid Rx signals, level or RSSI
•
Tone generator for caller recognition tunes
•
Programmable power down control
•
Programmable signal detection thresholds
•
Low Power operation with ‘Zero Power’ mode
•
Uncommitted Aux ADC with switchable input
to monitor signals
•
Silent operation by removal of unwanted calls
•
XTCSS channel and data signalling
•
Voice processing facilities, including Tx and Rx
gain setting and voice/subaudio filtering
•
C-BUS serial host interface
•
RF interface allowing 1 or 2 point modulation
•
Programmable soft limiter
•
Enhanced CTCSS and 23/24 bit DCS codecs
•
Zero ‘Talkdown’ CTCSS decoder performance
prevents dropouts
•
All call code and monitor modes for CTCSS
•
Audio scrambler
•
Selectable voice companding
1.1
Brief Description
CMX883, a full-function half-duplex audio and signalling processor IC for FRS and PMR446 type facilities
for both complex and simple end-designs. Under the control of the host µC, all voiceband requirements
are catered for: voiceband and sub-audio filtering, pre/de-emphasis, compression and expansion and
audio routing and global level setting with single or two-point modulation in the transmit path.
The combination of new and standard signalling functions of this product offer, under software control,
increased functionality, versatility and privacy. Standard Extended-Code CTCSS and DCS are integrated
with the new XTCSS code implementation. XTCSS provides additional and improved squelch-centred
privacy codes with the added advantage of ‘silent operation’; no annoying interference from other sub-
audio users. XTCSS fitted radios enjoy more privacy and flexibility of operation.
With ultra low power requirements and graduated powersave, this product only requires a smaller, lower-
power µC than existing FRS/PMR446 solutions. It is available in compact SSOP and TSSOP packages.
2004 CML Microsystems Plc
CMLMICRO [ CML MICROCIRCUITS ]
