This webpage gives details of an interesting high speed MS mode from DK5EW. There is also a Yahoo group to discuss this: see http://uk.groups.yahoo.com/group/psk2k/
PSK2k is fully error correcting and call specific in operation so you will only see the QSO in progress and any non-QSO CQ or QST text. All other transmissions (other people also in QSO) are discarded. This allows multiple QSO’s to take place on a single frequency.
PSK2k can be operated in fully automatic mode if required. This enables QSO’s to be completed fully automatically without user intervention. Important advantages are that long term testing can be done, on QRP power for instance, without having to sit an monitor every period."