Hi Steve, I don't see SCS holding anyone back from coming up with a similar system tailor made for current computers. The reason you would want to do this is to use the technologies that succeeded in working well and not reinventing the wheel that sometimes seems to be happening with the plethora of new modes tend to be similar. Having a few really good modes that most hams would readily identify as being superior, would be better than dozens of modes that are not that different.
To be fair, this was a progression over the past 25 years, since computers became readily available to most hams, and that means all of us on discussion groups such as this one. We had to learn what worked and what did not, but all modes have some good and some bad and no mode will ever be satisfactory for all uses and for all conditions. After trying different modes, many hams go right back to PSK31 and the reason is that for casual keyboarding it seems to work reasonably well much of the time. While is is difficult to sort out all the terminology of the ALE standards due to the overlapping of MIL-STD, FED-STD, and STANAG, I have been working on a guide of this sort to give a little background. I did this for myself, but plan on having it available on the file section of the HFDEC yahoogroup (HF Digital Emergency Communications), as there might be others who are interested. I don't know if the 8PSK2400 ALE modems can run as well as some claim, but I would sure like to find out. Here in the U.S. we can not use the 2400 baud modems on the text digital areas of the bands, but maybe they would be legal if you sent documents with images, etc., on the voice/image portions of the bands and treated them like a FAX? After all FAX's often have only printed text material. And we can legally make the connection on the voice frequencies due to the permission of incidental tones for the signaling feature. This past week I made the decision to further research this issue but before I contact the FCC. I do have an e-mail in to Paul Rinaldo, W4RI, ARRL CTO, to see if he has any insights in these matters. Nothing heard back yet. Some concerns I have with the ALE STANAG waveforms: - When you look at the graphs of throughput to S/N ratios, they are not really all that good. Some of the ALE modes will go below zero dB S/N, (some of the newer ones) but then again, most of our newer digital modes will do that as well. And the ALE waveforms cut off sharply at say -5 or 10 dB and we have modes that are working at full speed below that point, although they do not ramp up to the very high speeds of ALE when you have good signals. - And those are often computer modeled ... not real world. In fact, one of the articles admitted that when they tried some of the computer modeled waveforms, they completely failed when used in real world tests. - At least one person who actually maintains and deploys ALE in the military is not very impressed with it as there are problems with not working that well, particularly no having good throughput such as for messaging. And these are extremely expensive modems which I understand cost around $5000. - The other issue is the paperwork claims of throughput vs. ISI. Many of the specs indicate 1 or 2 msec ISI as being "robust" but on the lower bands you can expect way more than that. The most ISI that I recall seeing in the specs is 5 msec. Many of us have seen cases where ever 45 baud RTTY has difficulty printing even though the signals sounded strong. My understanding is that the ionosphere can cause multipath to exceed 5 msec and even go much higher. Under those conditions I don't think that the ALE modems will work, but then again, maybe not much will work except a specialty mode such as DEX (DominoEX) which can handle extreme levels of ISI. - Finally, and I have brought this up many times before, and will continue to do so ... if most radio amateurs around the world can use high symbol rate transmissions, then where are all the results of comparison testing between these waveforms? Why do I not seem to hear them on the ham bands? Why are hams not using them on VHF? (Note: I would like to try this and now I think I have the capability to work the mode on 6 meters). How about some of the group members outside the U.S. tell us their real world experience with the 8PSK2400 waveform? Some solid numbers or comparisons to other modes? And why wouldn't the entire MARS program being using these waveforms on a daily basis since they legally can? Wouldn't it take one demo to show how well they work? 73, Rick, KV9U Steve Hajducek wrote: > Hi Rick, > > Take any non-GUI or even a GUI OS that has been tailored down for the > embedded application at hand that is running sufficient CPU/RAM and > you could implement a PI through PIII solution if SCS would allow it. > > PII and PIII if fully documented could be done using a PC Sound > Device Modem (PCSDM) solution, but to be compatible with SCS hardware > PACTOR x, you still need PI for the linking before moving forward to > PII and above and that along with the fact that SCS does not grant > permission to implement above PI via the PCSDM is the hitch in doing > so under a multi-tasking OS. > > In my opinion what SCS has been doing over the years is basing their > system on the best of other systems, PACTOR I being a hybrid of > PACKET and AMTOR. Then later after a good long study of U.S. MIL-STD > and NATO STANAG modems and waveforms, adding PII waveforms and > protocols to the mix after the PI link step, and later PIII. Its all > similar to having an ALE link step followed by MIL-STD/STANAG > waveforms which is the world standard in Government/Military > communications. If you look at PIII and those MIL-STD/STANAG modems > and waverforms you will see all the similarities, but not all the > benefits as ALE offers a full HF networking solution whereas PI does > not, its just an ARQ 2FSK 2 raw speed protocol similar to ALE DBM ARQ > which GTOR is heavily based. What would be best for the Amateur Radio > service is getting the various world regulatory issues addressed ( > such as with the FCC here in the U.S. ) to pave the way for all Radio > Amateurs to be able to take full advantage of the MIL-STD/STANAG > waveforms which will open the doors for more PCSDM based software > solutions to come along from the various authors taking in the full > range of these waveforms and not just a few aspects of them to the > benefit of the Amateur Radio Service. > > /s/ Steve, N2CKH > >
