With the unfolding technologies we won't be needing subbands. For the older technology such as PK-232 equipment the stop gap is to keep the automatic operation areas in place for now. Ideally, they would eventually not be needed. At this time I am not sure that the SCS modem is a solution. It would require improved software to go with the modem. But there is no reason that this could not be developed as a retrofix.
From everything I have been discovering, there is very little support (or even knowledge of ) the NTS/D. The current direction seems to be to move toward the internet as the solution for handling e-mail traffic with minimal ham activity. This is partially due to the desire for timely traffic handling (one hour maximum delivery time that can not be done by NTS/D) and partially due to the desire to reduce the number of automatic stations operating on HF. This is the basic philosophy of the Winlink 2000 system: only use ham radio for a short distance to bridge a gap in the internet, (unless longer distances are needed for wide spread disasters or for isolated stations such as boaters), keep HF stations off the air as much as possible to avoid HF forwarding due to the lack of bandspace as it is, and handle most of the short distance traffic via VHF/UHF packet to further keep messages off of HF, and also because an increasing number of new entrants do not have HF capability. For casual types of operation, I think this is a good thing. I do not consider such systems true emergency communications systems because with certain single point failures, the system becomes inoperative. The decentralized NTS system can still get through, albeit with inaccuracies in the information and not necessarily in a timely manner. Sometimes that is still better than nothing getting through at all. In answer to your question about SCAMP you have some excellent points. SCAMP could be programmed to work either way. You could have it shut down after the link is established if it detects QRM. However, I am not sure this is appropriate for several reasons. After all, it listened for a period of time (random detection time with the current design and could be set for any minimum time if this proves necessary) and then if the channel is clear, it begins to use the frequency because it would be responding to the human operator on the other end of the link. The busy detector should be disabled once the link is established because anyone else using the frequency is now the QRM. Further, if others knew that it would abort with any QRM, we all know that there would be malicious operators who would only have to send a dit or two on the frequency and it would shut down the link. With conventional data modes with human operators at both ends, if someone is calling CQ on the frequency and not one else has been heard for some time on the frequency and another station answers and then someone new comes up on the frequency, it is difficult to consider the new station as to having the frequency. Sometimes they might, sometimes not. Two solutions would be to either have some kind of QRL polling by the automated station or for the stations to be using ARQ operation. This also highlights the value of an ARQ mode. Since the ARQ feature means that there is a back and forth series of transmissions within a reasonable amount of time. Certainly, within 30 seconds, but usually much less (like 1 1/4 seconds for Pactor). Wouldn't it be reasonable that stations operating in ARQ mode will insure that there is not a hidden transmitter between two other stations that otherwise would think the frequency is busy? As was recently mentioned by the Winlink 2000 owner, during heavy use of the bands, such as contest weekends, Winlink 2000 HF operations are significantly affected in a most negative manner. So I agree that just having congestion can bring down HF networks due to so little space for so many signals. As far as Winlink 2000's content or any other newer e-mail systems, there is no broadcasting to my knowlege. All the connections are from one station to the other station. In fact, it would be very difficult (not impossible, but very difficult) for anyone to even monitor the transmission content. Since the content is not transparent to the amateur community, unlike almost any other amateur mode, this is a root problem that we have not come to grips with. 73, Rick, KV9U Tim Gorman wrote: > Rick, > > I think the problem is more complex than this. I believe you will find > that > sub-bands will ALWAYS be the answer of choice. > > First, I use a pk-232mbx on pactor in the automatic sub-bands as part > of the > NTS-D system. This box only listens for other pactor stations. If I > were to > be told that this was going to be banned from the ham bands, I would > drop out > of the NTS-D. So would others who use exactly the same equipment. None > of us > would have $1000 or more to get equipped with SCS modems. It would be > much > better to keep these operations in the sub-bands and keep them > operating than > to just kill the system by default. > > Second, I would be interested in how SCAMP operated when QRM came on the > frequency? Did it end the session so it wouldn't QRM the other guy? Or > was > the busy detector disabled after the session had been established? > > If the later, the busy detection scheme is only a placebo for many, many > situations and not a true fix. Since the systems today offer no true > trunk > system control signals (i.e. calls to a busy channel are not abandoned > by the > originating end but just continue to be attempted) as soon as the > automatic > station detects a clear channel (the station it could hear turns the > transmission over to a station that can't be heard) the session will be > started and will cause QRM. Bottom line? No difference. The QRM is just > delayed by one transmission period. > > The only situations which would be truly helped would be those where the > automatic station can hear ALL stations in the QSO on the frequency of > use. > > If SCAMP stops operation upon busy detection, even after a session is > established, it is likely that the system would come to a screeching > halt > during busy times of the day. Since it is likely this is when long > distance > propagation may be at its best, system throughput could be drastically > impacted. > > It would appear that the *only* way to minimize impacts of the automatic > stations is to maintain automatic subbands. Other operations who want to > venture into these areas should understand that protections against > QRM are > not what they are in other areas. > > For those who think that restricting automatic operations to small > subbands is > not fair to operations like Winlink, I would be happy to lay out > changes in > operation that would let Winlink pass all of its traffic on five 500hz > channels. That's not five channels per band but five total, and Pactor > II at > that. > > To those discussing email content. It is my opinion, for whatever that is > worth, that it is *not* the content of a specific communication that > is the > problem, per se, but the *regularity* of third party communications. > Regular > communications with third parties are specifically mentioned in the > Part 97 > rules. It would seem to be axiomatic that for one time use or even > non-regular use, almost any content could be allowed, even it is not what > most would consider acceptable. When the use is for third-party > communications on a regular basis, especially the *same* third party > all the > time, the use enters a different realm. > > For instance, I keep getting the issue of weather reports thrown out > when the > subject comes up. These are *important* to ships at sea. > > Well, what would happen if I started broadcasting the local NWS system on > 3920khz or 146.52Mhz during times of bad weather? Wouldn't those weather > reports be important to people on the road during periods of snow and > freezing weather? If I were to do this on a regular basis, e.g. 24/7, > does > anyone on here think it would take more than a few days for me to get a > letter from Riley? > > Would the Winlink people support having this type of operation on the ham > bands? > > Just as there are other radio services providing this service (i.e. > the NWS), > there are other radio services providing for regular, third party > email from > ships, yachts, and boats, be they on land or sea. > > tim ab0wr > > Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> 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/
