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#1
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![]() wrote in message ... You're assuming he ever did anything more than assemble a list of technical buzz words to string together at random. In this same spirit, I have decided how I would like to change the electric toaster industry. I believe that henceforth, all electric toasters should be made from polished unobtainium with "Q"-shaped dilithium heating elements, as it is obvious that this results in more even toasting of the bread and an undeniably higher-fidelity output. Further, the toasted bread should be ejected by carefully-aligned cavorite lifters, timed by observing both the thermal state of the bread (detected through counts of left-hand circular polarized neutrino emissions) and the state of a resublimated thiotimoline crystal being exposed to the transverse-modulated IR spectrum. Discuss! Bob "The New Radium" M. |
#2
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DTC hath wroth:
It sounds like you might have a causal peripheral understanding of communications theory and stumbled upon some obscure radio propagation concept and want to apply that obscure concept to to change the whole way we think of communications. Ponder for a moment why said obscure concept remained obscure. I could go on and on and pick each of your comments apart...but it would be a waste of time. Quite the contrary. Taking apart rants and speculation from the lunatic fringe is great fun. After one has mastered science and technology, it offers an additional challenge. Haven't you ever listened to the old Art Bell show? He collected callers claiming alien visitations, abductions, flying saucers, conspiracies, ghosts, amazing technology, and all kinds of other observed phenomenon best attributable to a general lack of sanity and education. He would treat them quite seriously, drawing out additional details that seem to fascinate his large and diverse audience. My guess(tm) is that reality and accurate science are fundamentally boring, and that speculation, lunacy and fantasy are suitable diversions. Some of his callers held prestigious academic or government positions, and apparently wanted to how far off the deep end they could go. I recognized one or two. To properly present a pseudoscientific hoax requires a good understanding of the science and technology, and not just a word salad of buzzwords. I must confess that I enjoy doing the same thing, as witnessed by this ummm.... discussion. Lacking a suitable solution to the general lack of technical sanity problem, I find it far more interesting to become part of the problem. For example, my rants on being a werewolf: http://www.LearnByDestroying.com/nooze/werewolf.txt http://en.wikipedia.org/wiki/Art_Bell In 1998, Bell was named as recipient of the less-than-prestigious Snuffed Candle Award. The Council for Media Integrity cited Bell "for encouraging credulity, presenting pseudoscience as genuine, and contributing to the public's lack of understanding of the methods of scientific inquiry." That's why it's called "the magic of radio". When the magic wears off, what's left is boring and mundane science and physics. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#3
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Jeff Liebermann wrote:
[radically snipped] Haven't you ever listened to the old Art Bell show? Some of his callers held prestigious academic or government positions, and apparently wanted to how far off the deep end they could go. I could be wrong as I'm going back to a late night show over five years ago and I seem to recall it was one of his. He was talking about GPS and played back a snippet of a conversation of above mentioned prestigious academic person that went ballistic trying to validate his credentials. But I digress... I so wanted to point out that Art's (if indeed it was his show) was a disingenuous presentation of GPS as it led the less informed to believe there was a very dark and pervasive side to GPS. Continuing the only good aspects of GPS were promoted by manufactures and dealers of GPS systems. Good or bad...the bottom line was he attracted an audience and an audience translates to advertising revenues. |
#4
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![]() "Jeff Liebermann" wrote in message ... audience. My guess(tm) is that reality and accurate science are fundamentally boring, I think a lot of people perceive them as such, but that perception is, without fail in my experience, the result of a nearly-complete ignorance of these subjects on the parts of those people. There are a practically infinite number of incredibly interesting, beautiful, weird, mind-blowing things going on in real science - if anything, it's the speculation, lunacy, and fantasy that winds up looks really dull, if you have any sort of understanding of the real world. Most of what passes for interesting material on the Art Bell show would be kicked out as too dull, too unimaginative, and/or too mundane by any decent science-fiction editor. Bob M. |
