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BPL strikes another win ...
On Aug 16, 8:02 pm, Owen Duffy wrote:
Yes Roy, it is incredibly naive! Just another of the hundreds of false reasons why 'BPL won't affect me'. That statement doesn't make sense. What would me transmitting on my legal licensed frequencies have to do with BPL effecting me or not? If BPL is in this area, it's going to effect me whether I transmit or not, if it trashes my receiver. It's not naive. I just don't care what they think. I think it's a lousy system, they approved it, and now they are going to have to live with the problems that are sure to come up. I'm not going to be changing my operation any time soon. I don't know of the situation in the US, but in Australia, a licence to transmit on a given frequency does not override another law that in a very general way prohibits interfering with a telecommunications carriage service. That would be all well and good if they used a single frequencies one could avoid... The way I understand it, I stand a good chance of trashing them no matter what frequency I'm on. If they are worried about interference to a carriage system, they should not place it in the same spectrum with another existing service when using power lines, or any other type of leaky or non shielded wiring. What about their interference to HF radio users? Not all are hams. Some are commercial users, such as Houston Universal Radio, which supplies radio services for commercial aircraft. I guess they will have to shut down also.. I'm sorry.. I don't buy it.. It's a lousy system and it's not my fault that it is lousy. Why should amateurs pay for this mistake in planning? The fact remains that we hams do not well understand our operating environment, and sadly, seem to have little interest in it. How do you come to this conclusion? Here in the U.S., according to most all I read, it's up to the unlicensed emitter to make sure they do not cause interference to licensed stations. http://www.ntia.doc.gov/ntiahome/fcc...s_08132003.htm http://www.ieee.org/organizations/pe...p/pesview.html http://www.arrl.org/tis/info/HTML/pl.../BPL_paper.pdf https://www.arrl.org/forms/fdefense/ Yes, that's right. The ARRL is suing the FCC over this. I agree with that decision 100%. I intend to hold them to that. Being an unlicensed emitter, I think they should have to accept any interference that comes their way. And not all will be hams.. What if they decide to run BPL near Houston Hobby airport where Universal Radio is located. Do you think they will choose BPL over commercial aircraft comms? I doubt it.. I don't think amateur stations should be considered any differently, being we are licensed stations. Myself, I think the FCC should be horsewhipped for their performance in deciding the BPL issues. They choose to ignore valid test data, and go with who has the money to spend. This is why I really could care less what they have to say to me about any operating I might do. I'll sit right on my front porch and tell them to bite me if they show up to complain. They promoted the flawed technology. I had nothing to do with it. And I have a legal right to operate on any of my assigned frequencies without undo or unwarranted restrictions. Imposing "quiet hours" will not help. Lowering my power will probably not help too much if I'm using gain antennas pointed at the offending lines, and there is no way to avoid that if I want to work anywhere to the east. Oh well, there will probably be more development of simulators for the HF experience in the future! And there are probably people that would enjoy such a thing.. : ( MK |
BPL strikes another win ...
On Aug 16, 2:41 pm, John Smith I wrote:
wrote: Yeah, the image you attempted to paint in my mind of a toothless old "HF-RF-Terrorist" with a measly KW+ amp doing any sort of meaningful disruption of internet communications is, to say the least, highly comic ... however, you might succeed in enraging your close neighbors into killing you. Regards, JS I've been running that station for years with no problems to the neighbors. Any other ignorant comments? BTW, you'll be thinking toothless if I ever run across you in person. It will take great restraint for me not to beat you half to death. I can't stand a smartass, and you are a primetime smartass. Smartasses don't last very long around me, and I still have all my teeth to prove it. MK |
BPL strikes another win ...
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BPL strikes another win ...
On Aug 16, 11:16 pm, John Smith I wrote:
At 6'2", 220 lbs and buffed to the max, I'd snap ya like a matchstick, IDIOT! JS Yea, thats what they all say... MK |
BPL strikes another win ...
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BPL strikes another win ...
On Aug 16, 11:29 pm, John Smith I wrote:
wrote: On Aug 16, 11:16 pm, John Smith I wrote: At 6'2", 220 lbs and buffed to the max, I'd snap ya like a matchstick, IDIOT! JS Yea, thats what they all say... MK You are lucky you can say it all all, ya toothless old hag ... obviously you have had the chit knocked out of you many time with that mouth--course you could just be a coward and pick on the little guys. IDIOT! JS Right, I'm the coward posting using my real name, while you hide behind a fake one and run your mouth. I've got news for you. *You* are the one with the mouth. I never get mouthy with anyone until I get the same from them first. And you run yours in *every* thread I see you in. I'm not wasting any more time with you. I have better things to do. I will totally ignore you from now on, so you won't have to worry about my mouth, and I won't have to listen to yours. Any fool can go back through the thread and see where the smart mouth first gets kicked in. I think they will find "John Smith I" next to them. It's always the same time after time. You end up disagreeing with whatever I say, so you start up with the snide smartass remarks. You don't see me getting smart and snotty with people I disagree with. I can disagree without being a total ass. Of course, you can live in a state of denial, and think you are not a smartass, but thats a personal problem you will have to deal with on your own. Later.. MK |
BPL strikes another win ...
