Codec2 is an open source alternative which uses half of the bandwidth of AMBE to encode speech of similar quality, created by David Rowe and lobbied by Bruce Perens. Codec2 still continues to evolve, with additional "modes" being developed, refined and made available on a continuous basis. This has resulted in an open source codec that has progressively increased its robustness and performance – when subjected to some of the most challenging RF and acoustic environments.
FDMDV - Frequency Division Multiplex Digital Voice (AMBE Vocoder based)
FDMDV (Frequency Division Multiplex Digital Voice) is based on 15 carriers using
the 1400 LPC CODEC. High power in each carrier combined with a narrow 1.125 KHz
bandwidth provide good robustness with fast sync for a near SSB experience. FDMDV
is new and not derived from DRM technology.