Unfortunately Peter, G3PLX, is missing some important point in his comments whereas I can follow and agree to most of his statements:
1. There is a bandplan which allows a max. of 2700 Hz. I assume that there was a lengthly discussion about those limits before they were established. 2. Even though the majority of the existing and normally used digital modes don't occupy the 2700 Hz we don't know yet what the future might bring on robust digital modes for HF which need more than 1500 Hz. 3. The discussion about unattented operation and the problems caused by them has the side effect of hindering progress in developing and experimenting with digital modes. Another observation from me: Did anybody complain about the ignorance (or arrogance?) of FJ/OH2AM using the spectrum from 14100 to 14130 for receiving? I haven't heard complaints so far, even though many called between 14100 and 14110 jamming beacons as well as digital modes just to get a new DXCC entity (to avoid any misinterpretation: I have worked them on 17, 20, 40 and 80, so there is no frustration causing this comment). It shows, however, for whatever reason the attitude of a significant number of ham's towards digital modes. On the other hand it reinforces the need for a factual based and non emotional discussion of all aspects of digital modes in amateur radio services, one to protect the possibility for new development, and second the need for a good lobby work at regulatory authorities like the FCC and others because we are still a small minority. 73 Juergen, DL8LE --- In digitalradio@yahoogroups.com, Mark Miller <[EMAIL PROTECTED]> wrote: > > Forwarded with the permission of G3PLX > > > >Subject: Your excellent petition > >Date: Wed, 26 Dec 2007 20:37:30 -0000 > >X-Mailer: Microsoft Outlook Express 6.00.2900.3138 > > > >Mark: > > > >I hope I have the right email address.... > > > >This is just a note to offer my congratulations and express my > >admiration for the work you have put in to your petition to FCC, > >which I have only just seen as a result of various people drawing my > >attention to it in the last few days. > > > >You may know that I was the only non-U.S. citizen to be invited to > >serve on the ARRL Digital Communications Committee when it was > >considering what should be the response of the ARRL to the moves in > >Europe towards "separation by emission width", which are now built > >into the IARU region 1 bandplan. It was me that first proposed the > >change from "segregation by mode" to "segregation by emission width" > >within IARU region 1. The ARRL committee subsequently reported back > >to the ARRL board, and you will be well aware of the result. I > >resigned from that committee before it reported, because it was > >clear to me that the committee was dominated by a small group whose > >sole aim was to gain additional spectrum for voice-band unattended > >digital traffic-handling. They were simply hijacking the "separation > >by emission width" debate to further this aim. The result was a > >disaster, and it's down to people like yourself to sort out the mess! > > > >While I was on the committee, however, I tabled arguments almost > >exactly identical to those you have outlined in your petition, > >drawing attention to the inappropriate use of ARQ techniques (not > >just Pactor 3) in the amateur service. The use of ARQ in a congested > >band is counter-productive, since in the face of co-channel > >interference (which results from congestion), it INCREASES the > >amount of time-bandwidth it uses, thus making the congestion worse. > > > >I went on to generalise this discussion. To be able to survive > >congestion in an unregulated band, there must be a mechanism that > >causes individual transmitting stations to REDUCE their output (in > >time-bandwidth terms) when faced with undesirable congestion. The > >AX25 protocol, much maligned for HF use, did achieve this. I will > >come back to this, but it's also self-evident that all traditional > >one-to-one amateur operation has this desirable feedback mechanism - > >an operator faced with QRM due to congestion will shorten his > >transmissions or close down, thus reducing the congestion, or at > >least he will do so if he doesn't have any important traffic to pass. > > > >This leads to an important conclusion about amateur radio in an > >unregulated environment where the level of activity is > >congestion-limited. It will ONLY be stable and self-limiting if > >there are enough people on the air who are just there for fun, and > >who will QRT if/when it stops being fun. If we ever got to the > >situation where a significant fraction of the activity was by people > >who needed to be on the air for a purpose, then there will be an > >increasing tendency for congested bands to exhibit 'grid-lock' behaviour. > > > >We don't have a big problem over here in Europe. For a start, the > >use of amateur radio for third-party traffic is illegal everywhere > >except the USA, so virtually all amateur activity is of the > >recreastional (fun) type. But I can see it becoming a real problem > >in USA, and especially if ARQ modes like Pactor become a dominant > >fraction of the total. When we were discussing "emission width > >segregation" in Europe, it became clear that although disparity in > >emission widths was the most significant source of conflict between > >operators of different modes, it wasn't the only source of conflict. > >We identified "unattended operation" as another major source. With > >this in mind we created, within the bandplan, segments for this type > >of operation. This is working well. There is no longer a > >significant level of complaint by one-to-one operators from unattended systems. > > > >I said I would come back to AX25. The fact that AX25 'backed off' in > >the face of errors (which could be due to congestion) meant that > >multiple AX25 links could share a channel in a stable way. Pactor > >has no such characteristic. Co-channel QRM between two Pactor links > >results in neither link passing any traffic until one link aborts. > >The logistic consequence of this is that Winlink sysops will always > >choose to operate on a channel on which they can be sure no other > >Pactor link will take place. They will always prefer to be subjected > >to random QRM from another service than to be subjected to QRM from > >another Pactor link. > > > >This unfortunate characteristic has meant that the interference from > >Pactor to other services is maximised rather than minimised, and it > >also means that the Winlink organisers complain bitterly that there > >is insufficient space within the designated automatic sub-bands. The > >total volume of traffic handled by these unattended stations could > >easily be passed within the automatic sub-band limits, given a > >mechanism by which the stations involved could co-ordinate their > >activity. However, it cannot be done with Pactor or Winlink in their > >present forms, and while these stations are free to roam the bands, > >there will be no incentive to improve their channel utilisation. > > > >In theory at least, the same arguments for segregating unattended > >ARQ stations applies to ALL amateur activity which has a purpose > >other than recreation. Only truly recreational activity is > >self-limiting without regulation. Any other activity in which > >amateur radio performs a service to a third party, will be > >vulnerable to grid-lock in the face of band congestion in an > >unregulated channel structure. To be truly a service to the > >community, these activities should have their own channels. This > >would be worth exploring. There are huge tracts of the marine and > >aviation bands lying vacant now. > > > >These thoughts go far beyond your present petition, but I hope I > >haven't bored you by expounding them to you. I hope you have a good > >result with your petition, but even if you don't succeed, I hope > >your actions will be enough to kickstart the debate about how > >amateur radio can simultaneously (a) survive in a deregulated world, > >and (b) provide a service to the community. I don't think it can do > >both without changes to the rules such as you are proposing. > > > >73 > >Peter G3PLX > > > > >