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BPL strikes another win ...
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BPL strikes another win ...
Roy Lewallen wrote in
: .... want), or the FCC will solve the problem with a regulatory change in favor of the ones with the money, or a little baksheesh will change A solution in the stroke of a pen. It is the golden rule, he who has the gold makes the rules. Owen |
BPL strikes another win ...
Owen Duffy wrote:
Roy Lewallen wrote in : ... want), or the FCC will solve the problem with a regulatory change in favor of the ones with the money, or a little baksheesh will change A solution in the stroke of a pen. It is the golden rule, he who has the gold makes the rules. Money is Honey, my little sonny, and a rich man's joke is always funny. Owen, I prescribe 2 weeks or R and R for you and Roy. Skepticism is healthy, but a descendence past pessimism into gloom is not healthy. Beer and chips for everyone, and the floggings will continue until morale improves. ;^) - 73 de Mike KB3EIA - |
BPL strikes another win ...
Michael Coslo wrote:
... Owen, I prescribe 2 weeks or R and R for you and Roy. Skepticism is healthy, but a descendence past pessimism into gloom is not healthy. ... - 73 de Mike KB3EIA - I'd say Owen, and especially Roy, are right on. If you must escape gloom at the price of ignoring truth, how then do you expect anything to get better. Lady justice might be required to wear a blind fold (these days she peeks into wallets), Joe Blow public needs to have his/her eyes wide open! With the new 700Mhz freqs in the process of "arrangement" so that the BIG MONEY telcos get 'em and the telcos remain in control of expensive voice/data lines, and are allowed price control and use control, BPL is a sure to be attempted as an escape route. Now you can fight this issue anyway you choose--but the real answer is to attack the beast in the heart, unfortunately the telcos are still one particularly ugly, brazen and large dragon! And of course, as Roy pointed out, these telcos are under the protection of corrupt, self-serving public servants who oppose the will of their masters (Joe Blow public.) Now, run and hide from those fact, or not ... Regards, JS |
BPL strikes another win ...
John Smith I wrote in
: Dave Oldridge wrote: ... Rocks break swords. Any system that leaks RF in one direction will leak it both ways. And mice scare elephants, but for no good reason and little consequence ... When it's a few milliwatts of BPL up against an induced signal from a kilowatt transmitter, then the mouse is the BPL. And, according to the regulations, if I have to run the full legal limit to be heard over the din, then it's legitimate. Of course in a plutocracy like the Benighted States of America, whoever has the most bucks makes the final policy and then hires state-paih thugs to enforce it. -- Dave Oldridge+ ICQ 1800667 |
BPL strikes another win ...
Roy Lewallen wrote in
: wrote: How would I get fined for pointing my antenna to Europe? It legal for me to point my antenna to Europe, run an amp, and talk all day if I want to. . . . . . So while you are moaning and groaning about the problem, I will be taking care of it myself in an orderly military manner. Any problems they have will be due to their own shoddy system design and line leakage which is a two way street I remind.. Not my gear. So they won't have a leg to stand on if they or even you complain to the FCC. Do you really seriously believe that if your amateur operation was causing a huge company to lose money that the FCC or any other government entity would take your side? Boy, have I got news for you! But I'm enough of an anarchist to know that, unless the huge company really LEANS on Industry Canada, they'll do what they usually do about interference complaints. Which is to say, they'll harrass whoever they can find but won't do enough legwork to really prove anything in court. -- Dave Oldridge+ ICQ 1800667 |
BPL strikes another win ...
Dave Oldridge wrote:
... You need a good book on digital error correction algorithms in digital communications. Unless you have constructed a real rf jammer (white noise really), BPL will eat up any legitimate amateur communications you can throw at it .... however, rumors do prevail, like the one about the tin foil hat. Regards, JS |
BPL strikes another win ...
If BPL is in this area, it's going to effect me whether I transmit or
not, if it trashes my receiver. It's not naive. I just don't care what they think. I think it's a lousy system, they approved it, and now they are going to have to live with the problems that are sure to come up. I'm not going to be changing my operation any time soon. =================================== Here in the UK BPL (or PLC =Power Line Communication as it is called here) is not an issue since ADSL via telphone line) is sufficiently developed be it not everywhere at a 2Mbits/sec or higher speed (as yet). I have followed ARRL's involvment in 'fighting BPL' and noticed they have tested in/around their HQ a Motorola BPL system that apparently does NOT interfere with HF comms . Other BPL systems are giving a lot of problems . So there seem to be purely technical issues with BPL as well. Also it seems to be very doubtful that BPL will be viable as a cost effective HS comms system considering other more viable methods like fibre or community satellite/high power Wifi systems ,the latter particularly promising for rural communities. Here in the north of Scotland HV pylons ( carry trunk fibre optic cable Frank GM0CSZ / KN6WH |
BPL strikes another win ...
