GM Rick, Alternate Link Call (AQC) ALE is basically 2G Plus ALE in that its an advanced 8FSK form of ALE where most all of the un-necessary overhead of ALE has been removed and new capabilities have been added, to include a PSK burst mode. The linking time to setup is must faster with AQC-ALE and the ability to achieve a linked state in the face of poor channel conditions is hugely improved.
Remember this, ALE is the great facilitator of follow on traffic, be it data or voice ( analog or digital) or remote signaling for command and control and where the data may be of any format and not just 8FSK ALE or other MIL-STD protocols, there are no limitations to what follows after the ALE Link Quality Analysis (LQA) has been used to select the best channel from those provided to work with. GTOR and PACTOR I are a challenge within the frame work on an event driven OS to implement, if you take control of the OS and limit the interrupts to a point of which the application is in control of environment, which would for the most part preclude the multi-tasking 3rd party application aspect of the OS to point where only the digital communications application is running, then it even these fast timing ACK/NAK protocols would work, even AMTOR ARQ which is even a worst case than PACTOR I timing. As to the new PACTOR x and CLOVER modes, they do not have the same short turn around timing, PACTOR III is basically modeled after the newer Military waveforms which run on the MIL-STD-188-110x modem. The work that Patrick has done with FAE ARQ to date is the best example of an FSK ARQ protocol for Amateur Radio designed for the PC Sound Device Modem (PCSDM) in my opinion, it provides the best aspects of the MIL-STD ALE DBM ARQ protocol ( developed from the MIL-STD's which Kantronics also worked up GTOR from) and PAX/PAX2 into a new protocol that I find to be perfect for Amateur Radio at keyboard to keyboard, file transfer and HF e-mail needs. What the Amateur Radio Service will see come along on the PCSDM in the way of a high speed PSK modem waveform that provides all the desired features and is legal in all countries for use is yet to be seen. Its obvious to me that the MIL-STD-188-110x modem with one of a number of DLP waveforms are contenders, timing is not an issue as far as the OS is concerned and the speed is certainly there, just as fast and even faster and as and more robust than is PACTOR III which the ham world uses as the yard stick for some reason, tailoring down of the PSK carrier and symbol rate for less than 3Khz signal BW is doable, some hardware modems support it and I did in MARS-ALE, but its still to much under current FCC rules for Amateur Radio here in the U.S., so stay tuned for more developments to come is what I say and for now embrace the legal FSK ARQ waveforms on the PCSDM. /s/ Steve, N2CKH At 11:43 PM 6/18/2007, you wrote: >Steve, > >Can you give us some current information on AQC-ALE? I had not been >familiar with this term but did a little web surfing and found a very >interesting document: > >http://www.dsto.defence.gov.au/publications/2402/DSTO-CR-0214.pdf > >That covers a rather full spectrum of digital modes, including amateur >ones. > >Curiously, some of the information seems to support my comments a while >back about using multiple PSK like tones to come up with a higher speed >modem, without having too high a baud rate. Is this still too difficult >to implement in software such as the 64 tone with moderate baud rate, >can still have a high bps rate. > >It is interesting to note that many of these modes do not work below + >10 dB S/N. We already have some pretty good speeds with WinDRM types of >modulation that effectively using a QAM protocol with significant >throughput at somewhat lower than +10. > >Amateur radio, being very different from commercial/military use of >radio, does not typically need a calling system since we do this with >the CQ in most any mode. I can see some applications from ALE for >emergency use or for personal preference, but it will never be all that >popular with the average digital ham that doesn't use it in this manner. > >I was surprised to see your comment that Pactor and Clover could be used >via sound card modems if they were not proprietary. The conventional >wisdom is that these modes require a much too fast switching time to >implement with non real time computers and even Linux was not able to >work well enough with Pactor I to equal a hardware modem. > >What I do think is very doable is to use the waveforms that we know >work, and the techniques that we know work with weaker signals and yet >can scale up for improved speeds under good condx, and do this using an >ARQ pipelining technique of performing the computer time on the last >packet in the background while the next packet is coming through. In >fact, this is what I hope will come out of the ARRL's interest in >possibly developing a new HF mode(s) for soundcards. > >73, > >Rick, KV9U
