Charles Brabham wrote: > > > Packet radio gets by with a simple carrier detect, PACTOR can only > detect other PACTOR stations, and from what I can tell, ALE has no > busy detection at all. Absolutely not the case. ALE listen's before transmit for other ALE by protocol. And the commonly used ham implementation has a busy detection mode that works for rtty, carrier, and most CW. Just does OK on voice, but that's less of an issue as any operation in the voice sub-bands are attended.
Problem is, just like other mode operators have found out, it's unworkable as the majority of legal, in progress qso's will be derailed by someone else firing up. Since the CW op has no way to ask in ALE, PSK, whatever mode "is the frequency in use", all they can do is interfere. so the mythical busy detection software would have to have a way to answer back "sorry OM, the frequency is in use" in every imaginable mode. I see this in the PSK bands by CW & RTTY ops, and happens to pretty much any digi mode. It's not unique to ALE for sure. Fact: Radio is vulnerable to "hidden terminal" effect like most shared media. We live in that world. And because of that, there will be some unintentional interference. Regarding busy detection, I've posted youtube video's of ALE's busy detection in action. Packet's is not the most effective, by any means. All that said, until there is mutual respect of the digi modes right to exist, no one will widely use the busy detection as it's too easy to hold off or interfere with a station running it. see it happen every day on the busy ALE frequencies, and for sure this has soured winlink on busy detection. It's not technology, it's your fellow hams. When I see all psk ops wait for 2 complete transmission cycles to ensure there is no hidden terminal effect, then ask "is the frequency in use" before transmitting I'll concede. Same for RTTY. Until then, it's just one mode complaining about the other, and we won't see progress. Have fun, Alan km4ba
