One of the test frequencies on 80 meters continues to be 3584 dial frequency plus audio frequency. I usually use 1500 Hz to center the best for my rig.
Las night I had pretty good copy on Skip KH6TY and Dave, W1HKJ, and the W3? station when they used MFSK16. QRN was S9 or a bit higher. The problems with MFSK16 is that it is often very difficult to figure out where the tones are and position the passband correctly in the waterfall in order to decode the signals. When I used Multipsk, I could not differentiate the signal even though I could hear it just fine. Maybe I need to work on setting up the waterfall better? When I used Ham Radio Deluxe/Digital Master 780, I could much more easily see the tones and get it to decode. When I tried running both programs, Multipsk seemed to decode the best, however there were a few times that DM780 was able to correctly decode when Multipsk did not. The frequency between the two was off by something like 30 - 50 Hz or so. If I understand it right, DM780 does not have a correction for digital modes other than something for SSTV, whereas Multipsk has a calibration you can do. And the error was close to difference so that probably explains it. From Patrick's recent comments, the more tones you have and the closer they are together, the more critical the need for accuracy on calibration. I was not listening when the stations were running DEX, but from my experience, DEX 11 would have been very marginal in such conditions even though slower DEX baud rates may have worked a bit better, but the throughput is quite slow and may not be fast enough to be useful for messaging. DEX's advantages seem to be ease in tuning and ability to handle extreme ISI. When I tried to call Skip, I lost the center frequency and could not find it again, so could not decode his signal. Could not see a tail to lock on with the cursor. This is the main problem with MFSK16 for me. Since it requires extremely accurate tuning of only a few Hz, if you can not find the edges of the tones, it can be impossible to get it tuned in. One thing that I have tried to remember to do is to record the center frequency when you do lock in on a signal as both programs give you the audio frequency to the nearest Hz. That way as long as they don't move, you should be able to get your QRG on theirs. But I was not able to do it last night. When Skip switched to PSK31, it was no problem at all to tune in to the signal, but PSK does not work well with that level of QRN and I could only decode a few characters and not enough to make out what he was saying:( The stations mentioned some thing else like DSX or something like that (can't remember but similar to DEX). Is there another DEX type derivative? Or was that a typo or hit? Glad to see that others are using my DEX coined acronym for Domino EX:) 73, Rick, KV9U kh6ty wrote: > Ralph, > > A group of us were beta testing a brand new mode for NBEMS on HF, > especially designed to survive extremely high, almost > continuous, levels of static (such as follows a hurricane). One > station was in Florida, one in Alabama, one in Georgia, and one in > South Carolina. We were on 3854, USB, around 1500 Hz tone frequency, > so that is probably what you heard, since you are close by. The new > mode is called "DEX" and is expected to be released for NBEMS HF beta > testing with this group in about two weeks. > > 73, Skip KH6TY > NBEMS Development Team > >