John Smith I wrote in news:fa4i2a$jve$1
@news.albasani.net: Dave Oldridge wrote: ... You need a good book on digital error correction algorithms in digital communications. Unless you have constructed a real rf jammer (white noise really), BPL will eat up any legitimate amateur communications you can throw at it ... however, rumors do prevail, like the one about the tin foil hat. So how is it gonna eat up having its receiver saturated? I'm pretty familiar with digital comms and, with the exception of some pretty slow speed stuff designed for weak signal work, most of it is not very good unless you have a really solid signal-to-noise ratio. I'm just saying that if it's getting out to my antenna that loud, then my kilowatt is gonna have a fair chance at saturating the thing's receiver. And the more noise they make, the more I'm apt to have to use the kilowatt to shout over them. Of course in our current enforcement situation here, I'd probably simply be told to stand down and have to go to great legal lengths to appeal the ruling. -- Dave Oldridge+ ICQ 1800667 |
BPL strikes another win ...
Dave Oldridge wrote:
John Smith I wrote in news:fa4i2a$jve$1 @news.albasani.net: Dave Oldridge wrote: ... You need a good book on digital error correction algorithms in digital communications. Unless you have constructed a real rf jammer (white noise really), BPL will eat up any legitimate amateur communications you can throw at it ... however, rumors do prevail, like the one about the tin foil hat. So how is it gonna eat up having its receiver saturated? I'm pretty familiar with digital comms and, with the exception of some pretty slow speed stuff designed for weak signal work, most of it is not very good unless you have a really solid signal-to-noise ratio. I'm just saying that if it's getting out to my antenna that loud, then my kilowatt is gonna have a fair chance at saturating the thing's receiver. And the more noise they make, the more I'm apt to have to use the kilowatt to shout over them. Of course in our current enforcement situation here, I'd probably simply be told to stand down and have to go to great legal lengths to appeal the ruling. Digital is not analog, when adverse conditions have made an analog signal totally unusable, a digital signal, most likely, may still be achieving 100% error free data transfer--it is just the nature of the beast. The "intelligence" of the software controlling the data transmission(s) is the single most important factor--as logic would dictate. Even under almost total saturation (it would be virtually impossible for 100% saturation, baring hooking the kw+ rig directly to the power lines) of the BPL signal some type of heterodyne would be occurring with the KW signal. Since digital is simply detecting an ON/OFF signal, in conjunction with spacing/length of these, an on/off signal is still detectable in this heterodyne--given the software is aware and capable of reading this signal and switching "modes" to do so, no harm is done to the data ... and without doubt, new error correction methods will also develop as BPL grows and hf-rf-terrorist-hams challenge this system .... LOL! Digital is magnitudes more robust than analog, again owing to the very nature of the beast and the simplicity of the on/off, pulse width, timing nature of the signal. Regards, JS |
BPL strikes another win ...
John Smith I wrote:
... Or, to sum up the previous post, digital, like cw, will get through when nothing else will ... or, have you ever copied cw as a heterodyne on some key clowns jamming signal? Regards, JS |
BPL strikes another win ...
John Smith I wrote in
: Dave Oldridge wrote: John Smith I wrote in news:fa4i2a$jve$1 @news.albasani.net: Dave Oldridge wrote: ... You need a good book on digital error correction algorithms in digital communications. Unless you have constructed a real rf jammer (white noise really), BPL will eat up any legitimate amateur communications you can throw at it ... however, rumors do prevail, like the one about the tin foil hat. So how is it gonna eat up having its receiver saturated? I'm pretty familiar with digital comms and, with the exception of some pretty slow speed stuff designed for weak signal work, most of it is not very good unless you have a really solid signal-to-noise ratio. I'm just saying that if it's getting out to my antenna that loud, then my kilowatt is gonna have a fair chance at saturating the thing's receiver. And the more noise they make, the more I'm apt to have to use the kilowatt to shout over them. Of course in our current enforcement situation here, I'd probably simply be told to stand down and have to go to great legal lengths to appeal the ruling. Digital is not analog, when adverse conditions have made an analog signal totally unusable, a digital signal, most likely, may still be achieving 100% error free data transfer--it is just the nature of the beast. Actually, I've found that, except for very slow data rate stuff, digital signals require a BETTER signal-to-noise than analog to be readable. And there is no partial readability with most of the commercially-used digital modes. That is to say you either have error-free transmission or none whatever. The "intelligence" of the software controlling the data transmission(s) is the single most important factor--as logic would dictate. Even under almost total saturation (it would be virtually impossible for 100% saturation, baring hooking the kw+ rig directly to the power lines) of the BPL signal some type of heterodyne would be occurring with the KW signal. Since digital is simply detecting an ON/OFF signal, in conjunction with spacing/length of these, an on/off signal is still detectable in this heterodyne--given the software is aware and capable of reading this signal and switching "modes" to do so, no harm is done to the data ... and without doubt, new error correction methods will also develop as BPL grows and hf-rf-terrorist-hams challenge this system ... LOL! You cannot recover data with a modem whose input transistor is biased off by rectified RF. I know this. I've tried it. Digital is magnitudes more robust than analog, again owing to the very nature of the beast and the simplicity of the on/off, pulse width, timing nature of the signal. The only real advantage digital has is its error-correction algorithms. Those can do very good work when they actually have enough data to work with. But once the data recovery by the the very ANALOG device that is receiving the signals drops below their threshold, then the recovery becomes terrible. Some modems are better than others. My old Telebit 19.2K could suck 1200 baud recovery out of a phone line you couldn't talk on. But give it a couple of volts of RF in the mix and it would drop stone cold dead. And BPL has the "disadvantage" of not being able to filter our frequencies AND use them at the same time. At worst, I'd drive the BPL machinery to other parts of the band from where I was working.... -- Dave Oldridge+ ICQ 1800667 |
BPL strikes another win ...
