CML Microcircuits
COMMUNICATION SEMICONDUCTORS
D/881/7 March 2004
CMX881
Baseband Processor for
PMR and Trunked Radios
Provisional Issue
Full-Feature Audio-Processing, Signalling and Data for
Half Duplex Dual-Mode Analogue PMR and Trunked Radios
Features
•
Automatic signal type scanning and IRQ on
detection of valid Rx signals, level or RSSI
•
Tone generator for caller recognition tunes
•
Programmable powerdown control
•
Programmable signal detection thresholds
•
Low Power operation with ‘Zero Power’ mode
•
Uncommitted Aux ADC with switchable input
to monitor signals
•
Meets ETS 300 086, MPT1327, PAA1382 and
ETS 300 230 specifications
•
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
•
DTMF transmitter
•
Programmable Selcall codec
•
Robust half-duplex FFSK/MSK modem, 1200/2400bps with CRC and parity generator/checker, gets
data through when signal is too degraded for voice – for text messaging/paging, location transfer,
etc. applications.
1.1
Brief Description
CMX881, a full-function half-duplex audio and signalling processor IC for both PMR and Trunked radio
systems suitable for 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 and audio routing and
global level setting with single or two-point modulation in the transmit path.
The combination of CTCSS and DCS functions and Selcall operation of this product offer, under software
control, increased functionality, versatility and privacy.
To cater for call setup and system signalling the CMX881 provides an embedded 1200/2400 bps
MSK/FFSK free-format modem for text messaging/paging, passing GPS location data with checksum
generation and reception and sync detection in the Rx path.
2004 CML Microsystems Plc
CMLMICRO [ CML MICROCIRCUITS ]
