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AM electromagnetic waves: 20 KHz modulation frequency on anastronomically-low carrier frequency
On 6/30/07 11:27 PM, in article , "John Smith
I" wrote: Don Bowey wrote: ... You are an idiot ... bother some one who has the time to take you to task ... Open your mind. |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
On Jun 30, 2:55 pm, John Smith I wrote:
Radium wrote: ... I am getting conflicting answers. Some say it's possible to modulate a carrier frequency at a frequency higher than the carrier frequency, others say it isn't. Who is right? Radium: Use simple logic, you can modulate a dc (0 Hz) with higher freq (voice), (hint, your telephone line is an example) right? However, when you get into RF--possible, usable, desirable are seperate and distinct things. Again, with simple logic, modulating a 30 CPS signal with limited voice freq (say 5K wide) is going to create a LOT of harmonics and mixed signals, ain't it? Suggesting a very wide band receiver would be needed to begin with ... in my humble opinion, and for various reasons, NO, it is NOT possible ... Regards, JS radium, I applaud you in your interest generating discussion. if there are no questions there are no answers; dumb or smart! to me your questions came across wonderfully, and generated both responses. as humans we stand on two legs, most of us that is. men get the honor and privilage to stand on three legs from time to time. this is our blessing and our curse! ps. how would u like to change the cell phone industry? and your discussion group of course! remeber all things are possible!!!!!!!!!!!!!!!! |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
Don Bowey wrote:
Open your mind. Geesh! Hook up a 20X linear behind an xmitter and see if you can't find some artifacts ... JS |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
DTC wrote:
Jeff Liebermann wrote: Argh, that brings back fond nightmares of Ma Bell. And of splicing damaged buried plant in a wet trench...that stuff had a bite to it. The Coax we used for the repeaters was fed with 250-0-250V DC and the current was regulated at 49mA. The only time the cable jointers worked on it the power feed was disabled. |
AM electromagnetic waves: 20 KHz modulation frequency on anastronomically-low carrier frequency
On 7/1/07 8:05 AM, in article , "John Smith I"
wrote: Don Bowey wrote: Open your mind. Geesh! Hook up a 20X linear behind an xmitter and see if you can't find some artifacts ... JS Sheesh.... That has nothing to do with helping someone understand AM. It appears you are more interested in dumping your blog on this board, than providing something to clarify the real answers for an electronic novice. |
AM electromagnetic waves: 20 KHz modulation frequency on anastronomically-low carrier frequency
On 7/1/07 8:05 AM, in article , "John Smith I"
wrote: Don Bowey wrote: Open your mind. Geesh! Hook up a 20X linear behind an xmitter and see if you can't find some artifacts ... JS By the way, I have. A 10B to a GPT750. |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
Don Bowey wrote:
That has nothing to do with helping someone understand AM. It appears you are more interested in dumping your blog on this board, than providing something to clarify the real answers for an electronic novice. So, you will decide what he needs to know and what he doesn't? If he becomes aware of the more esoteric and trivial it is dangerous. Get real control freak! JS |
AM electromagnetic waves: 20 KHz modulation frequency on anastronomically-low carrier frequency
On 7/1/07 8:39 AM, in article , "John Smith I"
wrote: Don Bowey wrote: That has nothing to do with helping someone understand AM. It appears you are more interested in dumping your blog on this board, than providing something to clarify the real answers for an electronic novice. So, you will decide what he needs to know and what he doesn't? If he becomes aware of the more esoteric and trivial it is dangerous. Get real control freak! JS You really are thick headed if you can read Radium's posts and can't see how he can't even deal with the real topic, much less the junk you toss in. The more esoteric material should come after there is a grasp of the basics. |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
Don Bowey wrote:
You really are thick headed if you can read Radium's posts and can't see how he can't even deal with the real topic, much less the junk you toss in. The more esoteric material should come after there is a grasp of the basics. What, you have already given up on him and consigned him to a special education class? Damn, I missed him being that dense, of course I tend to give everyone the benefit of the doubt--even you ... JS |
AM electromagnetic waves: 20 KHz modulation frequency on anastronomically-low carrier frequency
On 7/1/07 8:55 AM, in article , "John Smith I"
wrote: Don Bowey wrote: You really are thick headed if you can read Radium's posts and can't see how he can't even deal with the real topic, much less the junk you toss in. The more esoteric material should come after there is a grasp of the basics. What, you have already given up on him and consigned him to a special education class? Damn, I missed him being that dense, of course I tend to give everyone the benefit of the doubt--even you ... JS As a matter of fact, as you should be able to see, I am working here in support of his learning process while you do nothing but rag on in support of your blog. |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
Don Bowey wrote:
As a matter of fact, as you should be able to see, I am working here in support of his learning process while you do nothing but rag on in support of your blog. idiot JS |
AM electromagnetic waves: 20 KHz modulation frequency on anastronomically-low carrier frequency
On 7/1/07 11:11 AM, in article , "John Smith I"
wrote: Don Bowey wrote: As a matter of fact, as you should be able to see, I am working here in support of his learning process while you do nothing but rag on in support of your blog. idiot JS OK, you win. |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
Don Bowey wrote:
[pure crap!] "In the mid-1870s, a form of amplitude modulation—initially called "undulatory currents"—was the first method to successfully produce quality audio over telephone lines. Beginning with Reginald Fessenden's audio demonstrations in the early 1900s, it was also the original method used for audio radio transmissions, and remains in use by some forms of radio communication—"AM" is often used to refer to the mediumwave broadcast band (see AM radio)." Taken from this URL: http://en.wikipedia.org/wiki/Amplitude_modulation And, please read the WHOLE PAGE before making a larger idiot of yourself ... JS |
"Radium" [email protected] COMPLETE IDIOT..........
