Just to clear up a few things: 1. Is it correct that just because a mode is listed in the NBEMS mode list, does not mean that you could not use it with flarq as an ARQ mode?
Therefore, any of the modes could theoretically be used, even if not recommended or even if they might not work very well but flarq will ARQ any of them? 2. Could you explain how the MFSK modes are made more robust and yet can still work with other programs? On another note, thanks for confirming what I suspected about the drift issue. I recently was told that I my preference for purchasing only TCXO rigs was overkill, even for VHF, but when you look at the ppm issues with modes such as MFSK, even a few Hz is a problem. 73, Rick, KV9U kh6ty wrote: > PSK31 and PSK63 are still there for use in QSO's but neither mode is as good > as MFSK16 or MFSK32, or our new Thor modes, for ARQ messaging when high > static conditions on 80m or 40m exist, which is most of the time in the > summer or before and after a hurricane, so MFSK16 or MFSK32, wider, but the > same speeds as PSK31 and PSK63, are recommended for NBEMS messaging over > PSK31 and PSK63. The MFSK16 and MFSK32 modes are not your grandmother's MFSK > modes, but have been made more robust under static conditions on HF when > PSK63 and PSK31 get pulled off frequency by the AFC if there is a static > crash between ARQ transmissions. It was a tough decision not to include > PSK63 in the recommended NBEMS mode list, but the job of NBEMS is to > accomplish the most reliable messaging for any given speed, and the modified > MFSK modes are simply more reliable, although they are wider. > > For VHF messaging, PSK31 and PSK63 lose out again over DominoEx11 and > DominoEx22 at the same speed, because many VHF multimode transceivers have > no TCXO and drift too much to maintain tuning on 2 meters during an ARQ > transfer, whereas DominoEx has a wide tolerance to mistuning or drift, such > that no AFC is needed and provides a lower minimum S/N than the PSK modes at > the same speed. > > PSK31 and PSK63 are easier to recongnize among the background noise on VHF, > so it is often best to establish tuning with PSK41 or PSK63, check to see if > there is no adjacent frequency activity, and then switch to DominoEx for the > ARQ transfer. > > The popular IC-746Pro, for example, drifts 100 Hz between receiving and > start of transmitting, unless a TCXO is added, causing the loss of the first > few characters or words on PSK63, so I have switched our 2 meter digital net > from PSK63 to DominoEx. > > 73, Skip KH6TY > NBEMS Development Team > > >
