++++++++++++++++++ See also Broadband Over Power Lines ++++++++++++++++++ Date: Wed, 10 Apr 2002 23:13:43 +1000 From: "Graeme Zimmer" To: "Low Power Amateur Radio Discussion" Subject: [124383] Mains Communication Interference. Hi, I was reading my April copy of Circuit Cellar, where I was horrified to read a rather glowing report of the "Home Plug" power-line communications system. This is a wideband digital system which uses 83 subcarriers spaced every 200 Khz from 4.5 to 20 Mhz. Due to the impossibility of preventing signal leakage from the mains, it will likely make life for Hams and SWLs very difficult. The article was written by Tom Cantrell (email twc at charter.net ) who is the West Coast Editor of Circuit Cellar Magazine. Tom seems to be a nice bloke, and a very capable engineer, but he doesn't seem to have a clue how nasty these systems could be to our hobby. If you receive Circuit Cellar, you should carefully read the article and then send Tom an email telling him how you feel. If you don't get the mag, some alternative details follow (please read them, then write to Tom). Interesting submission from the RSGB is at http://www.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP013.pdf and from the BBC is at http://www.qsl.net/rsgb_emc/emcplc.pdf BTW, details of Home Plug is at http://www.cebus.org/HomePnP.html regards ........... Graeme Zimmer .......... VK3GJZ +++++++++++++ Date: Thu, 11 Apr 2002 00:08:37 +1000 From: "Graeme Zimmer" To: "Low Power Amateur Radio Discussion" Subject: [124390] Mains Communication Interference Message-ID: <001701c1e099$362cac40$f01836cb at newlaptop> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Sorry, The BBC references are at ... http://www.bbc.co.uk/rd/pubs/papers/pdffiles/hf2000jhs.pdf http://www.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP012.pdf ................. Graeme Zimmer +++++++++++++++++ Date: Fri, 12 Apr 2002 03:16:44 +1000 From: "Graeme Zimmer" To: "Low Power Amateur Radio Discussion" Subject: [124495] End of QRP? Recently I posted a note about the threat to our hobby from the HomePlug Power Mains communication system. I was saddened to see only one reply. So I thought I'd have just one more try. Here is a summary: The system transmits data on the mains wiring using hundreds of broad-band carriers in the HF band. The modems put out a relatively high signal level. Around 100 mW it seems. Can you image a 100mW broad band noise source in the next room? Can you imagine the signal being piped into your house on your mains cabling? Can you imagine tens of thousands of them around the country? The BBC calculates that the signal level is around 50db higher than the European Conducted Emission limits. This level even exceeds the European immunity test level. As this is a very stringent test by USA standards, the level will certainly be high enough to directly affect a large number of appliances ! The calculated interference level are awesome. It will be so high for some SWLs that even outside antennas will be useless even for strong SW stations. The really scary bit is that around large centers the effects will extend out to 100 Km or so. The interference will actually be bad enough to effect ships at sea and even aircraft. To put this in perspective, a friend of mine (here in Australia) has been doing low power tests in the 13 MHz ISM "junk band" With around 1 mW output, his best distance reception has been 16,300 kms. He is frequently heard in USA. These Home plug modems are putting out one hundred times that power level (and there will be tens of thousands of them). In other words, it is likely that Modems in USA will cause significant radio interference in Australia !!!! I hope that we can manage to get them banned. What can you do ? Firstly read these documents..... http://www.qsl.net/rsgb_emc/emcplc.pdf http://www.bbc.co.uk/rd/pubs/papers/pdffiles/hf2000jhs.pdf http://www.