"Radium" wrote in message oups.com... On Jul 1, 7:24 am, wrote: Analog cells phones should stop using FM and should start using AM between frequencies of 40,000 to 285,000 Hz. I chose 285 KHz to be the highest radio frequency for cell-phones because it is roughly the highest-frequency categorized as "long wave" radio. IDIOT!......complete idiot...... |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
On Sun, 01 Jul 2007 12:16:35 -0700, Radium
wrote: On Jul 1, 7:24 am, wrote: radium, I applaud you in your interest generating discussion. if there are no questions there are no answers; dumb or smart! to me your questions came across wonderfully, and generated both responses. as humans we stand on two legs, most of us that is. men get the honor and privilage to stand on three legs from time to time. this is our blessing and our curse! Thanks for your understanding. ps. how would u like to change the cell phone industry? Analog cells phones should stop using FM and should start using AM between frequencies of 40,000 to 285,000 Hz. --- Good idea. The available spectrum between 40kHz and 285kHz is 245kHz wide, so at a little less than 3kHz per channel the maximum number of channels available would be 82. That means that no more than 82 people can be on the air at the same time. Probably all over the world, to boot, what with those frequencies being able to propagate over long distances. That's probably a good thing, because with those 1875 meter long 1/4 wave whips at 40kHz and those 263 meter 1/4 wave whips at 285kHz on the mobiles, any more people on the air than that would certainly create a hazardous situation. -- JF |
AM electromagnetic waves: 20 KHz modulation frequency on anastronomically-low carrier frequency
On 7/1/07 11:53 AM, in article , "John Smith I"
wrote: Don Bowey wrote: [more crap!] Oh, that explains it, your understanding of amplitude modulation is: AM = Black Magic. ROFLOL! JS OK you stupid ****, I'm almost out of patience with your ignorance. I was hoping you might learn something, but I see that is unlikely. AM is a process of frequency multiplication. Now you tell me where you think such multiplication takes place on a phone line, and I'll follow-uo by telling why you're full of crap. SIMECS! |
"Radium" a COMPLETE IDIOT... - More Likely An In-Complete-Want-To-Be [.]
On Jul 1, 12:50 pm, "Porgy Tirebiter" wrote:
"Radium" wrote in message oups.com... On Jul 1, 7:24 am, wrote: Analog cells phones should stop using FM and should start using AM between frequencies of 40,000 to 285,000 Hz. I chose 285 KHz to be the highest radio frequency for cell-phones because it is roughly the highest-frequency categorized as "long wave" radio. - IDIOT!......complete idiot...... PT - Once again why waste your time replying to his posts ? ? ? {Oops Like I Am Doing Too !} Actually "Radium" would appear to be an In-Complete-Want-To-Be driven by the 'urge' to Post these Forever Ponding Questions for others to charge at like Don Quijote's quest to slay Windmills {a fool's errand} http://en.wikipedia.org/wiki/Don_Quixote http://en.wikipedia.org/wiki/Fool%27s_errand FWIW - While many of his Post might fit into the "sci.electronics.basics" NewsGroup; often they would be consider OFF-TOPIC in other NewsGroups like : rec.radio.shortwave, rec.radio.amateur.antenna, alt.cellular.cingular, alt.internet.wireless, etc IMHO - In another life "Radium" would have made a great High School Science Teacher : Who's Students when on to do great things with their lives : Because "Radium" Touched Them With A Thirst For Knowledge And A Quest For Answers. -but- These NewsGroups are NOT a High School Science Class -and- "Radium" is just being 'radium'. http://en.wikipedia.org/wiki/Radium -alas- Our "Radium's" Half-Life of Readable Interest http://en.wikipedia.org/wiki/Half-life is at best about 16.04 Seconds ~ RHF |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
Radium hath wroth:
