How to Design BPL-Buster Communications
By careful analysis of interfering signals, a communications system can be designed to optimally operate in the presence of BPL interference. Yes... there are limitations, but with repetetive or multi-carrier signals such as some of the BPL signals we have heard, we can exploit the holes in the time domain or frequency domain to our benefit. Take for example, a PowerLine Communication device that has some characteristic of the signal synchronized with the power frequency... 60 Hz in USA. In the frequency domain, this shows up as spectral lines 60Hz or 120Hz apart, or some multiple of it. In the time domain, the peak power of such a signal may coincide with the crossover of the 60 Hz cycle or the ramp part of the cycle. Even though the peak power is S9+, the gap between the peaks may be big enough to drive the proverbial mack truck through. Take a look at this image, it is a waterfall display sampled from the ARRL video of Briarcliff Manor NY, BPL system: http://expeditioncave.com/bpl Different types of BPL emissions might require different flavors of countermeasure signals for us to communicate through the interference. For example, with a multi-carrier BPL interfering signal, we could use a multi-carrier communication countermeasure signal with its carriers interleaved with the interference. Or, if our throughput requirement is low (such as keyboarding), a single PSK carrier or two at exactly the right frequency between a couple interfering carriers might be sufficient. No Kilowatt Vigilante Justice I am not advocating that we counter BPL's harmful interference with hams dealing out their own vigilante justice interference by pummelling the power line with a kilowatt of AM or CW. What I am advocating is that we combine a little ham ingenuity with technology tools, to continue what we do best, communicate on the airwaves. FCC May Protect BPL Beyond Part 15 In a very significant recent FCC ruling, the national power grid, a.k.a. the electric power companies, who have Part 15 "carrier current" control systems on Low Frequencies, were able to win a sort of "protected status" during proceedings over proposed Low Frequency ham band(s). The FCC cited the essential nature of AC power to the public and national security concerns when they turned down the LF ham band allocations. We are dealing with almost exactly the same situation brewing with BPL being used by the power companies and municipalities for infrastructure control systems. By doing so, they are now jockeying to fit within the precedent of the previous FCC ruling, to add legal weight in their favor, for a protected status based upon national security or essential services to the public. Compromise is the Norm for the Legal Arena I wholeheartedly encourage those who are so inclined, to continue the legalistic challenges to BPL's pollution of the airwaves. However, this BPL interference problem exists in the present, and it is going to get worse before it gets better! In USA, the wheels of justice turn slowly. In most litigation, compromise is the norm; the ones who really win are the lawyers. BPL Busters Not A Total Solution BPL-Buster communication is not a panacea for the predicament we have found ourselves in with BPL interference. However, it can be a tool, a resource we could use to continue operating in the face of noise. Bonnie Crystal KQ6XA The K3UK DIGITAL MODES SPOTTING CLUSTER AT telnet://208.15.25.196/ <a href="http://dxcluster.blogspot.com";><img src="http://feeds.feedburner.com/DigitalSpotter.gif"; height="67" width="200" style="border:0" alt="Digital Spotter"/></a> 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/
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