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP012.pdf Then write to .... Tom Cantrell twc at charter.net West Coast Editor Circuit Cellar Magazine He has just written a glowing review of the HomePlug system, but seems to have absolutely no idea of how important the HF spectrum is world wide. He seems to think that HF is now superseded and should be reallocated. Anyway, it is one tiny chance for us to be heard by someone with some influence. And please don't bother writing to me. I am already aware of the issue. Write instead to Tom. Tell him how much you enjoy your hobby (both QRP and SWL) and how much you dread this system coming to a house near you, sometime soon. Thanks for listening ................. Zim ................ VK3GJZ ++++++++++++++++++ Date: Fri, 12 Apr 2002 08:58:23 -0400 From: Alex To: gzimmer at bigpond.com Cc: Low Power Amateur Radio Discussion Hi there, Graeme Zimmer wrote: > > Recently I posted a note about the threat to our hobby from the HomePlug > Power Mains communication system. > I was saddened to see only one reply. Yes, it really is a shame that you received only one reply. This is really an issue we need to be aware of, maybe even more so as QRPers. Our fellow QRPer and ARRL Lab Supervisor, Ed Hare, W1RFI is very much involved as a liaison with the industry. Read the article "Inside Your League: The Lab--Part 2 RFI and a Look Around the Lab" at: http://www.arrl.org/news/features/2002/02/27/2/ You can read in the article that because of the involvement of Ed and other members of the ARRL staff, the HomePlug specification now includes protection of the ham bands: Hare represents ARRL on these committees. In addition he maintains a liaison with the FCC, VDSL Committees, Home Phoneline Networking Alliance and HomePlug Powerline Alliance. This last group, HomePlug, may not be well known to hams, but we should be aware of their existence and the consequences of their work. The HomePlug Powerline Alliance is a not-for-profit corporation formed to create specifications for high-speed home power line networking products. HomePlug devices superimpose HF signals onto the electric wiring. Therefore, a potential for interference exists. As a result of the League's involvement, HomePlug specifications include protection against interference to the ham bands. 73s, --Alex (KR1ST) ++++++++++++++++++++ Date: Fri, 12 Apr 2002 09:41:34 -0400 From: "Hare,Ed, W1RFI" To: "'qrp-l at Lehigh.EDU'" Cc: "'twc at charter.net'" , "Bodson, Dennis (Dir, Roanoke)" Subject: [124509] Re: End of QRP? These technologies are generally known as PLC (power-line communications). There are two types. The devices that operate under the HomePlug specification are designed to network computers in a local area, using a building's electrical wiring as the interconnect. Other PLC technology is known as "access" PLC, intended to provide internet service using utility-owned electrical wiring. The HomePlug specification is very tightly defined. It operates from 4.0 - 10.0 MHz, at a power level of -50 dBm/Hz. (That is 0.01 microwatts in every Hz of bandwidth. In a typical 2500 Hz bandwidth, the transmitted power will be 25 microwatts.) This is just about at the limit of what the Part 15 rules will permit. Even more important, the HomePlug specification includes notches in the amateur bands, to a level of lower than -80 dBm/Hz (0.00001 microwatts in each Hz of bandwidth). This is about 30 dB better than what the FCC rules permit. HomePlug did this in a sincere attempt to mitigate widespread harmful interference from the operation of their products. I find it unfortunate that the editor of the article will be getting letters that will not include any of this important information. If every industry took such steps, we would all be quite pleased, I am sure. The joint ARRL/HomePlug report about the testing that was behind their decision to do this is posted at: Mea culpa. The correct URL is: > > http://www.arrl.org/~ehare/rfi/homeplug/HomePlug_ARRL_Dec_2000.pdf When ARRL worked with them, we did so under the auspices of a non-disclosure agreement. Now that the specification is finalized, the details that were shared with us in confidence are no longer confidential, so the report was released a couple of months ago. I have an ARRL web-page RFI Update column scheduled on this issue, but have been sidetracked into several interference studies related to the 70-cm RFID/Savi Technologies FCC rulemaking. 