John Smith I wrote in news:fa8ql8$d5s$2
@news.albasani.net: John Smith I wrote: ... Or, to sum up the previous post, digital, like cw, will get through when nothing else will ... or, have you ever copied cw as a heterodyne on some key clowns jamming signal? Lots of times. My CW error-correcting hardware is excellent, is always on, and conveniently located in my head. But you're missing my point. A modem is always an analog device. And if it's listening on a frequency with a loud signal on it, then it can be saturated by that signal. I've not seen many that could copy the heterodyne. Mostly they just stop giving any recovery at all. -- Dave Oldridge+ ICQ 1800667 |
BPL strikes another win ...
Dave Oldridge wrote:
At worst, I'd drive the BPL machinery to other parts of the band from where I was working.... At worst some neighbor would get ****ed off that you are messing up their Internet and start a FUD campaign to force you off the air for "dangerous radiation". It happened here with the cell phone companies and as a side effect anyone with more than 20 watts output needs to get their station certified as safe. I know there was a chance of hams getting a blanket excemption, but I don't know if it was approved or not. Geoff. -- Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM IL Voice: (07)-7424-1667 U.S. Voice: 1-215-821-1838 Visit my 'blog at http://geoffstechno.livejournal.com/ |
BPL strikes another win ...
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BPL strikes another win ...
John Smith I wrote:
Digital is not analog, when adverse conditions have made an analog signal totally unusable, a digital signal, most likely, may still be achieving 100% error free data transfer--it is just the nature of the beast. Hi John, The error here is that that digital signal in a bpl setting is trying to function in an analog world. And for all practical purposes, while it is on the line and till it hits the modem, it is just another RF signal. Disregard the 1 and 0 aspect, and think about the rapid stream of pulses. Each one on it's own is just a "state of 1 or 0, but taken together, they are pulses that occur at RF frequencies in toto. So here you have a string of pulses that are running at say 10 MHz. If no other signal gets into that line, all is well. But that same line, which can inadvertently radiate outward, can pick up another signal on the same frequency - and it is very likely that whatever frequency you might be transmitting on will affect it, since the pulsed frequency equivalent (sorry for the goofy term, I'm not sure what else to call it) varies by quite a bit, thereby making it vulnerable to lots of different frequencies being transmitted. Then if say the local school bus company is transmitting on some frequency near the BPL line, that power line might pick up some of that transmission, and send it down the line into someone's modem. That modem won't be able to make any sense of the messed up packets it is receiving. It'll call for a resend, and receive more gibberish. The "intelligence" of the software controlling the data transmission(s) is the single most important factor--as logic would dictate. Even under almost total saturation (it would be virtually impossible for 100% saturation, baring hooking the kw+ rig directly to the power lines) of the BPL signal some type of heterodyne would be occurring with the KW signal. A packet is a surprisingly delicate thing. It takes nowhere near hypothetical 100 percent saturation with an RF signal to change one bit, which can disrupt a packet. Digital is magnitudes more robust than analog, again owing to the very nature of the beast and the simplicity of the on/off, pulse width, timing nature of the signal. John I might respectfully suggest that you do a little studying on the nature of digital signals. I've been dealing with them since the late 70's, and they aren't anywhere near as robust as you believe. - 73 de Mike KB3EIA - |
BPL strikes another win ...
Owen Duffy wrote:
(Geoffrey S. Mendelson) wrote in : ... At worst some neighbor would get ****ed off that you are messing up their Internet and start a FUD campaign to force you off the air for "dangerous radiation". Interesting that you mention that. Some of our good friends in Tasmania started a FUD campaign to scare ordinary electricity consumers about the electromagnetic raidation hazard of electric blankets when they were BPL 'enhanced'. Good grief. The answer is to power them with DC, and tell 'em that it will serve as a magnet, thereby allowing magnetism's great healing properties. Could sell little boxes with diodes in them. Maybe a crystal or two for harmonic hegemony and celestial peace too.... ;^) There is some steady, sound engineering / scientific work going on to discover and reveal the impact of BPL, it is small in scale but IMHO credible and ongoing. Uninformed and redneck comment from the amateur community makes the job just that much harder. I find much of the commentary very uninformed. Much of this has to do with the Digital folks not understanding the RF folks, and vice versa. Especially alarming is the digital folks not understanding that a high speed digital signal is for all intents and purposes an RF signal. It isn't 1's and 0's any more, it is an RF signal until it gets into the computer. Of course, the RF savants have a hard time understanding things like "Whaatya mean Vista dropped my IP address, and the only cure is to reboot. It's been working for three days now - it just couldn't suddenly quit. Electronics doesn't work like that!" At that point, I offer them the choice of being right, or getting things working. - 73 de Mike KB3EIA - |
BPL strikes another win ...
