> Jim WA0LYK wrote: > > Bonnie, > your award winning design apparently had to do with co-channel > interference. This is not the same as on-channel > interference that increases the total noise level, which is what > BPL interference is. On-channel interference requires different > techniques to solve than co-channel interference.
Hi Jim, On-channel as you describe it, is co-channel. But, in fact, the term "On-Channel" has been coined by "HD radio" for a system which does not have two signals sharing the same spectrum, so the trademarked term probably should be avoided for clarity. Co-channel means the two signals (desired and undesired), occupy the same channel. In other words, the undesired BPL interference and the desired ham signal share the same chunk of spectrum, in this case: the passband of the ham receiver. The BPL is also transmitting on a much wider area of spectrum, that includes the smaller chunk of spectrum that the ham radio signal occupies. But, whatever you want to call it, in this instance, I am discussing the mitigation of only that portion of the BPL "noise" that is within the ham receiver's passband. The overall BPL signal may appear as "noise" to the human ear, but if you look more closely with signal analysis, there are certain qualities of the BPL signal that may be exploited to enable ham radio communications to pass through. I won't go very much further into the techniques at this time, but, the basic principle is that there are "holes" and "fuzzy spaces" in frequency/ phase/ time domain of the interfering BPL signal that we can pass ham signals through. I have previously described two digital methods (RMPSK and Olivia 2kHz), that could provide some mitigation for BPL interference. These methods may enable the hams who are presently off the air due to BPL, to at least get back on the air with text-based HF communication. There are other, more complex BPL-busting methods that could be developed for voice and faster data. Even using advanced techniques, there are certainly S/N limitations, but, improvements on the order of 20dB or 30dB may be enough in many cases to enable ham communications in the BPL environment where none existed using conventional methods. There may also be control techniques we can use that are interactive with BPL's ingress-response, or interactive with BPL system loading trends. These techniques require more characterization of the BPL system, and adaptive communication design beyond what we have been discussing so far. Bonnie KQ6XA . 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/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> 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/
