I have tried to get some interest with DominoEX11 and DominoEX11/FEC by calling CQ with Multipsk and RS ID turned on. Not much response so far. As I have mentioned in the past, the basic 11 baud DominoEX mode did not seem to perform quite as well as MFSK16 which I generally consider to be the best all around mode for robustness, moderate footprint, and reasonable thoroughput but I would like to do many more tests.
Using Patrick's parameters of bandwidth, speed, and sensitivity: MFSK16 seems to me to be one of the most robust modes for its bandwidth of just over 300 Hz and with a throughput of about 40 wpm of text. It is very robust against selective fading and it seems to be able to do this while operating at the lowest possible S/N ratios of any sound card modes. MFSK16 is also robust against multipath such as on NVIS circuits on the lower HF bands. For its bandwidth MFSK16 is also quite resistant to nearby interferance and sometimes even interference within the desired signal. DEX has advantages in that it is much more forgiving in tuning, is narrower in bandwidth than MFSK16, is nearly double the speed (77 wpm) when in the 11 baud mode. Similar to Olivia, it has the ability to be manually switched to different baud rates if conditions change. You can increase baud rate up to double at 22 baud (154 wpm) with a bandwidth of 388 Hz so it never comes close to exceeding 500 Hz. If needed, you can drop down as low as 4 baud (27 wpm) and BW of only 140 Hz. The other alternative is to use the FEC option if it is available on your software. The Viterbi coding is the same as used in MFSK16 so it would be interesting to compare the performance between these to modes, particularly at the 11 baud speed of DEX11/FEC which closely matches the speed of MFSK16 and seems to me to be ideal for many hams involved in keyboarding. My experience with DEX/FEC is that it seemed much better than just DEX. I wonder if others have found this true as well. The sensitivity of the DEX11 mode is -12 and with FEC is around -13 and this is very close to the MFSK16 at -13.5 db S/N. At slower baud rates, DEX and DEX/FEC should do even better than MFSK16, but I have not used it enough to get a feel for this. And there have been no other signals that I have noticed. Has anyone been trying DEX and DEX/FEC and can report on their user experience? Also, how about for the next week or so we make an effort to use DEX and DEX/FEC as a primarily mode and then report back with a feel for how well it does? 73 and calling CQ DEX11 (no FEC to start), just above the PSK watering hole on 20 and also with a dial frequency of 10133 on 30 meters and operating up about 1500 Hz later when 20 is closing down. Rick, KV9U zl1bpu wrote: >Folks, >Given the recent discussion in the USA about restriction of audio >subcarrier generated digital modes (i.e. most of them!) to 500Hz >bandwidth, perhaps now is the time to remind you about - > > DominoEX DominoEX DominoEX DominoEX > >Yes, this super mode, which has all the advantages of MFSK16 with none >of the disadvantages, meets these requirements easily at 16 baud >(355Hz BW). > >DominoEX now sports FEC (same technique as MFSK16), and performance is >within 2dB or so of MFSK16. The major advantages are improved >tolerance of multi-path and Doppler effects, and the impressive >tolerance of drift and poor tuning. > >DominoEX with FEC is now available in MultiPSK by Patrick F6CTE and a >new alpha version of ZL2AFP DominoEX with soft decision decoding. This >version is a small program which will operate on older slow laptops. >Without FEC, DominoEX is also available in gMFSK. > >See www.qsl.net/zl1bpu/DOMINO > >73, >Murray ZL1BPU > > > > > >
