Frequency Scrambler Software
Frequency inverted signals are unintelligible until decoded and descrambled by the intended receiver

VOCAL’s Frequency Scrambler provides a basic level of assurance for radio, mobile and VoIP communications used by commercial, police, public safety and other organizations.

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VOCAL’s Frequency Scrambler discourages interception and use of transmitted communications by casual listeners, competitors or other unauthorized eavesdroppers. Frequency scrambling can also be used over a voice encoded channel such as GSM to further obfuscate ongoing conversations. Listening to this inverted signal as it is transmitted would be unintelligible.

Our Frequency Scrambler is available for licensing as a standalone algorithm or as part of a more comprehensive library. Our source code is optimized for microprocessors and DSPs from TI, ADI, Intel, ARM and other vendors. With over 25 years of custom design and development experience in the telecommunications industry, contact us to discuss your secure communications application requirements.

Frequency Inversion

The Frequency Scrambler software uses a frequency value to invert the frequency of the input signal and provide a mirror image at a different frequency range. In a similar manner, inverted signals can be descrambled using the same frequency offset.

Frequency inversion can be performed using a single frequency value over the entire communication session. For greater protection, inversion can use different frequencies that change periodically during the communication. This allows for the implementation of a frequency hopping or rolling system using randomly generated frequencies or values selected from a predefined sequence of frequencies. Split band scrambling is also available for an additional level of communications assurance.



VOCAL’s software is available for the following platforms. Please contact us for specific Frequency Scrambler supported platforms.

ProcessorsOperating Systems
  • Texas Instruments – C6000 (TMS320C62x, TMS320C64x, TMS320C645x, TMS320C66x, TMS320C67x), DaVinci, OMAP, C5000 (TMS320C54x, TMS320C55x)
  • Analog Devices – Blackfin, ADSP-21xx, TigerSHARC, SHARC
  • PowerPC
  • MIPS – MIPS32, MIPS64, MIPS4Kc
  • ARM – ARM7, ARM9, ARM9E, ARM10E, ARM11, StrongARM, ARM Cortex-A8, Cortex-M1
  • Intel / AMD – x86, x64 (both 32 and 64 bit modes)
  • Google Android
  • Apple iOS / iPhone / iPad & MacOS
  • Unix,  Linux, μClinux, BSD
  • Microsoft Windows ACM / RTC / CE / Mobile
  • Symbian
  • eCOS / eCOSPro
  • Wind River VxWorks
  • Green Hills Integrity
  • Micrium μCOS