ALE 400 and RTTY are not all that different in bandwidth. RTTY is wider than we might like to admit depending upon how you measure the drop off at the edges.
The difference is dramatic between the two modes in terms of ability to work under more difficult conditions and deeper into the noise. Add to that the ability to have not only an ARQ soundcard mode, but one that employs Memory-ARQ which until the invention of FAE, was only available on the SCS Pactor hardware. Not even Kantronics or HAL seemed to be able to figure out the proper implementation of Pactor 1. That is why the SCS modems always worked better than third party equipment. The benefits are definitely worth it over the older technology such as RTTY which I have not really used in years because of its poor performance. The main use of RTTY is for quick contest exchanges, but for those of us who have other interests in amateur radio, it offers little value. The higher speed MIL-STD/FED-STD/STANAG modes mostly use single tone PSK but there are specifications for multitone modems as well. In order to get the higher throughput, we have no choice but to get wider signals. Some of the modes are incredibly inefficient such as the rather old 8FSK125 voice bandwidth mode. Some want to keep this mode for "interoperability" with hardware ALE, but I am skeptical that amateurs will adopt these older technologies that were never intended for shared frequencies and we will continue to develop newer modes that work more appropriately on amateur bands. Some will be narrow and some will be wider depending on the throughput needed. We are already doing this with OFDM modes for image/FAX. While satellites have never interested me personally, there are a few hams who are interested in this technology and it has possibilities. 73, Rick, KV9U Brian A wrote: > I'm not trying to be a pain in the butt, honest. > > If one put ALE400 and RTTY side by side for the average ham ALE-400 > would be a hard sell. Same speed in twice the bandwidth. > > I guess one may conclude all the bells and whistles of ALE, ARQ etc > are doubling the bandwidth requirements. One can copy RTTY with a 200 > HZ filter. I doubt one can do the same with ALE-400. Are the > benefits really worth doubling the bandwidth? Put another way, halving > the number of stations possible for a given band. Perhaps so, but > certainly only for a narrow slice of the ham hobbiest needs. > > We need narrower bandwidths not wider bandwidths for real progress > with the real life crowded bands. I think that is why PSK has worked > so well. Anybody pushing for wider bandwidths seems to be swimming > against the current. > > I want to point out the old fashioned analog mode of SSB this weekend > had at least one station making 10,000 DX QSO's in a 48 hour period. > This was the bottom of the sunspot cycle with incredible QRM. > > It just seems to me that to replace existing technology, the newer > stuff has to be able to do all the old technology could do and much > more in the same or less bandwidth. I'm not seeing this in these > digital modes. Yep, laws of physics do tend to get in the way. > > Those interested in what can be done if the bandwidth were available > should read the proceedings of the AMSAT meeting held this month in > Pittburgh. They are talking about a geosyncronous satellite with 6MHz > of bandwidth available. Supposedly being able to be reached with 5 > watts and a 60cm dish. They think this is the future of emergency > communications. > > 73 de Brian/K3KO > Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/drsked/drsked.php Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
