Hi all, I would like to test one of these ARQ modes. Anyone around for a test on 40- or 80m? I am calling cq on 3585 usb in Thor right now.
73 de LA5VNA Steinar kh6ty wrote: >> 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? >> > > Yes, but some modes cannot be used as an ARQ mode due to either too much > latency or ascii or control code support. The only modes tested with flarq > are DominoEx, MFSK16,32,64, PSK31,63,125,250, Thor (all speeds) and > MT-63-2000. The latency of MT-63 is so great, only the fastest speed is > enough to enable ARQ to work. > > >> 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? >> > > See above. Of the available modes for ARQ, the ones listed for NBEMS are the > ones recommended for messaging. However, on VHF when signals are near the > noise, it is sometimes easier to tune with PSK31 (because the idle carriers > stand out more clearly against the noise background on the waterfall than > the multi-tone modes) and then switch to MFSK16 or DominoEx11 without > changing the tuning. > > >> 2. Could you explain how the MFSK modes are made more robust and yet can >> still work with other programs? >> > > We worked with ZL1BPU, one of the authors of MFSK16, to implement several > enhancements, one of which is called "puncturing", which averages the signal > level and if a signal sample is significantly above the average, it is > assumed to be a static burst and the AFC is momentarily disabled. The fldigi > MFSK modes are compatible with MFSK16 or MFSK8 in other programs, but it is > necessary to use fldigi in order to get the advantage of the enchancements. > > >> 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. >> > > Generally, not on HF so much, as transceivers tend to have less drift on HF, > especially on 80m and 40m, but definitely on VHF, where excessive drift can > often be a serious problem for some digital modes. > > 73, Skip KH6TY > NBEMS Development Team > > > > No virus found in this incoming message. > Checked by AVG - http://www.avg.com > Version: 8.0.138 / Virus Database: 270.6.5/1620 - Release Date: 19.08.2008 > 06:04 > > >
