Product description

The CMX264 is a frequency domain voice scrambler for use in analogue cellular phone systems, fixed and rolling code voice scrambler applications. The device is designed to be compatible with existing mobile and cell phone systems. It contains separate Tx and Rx paths for full duplex operation and operates under µProcessor control via a simple serial interface. In the Tx path, scrambling is achieved by splitting the audio band into two parts, or sub-bands, and frequency inverting each one. The frequency at which the signal is split, the “split-point”, can be either fixed or rolling between four possible settings (this is achieved through using a 4.433619MHz crystal) resulting in a transmitted audio signal which is unintelligible to eavesdroppers. De-scrambling is achieved by a receive device set to the same split point as the remote transmitter. Please use the links below to hear this scramble/descramble voice demonstration.

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Devices are available through our distributors below:


  • SalesNetworkLogo_2
  • Mouser_logo
  • RFMW logo

Block diagram

CMX264 voice scrambler block diagram

Technical Portal

No additional information available.


  • Full Duplex Operation
  • High Recovered Audio Quality
  • Uses Split-Band Inversion
  • Fixed or Rolling Code Capabilities
  • Simple Serial Interface
  • Low Power Requirement with Standby Mode


  • Mobile Radio
  • Fixed Code Voice Scramblers
  • Rolling Code Voice Scramblers

Power supply requirement

  • 3.0 V

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Design resources

CMX264 Scrambler IC Demonstration Please use the links below to hear this scramble/descramble voice demonstration. To use the audio aspects of this demonstration, you will need a multi-media function on your computer. Please ensure that the volume function is activated.

C-BUS Guides

Guides to operation and interfacing

Variable Split-Band Scrambling

How it works

Package: D5

24-pin SSOP

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