The general manager of that organization was not wrong! This discussion is mixing apples and oranges as to what BPL interferes with. Digital techniques can not eliminate the interference at RF that BPL introduces. As I have mentioned before, don't forget the RADIO side of things when advocating digital techniques.
It is true that the recovered audio from a digital signal will be free of the BPL noise heard in an analog radio. However, that recovered audio must first be detectable by the radio receiving it. If BPL causes enough RF interference to reduce the signal to noise ratio needed by the digital processing you simply lose the whole signal. No amount of digital processing can recover a signal that is below the required signal to noise ratio. BPL DOES reduce the signal to noise ratio at your radio! To advocate that digital techniques can mitigate BPL interference is simply wrong and can ultimately be harmful to ALL of ham radio. I hope someone at the FCC has not seen this thread and uses it in the future to justify their decision on BPL's harmful interference potential. Ultimately, all digital techniques can really do is eliminate the noise from the audio. Digital techniques and signals can not give you a stronger RF signal. Digital signals CAN NOT REDUCE OR MITIGATE the harmful interference caused at RF nor can they recover the lost signal to noise ratio with the consequent reduction in our ability to operate either analog or digital modes. This is what that general manager is trying to tell you. Please don't treat the radio part of these systems as a simple black box that replaces an ethernet wire! Please do the homework required to understand what happens in your radio at RF both on transmit and receive. In other words, do a little RF engineering in addition to the baseband and digital processing engineering. If this thread is also advocating purchasing new radios and amplifiers that can handle higher transmitting powers in digital modes in order to increase signal to noise ratios, then perhaps that is a solution. However, this again is at RF, not because of the digital techniques used and there will be a substantial cost thereby reducing the popularity of these modes. Jim WA0LYK --- In [email protected], Robert McGwier <[EMAIL PROTECTED]> wrote: > > expeditionradio wrote: > > BPL-Busting Modes/Techniques > > > > > > > > --- snip ---- > > The development of new amateur modes, semi-automated and automated > > frequency agile systems, advanced ARQ, and various sorts of FEC > > digital techniques are a possible avenue for amateurs to > > "communicate through" the interference caused by BPL. It may not be > > possible to entirely eliminate all the harmful interference BPL > > creates, but we need to start planning for mitigation. We need to > > research and characterize the various types of BPL signals so that > > we can design modulation and control techniques to compensate for > > them. > > > > > I recently had a general manager of a large amateur radio organization > tell me that if I made it possible to communicate through BPL or in any > way mitigated BPL through DSP techniques, I would begin to sing soprano > and the GM did not mean falsetto. > > > > Using radio engineering and specially-designed digital signal > > processing, we can develop "BPL-Busting Modes". These new modes > > and systems could carry any combination of voice/image/text/data. > > Frequency hopping, spread spectrum, wideband OFDM, multi-PSK, ALE, > > and MFSK are mode/systems that we could implement immediately in > > new formats... > > > > Unfortunately, hams in USA don't have the freedom within the > > USA FCC rules to advance some of these yet. We look to hams in other > > countries to pioneer these new techniques. > > > Any technique that would allow higher rates and near bullet proof > performance would necessarily sound a whole lot like noise and would > necessarily be fairly wideband and would not work in today's traditional > radios but would certainly work in the SDR radios. I am afraid that if > I didn't have the general manager alter my singing pitch, the rest of > ham radio might. > > > > Under USA FCC current Amateur Radio Service rules, we do not have > > the freedom that other countries have, to take advantage of some of > > the most useful technologies that could help us to "communicate > > through" BPL interference. We are still locked in our technology > > prison. Hopefully, in the near future, we will have more freedom... > > with bandwidth-based spectrum management. > > > > I say that we can do turbo trellis coded based OFDM that are designed > for fading dispersive channels with cochannel interference. One of > these years when I have yet another life to give, I am certain I can do > it and pound tons of data through. The research in ARQ and the > development of ALE should indeed allow us to greatly improve the > robustness of our link to effectively use the fancier modulations. > > 73 Bonnie KQ6XA > > > > > > > > > > Thank you for starting an interesting thread. > > 73 > Bob > N4HY > > > -- > AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, > NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman > "You see, wire telegraph is a kind of a very, very long cat. > You pull his tail in New York and his head is meowing in Los > Angeles. Do you understand this? And radio operates exactly > the same way: you send signals here, they receive them there. > The only difference is that there is no cat." - Einstein > Need a Digital mode QSO? 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