73, Ed Hare, W1RFI ARRL Lab 225 Main St Newington, CT 06111 Tel: 860-594-0318 Internet: w1rfi at arrl.org Web: http://www.arrl.org/tis Subject: End of QRP? From: Graeme Zimmer (gzimmer at bigpond.com) Date: Thu Apr 11 2002 - 13:16:44 EDT +++++++++++++++++++ Date: Fri, 12 Apr 2002 10:45:42 -0400 From: "Hare,Ed, W1RFI" To: qrp-l at Lehigh.EDU Subject: [124521] RE: End of QRP? Hi, Tom, Thanks for the followup. For those interested, ARRL and Amateur Radio's viewpoint of Part 15 is written up at: http://www.arrl.org/tis/info/part15.html 73, Ed Hare, W1RFI ARRL Lab 225 Main St Newington, CT 06111 Tel: 860-594-0318 Internet: w1rfi at arrl.org Web: http://www.arrl.org/tis ++++++++++++++++++ Date: Fri, 12 Apr 2002 23:58:24 +0900 From: Junichi Nakajima To: qrp-l at Lehigh.EDU Subject: [124523] Re: End of QRP Hi all, The PLC problem also occurred in Japan. Not only the QRPers, DXers are very angry to the situation. Thousands of amateurs had send objection to the government. The companies which promote PLC bussiness had requested a relax of restriction of emission in HF. Japanese government is considering that it will be possible or not. ICOM is the sole protesting company to ARIB. JARL and ARIB (PLC promoting business group) had carried out joint experiment last January and you can see the photos at http://www.excite.co.jp/world/url/body/?wb_url=http%3A%2F%2Fwww.jarl.or.jp%2FJapanese%2F2_Joho%2F akagi0126.htm&submit=%83E%83F%83u%83y%81%5B%83W%96%7C%96%F3&wb_lp=JAEN&wb_dis=2&wb_co=excitejapan or http://www.jarl.or.jp/Japanese/2_Joho/akagi0126.htm http://www.ad.wakwak.com/~semba/20020126akagi_plcexam/20020126akagi_plcexam_photos.html http://www.geocities.co.jp/Technopolis-Mars/7270/index.html  Please use a translation site to understand the Japanese contents. PLC typically pouring 200mW OFDM noise spectrum into the power line continuously, and un-balanced line emit huge amount of radio. It will never stop once installed. If a neghboring house install the PLC, it means a death to amateur radio from one's house. We, QRPers can escape to fields, but DXers who had built towers can not escape from it. Surely it will interfere whole radio in HF including aircraft, ship and broadcasting listeners. We are not sure why the ARRL and FCC had allowed the HomePlug which have insufficient -30dB notches only in amateur radio band. It becomes previous instance of the PLC promoting group. We would be happy if you let me know actual interference case of the HomePlug alredy happend in U.S. Rgds., JL1KRA Junichi ++++++++++++++++++ Date: Fri, 12 Apr 2002 11:32:27 -0400 From: "John J. McDonough" To: "Low Power Amateur Radio Discussion" Cc: Subject: [124524] Re: End of QRP? ----- Original Message ----- From: "Hare,Ed, W1RFI" Subject: Re: End of QRP? > Even more important, the HomePlug specification includes > notches in the amateur bands There was a very good article on this in Scientific American a couple of months ago. The general gist was that if they put any sort of signal into the ham bands the resulting FCC reviews and possible litigation would keep them from going commercial for years, so they decided avoiding that was a better choice. I think we have a lot to thank the League for. 72/73 de WB8RCR http://www.qsl.net/wb8rcr didileydadidah QRP-L #1446 Code Warriors #35 ++++++++++++++++ ate: Fri, 12 Apr 2002 12:18:09 -0400 From: Steven Weber To: qrp-l at lehigh.edu Subject: [124528] Re: End of QRP? There's another wirelss scheme being proposed for PDA's and accesories which use magnetic induction at mid HF frequencies. I imagine they use a small loop antenna of some sort, haven't seen any details of that end yet. But they run on very low power and have a range of a meter or two, so shouldn't be a problem... 