John, You have brought this up before, but I am like most hams and try to do the right thing. I use wide modes, narrow modes, and in between modes. Much depends upon who you are trying to contact and the current conditions.
If I want to work a PSK31 or CW station, then of course I will be narrow as can be. If conditions are terrible on 80 meters and not much else is on, then I may use Olivia, even using the wider formats, but mostly to test and see if they really work better. Not long ago I parked down on 160 around 1807 and answered a ham calling CQ on Olivia (500 Hz). He was almost shocked that there really were hams using digital modes down there, HI. Rules of thumb that I have been trying to follow, and I hope more hams will give serious consideration: - Follow the IARU recommendations. Here in the U.S. we don't absolutely have to follow it, but it sounds like some countries are required to do so. For example, I don't intentionally use modes wider than 200 Hz below 3580, 7035, 10140, 14070, etc. I may have forgotten, but it was not intentional and I keep a copy of the IARU band plan available for reference. (Note: 500 Hz digital modes are in the IARU band plan on the lower few kHz of 160, but that is a rare exception). - if conditions are bad, and there are few stations on the band, then wider modes may be more appropriate. Then again they may work against you, depending upon their design. - I generally prefer modes that are under 500 Hz. Partly because they increase spectrum efficiency so that there can be more simultaneous users. I totally disagree with those who believe that having the widest and faster possible mode is more "efficient" on a shared, non-channelized resource such as we have on the ham bands. - The medium bandwidth modes often work better than the very wide ones or the very narrow ones. Partly that is due to being newer technology, but also because having many simultaneous tones spread out over a wide area (OFDM) just does not work well under difficult conditions since individual tones are necessarily of reduced strength. As a good example, Pactor 3 drops down to only two tones, although separated by something around 700 Hz, when it goes to its most robust speed level. Another example is comparing the older 8FSK125 MIL-STD-188-141A "ALE" mode to the 8FSK50 FAE400 mode. Even though the FAE400 modes is very much narrower by at least 5 times, with greatly increased spectrum sharing, it actually works much more robustly and can have higher throughput than the extremely wide 141A mode unless conditions are good enough to allow the 141A mode to get through. Even then the 141A mode is not 5 times faster (maybe 2X) under the very best of conditions. - Other factors include what other hams are willing to operate and since expensive hardware is relatively rare you won't find many contacts with those modes, and it does not work well for local/regional public service/emergency use which is a large part of my interest since almost no other operators have those types of modes. I only returned to digital modes when sound card technologies became available and I suspect that is true for most other digital operators. 73, Rick, KV9U John Becker, WØJAB wrote: > Oh thank the Gods, Here I was thinking that you was one of the > anti wide - anti hardware type guys, > > > At 04:07 PM 3/5/2009, you wrote: > >> I am not necessarily opposed to other hams using Pactor modes, but the >> one issue that is consistently ignored seems to be the transmission of >> fax/image data when using the wide bandwidth modes. If kept at 500 Hz or >> less, the changes in the rules a few years back finally allows fax/image >> to used in the RTTY/Data areas. But it does not allow it for any modes >> greater than 500 Hz such as when using P3. >>
