Skip has expressed some very important points. It is interesting that Peter, TY1PS, from Benin, Africa, wrote a program for Clover II, many years ago that automatically transmitted an image of the operator. However, it was not legal to use here in the U.S. until this coming Friday:(
Now that the rules will change for the U.S. it is likely that someone will come along with an open source program that might even work across OS platforms. We must always keep in mind the use of bandwidth vs. the amount of total bandwidth available vs. the number of users. That is why Pactor 3 is such an inappropriate mode in most cases. It takes out a very large amount of real estate, particularly if it is a BBS system/e-mail server on a fixed frequency. The idea expressed by someone recently, that it is better to have a wide band mode operating for a shorter period of time than several narrower band modes is not correct on a frequency band. This would only be true if we had channelized operation with a specific fixed bandwidth for the channel. Except for the anomaly on 60 meters, amateur frequencies are within a band and are specifically not channelized because of the dynamic nature of ham radio where we have a constantly changing accomodation for the number of users and propagation. This is particularly true where we have mixed bandwidth modes in the Data/RTTY subband. Accomodating 4 or 5 users simultaneously in the same space is far better than accomodating a single user for a shorter time. And that is for good conditions. Under less than ideal conditions, the wide band mode may not be able to perform all that much better than the narrower mode. And, as we have seen from the SSTV operators, only a few, a very few, radio amateurs are interested in this mode therefore it uses a very small amount of bandwidth in what will be an increasing area here in the U.S. on the 80 and 40 meter bands. I used to think that if we had very fast modes, we would find ways to use the up the bandwidth and data throughput for day to day purposes. This is akin to "Parkinson's Law" that when you have extra storage, you find ways to fill them up with "stuff." But it does not seem to be happening since we can send pictures, FAX, voice, all mixed in the voice/image parts of the bands. And no one seems to be doing it. I asked a while back just what radio amateurs would be sending on high speed HF connections, other than e-mail/BBS/emergency uses and there was a dearth of responses. By the way, do any of you digital operators want to get on any of the "image" frequencies here in the U.S. and try sending FAX docs and pictures along with voice chatting? Should we have some spot frequencies to call on each of the HF bands? 73, Rick, KV9U Skip Teller wrote: >Thanks, Bonnie, for granting us a PSK31 "watering hole" from 3580 to 3583. ;-) >That is large enough to accomodate ALL PSK31 users on 80m in the whole world! >In fact, if you monitored the recent European PSK63 contest, you would see >that there was minimal interference, even using PSK63, which is twice as wide >as PSK31. > >I realize that it is convention that wider modes operate from the top of a >band segment downward, but that does not necessarily have to be how it is >done. The object should be to accommodate as many users as possible without >undue mutual interference and I hope those "kilowatts" and wide digital >signals will respect those simply trying to talk to each other with >"antiquated" narrowband text modes. Very few people are interested in anything >more, such as sending multimedia over HF, although it is nice to see what a >ham or hamshack looks like. I have a feature in DigiPan that looks up a >callsign on QRZ.COM automatically, and if the ham has posted a picture on >there, you can instantly see what he or his shack looks like. Broadband is >quickly becoming ubiquitous, and the Internet, coupled with ham radio, makes >it all possible without taking away bandwidth for simple text communications. >I wrote a program called "QuickPSK" that could send a thumbnail of your face, >in color, in 2 minutes using PSK63 characters. It was interesting, and fun, to >do this, but never became popular, as in most cases, especially with DX >stations where English is not the primary language, an exchange of callsigns, >signal report, and a few other pleasantries is all that is desired. > >For sending larger pictures, MixW can send a raw fax picture in the same >bandwidth as MFSK16, in two minutes, which is apparently a reasonable length >of time to wait for a picture. Faster data rates for multimedia simply cuts >down on the waiting time, but takes away bandwidth others need for simple text >communicating due to the wider signal. The Pactor-II/Pactor-III comparison is >applicable this case. It is a much more efficient use of bandwidth on HF to >have four or five Pactor-II stations using the same space as a single >Pactor-III station. To the operator, downloading email automatically, the time >difference is not that significant, as on HF, Pactor-III seldom can be used at >the highest speed level, but will dominate a wide space as it varies in width >with speed whether or not it can utilize the whole space. > >What is missing from the argument that we need faster data transfer on HF is >that there is a very limited amount of spectrum on HF which must be shared by >many users for whom simply exchanging text is all they need to "communicate". >That is why ATV is only allowed on the UHF bands - it simply consumes too much >bandwidth needed by others in order to make the pictures "move" in real time. >The FCC is not putting us in "technology jail", as you repeatedly infer. They >are only trying to accommodate a million users on a limited amount of HF >spectrum by rules that prevent a few from hogging the spectrum for their own >purposes at the expense of the majority. The entire SSTV activity gets along >using only one or two frequencies per band, as it is usually a group activity >and, being an amateur activity and not a commercial one, can afford to wait >1-2 minutes of a picture to complete. This leaves the rest of the band for >non-multimedia communications, which is as it should be with the limited >amount of spectrum available on HF. > >73, Skip >KH6TY > > > >------------------------------------------------------------------------ > >No virus found in this incoming message. >Checked by AVG Free Edition. >Version: 7.1.409 / Virus Database: 268.15.15/581 - Release Date: 12/9/2006 > >