Dave Oldridge wrote:
... Lots of times. My CW error-correcting hardware is excellent, is always on, and conveniently located in my head. But you're missing my point. A modem is always an analog device. And if it's listening on a frequency with a loud signal on it, then it can be saturated by that signal. I've not seen many that could copy the heterodyne. Mostly they just stop giving any recovery at all. There are very rugged modems. Most people just accept the modem which was included with their computer. A cheap modem implemented, almost totally, in software; these can exhibit poor performance. You get what you pay for, and like I say, BPL is a developing technology; or, in other words, problems must be found before they can be fixed. Your KW+ signal will be a great aid, possibly, in that direction ... Having worked in the software/algorithm/data-compression aspects of modems, I have experienced high levels of line noise on standard modems which needed new techniques to solve ... Although I have seen many instances where line noise is at such levels even speech is horrible, and data xmission slows to a crawl, there are few instances where it becomes absolute zero--baring the physical disconnection of the line. If you are inducing interference of a noticeable level in a persons home/business that is noticeable, it will be more than just noticeable on the BPL modem! Regards, JS |
BPL strikes another win ...
Dave Oldridge wrote:
John Smith I wrote in : Dave Oldridge wrote: John Smith I wrote in news:fa4i2a$jve$1 @news.albasani.net: Dave Oldridge wrote: ... You need a good book on digital error correction algorithms in digital communications. Unless you have constructed a real rf jammer (white noise really), BPL will eat up any legitimate amateur communications you can throw at it ... however, rumors do prevail, like the one about the tin foil hat. So how is it gonna eat up having its receiver saturated? I'm pretty familiar with digital comms and, with the exception of some pretty slow speed stuff designed for weak signal work, most of it is not very good unless you have a really solid signal-to-noise ratio. I'm just saying that if it's getting out to my antenna that loud, then my kilowatt is gonna have a fair chance at saturating the thing's receiver. And the more noise they make, the more I'm apt to have to use the kilowatt to shout over them. Of course in our current enforcement situation here, I'd probably simply be told to stand down and have to go to great legal lengths to appeal the ruling. Digital is not analog, when adverse conditions have made an analog signal totally unusable, a digital signal, most likely, may still be achieving 100% error free data transfer--it is just the nature of the beast. Actually, I've found that, except for very slow data rate stuff, digital signals require a BETTER signal-to-noise than analog to be readable. And there is no partial readability with most of the commercially-used digital modes. That is to say you either have error-free transmission or none whatever. The "intelligence" of the software controlling the data transmission(s) is the single most important factor--as logic would dictate. Even under almost total saturation (it would be virtually impossible for 100% saturation, baring hooking the kw+ rig directly to the power lines) of the BPL signal some type of heterodyne would be occurring with the KW signal. Since digital is simply detecting an ON/OFF signal, in conjunction with spacing/length of these, an on/off signal is still detectable in this heterodyne--given the software is aware and capable of reading this signal and switching "modes" to do so, no harm is done to the data ... and without doubt, new error correction methods will also develop as BPL grows and hf-rf-terrorist-hams challenge this system ... LOL! You cannot recover data with a modem whose input transistor is biased off by rectified RF. I know this. I've tried it. Digital is magnitudes more robust than analog, again owing to the very nature of the beast and the simplicity of the on/off, pulse width, timing nature of the signal. The only real advantage digital has is its error-correction algorithms. Those can do very good work when they actually have enough data to work with. But once the data recovery by the the very ANALOG device that is receiving the signals drops below their threshold, then the recovery becomes terrible. Some modems are better than others. My old Telebit 19.2K could suck 1200 baud recovery out of a phone line you couldn't talk on. But give it a couple of volts of RF in the mix and it would drop stone cold dead. And BPL has the "disadvantage" of not being able to filter our frequencies AND use them at the same time. At worst, I'd drive the BPL machinery to other parts of the band from where I was working.... Obviously, we have NOT seen the same equip/software/algorithms and successes ... dream on ... Regards, JS |
BPL strikes another win ...
Michael Coslo wrote:
... John I might respectfully suggest that you do a little studying on the nature of digital signals. I've been dealing with them since the late 70's, and they aren't anywhere near as robust as you believe. - 73 de Mike KB3EIA - It is as if you have looked at one form of plant life and declared all plant life the same. How you choose to implement digital, timing with pulses, pulse durations, etc., or any combination--takes digital into the world of variety. Although it can be difficult to get the machine code out of a modems hardware and study it (really impossible for the avg computer user), astute hacker/programmers do it all the time. You are stuck in the "already all is known world" and see every new and interesting problem as halting to that technology in question. Mans history reveals such thinking to be the lie it is. We deal in computers, we deal in a world where nothing is impossible--some things just ain't been done yet ... Regards, JS |
BPL strikes another win ...