72, Steve, KD1JV "Melt Solder" White Mountains of New Hampshire http://www.qsl.net/kd1jv/ ++++++++++++++++++ Date: Fri, 12 Apr 2002 12:35:59 -0400 From: "Hare,Ed, W1RFI" To: "'nakaji at crl.go.jp'" , Low Power Amateur Radio Discussion Subject: [124530] RE: End of QRP Thank you Junichi-San. The URL you gave was too long for my Windows system to recognize, so I downloaded it and put it on: http://www.arrl.org/~ehare/rfi/homeplug/jarlplcexperiment.html I will try to run the other sites through one of the translation pages and post URLs for English translations later. I have also shared the URL with those have asked me to send email information about PLC as I get it. If anyone wants to be in my address book for PLC information, let me know. > We are not sure why the ARRL and FCC had allowed the HomePlug which > have insufficient -30dB notches only in amateur radio band. HomePlug is permitted under FCC rules, so ARRL was in no postion to allow or not allow the new technology. In looking at the URLs you supplied, however, the tests you ran were NOT of the HomePlug devices, but of "access PLC." The measurements ARRL made of the HomePlug specification indicated that the 30 dB specification, although not adequate to protect against all possible cases, was a major imrprovement over the levels permitted by Part 15. The technology was going to deploy with or without us, so helping the industry to understand the interference potential and the reasons to do more than the rules require was pretty important. For the record, similar notches were included in the Home Phone Networking Alliance and the VDSL specifications, for exactly the same reasons. Just as soon as I am done with some final testing on the 70 cm RFID reports, I want to try (again) to contact some of the companies developing access PLC technology. 73, Ed Hare, W1RFI ARRL Lab 225 Main St Newington, CT 06111 Tel: 860-594-0318 Internet: w1rfi at arrl.org Web: http://www.arrl.org/tis > -----Original Message----- > From: Junichi Nakajima [mailto:nakaji at crl.go.jp] > Sent: Friday, April 12, 2002 10:58 AM > To: Low Power Amateur Radio Discussion > Subject: Re: End of QRP > > > Hi all, > > The PLC problem also occurred in Japan. +++++++++++++++++ Date: Fri, 12 Apr 2002 13:05:12 -0500 From: Dave Hottell To: "Low Power Amateur Radio Discussion" Subject: [124541] Re: End of QRP? Hi gang, Ed Hare wrote: >Even more important, the HomePlug specification includes notches in the >amateur bands, to a level of lower than -80 dBm/Hz (0.00001 microwatts in >each Hz of bandwidth). This is about 30 dB better than what the FCC rules >permit. OK, while the power level here sounds low, will this not result in intolerable levels of interference? If I did the math right, at 500 Hz of bandwidth and -80dBm/Hz, do we not get a power level of -53dBm? Isn't this an S9+ noise level on a typical ham receiver with a 500 Hz bandwidth sensitivity of -130dBm? On a bandwidth of 2500 Hz the level becomes -46dBm. S9++. Even if the PLC signal were only 1 Hz wide the level would be -80dBm which would be still be about an S9. Virtually all of the signals we receive are at levels lower than this, are they not? It is true that we have quite a bit of ambient noise in the 4-10 MHz range, but no where near this much. And this stuff is going to be carried for miles on the good conducting copper and aluminum power lines. Remember that we have guys using micro-watt transmitted signal levels communicating over thousands of miles -- with more than 100dB of attentuation in path loss. I tend to agree with the fellow from Japan that hams will find this new technology intolerable. Unless I've got it all wrong, sounds like this is sure enough is a killer for all amateur communications. 73 es gl, Dave AB9CA +++++++++++++++++++ Date: Fri, 12 Apr 2002 14:37:13 -0400 From: "Hare,Ed, W1RFI" To: Low Power Amateur Radio Discussion Subject: [124542] RE: End of QRP? You also have to figure in path loss and the gain of the transmit and receive antennas. By my estimation, the residential wiring would be about -10 to -20 dBi. At 0.03 kM separation, the path loss on 7 MHz would be 19 dB. The testing we did at KB1BE indicated that when a signal of -80 dBm/Hz was put on his residential electrical wiring, it was just audible to the antennas at his station, located as close as 20 feet to the house. Again, do NOT confuse the HomePlug devices with access PLC. HomePlug is designed to network computers within a building using that building's electrical wiring. Access PLC is designed to use the miles of utility electrical wiring to provide IS service to residences and businesses. 