PMR Signalling Processor
CMX881
CMX881 Functions and Facilities
Half Duplex Operation
Working in a half duplex mode, when the product is in Tx the Rx sections can be powered down to
extend battery life, conversely in Rx major sections of the Tx can be treated in the same manner.
Serial Control and Data Interface
C-BUS: Serial control, data and command program interface compatible with SCI, SPI and Microwire
type interfaces.
Power Requirements and Economy
With an ultra low power requirement, the CMX881 operates from a single 2.7 to 5.5 Volt supply with
graduated ‘Sleep Mode’ powersaving facilities for both Rx and Tx modes.
Signalling:
CTCSS
Zero ‘Talkdown’ performance eliminates unwanted breaks in communication. The CMX881 is pre-
programmed with 39 standard CTCSS (+ Notone and DCS ‘turn off’ tone) frequencies, any one of which
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.
2004 CML Microsystems Plc
3
D/881/7
CMLMICRO [ CML MICROCIRCUITS ]
