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CMX138

Audio Scrambler and Sub-audio Signalling
Processor
Features:
  • Programmable Audio Scrambler
  • Full Audio-band Processing:
    - Pre and De Emphasis
    - Compander
    - Scrambler
    - Selectable 2.55 and
    3.0 kHz Filters
  • Auxiliary ADC and DAC
  • C-BUS Serial Control/Data Interface to Host µController
  • Two x Analogue Inputs (Mic. and Discriminator)
  • Selectable Audio Processing Order
  • CTCSS and DCS Sub-Audio Signalling
  • Auxiliary System Clock Output
  • Single-point Modulation Tx Output
  • Flexible Powersave Modes
Applications:
  • Leisure Radio Systems:
    • FRS, MURS, PMR446 and GMRS
Packages:
  • CMX138E1 - 28-pin TSSOP
Supply Requirement:
  • 3.0 to 3.6 V
Description
The CMX138 is a half-duplex audio scrambler and sub-audio signalling processor for analogue two-way radio applications. This makes it a suitable device for the leisure radio markets (FRS, MURS, PMR446 and GMRS).

This device provides a user programmable frequency inversion audio scrambler with compander and pre/de-emphasis - performing simultaneous processing of sub-audio and in-band signalling.

Other features include: an auxiliary ADC channel and an auxiliary DAC interface (with optional RAMDAC) to facilitate transmitter power ramping.
The device has flexible powersaving modes and is available in a 28-pin (E1) TSSOP package.

 

Block Diagram

 

CMX138: A half-duplex audio scrambler and sub-audio signalling processor

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