Harold, While I have heard of FHSS (Frequency Hopping Spread Spectrum) and similar concepts of spreading out the modulation over a number of frequencies for security reasons (type of encryption), that is not what I referred to. Actually, many of us use SS technology for some of our non-amateur technologies.
Bonnie says that hams don't use frequency hopping now on ALE but was not able to explain it. However, I am coining the term frequency hopping, as meaning jumping from one frequency to another for short periods and it well describes what ALE actually does. I reject any references to the use of the term channel as this is Bonnie's attempt to try and move amateur radio toward channelization. We have a band of frequencies except on the 60 meter band where we have some spot frequencies. I parked on one of the 20 meter "ALE frequencies" for a short time today and periodically heard some ALE signals. Sometimes for quite a few seconds, perhaps as long as 10 seconds? If many were doing this, it would be very annoying as it would obviously interfere with a busy channel with a hidden transmitter. The emergency use of this mode is rather limited on amateur radio since we rarely would call up a region or even a state, but it could theoretically happen if there were a number of hams actively monitoring. You will not find many of us setting up an all call 24/7 due to the inevitable pranksters. I can see where it would work OK on MARS and commecial circuits. If it does catch on with some hams, it will very likely be a selcal type of mode for friends to connect like we do now for skeds. It can be especially useful for the less technically astute who are not that knowledgeable about propogation. Which is why it is used for commercial/military where the operators (really the users) don't have to know anything other than to push this button. I have a friend in the business who has set up commercial full duplex HF ALE links and it is very humorous hearing about the users performance expectations, or lack thereof. You would not believe the cost of these systems paid for with our tax dollars! To somehow equate a minor technology such as ALE with the sea change of SSB is unwarranted. I was first licensed in 1963 and was an SWL and experiementer from age 12 when I was exposed to the "virus" in the form of Popular Electronics Magazine:) You could say that some hams were not infatuated with SSB even then. But a few had the add on Heath SSB adapter and would demo it and most wanted it but had difficulty affording it then. Eventually, almost all hams went to SSB due to its superiority over most (but not all) of the characteristics of AM, and the eventual lower cost. ALE is likely going to be a subset of amateur radio and that is OK. Just like QRP, AM, ESSB, high end contesters, EME enthusiasts, etc. But because of the way amateur radio works ... not dissimilar to fishing ... I am willing to bet that most hams will opt for that approach for most of their operating. 73, Rick, KV9U Harold Aaron wrote: >I think there is some confusion over frequency hopping, so I will throw >my 2 uneducated cents into the discussion. My limited experience is >with MARS-ALE, and I have been using it for only a month or so. The >term frequency hopping as I understand it, relates to changing >frequencies very quickly while transmitting and receiving - hence a link >is already established between stations and some form of synchronization >allows them to hop - rate and frequency. This requires some serious >technology, and started as a secure and jam-proof means of >communications within the DOD. > > > >According to the definition above, ALE is not a frequency hopper. ALE >is more of a channel hopper (scanner). A list of previously entered >frequencies is "scanned." The issue of whether or not to send a >sounding is operator controlled. Therefore, ALE can be scanning and not >transmitting at all. This would most likely be used in an attended >mode. > > > >When soundings are enabled, transmissions are sent out periodically >identifying the sending station in order to build a database for lack of >a better term of stations within range, signal strengths and such. A >sounding period - time in which transmissions occur on each programmed >channel is normally one hour. The main thing to gather from this is that >sounding transmissions on an individual frequency or channel are >infrequent, and are very short in duration - 2-3 seconds. Also, normal >power outputs are in the order of 25 - 50 watts, and most antennas are >NVIS - hence limited propagation. > > > >A Voice Detect option is built into the software and the purpose is to >detect voice activity on a channel to prevent transmission it the >channel is in use. > >The main purpose of ALE is to establish communications between different >stations. The database I referenced earlier logs stations and their >signal strengths for each channel. ALE then uses this information to >determine the frequency with the best chance of establishing a link. >Once a link is established information may be passed by a variety of >means - remember, ALE is soundcard based. PSK, MFSK, PACTOR, AMTOR, >voice or CW transmissions may be used once a link is established >depending upon the frequency and authorized modulation schemes. > >ALE is pretty much the up and coming standard for emergency >communications between federal entities, so it is for sure here to stay. >I think it is very interesting that "hams" are providing significant >technical support in the development of this system, and it should >provide reassurance that ham radio operators are not a dying breed. I >can only imagine the uproar when SSB was accepted as a transmission >scheme to be used within the ham bands... Donald Duck was the focus of >many a serious slanderous remark for sure. > >I apologize if any of my information is incorrect, but I thought a >novice point of view might be in order. > >I have to ask, have you been QRMed by an ALE station conducting >soundings? I could see it being a problem if a link was established on >a channel following a link-up. I had much rather shoot the HOLA guy on >20 meters! <Ha> > > Best, > >Harold KI4MF/NNN0BBXT > > > > > 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/
