Nothing is 100%, including human ability to determine if the frequency is busy. SCAMP's busy detector exceeds human ability (OK, at least my ability) based upon my beta testing of the software. It can detect solid carriers, even if very weak, therefore a timer might be used in case of spurious signals or local signals causing this kind of condition. And it detects weak SSB signals as well as digital signals. The software also had adjustments to ignore signals that were weaker than the noise level by a set db level. The default was *very* sensitive. The developer, Rick, KN6KB, may be a bit modest when discussing his software as I never found any problems with it being able to detect a "busy" frequency. Or perhaps better to say what a human would consider a busy frequency. Pretty hard to find fault with that.
I have no idea how it works, since it is currently proprietary information but it seems to handle the frequency bandwidth just fine and no delay as it detects (scans?) a given area. QSB can, and does, fool a human operator from time to time depending upon how long you listen to a given frequency. Also, the software has a listen timer as well. This could be set for most anything, but if it was a station operating under automatic control, it would have been sitting there for some time just waiting for someone to come on frequency and it would "know" whether the frequency was busy at the time that a query comes in from a station requesting a connection. The hope is that Rick, KN6KB, will release this into the GPL as he has promised to do some time in the future. Same thing with the SCAMP mode. The main thing is that this is a solution that reasonable people would find quite useful and acceptable. If you had had the opportunity to test it out, you would have been pleasantly surprised as I was. 73, Rick, KV9U mulveyraa2 wrote: > The software would need to be able to determine whether any of >*dozens* of possible signals are present in the passband. In the case >of some of the more exotic ( and even less exotic modes ), it needs to >try to decode multiple bandwidths and bitrates. This takes quite a >bit of time. > > Of course, along with that, you need to deal with frequency >offsets. So there may be an Olivia signal at some frequency F+N, at >which point the detector can decode it. But if the detector is >starting to scan at frequency F, it needs to then attempt to decode >all of those possible signals at F, then F+1, then F+2, etc, until it >finally gets to F+N, where the target signal is functioning. This can >take a lot of time. And in modes where even a 10hz offset causes >problems, you can have a real problem. > > But - ooops! A new signal has just popped up at F+N-X, which the >busy detector had already determined was empty of signals. Or the >Olivia signal at F+N just had a turn-around, so it appears empty. Or >the QSB had dropped the signal just far enough that it can't be >decoded, and therefore doesn't appear to be a valid signal. > > So determining when a passband is busy is actually a very, very, >tough problem to crack. > >- Rich > > > > ------------------------ Yahoo! Groups Sponsor --------------------~--> Something is new at Yahoo! Groups. Check out the enhanced email design. http://us.click.yahoo.com/SISQkA/gOaOAA/yQLSAA/ELTolB/TM --------------------------------------------------------------------~-> 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/