#5
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![]() "Jeff Liebermann" wrote in message ... I'll make it really simple for you. FM is "hi-fi", while AM is noisy "no-fi". Don't you want to be cool strutting down the street with your iPhone watching HDTV with 7.1 sound? It wouldn't do to have it sound like the typical AM broadcast station. For decent quality, you gotta have FM. FM is not inherently any more 'hi-fi' than AM. Fidelity is a product of bandwidth, not modulation type. AM is not even so susceptible to noise as the frequency goes up, since the energy of the noise pulses goes down logarithmically as frequency goes up. AM is used for aeronautical communications very successfully for several reasons, one of which is the LACK of 'capture effect'. There are still some frequencies where AM will be more susceptible to interference than FM, but FM would still suffer, for instance the segment between 1330-1400 MHz which is the natural frequency of Hydrogen (lots of that around). |
#6
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"Brenda Ann" hath wroth:
"Jeff Liebermann" wrote in message .. . I'll make it really simple for you. FM is "hi-fi", while AM is noisy "no-fi". Don't you want to be cool strutting down the street with your iPhone watching HDTV with 7.1 sound? It wouldn't do to have it sound like the typical AM broadcast station. For decent quality, you gotta have FM. FM is not inherently any more 'hi-fi' than AM. FM was invented by Edwin Armstrong specifically to eliminate the noise problems of AM broadcasting. What I think you might be referring to is the huge ****ing match between Armstrong and John Carson over whether FM was any better than FM in the 1930's. The consensus is that very narrow band FM isn't that much better than AM (of equal occupied bandwidth), but wide band FM (as used in broadcast FM and TV) is far better than AM for just about everything. http://fecha.org/armstrong.htm Fidelity is a product of bandwidth, not modulation type. Correct. Actually, it's also a function of modulation linearity (distortion and intermod) and encoding method (dynamic range), but I don't wanna slither down that diversion. Pretend I didn't mention it. AM is not even so susceptible to noise as the frequency goes up, since the energy of the noise pulses goes down logarithmically as frequency goes up. If you're thinking of impulse noise, you're mostly correct. However, there are plenty of other sources of AM noise available. For example, the typical VHF aircraft radio requires substantial filtering of the magneto to avoid hash. Same with any onboard motor. If you've ever tried to install a TV (VSB is a form of AM) in a vehicle, you'll also find that ignition and motor noise can be a problem. Also, your statement isn't quite right. I think what you meant to say is that as the frequency increases, the energy produced by an impulse source, in a given bandwidth, goes down. Even that's not accurate as I have a fluorescent lamp calibrated noise source that's quite noisy well into the GHz range. AM is used for aeronautical communications very successfully for several reasons, one of which is the LACK of 'capture effect'. The FAA, FCC, and various manufactories have tried to move aircraft radios away from AM and towards FM several times in the past 30 year or so. They failed mostly due to international WRC reluctance to swap out expensive radios. It took literally forever to get GPS receivers TSO approved and about 15 years for nav/com radios to go from 50KHz to 25KHz channel spacing, and that was just the FAA. Where else can you find an industry, where progress is somewhat retarded by a regulatory agency of the federal government? I listen to a mix of VHF aircraft AM channels and FM ham and public safety channels on my scanner almost constantly. It's easy to recognize the AM stations by their uniformly crappy audio. Most domestic ground to ground airport traffic is now all FM, as is military ground to ground and ground to air. The reason is that it's difficult to find a decent AM aircraft band walkie talkie. So, they use commercial FM radios. The only AM walkie talkies are used by experimental aviation and ultralights, some of which do not have much of an electrical system that can handle the grossly inefficient AM transmitters. Also, nobody really cares about the "capture effect" as the tower usually has multiple receiver sites and can generally deal with simultaneous transmit collisions. However, they do care about the heterodynes produced by simultaneous transmissions, which obliterate both transmissions. With FM, they could use commercial receiver voting systems and largely eliminate the problem. There are still some frequencies where AM will be more susceptible to interference than FM, but FM would still suffer, for instance the segment between 1330-1400 MHz which is the natural frequency of Hydrogen (lots of that around). If my AM or FM receiver is sensitive enough to hear something in the "water hole", it would be attached to a very big dish antenna. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#7