A packet is a surprisingly delicate thing. It takes nowhere near hypothetical 100 percent saturation with an RF signal to change one bit, which can disrupt a packet. Digital is magnitudes more robust than analog, again owing to the very nature of the beast and the simplicity of the on/off, pulse width, timing nature of the signal. John I might respectfully suggest that you do a little studying on the nature of digital signals. I've been dealing with them since the late 70's, and they aren't anywhere near as robust as you believe. Depends a lot on the encoding technique used. Amateur HF packet using surplus Bell 202 modems is pretty bad in terms of interference handling. COFDM with a rate 1/4 FEC is pretty good. One needs to select a coding suited to the channel (e.g. using the coding used for getting 56 kbps through a 3kHz phone line is probably not appropriate for a ionospheric HF path). I would venture to say that with today's technology, one should be able to get within 0.5dB of the Shannon limit without too much trouble. So, since a BPLish signal can be many MHz wide, and the putative interfering signal is going to be pretty narrow band in comparison, they can code around it. - 73 de Mike KB3EIA - |
BPL strikes another win ...
In article ,
Jim Lux wrote: I would venture to say that with today's technology, one should be able to get within 0.5dB of the Shannon limit without too much trouble. So, since a BPLish signal can be many MHz wide, and the putative interfering signal is going to be pretty narrow band in comparison, they can code around it. For a relatively weak interfering signal, that's probably true. That's not likely to be the case in a lot of situations, though. A strong interfering signal - say, a few watts of HF coming from a wire antenna, a few houses away from a BPL receiver - is likely to be strong enough to saturate the RF front-end of the BPL receiver. This will result in a severe "de-sense" problem - it'll wipe out most other signals within the receiver passband. Ham (and other narrow-band) HF receivers deal with this problem by limiting their receiver passband. Single-band filters prior to the first mixer or first RF amp will keep out interferers outside that one band, and narrow-bandwidth multi-pole filters after the first mixer can reduce the impact of interfers that are closer to the desired signal. This approach doesn't work with systems which have a "wide-open" broad-bandwidth front end, such as a typical BPL receiver, as the receiver's front end *has* to be left open to the entire bandwidth of the desired incoming signal. Many modern ham HTs have similar problems... their "DC to daylight" front ends are easily desensed, or driven into severe intermodulation by nearby VHF transmitters (e.g. police, fire, paging, and so forth). I imagine it's possible to reduce the severity of a BPL receiver's desense problems by using a wide-dynamic-range front end... but these take more power and aren't as suitable for large-scale chip integration, and are thus going to be more expensive to build. Even a "ham-friendly" BPL transceiver, with deep transmitter notching of the ham-band frequencies, is likely to have trouble when it finds several volts of (e.g.) 40-meter RF coming into its input terminals. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
BPL strikes another win ...
John Smith I wrote in
: Dave Oldridge wrote: ... Lots of times. My CW error-correcting hardware is excellent, is always on, and conveniently located in my head. But you're missing my point. A modem is always an analog device. And if it's listening on a frequency with a loud signal on it, then it can be saturated by that signal. I've not seen many that could copy the heterodyne. Mostly they just stop giving any recovery at all. There are very rugged modems. Most people just accept the modem which was included with their computer. A cheap modem implemented, almost totally, in software; these can exhibit poor performance. You get what you pay for, and like I say, BPL is a developing technology; or, in other words, problems must be found before they can be fixed. Your KW+ signal will be a great aid, possibly, in that direction ... Having worked in the software/algorithm/data-compression aspects of modems, I have experienced high levels of line noise on standard modems which needed new techniques to solve ... Although I have seen many instances where line noise is at such levels even speech is horrible, and data xmission slows to a crawl, there are few instances where it becomes absolute zero--baring the physical disconnection of the line. If you are inducing interference of a noticeable level in a persons home/business that is noticeable, it will be more than just noticeable on the BPL modem! Not so. Most home and business equipment is not DESIGNED to receive signals on frequencies where I operate (the single exception being some cable systems that use the 2m band). Nor is it using wiring that is WIDE OPEN to my signals. In fact the worst offenders are stereo systems with parallel speaker leads that need only a bit twisted pair, bypassing and a ferrite or two to eliminate all the pickup. Shielded wires may also need toroids to eliminate magnetic pickup that goes right through the shields. But sending an HF signal down an open power line is not just inviting interference, it's BEGGING for it, since you've given the system a very large antenna and put a sensitive receiver on the end of it. DELIBERATELY. That's like designing a gun with a plugged barrel and then firing it! -- Dave Oldridge+ ICQ 1800667 |
BPL strikes another win ...