73, Ed Hare, W1RFI ++++++++++++++++++ Date: Fri, 12 Apr 2002 15:13:35 -0400 From: "Mark J. Dulcey" To: w1rfi at arrl.org Cc: Low Power Amateur Radio Discussion Subject: [124544] Re: End of QRP? Hare,Ed, W1RFI wrote: > You also have to figure in path loss and the gain of the transmit and > receive antennas. By my estimation, the residential wiring would be about > -10 to -20 dBi. At 0.03 kM separation, the path loss on 7 MHz would be 19 > dB. The testing we did at KB1BE indicated that when a signal of -80 dBm/Hz > was put on his residential electrical wiring, it was just audible to the > antennas at his station, located as close as 20 feet to the house. But that's not good enough for some of us. I live on an urban lot. I'm not sure there are any points on my property that are 20 feet away from every house. I'm certain that any type of horizontal antenna will come closer than 20 feet to one or more houses at some point. If you live in any sort of multi-unit housing (I'm fortunate not to have this problem), things get even worse. Now there may be people IN YOUR VERY BUILDING that are using this stuff. The signals will be radiated from the power lines all around you, even the ones in the shack, so if the shielding on any of your station equipment is less than perfect, there will be another path for RF noise to come in through. And some signal will probably leak into your rig through the power supply, unless you run your entire station from batteries. Finally, the current ham bands get some protection. But what about possible future bands? And what about users of other radio services, such as shortwave listeners, who don't even get the benefit of the ham-band notches? And what about the household wiring that happens to be resonant on some important frequency, and has a lot more gain than -20dBi? All in all, I think the entire concept is a can of worms that is best left closed. It is true that under the Part 15 rules, you could insist that the offender cease operation of the equipment. But do you want to track down all the users, including the ones who, under some circumstances, could be hundreds or thousands of miles away? Do you want to be the one to have to tell a neighbor who has just dropped $500 on fancy home control gear that he is going to have to take it all back to the store? Many people don't want to have to string wires around their houses. (There are those of us who are exceptions; we recently had Cat 5 cable run to just about every room in our house.) But there are other ways - many less disruptive - to solve the same problem. Wireless operation on UHF or microwave frequencies (900 MHz, 2.4 GHz, etc.), for example, also have the potential to disturb some amateur radio operations, but don't have the same impact on existing operations, and lack the potential for long distance interference. (And don't get me started on RFID devices on 433 MHz...) ++++++++++++++++++ Date: Fri, 12 Apr 2002 15:32:36 -0400 From: "Hare,Ed, W1RFI" To: "'Mark J. Dulcey'" Cc: Low Power Amateur Radio Discussion Subject: [124548] RE: End of QRP? > But that's not good enough for some of us. I live on an urban > lot. I'm > not sure there are any points on my property that are 20 feet > away from > every house. I'm certain that any type of horizontal antenna > will come > closer than 20 feet to one or more houses at some point. > > If you live in any sort of multi-unit housing (I'm fortunate > not to have > this problem), things get even worse. Now there may be people IN YOUR > VERY BUILDING that are using this stuff. The signals will be radiated > from the power lines all around you, even the ones in the > shack, so if > the shielding on any of your station equipment is less than perfect, > there will be another path for RF noise to come in through. And some > signal will probably leak into your rig through the power > supply, unless > you run your entire station from batteries. Unfortunately, you are correct. The notches they put in, while very much appreciated by ARRL, cannot protect against such close interference potential. This was recognized by ARRL and HomePlug, with the best I could manage in that area was a general agreement that HomePlug would try to deal with that type of interference on a case-by-case basis. Keep in mind that they could deploy this product at the current FCC limits without the 30-dB notches, so this was all very much