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Jeff Liebermann wrote:
If you're thinking of impulse noise, you're mostly correct. However, there are plenty of other sources of AM noise available. For example, the typical VHF aircraft radio requires substantial filtering of the magneto to avoid hash. Same with any onboard motor. If you've ever tried to install a TV (VSB is a form of AM) in a vehicle, you'll also find that ignition and motor noise can be a problem. Dang it...my memory is slipping. What did Motorola call their noise filtering circuit on their old low band Motracs. Extenders[tm]? As I recall it was a simple noise blanker. |
#8
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DTC hath wroth:
Jeff Liebermann wrote: If you're thinking of impulse noise, you're mostly correct. However, there are plenty of other sources of AM noise available. For example, the typical VHF aircraft radio requires substantial filtering of the magneto to avoid hash. Same with any onboard motor. If you've ever tried to install a TV (VSB is a form of AM) in a vehicle, you'll also find that ignition and motor noise can be a problem. Dang it...my memory is slipping. What did Motorola call their noise filtering circuit on their old low band Motracs. Extenders[tm]? As I recall it was a simple noise blanker. "Extender". It was a 2nd almost identical receiver, tuned to a nearby empty frequency. If there was any impulse (ignition) noise, both receivers would detect the pulses. The 2nd (Extender) receiver would block the IF signal in the main receiver for the duration of the pulse. This resulted in a "hole" in the receive IF and audio, but it was far less noticeable than if the pulse were allowed to be heard. The tricky part of the design was getting the delays nearly identical in the two receivers. It also made the 80D/140D/Motrac/Motran radios rather huge and heavy. Extenders were considered a "standard option" on most Low Band (30-50Mhz) radios as this is where the ignition noise is the worst. The more generic term "noise blanker" applies to this scheme, as well as a mess of others that detect in a single receiver or blank in the IF or audio. GE decided that "extender" was a good name for their mobile repeater, and called it a "mobile extender" or more commonly just "extender". http://www.mbay.net/~wb6nvh/chpradio.htm Egads. I'm cleaning house and found a large box of 40 year old Motrash control heads and cables. Want some junk? There was also a scheme to eliminate ignition noise that involved running a wire to the points on the distributor. The assumption was that there was a substantial delay between when the points opened, and when the spark jumped in the spark plug. This allowed the receiver to be blanked before the noise pulse arrived, which really improved the noise blanker performance. I was working on the design when marketing decided that it should tilt at other windmills. Only a few prototypes were built, were never patented or produced, and worked really quite well. Cheaper too. That was all just fine because cars were begining to use electronic ignition systems, which didn't have easily accessible ignition points. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#10
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![]() "Radium" wrote in message oups.com... On Jul 1, 7:24 am, wrote in http://groups.google.com/group/sci.e...0c8ed13?hl=en& : how would u like to change the cell phone industry? Analog cells phones should stop using FM and should start using AM with SHF frequencies - at least 3 GHz and at most 30 GHz. Before making such a recommendation, I suggest you read up on a couple of topics. I'd suggest at least topics including: Near and far antenna performance. Path loss calculations Signal penetration Fading types Interleaving SAR Eb/No C/I Frequency stability and accuracy Component and radio design Modem methods Modulation methods. Vocoders Digital modulation General history of modulation techniques, AM, FM and digital Maybe others as they come up in your reading. and then study. Manufacturers and manufacturing history Company pioneering status IPR Regulatory compliance Government rule making processes (Nat'l and Intl) Spectrum use (bits / Hz) Standards setting Getting vendors to make components for you. Lead times Protecting customer's investment Security testing methods Engineering solutions requires you to keep you arms around all of this. If you are serious about your request and do not at least have a casual working knowledge of all these, you are wasting everyone's time. If your goal is to created fruitless discussion, you are right on track. No insult intended...just trying to tell it like it is. Bob F. |
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