The qpacketmodem object conveniently combines linear modulation with interleaving , two levels of forward error-correction coding, and a data integrity check. The object combines the packetizer object with symbol packing for modulation. Both hard-decision and soft-decision decoding are supported, assuming the forward error-correction codec supports it.

http://liquidsdr.org/doc/qpacketmodem/

Version 1.3.0 is finally tagged in the Git repository.

http://liquidsdr.org/blog/liquid-dsp-1.3.0/

The modem module implements a set of (mod)ulation/(dem)odulation schemes for encoding information into signals. For the analog modems, samples are encoded according to frequency or analog modulation. For the digital modems, data bits are encoded into symbols representing carrier frequency, phase, amplitude, etc.

http://liquidsdr.org/doc/modem/