worth the doing. And, if there is interference, I sure intend to remind HomePlug companies that it is time for a "case-by-case" solution. I think that by working with them the way we did, Amateur Radio better positioned itself to work with them after things are deployed. Rather than emailing some black hole at customer service, Amateur Radio will have a point of contact organizationally that will really smoothe over communications with an individual involved company. Over the past couple of years, ARRL has improved its communcation with the FCC in this area, too. We have a cooperative agreement with Riley (between Riley and me at the staff level) that a process will be followed that starts with a ham trying to work with a Part 15 emitter, followed by a letter and assistance from ARRL followed by an FCC advisory letter to the operator, telling him or her that the federal law requires that they correct harmful interference. This has not been fully tested wrt Part 15 devides, although the Commission has contacted the operator of an electric fence and a VHF scanner, to good effect. I think it was the best we could do at the regulatory and manufacturer level. 73, Ed Hare, W1RFI ARRL Lab 225 Main St Newington, CT 06111 Tel: 860-594-0318 Internet: w1rfi at arrl.org Web: http://www.arrl.org/tis ARRL is the National Association for Amateur Radio. It is supported by membership dues, individual contributions and the sale of publications and advertising. For more information about ARRL, go to http://www.arrl.org/news/features/inside-your-league.html. For more information about membership, go to http://www.arrl.org/join.html. Your contribution can also help support ARRL's ongoing efforts to protect Amateur spectrum. Go to https://www.arrl.org/forms/development/donations/basic/ to learn more about the ways you can support the ARRL programs and activities of most importance to you. You can help ARRL protect Amateur Radio for you and future generations to enjoy. +++++++++++++++++ Date: Fri, 12 Apr 2002 20:48:39 +0000 From: Larry Cahoon To: "Low Power Amateur Radio Discussion" Subject: [124559] RE: End of QRP? > >They use HomePlug PLCs to network computers using building electrical >wiring. The RF emissions are unintentional, but likely. It sure seems like a problem if the signals from these things get into the electrical system in the neighborhood. We could be seeing all sorts of security problems. 73 de Larry.........WD3P in MD http://www.qsl.net/wd3p/ ++++++++++++++++++ Date: Fri, 12 Apr 2002 17:49:42 -0400 From: "Hare,Ed, W1RFI" To: Low Power Amateur Radio Discussion Subject: [124566] RE: End of QRP? > 1) Did you use -80dBm/Hz over the entire band of 4 to 10 MHz > or was the > injected signal more limited in bandwidth? The signal was created using an aribitrary waveform generator. The un-notched part of the spectrum was at -50 dBm/Hz. It was about S6 on Paul's S meter. The notched part of the spectrum was measured at about -75 dBm/Hz, so the final spec came in a bit better. > 2) How closely did the noise source in the test match that > of HomePlug? It was a very close match. The generator signal would have communicated with an actual device. > 3) How many sources did you use? One. > 4) Was the test site an urban or rural environment? In other > words, what > was the noise level at the test site? How typical is this of > the average > ham location? It was an average suburban location. 73, Ed Hare, W1RFI ARRL Lab ++++++++++++++++++++ Date: Sat, 13 Apr 2002 01:30:54 -0700 From: "Dave Fifield" To: , "Low Power Amateur Radio Discussion" Subject: [124605] Re: End of QRP? Zim, I can stay silent on this no longer. I can only say so much, but what I have to say needs saying. Yes - HomePlug wipes out the shortwave bands. Wait till there's a few of them in your neighborhood and their signals start combining together (aggregating) - in the ham bands too.... Actually, IMO, this will not happen soon. I don't believe HomePlug nodes will ever be widely used. They have other technical and marketing issues besides interference. Several very large networking companies have decided that there are too many risks with the technology and will not be making products based on it and there