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#1
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Radium hath wroth:
There will probably need to be 8-10 times more cell sites built than are currently in use on 800/900 and 1800/1900MHz. Why? For a given radio system, higher frequencies don't go as far as lower frequencies. You can see how it works by just plugging in different frequencies a "free space loss" calculator such as: http://www.terabeam.com/support/calculations/free-space-loss.php For every 6dB of additional path loss, your range is cut in half. Incidentally, this is not my idea or a conspiracy. Mother nature made it that way and we have to live with the physics. I'll make it really simple for you. FM is "hi-fi", while AM is noisy "no-fi". FM has too much hiss. FM has a limiter that eliminates all AM noise components. That's exactly the way the soon to be obsolete analog cell phones operate. If you're hearing hiss, then there's something broken in your FM stereo. FM signals are lost very easily. I have a lost and found for missing signals. It's called a spectrum analyzer. If the signal wanders, I can usually find it. Not a problem. AM tends to retain reception of a signals even when this signal is extremely weak. Not really. If you really want weak signal reception, I suggest you look into SSB (scientific set back) modulation. Half the bandwidth gives you twice the sensitivity. In FM, once you go below a certain wattage, you completely lose the signal, and the annoying hiss begins. With AM it is much easier to receive the low-power signal. Nope. All FM receivers have a squelch to mute the receiver when there's not enough signal to make it worth listening. The squelch is much more efficient with FM than an AGC operated squelch for AM. Anyway, if someone calls with me on my cell phone with a crummy signal, I don't want to talk to them and I usually ask them to call me back when in a better area. The problem with AM audio is that the ultimate signal to noise ratio isn't very good. AM is noisy at any signal strength. The noise never really goes away. On the other foot, FM is noisy with very weak signals, but becomes very quiet once the limiter starts to work. That's why FM is preferred for music and why analog AM broadcasting sounds marginal at any signal level. AM maybe more vulnerable to electronic disturbances but so what? The magnetic RF interferences that are heard on the AM radio are entertaining compared to the deafening hiss on the FM radio. If your FM radio has a deafening hiss, you're probably not tuned to any station. Try listening to a station instead of between stations. If it has an AFC, turn it on. There may also be some kind of malfunction in your hi-fi as you should not be hearing any hiss when tuned to a station. For decent quality, you gotta have FM. Nope. For decent quality sound you need audio that is uncompressed PCM [similar to CDs and WAVE files] with a sample rate of at least 44.1 KHz and a bit-resolution of at least 16-bit. Or the analog equivalent. I thought you didn't like digital? You only gave me a choice of AM or FM. Now, you want digital. Well, digital is what today's cell phones use mostly to maximize spectrum efficiency. With compression and proper coding, you can pickup quite a bit of efficiency, at the expense of sounding like you're gargling ball bearings. Not too bad a tradeoff for voice. Really awful for music. Fortunately, none of the broadcasters or cellular carriers use raw CD data, mostly because it's not compressed. So, are you ready to go public with your idea? When's the IPO? -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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#2
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On Jul 15, 4:30 pm, Jeff Liebermann wrote:
Radium hath wroth: The problem with AM audio is that the ultimate signal to noise ratio isn't very good. AM is noisy at any signal strength. The noise never really goes away. On the other foot, FM is noisy with very weak signals, but becomes very quiet once the limiter starts to work. That's why FM is preferred for music and why analog AM broadcasting sounds marginal at any signal level. AFAIK, the main issue with AM is that it is much more vulnerable to magnetic disruptions than FM. That is why when you are listening to the AM radio at home and someone turns on the microwave-oven, you here those odd sounds on the receiver. Also, if there is a solar prominence you can hear the resulting magnetic disruptions on an AM radio receiver. They sound scary and enjoyable at the same time. Nope. For decent quality sound you need audio that is uncompressed PCM [similar to CDs and WAVE files] with a sample rate of at least 44.1 KHz and a bit-resolution of at least 16-bit. Or the analog equivalent. I thought you didn't like digital? You only gave me a choice of AM or FM. Now, you want digital. It depends, if I can find the analog-equivalent of 44.1 KHz-sample- rate, 16-bit-resolution digital audio, that just as good. If I a limited to only AM or FM for analog audio, I choose AM because I like the sounds generated by solar prominences and other RF magnetic disruptions. Ironically, for video, I prefer FM. Yup, video signals on FM carriers instead of AM carrier. The Y-luminance signal should be broadcasted on an FM carrier. That's the analog video I like. With compression and proper coding, you can pickup quite a bit of efficiency, at the expense of sounding like you're gargling