John Smith I wrote in
: Dave Oldridge wrote: John Smith I wrote in : Dave Oldridge wrote: John Smith I wrote in news:fa4i2a$jve$1 @news.albasani.net: Dave Oldridge wrote: ... You need a good book on digital error correction algorithms in digital communications. Unless you have constructed a real rf jammer (white noise really), BPL will eat up any legitimate amateur communications you can throw at it ... however, rumors do prevail, like the one about the tin foil hat. So how is it gonna eat up having its receiver saturated? I'm pretty familiar with digital comms and, with the exception of some pretty slow speed stuff designed for weak signal work, most of it is not very good unless you have a really solid signal-to-noise ratio. I'm just saying that if it's getting out to my antenna that loud, then my kilowatt is gonna have a fair chance at saturating the thing's receiver. And the more noise they make, the more I'm apt to have to use the kilowatt to shout over them. Of course in our current enforcement situation here, I'd probably simply be told to stand down and have to go to great legal lengths to appeal the ruling. Digital is not analog, when adverse conditions have made an analog signal totally unusable, a digital signal, most likely, may still be achieving 100% error free data transfer--it is just the nature of the beast. Actually, I've found that, except for very slow data rate stuff, digital signals require a BETTER signal-to-noise than analog to be readable. And there is no partial readability with most of the commercially-used digital modes. That is to say you either have error-free transmission or none whatever. The "intelligence" of the software controlling the data transmission(s) is the single most important factor--as logic would dictate. Even under almost total saturation (it would be virtually impossible for 100% saturation, baring hooking the kw+ rig directly to the power lines) of the BPL signal some type of heterodyne would be occurring with the KW signal. Since digital is simply detecting an ON/OFF signal, in conjunction with spacing/length of these, an on/off signal is still detectable in this heterodyne--given the software is aware and capable of reading this signal and switching "modes" to do so, no harm is done to the data ... and without doubt, new error correction methods will also develop as BPL grows and hf-rf-terrorist-hams challenge this system ... LOL! You cannot recover data with a modem whose input transistor is biased off by rectified RF. I know this. I've tried it. Digital is magnitudes more robust than analog, again owing to the very nature of the beast and the simplicity of the on/off, pulse width, timing nature of the signal. The only real advantage digital has is its error-correction algorithms. Those can do very good work when they actually have enough data to work with. But once the data recovery by the the very ANALOG device that is receiving the signals drops below their threshold, then the recovery becomes terrible. Some modems are better than others. My old Telebit 19.2K could suck 1200 baud recovery out of a phone line you couldn't talk on. But give it a couple of volts of RF in the mix and it would drop stone cold dead. And BPL has the "disadvantage" of not being able to filter our frequencies AND use them at the same time. At worst, I'd drive the BPL machinery to other parts of the band from where I was working.... Obviously, we have NOT seen the same equip/software/algorithms and successes ... dream on ... Algorithms will only help you by slowing down and using redundancy or by being frequency agile and thereby clearng off my frequency. And NO equipment DESIGNED to be a sensitive receiver at the frequencies you want to use will be immune to even stronger signals picked up by the open ANTENNA that you're using for a "transmission cable." Dream on. Look, I don't want to tell you how to engineer. But you've obviously got your mind made up and the facts and experience of others be damned. -- Dave Oldridge+ ICQ 1800667 |
BPL strikes another win ...
Dave Oldridge wrote:
... This thread is beginning to switch gears, now we seem to be on the subject of jamming; jamming is obviously possible. A simple 100 MW white noise generator driving my KW+ lab amp would tear up a good chunk of my neighborhood, given the right ant/circumstances. Heck, I would probably even be placing enough of a signal on the phone lines to slow up 56K dialup modems also. Somehow, I just wouldn't get anything out of it. And, given the few active hams in the US, the logic of logistics says, "moot point." But, for those egos imagining themselves special, deserving and empowered above mere mortals--they are allowed to dream. ROFLOL! However, it appears the world according to you will end up with laws/rules/regulations being passed to halt amateurs jamming of citizens use of the internet. With as much damage as some amateurs have done to the hobby and image of amateurs in general--I guess it won't matter too much. Regards, JS |
BPL strikes another win ...
