Rick W. wrote: > Hi Paul, > > Sounds like you might be getting caught up with some of your other work > and can devote some time again to digital modes:) For those who are not > aware, it was Paul's paper on ARQ concepts that lead to development of > several current uses of ham radio ARQ modes. > > Some comments and questions: > > 1. Years ago we had the outboard programmables but they never really > were all that popular. I know of only one ham in our area (multi-county > rural area) who had one. Can the paradigm be revived? I don't think it > can for the average HF digital ham since they do not seem to have that > much interest in ARQ modes. Most are quite happy to only use PSK31 and > no other mode. When it doesn't work, they don't tend to switch to MFSK16 > or Olivia. They just go and do something else. > > 2. Is it really true that computers (using a sound card) can not switch > fast enough? When I toggle the PTT on my sound card modes, I can barely > tell there is any delay in switching the rig. While I would not want to > key CW that way, it seems plenty fast enough for reasonable switching > speeds needed for an ARQ digital mode. Since we would not necessarily > need to exactly duplicate Pactor modes, couldn't there just be a few > extra milliseconds of padding to take care of differences in any delays > depending upon the computer? > > Based on the timing for Pactor 2 and 3, do you still find that the > average computer can not handle the window for the ARQ ACK/NAK response? > > 3. The SCAMP mode, developed by the Winlink 2000 group, proved > conclusively that you don't even need such close timing anyway since you > could do the decoding in the background (pipelining) during the time > that the next packet was being sent. SCAMP worked fabulously well with > good signals. If other slower protocols were used (but still keeping the > 1000 wpm speed) it would work with much more difficult conditions. > > 4. Other than a few of us who have significant interest in public > service/emergency communications and the need for absolute accuracy in > messaging, there seems to be nearly no interest:( > > I wish it was not this way, but consider that the FAE400 mode, which is > very sensitive, can work under fairly difficult conditions that would > make PSK31 impossible, and has ARQ built in, is almost never used after > a modest interest in testing it last year. > > 5. Therefore, it seems important to insure that there is a purpose for > the development of a new ARQ mode to meet some unmet need. I might > suggest that possible interest in having the capability to handle public > service messaging, with total accuracy, and under conditions that may > make CW difficult, and yet provide the access to automated e-mail that > can also handle time shifting store and hold for later retrieval. > > As an example, there are probably a few of us who used to be active with > CW/phone traffic handling a few decades ago, but who did not want to be > forced to adhere to a specific schedule during non emergency times. > Packet BBS systems had some of the paradigm but for decentralized > systems did not work well on HF since the mode requires very good > signals and throughput was often marginal to nil. > > A decentralized ad hoc, robust, low cost system that gave us a choice of > routing e-mail or holding it for a "local" ham could be a new paradigm > that enough radio amateurs might move toward. There is no other system > that can do this now and nothing on the horizon. > > I would personally be interested in hosting such a system. Any other > hams feel the same way? Or do you think such an approach would languish? > > 73, > > Rick, KV9U > > > > Paul L Schmidt, K9PS wrote: > >>Speed and resolution are, of course, relative :) While those chips >>are capable of crunching on half the HF spectrum at once, I was thinking >>initially of just audio (for which the on-board converters would be >>fine) - kind of a super-TNC, with capabilities (speed/bandwidth) similar >>to Pactor-III with no patents, open-source software, and significantly >>lower hardware costs. >> >>Sound card modes, of course, have gained popularity due to their >>flexibility and low cost - but can't handle the tight timing needed for >>pactor-type modes. >> >>It just seemed to me that something like a commercially-available low-cost >>FPGA board might be able to get the best of both worlds. >> >>Yeah, I'm suggesting a minor paradigm shift. Scary. >> >>73, >> >>Paul / K9PS >> >
Seems like I heard the same song and dance when AX.25 and 1200 baud appeared on 2M...what about RTTY and ASCII "they asked". But AX.25 at 1200 baud reigns and RTTY and ASCII on 2M no longer exist. Walt/K5YFW