ball bearings. Disgusting! I hate most forms of digital audio compression. For me, either keep it uncompressed or use WMA compression. All non-WMA digital audio compressions below 320 kbps sound like stinky human fart. Or an angry infant foaming at the mouth. Not too bad a tradeoff for voice. Really awful for music. Awful for both. The only digital audio compression I like is WMA. The sounds resulting from WMA compression sort of make me think of those RF electronic telecommunication devices used in The Bourne Identity. That movie features some really awesome devices that make those interesting sounds - for example, when the main character is getting his hand screened. I also associated these sounds with the electronic telecommunication devices used by the Soviet Union. Soviet Union has got some really psychedelic sounds in their electronics. You know, those fancy dial-up modems tones? Fortunately, none of the broadcasters or cellular carriers use raw CD data, mostly because it's not compressed. All digital audio compression formats other than WMA, stink badly!! Here are my rules for digital audio: A. Whether compressed or not, the audio must be monaural and with a sample-rate of at least 44.1 kHz. B. The only compression allowed is WMA. No other compression format is permitted. C. In its uncompressed form, the audio must have a bit-resolution of at least 16-bit D. If compression is used, then the sample-rate of the compressed and the uncompressed version of the audio must be the same. E. If compression is used, the only thing that should be decreased is the bit-resolution. The sample-rate must remain unchanged Let's say a song that was originally recorded in stereo is given to me. The song must to be converted to mono* via the following steps: 1. Record audio from CD [or other stereo audio source] into Wavelab, Adobe Audition [or other audio software] into a file. For simplicity let's call this file "Track1.wav" 2. Make a copy of Track1.wav and save the copy as "Track1B.wav" 3. Open Track1.wav and reduce the gain of its audio by 77.5% 4. Convert Track1.wav to monaural audio 5. Save Track.1 6. Open Track1B.wav and reduce its audio gain by 50% 7. Invert the phase of the left channel of Track1B.wav 8. Convert Track1B.wav to mono 9. Save Track1B.wav 10. Create a new stereo wave file whose bit-resolution is 16-bit and sample rate is 44.1 kHz. For simplicity let's call this file "untitled.wav" 11. Copy and paste the audio of Track1.wav into the left channel of untitled.wav 12. Copy and paste the audio of Track1B.wave into the right channel of untitled.wav 13. Convert untitled.wav to mono 14. Save untitled.wav *Songs that were originally-recorded in stereo need to be converted to mono via the above 14 steps because different sounds are recorded differently in the L and R channels. The audio that is originally panned to the center is significantly louder than the audio whose phase is different in the left & right channels. This is why I reduce the loudness of non-inverted stereo audio file by 77.5% [before converting it to mono]. In the stereo file whose left channel has its phase inverted, I decrease the loudness only by 50% and then convert it to mono. Usually -- the lead vocals, bass, and percussion are recorded identically in both the left and right channels. The piano, chorus, guitar, and synth pads are usually recorded differently in the left and right channel. |
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#3
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Radium hath wroth:
AFAIK, the main issue with AM is that it is much more vulnerable to magnetic disruptions than FM. Wrong. Take a magnet, any magnet. Wave it around your AM or FM radio. Hear anything different? You won't. Therefore, forget about magnetic disturbances. The main issue with AM is susceptibility to pulsed noise, as found in motors, fans, auto engines, and computahs. FM doesn't have as bad a problem because the limiter in the receiver clips everything to the same level, thus reducing the effect. That is why when you are listening to the AM radio at home and someone turns on the microwave-oven, you here those odd sounds on the receiver. No. Microwave ovens operate at 2400Mhz. AM broadcast operates at 1MHz. No way there's going to be any interference there. However, the microwave oven may have a fan or CPU that runs the display, that belches garbage at 1MHz. I just tried mine and there's a tiny bit of buzz coming from the display section when I shove an AM radio right up to the display. If that's what you're hearing, I would test it with a different microwave oven. If only yours has the problem, I suggest you consider a replacement. Also, if there is a solar prominence you can hear the resulting magnetic disruptions on an AM radio receiver. They sound scary and enjoyable at the same time. You can also hear lightning storms. In the US, most of those are in the south east of the country. Nothing like interference from 3000 miles away. Lightning detectors operate in the 25-50KHz region. Incidentally, there are about 8 million lightning hits per day, which is why the noise sounds almost continuous. (chomp...) Sorry, my time is up. Please insert $0.25 for the next 3 minutes. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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#4
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In rec.radio.amateur.antenna Jeff Liebermann wrote:
Radium hath wroth: AFAIK, the main issue with AM is that it is much more vulnerable to magnetic disruptions than FM. Wrong. Take a magnet, any magnet. Wave it around your AM or FM radio. Hear anything different? You won't. Therefore, forget about magnetic disturbances. The main issue with AM is susceptibility to pulsed noise, as found in motors, fans, auto engines, and computahs. FM doesn't have as bad a problem because the limiter in the receiver clips everything to the same level, thus reducing the effect. That is why when you are listening to the AM radio at home and someone turns on the microwave-oven, you here those odd sounds on the receiver. No. Microwave ovens operate at 2400Mhz. AM broadcast operates at 1MHz. No way there's going to be any interference there. However, the microwave oven may have a fan or CPU that runs the display, that belches garbage at 1MHz. I just tried mine and there's a tiny bit of buzz coming from the display section when I shove an AM radio right up to the display. If that's what you're hearing, I would test it with a different microwave oven. If only yours has the problem, I suggest you consider a replacement. Also, if there is a solar prominence you can hear the resulting magnetic disruptions on an AM radio receiver. They sound scary and enjoyable at the same time. You can also hear lightning storms. In the US, most of those are in the south east of the country. Nothing like interference from 3000 miles away. Lightning detectors operate in the 25-50KHz region. Incidentally, there are about 8 million lightning hits per day, which is why the noise sounds almost continuous. (chomp...) Sorry, my time is up. Please insert $0.25 for the next 3 minutes. Don't tell him about whistlers. -- Jim Pennino Remove .spam.sux to reply. |
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#5
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On Jul 15, 5:38 pm, Jeff Liebermann wrote:
Radium hath wroth: AFAIK, the main issue with AM is that it is much more vulnerable to magnetic disruptions than FM. Wrong. Take a magnet, any magnet. Wave it around your AM or FM radio. Hear anything different? You won't. Therefore, forget about magnetic disturbances. That's because this magnet isn't vibrating fast enough. If it were to vibrate at the carrier frequency, you would most likely hear something. Also, if there is a solar prominence you can hear the resulting magnetic disruptions on an AM radio receiver. They sound scary and enjoyable at the same time. You can also hear lightning storms. In the US, most of those are in the south east of the country. Nothing like interference from 3000 miles away. Lightning detectors operate in the 25-50KHz region. Incidentally, there are about 8 million lightning hits per day, which is why the noise sounds almost continuous. The AM audio cause by lightning is so boring. All you get are clicks and pops. Now a solar prominence, this results in some terrifying tones on the AM radio, they resemble the second set of tones played by the Emergency Alert System -- the higher-pitched tones. At times the cosmically-induced AM radio disruptions sound like the audio you get when playing the 1st level of the 1st-stage of Super Mario Bros 1 on channel 4, when the receiver is connected to channel 3. Instead of hearing the game's music, you here those frightening yet enjoyable tones. Sometime you can here these same sounds on a PA system or an airplane. When I was in 1st-grade, the schoolbus I went in had a CB radio which would often make these scary sounds. Such sounds would -- and still to a much smaller extent -- make my eyes water in fear, dissociation, enjoyment, and psychdelia. When the sun emits a prominence, that prominence causes high-power waves of magnetic energy in the RF region to be emitted. These waves can be heard on the AM radio on Earth. This is the sound that affects CBs and other radio receivers using AM. The main reason why anyone would prefer FM over AM is if they can't handle these terrifying sounds w/out going hysterical. There are some who have had emotionally-strong experiences with these sounds -- perhaps a fire on an aircraft -- when these sounds are heard, flashbacks occur which can entirely consume an individual's psyche. Such an individual might not even know why he/she is getting psychologically-excited while listening to the sounds because the brain involuntarily suppresses emotionally-intense memories. Here is what use to happen -- and still happens to some extent -- to me when I hear the sounds I describe: 1. Psychogenic shock and psychological dissociation due to the extreme fear/enjoyment caused by the sounds. 2. Flashbacks of my house in Stamford, Connecticut in which my parents and me moved out when I was around 2.5 years of age. 3. Enjoyable yet terrifying thoughts about outer space due to the knowledge/belief that the source of the sounds is in outer space 4. Fear of -- and obsession with -- magnetism due to knowledge/belief that the radio waves are magnetic 5. Decrease in heart rate 6. Slow deep breathing 7. Muscle relaxation 8. Increased tear production Ain't it interesting when things that are so scary are also so enjoyable at the same time. Why else would they develop virtual reality systems? Or visit outer space? We tend to enjoy what we fear. At times. |
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#6
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Radium hath wroth:
On Jul 15, 5:38 pm, Jeff Liebermann wrote: Radium hath wroth: AFAIK, the main issue with AM is that it is much more vulnerable to magnetic disruptions than FM. Wrong. Take a magnet, any magnet. Wave it around your AM or FM radio. Hear anything different? You won't. Therefore, forget about magnetic disturbances. That's because this magnet isn't vibrating fast enough. If it were to vibrate at the carrier frequency, you would most likely hear something. Actually, what you'll hear is whatever is driving the magnet at the carrier frequency. For example, if you shove the magnet into a solenoid coil, and drive the coil at 1MHz, the magnet will move very slightly at 1MHz. However, the crud that you'll hear at 1MHz is coming from the solenoid coil, not the magnet. If the magnetic field cuts across some wire, that happens to be the antenna of your 1MHz receiver, then yes, you'll hear something, but only if it's moving at 1MHz. The AM audio cause by lightning is so boring. If you've ever been hit by lightning, I don't think you'll find it very boring. With 8 million hits per day, chances are good that you'll get hit. Ummm... could you step outside for a moment? All you get are clicks and pops. Oh no. It's much better than that. You get snap, crackle, pop, crash, hiss, zap, buzz, braaaaaap, and other noises, all to the accompanyment of loud thunder and the smell of ozone. It can also make the fur stand up on your back. If all you hear are clicks and pops, your receiver is comatose. When the sun emits a prominence, that prominence causes high-power waves of magnetic energy in the RF region to be emitted. These waves can be heard on the AM radio on Earth. This is the sound that affects CBs and other radio receivers using AM. Ummm... coronal mass ejections and solar flares are particles, not radio waves. The interference to radio communications is mostly from these particles effects on the ionospheric layers. There is some RF involved, but it's at microwave frequencies and requires a big radio telescope to see. http://www.nrao.edu/pr/2001/radiocme/ The main reason why anyone would prefer FM over AM is if they can't handle these terrifying sounds w/out going hysterical. Hmmm... All my communications radios except the aircraft navcom stuff is FM. Maybe that explains why I'm spending time explaining to you the basics. I'll try not to get too hysterical. There are some who have had emotionally-strong experiences with these sounds (...) Not a problem. Everyone knows that too much RF rots the brain and causes cancer of the vocabulary. Anyone involved in RF has to be insane or will shortly be insane. (chop...) We tend to enjoy what we fear. At times. I don't fear anything, so that might explain why I'm not enjoying myself. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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#7
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Jeff Liebermann wrote:
If you've ever been hit by lightning, I don't think you'll find it very boring. With 8 million hits per day, chances are good that you'll get hit. Ummm... could you step outside for a moment? Reminds me of an afternoon when I was 600 ft up a 1,000 ft TV tower climbing on the inside. The tower took a hit and the lightning bolt followed a aircraft cable hoist line down the inside of the tower. Right between my legs. |
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#8
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On Jul 15, 6:58 pm, Jeff Liebermann wrote:
Radium hath wroth: The AM audio cause by lightning is so boring. All you get are clicks and pops. Oh no. It's much better than that. You get snap, crackle, pop, crash, hiss, zap, buzz, braaaaaap, and other noises, all to the accompanyment of loud thunder and the smell of ozone. It can also make the fur stand up on your back. One thing that I do like are the sharp sawtooth wave patterns that show up on FM video receivers whenever lightning strikes. FM video receivers receive Y [luminance] signals present on FM radio waves. Electrical disturbances affect the FM video receiver causing those beautifaul zapping and buzzing sawtooth patterns on the screen. |
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#9
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"Radium" wrote in message oups.com... | On Jul 15, 6:58 pm, Jeff Liebermann wrote: | | Radium hath wroth: | | The AM audio cause by lightning is so boring. | All you get are clicks | and pops. | | Oh no. It's much better than that. You get snap, crackle, pop, | crash, hiss, zap, buzz, braaaaaap, and other noises, all to the | accompanyment of loud thunder and the smell of ozone. It can also | make the fur stand up on your back. | | One thing that I do like are the sharp sawtooth wave patterns that | show up on FM video receivers whenever lightning strikes. FM video | receivers receive Y [luminance] signals present on FM radio waves. | Electrical disturbances affect the FM video receiver causing those | beautifaul zapping and buzzing sawtooth patterns on the screen. The only FM on standard TV is the audio. Video is vestigial sideband AM. BTW my grand daughter had that figured out by the time she was 12 y.o. |
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#10
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"Radium" wrote in message oups.com... One thing that I do like are the sharp sawtooth wave patterns that show up on FM video receivers whenever lightning strikes. When, pray tell, have you ever seen an "FM video receiver"? Bob M. |
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