Actually, the statement that a solution is possible is unproven. A more accurate one might be that a solution may be possible. However, 802.11 is NOT a good example to use in citing how it might be done!
The statement about 802.11 doesn't tell the whole story, not by a long shot. These types of wireless protocols have collision avoidance and interference mitigation built into the protocols. In other words, the transmitters and receivers work together. 802.11 collision avoidance is implemented by carrier sensing and random timing before starting to send and/or requires a sender to forward a 'request to send' packet to the receiver and should transmit only after receiving a 'clear to send' packet back. Even then, there are problems with these techniques where hidden terminals can wreak havoc, so they are not perfect either. Although the spectrum looks full, it is also very well controlled. BPL has none of this, so it is not even comparable. You can't ask BPL for a request to send or even to stop sending for a period of time. An even bigger problem is coordinating sending and receiving when you have two terminals that are 1000's if not 10,000's of miles apart which can happen on HF. What BPL is doing at any instant of time at your location is absolutely no guarantee that the same thing is happening at the receiving end. You may transmit in a perceived "hole" (be it in frequency, time or phase) at your end, but at the receiver, chances are that there is no corresponding "hole" when the signal arrives. This isn't to say that some method can't be developed in time after careful long term assessment of BPL characteristics. However, your derision of Ed Hare being stuck in an analog world is not justifiable. Your statements and examples like: > Yet, in digital networking we are able to work within and around > this sea very effectively to do what we must do to communicate. If > Hams can stop thinking of BPL as simply NOISE and investigate its > specific nature, their great history of Ham Radio innovation will > eventually prevail. don't come close to refuting what Ed said about BPL and its noise characteristics. You can "...do what we must do to communicate..." only because others have done the groundwork on the protocols to insure collision avoidance is part of the basic operation. I am surprised that chose to ignore this in your comparison. Although your spectrum analyzer may show lots of RF, it is all very much in a controlled environment and not at all like BPL. You live in a digital world so I tell you what, here's a little problem for you to solve. Start up a laptop in your wireless network that acts just like BPL. Make sure it has all collision avoidance defeated, not just RTS/CTS but all CA, so it begins transmitting as soon as data is ready, even if another node is transmitting. While you're at it turn off all power control too, just run at maximum output. Then, like BPL, make it constantly send data. Let us know how quickly the whole network deteriorates. As an exercise, see how quickly you can arrive at a solution that can be applied to the other nodes to solve the problem of the uncontrolled transmitter and let us know what that solution is. This problem is much more closely aligned to the BPL issue than simply describing normal wireless operation as being similar. Jim WA0LYK --- In [email protected], "John Champa" <[EMAIL PROTECTED]> wrote: > > Ed, > > Nobody said it is available now, only that a solution is possible. Bob even > pointed out that any solution may be too expensive anyway. > > If we can pause for a minute and stop thinking in strictly analog terms, > then it is clear a solution is possible. For example, I work in a virtual > sea of BPL. It's thick and heavy. Any spectrum analysis indicates such. > > Of course we don't call it "BPL", because it is the same stuff but it is > aimed deliberately at us. It's called 802.11g, 802.11a, and other assorted > OFDM products. > > Yet, in digital networking we are able to work within and around this sea > very effectively to do what we must do to communicate. If Hams can stop > thinking of BPL as simply NOISE and investigate its specific nature, their > great history of Ham Radio innovation will eventually prevail. > > Remember, somebody once said with equal certainty that 200 Meters and down > was absolutely worthless! (HI) > > 73, > John - K8OCL > > > > >From: "Hare, Ed W1RFI" <[EMAIL PROTECTED]> > >To: <[EMAIL PROTECTED]>,<[email protected]> > >Subject: RE: [digitalradio] Re: BPL-Busting Modes/Techniques > >Date: Wed, 25 Oct 2006 11:03:15 -0400 > > > >I strongly disagree. If a digital solution exists to dig signals 60 dB > >out of poorly correlated noise, where can I download a copy or > >information so I can copy signals 60 dB below the present ambient noise > >levels? > > > >Ed Hare, W1RFI > >ARRL Laboratory Manager > >225 Main St > >Newington, CT 06111 > >Tel: 860-594-0318 > >Internet: [EMAIL PROTECTED] > >Web: http://www.arrl.org/ > >Member: ASC C63 EMC Committee > > Chairman: Subcommittee 5, Immunity > > Chairman: Ad hoc BPL Working Group > >Member: IEEE P1775 BPL EMC Committee > >Member: IEEE, Standards Association, Electromagnetic Compatibility > >Society > >Member: ICES SCC-28 RF Safety > >Member/Secretary: IEEE EMC Society Standards Development Committee > > Chairman, BPL Study Project > >Member: Society of Automotive Engineers EMC/EMR Committee > >Board of Directors: QRP Amateur Radio Club International > > > 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/
