V4 is a sound card digital protocol optimized for keyboard operation over HF. It uses 4FSK modulation and strong Viterbi FEC encoding for robustness even in weak signal or poor propagation conditions. V4 can be implemented on most computers using standard PC sound cards with radio interfaces. It is in Alpha testing but looks like a good start. This mode may be a good one for NVIS for digital nets. Watch this one for a good future.
The Alpha version of the software can be downloaded from the files section of the V4 Protocol Yahoo Group.
V4 Protocol and V4 Chat document