CVSD Codec

Continuously Variable Slope Delta modulation, or CVSD, is a codec which was designed for use in military wireless communication systems.   This codec supports various bitrates, depending on the sampling rate. For example, CVSD which encode a bit per sample, will encode an 8kHz 16-bit linear sample stream to a 8kbps data stream.   The CVSD codec is used in the MIL-STD-188-113 with 16kbps and 32kbps data rates for 8kHz sampling.


CVSD is a delta modulation technique which uses an adaptive step size.  The CVSD encoder compares the input signal with a reference signal.  If the input signal is greater than the reference signal, then a 1 is encode, otherwise a 0.  The delta slope is modified based on the previously encoded bits.  Consecutive 1s or 0s will increase the step size, while alternating values will decrease the step size.

Vocal’s firmware consists of the following:

VOCAL’s CVSD software is available for the following processors and operating systems. Please contact us for other supported platforms.

ProcessorsOperating Systems
·        Texas Instruments – C6000 (TMS320C62x, TMS320C64x, TMS320C645x, TMS320C66x, TMS320C67x), DaVinci, OMAP, C5000 (TMS320C55x)

·        Analog Devices – Blackfin, TigerSHARC, SHARC

·        PowerPC

·        MIPS – MIPS32, MIPS64, MIPS4Kc

·        ARM – ARM7, ARM9, ARM9E, ARM10E, ARM11, StrongARM, Cortex-A8/A9, Cortex-A53,Cortex-M3/M4/M7

·        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

·        VOCAL LANsEND

·        Micrium μCOS