are only a very small handful of silicon vendors who make chips for it. Wireless networking (WiFi or WLAN or IEEE 802.11b/a and later, g) has much more appeal to these companies. WLAN can get to places that HomePlug can't, it has security (well, it will have with the new encryption), it has low cost, it has fast bit rates, it has robustness and it doesn't interfere. HomePlug has none of these things - it is limited to where it will work (poor connections are the norm), it is thoroughly insecure, it is expensive to produce, it has limited bandwidth, it is not robust (very prone to impulse noise hits, and ham radio, as it happens!) and it interferes with just about everyone in the bands it operates over. IMO, it is a doomed technology (I sure hope so anyway!). How do I know all this? It's my job to. If you look at the front page of the ARRL report on HomePlug tests that they did, you will notice my name is on there as I was an attendee at the tests. I have been closely following the HomePlug technical group (amongst others) for some time now. Partly at my insistance and some tests that we did, the 30dB notches were added to protect our bands. The issue that I have always had with HomePlug is that unless the implementers of this technology have the forethought to make these notches mobile/programmable, we could be in for a shock if and when we get a new allocation at 5MHz or if the 40m band is moved/expanded/split. This may happen sooner than everybody thought! As Ed notes, the Home Phoneline Networking Alliance's HPNA 2.0 specification was tested thoroughly for ham radio problems, both ingress and egress. Again, it was at my insistance very early on in the process of developing the HPNA 2.0 spec, that we added a nice big notch that more than covers the 40m band - I worked for a small start-up company called Epigram that invented HPNA 2.0 and was later bought by Broadcom. Actually, I run an 8 node HPNA 2.0 network right here in my house and have never heard any interference from it, either in the shortwave bands or in the 40m ham band. We did some HomePlug testing at my house (with my neighbor's help) and found that it was indeed audible in the ham bands but could not be called an "interferer" since it was too low level. However, IMO, it is thoroughly annoying to have to listen around it. Shortwave bands were wiped out for about 50 to 100 feet in all directions from the home with the HomePlug nodes operating in it. IMO, the only way we hams are ever going to get our spectrum allocations protected is if we pay for the priviledge somehow. Until that day, there will always be greedy industries that want to use our valuable allocations. Lucky for all of us there are people like Ed Hare and his team, and several other hams (who I won't embarrass here) in the datacomms industry, who are looking out for potential interference threats all the time. Cheers es 72, Dave Fifield, AD6A ----- Original Message ----- From: "Graeme Zimmer" Subject: Re: End of QRP? (snip) > If these notches get the Ham interference down to the "just perceptible" > level, this then means that Short Wave Listeners and Comercial HF users are > left with signals that are 1000 times (30db) stronger. Is this correct? +++++++++++++++++ Date: Sat, 13 Apr 2002 07:32:54 -0700 From: "Bob Tellefsen" To: Subject: [124616] Re: End of QRP? Good post, Dave. We need all the light that can be shed on this issue, lest we panic before it's time. Let's hope that you are right, and that it won't be economically attractive for someone to foist this system on an unsuspecting world. 73, Bob N6WG +++++++++++++++++ Date: Tue, 16 Apr 2002 08:43:44 -0500 From: "Aartec" To: "qrp-l at Lehigh. EDU" Subject: [124857] Re: End of QRP Maybe this reference has already noted, sorry if this is redundant but for more information on "Homeplug" you can check EDN magazine. EDN is a major design magazine for the electronics industry and Homeplug was the cover story in the March 21, 2002 issue. The article can also be found on-line at: http://www.e-insite.net/ednmag/index.asp?layout=article&articleId=CA200390 I sure am glad to see the work that has been done to protect our ham bands from this technology. 72 Jerry W0PWE +++++++++++++++++