Dave Platt wrote:
In article , Jim Lux wrote: I would venture to say that with today's technology, one should be able to get within 0.5dB of the Shannon limit without too much trouble. So, since a BPLish signal can be many MHz wide, and the putative interfering signal is going to be pretty narrow band in comparison, they can code around it. For a relatively weak interfering signal, that's probably true. That's not likely to be the case in a lot of situations, though. A strong interfering signal - say, a few watts of HF coming from a wire antenna, a few houses away from a BPL receiver - is likely to be strong enough to saturate the RF front-end of the BPL receiver. This will result in a severe "de-sense" problem - it'll wipe out most other signals within the receiver passband. Ham (and other narrow-band) HF receivers deal with this problem by limiting their receiver passband. Single-band filters prior to the first mixer or first RF amp will keep out interferers outside that one band, and narrow-bandwidth multi-pole filters after the first mixer can reduce the impact of interfers that are closer to the desired signal. This approach doesn't work with systems which have a "wide-open" broad-bandwidth front end, such as a typical BPL receiver, as the receiver's front end *has* to be left open to the entire bandwidth of the desired incoming signal. Many modern ham HTs have similar problems... their "DC to daylight" front ends are easily desensed, or driven into severe intermodulation by nearby VHF transmitters (e.g. police, fire, paging, and so forth). I imagine it's possible to reduce the severity of a BPL receiver's desense problems by using a wide-dynamic-range front end... but these take more power and aren't as suitable for large-scale chip integration, and are thus going to be more expensive to build. You can do pretty well these days.. Consider if you're using a direct conversion receiver using a mux driven by quadrature clocks into a low pass filter like the SDR1000.. it has fairly good out of band strong signal rejection. Granted, in band, the performance is limited by the following audio stages. There's also a variety of receiver designs intended for GPS in a strong signal environment that avoid desensing, while still retaining wideband receive for the desired signal. One can also do adaptive analog cancellation. I would imagine that first (and second) generation clunky BPL receivers would have all sort of problems, but the wide open receiver with strong interferer problem is such a prevalent one, they'll have to come up with a solution that fits in their price bracket. (or, they won't, because they don't really need BPL to actually work.. They just have to keep the BPL industry alive, and speculative future performance might be enough for that...) |
BPL strikes another win ...
Dave Oldridge wrote:
... http://pr-gb.com/index.php?option=co...281&It emid=9 http://www.bpltoday.com/public/1212.cfm?affID=prgb1 Regards, JS |
BPL strikes another win ...
Dave Oldridge wrote:
... Algorithms will only help you by slowing down and using redundancy or by being frequency agile and thereby clearng off my frequency. And NO equipment DESIGNED to be a sensitive receiver at the frequencies you want to use will be immune to even stronger signals picked up by the open ANTENNA that you're using for a "transmission cable." Dream on. Look, I don't want to tell you how to engineer. But you've obviously got your mind made up and the facts and experience of others be damned. My son, in florida, contracts to supply firmware for these modems ... advise all you wish; I will continue to make your posts available to him. grin Regards, JS |
BPL strikes another win ...
Michael Coslo writes:
Owen Duffy wrote: Good grief. The answer is to power them with DC, and tell 'em that it will serve as a magnet, thereby allowing magnetism's great healing properties. Could sell little boxes with diodes in them. Maybe a crystal or two for harmonic hegemony and celestial peace too.... ;^) And do remember that a ham antanna doesn't 'radiate'. It 'emanates energies'. 73 LA4RT Jon |
BPL strikes another win ...
Jon ?Q?K=C3=A5re?= Hellan wrote in
: Michael Coslo writes: Owen Duffy wrote: Good grief. The answer is to power them with DC, and tell 'em that it will serve as a magnet, thereby allowing magnetism's great healing properties. Could sell little boxes with diodes in them. Maybe a crystal or two for harmonic hegemony and celestial peace too.... ;^) And do remember that a ham antanna doesn't 'radiate'. It 'emanates energies'. 73 LA4RT Jon LA4RT Jon, I wrote no such thing, you have misquoted, you are a fraud. Owen |
BPL strikes another win ...
Owen Duffy writes:
Jon ?Q?K=C3=A5re?= Hellan wrote in : Michael Coslo writes: Owen Duffy wrote: Good grief. The answer is to power them with DC, and tell 'em that it will serve as a magnet, thereby allowing magnetism's great healing properties. Could sell little boxes with diodes in them. Maybe a crystal or two for harmonic hegemony and celestial peace too.... ;^) And do remember that a ham antanna doesn't 'radiate'. It 'emanates energies'. 73 LA4RT Jon LA4RT Jon, I wrote no such thing, you have misquoted, you are a fraud. Owen Sorry. I didn't notice that I cut everything you wrote, but left your name in. Jon |
BPL strikes another win ...
Dave Oldridge wrote:
Algorithms will only help you by slowing down and using redundancy or by being frequency agile and thereby clearng off my frequency. And NO equipment DESIGNED to be a sensitive receiver at the frequencies you want to use will be immune to even stronger signals picked up by the open ANTENNA that you're using for a "transmission cable." Good point, Dave. Any error correction comes with the expense of time, and of course slows down the transmission of the data. The packet doesn't jibe, so it is asked for again, and again, and so on. Better be a heck of a algorithim when the interfering signal is really strong as to swamp the modem's reciever. There are plenty of examples to the contrary of the digital signal as robust entity. Experiments have been made in which a 5 watt signal in a car with a mobile antenna will knock out nearby BPL signals. 100 watts in a car will do even more damage, and a base station yet more. Other experiments have shown the so called notches being abandoned after the system was unable to send good packets. Kind of like it was getting desperate almost. Seeing as how qrp levels into inefficient antennas can cause problems, I have to wonder what will happen during the next sunspot max. The whole BPL affair makes me kind of wonder why shielding was invented. And for what? a DSL speed "broadband" digital signal? BPL is a poor solution to the problems of ten years ago. It is the 8-track of broadband access. - 73 de Mike KB3EIA - |
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