ps. how would u like to change the cell phone industry? Analog cells phones should stop using FM and should start using AM between frequencies of 40,000 to 285,000 Hz. Analog cell phones are going to be history in the US on Feb 18, 2008. Japan killed off analog around June 1999, Korea in Jan 2000, most of Europe in 1997, etc. 40KHz thru 285Khz? Great idea. Just one minor problem. A 1/4 wave antenna at about 100Khz frequency is 750 meters long. That's going to be a rather large antenna for literally dragging behind you. Maybe a balloon? Maybe a loop like this one? http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=10850 Of course propagation might be a problem, as it will only work at night and you'll have to connect to a cell site on the opposite coast for those frequencies to work. The customers can be ignored when they complain about atmospheric static and noise. Of course, 240KHz of usable bandwidth is much less than the hundreds of MHz currently in use by cellular providers, so there will substantially fewer users. Let's see.... there are 240 million subscribers in the US. Your AM system can handle about 40 users (6KHz channels), so your cell phone bill will only be 6 million times larger than it is currently. Now do you see why the microwave bands are so in demand for cellular. As I learned recently, 40 KHz is the minimum radio frequency required to coherently transmit/receive audio signals. Coherently? I would be worried if you planned to incoherently transmit/receive audio signals. Perhaps if you added 40KHz to your word salad, it would make your blather more coherent. (Hint: Look up the definition of coherent and then use it where appropriate). Actually, you're close. 40KHz is the common frequency used by ultrasonic TV remote controls. I've seen PWM modulation system using a pair of these to act as a crude cordless phone (that doesn't require FCC type certification). You could probably go down to 20KHz, but then intermodulation products (mixes) between the audio and the carrier will begin to be a problem. Congratulations, you got one thing mostly correct. The highest sound a human can hear is 20 KHz. Voice is from 300 to 3000Hz. You could probably get away with 300 to 2400Hz. If you're planning to transmitting AM hi-fi or data, then you might need the 20KHz. The radio-frequency used must be at least 2x the intended frequency of the information being transmitted/received. Ummm... no. You're apparently thinking of the Shannon rule for information bandwidth: http://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theorem If your input audio is perhaps bandwidth limited to 3KHz, a 6KHz carrier will not work. You'll get considerable mixing (aliasing) and audio intermodulation crud. The carrier would need to be somewhat higher in frequency as limited by whatever output RF filtering is used. I chose 285 KHz to be the highest radio frequency for cell-phones because it is roughly the highest-frequency categorized as "long wave" radio. Nope. See details at: http://en.wikipedia.org/wiki/Longwave -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
"Radium" a COMPLETE IDIOT... - More Likely AnIn-Complete-Want-To-Be [.]
On 7/1/07 2:11 PM, in article
, "RHF" wrote: On Jul 1, 12:50 pm, "Porgy Tirebiter" wrote: "Radium" wrote in message oups.com... On Jul 1, 7:24 am, wrote: Analog cells phones should stop using FM and should start using AM between frequencies of 40,000 to 285,000 Hz. I chose 285 KHz to be the highest radio frequency for cell-phones because it is roughly the highest-frequency categorized as "long wave" radio. - IDIOT!......complete idiot...... PT - Once again why waste your time replying to his posts ? ? ? {Oops Like I Am Doing Too !} Actually "Radium" would appear to be an In-Complete-Want-To-Be driven by the 'urge' to Post these Forever Ponding Questions for others to charge at like Don Quijote's quest to slay Windmills {a fool's errand} http://en.wikipedia.org/wiki/Don_Quixote http://en.wikipedia.org/wiki/Fool%27s_errand FWIW - While many of his Post might fit into the "sci.electronics.basics" NewsGroup; often they would be consider OFF-TOPIC in other NewsGroups like : rec.radio.shortwave, rec.radio.amateur.antenna, alt.cellular.cingular, alt.internet.wireless, etc IMHO - In another life "Radium" would have made a great High School Science Teacher : Who's Students when on to do great things with their lives : Because "Radium" Touched Them With A Thirst For Knowledge And A Quest For Answers. But a teacher MUST be rational. You rate Radium with more potential than I can. This most recent post is really off the wall. -but- These NewsGroups are NOT a High School Science Class -and- "Radium" is just being 'radium'. http://en.wikipedia.org/wiki/Radium -alas- Our "Radium's" Half-Life of Readable Interest http://en.wikipedia.org/wiki/Half-life is at best about 16.04 Seconds ~ RHF . . . . |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
"Ian Jackson" wrote in message ... In message , cledus writes snip The fundamental answer is no, it is not possible to generate AM where the baseband signal is a pure 20 kHz sinewave and Fc20kHz. The reason is that the modulated waveform consists of the sum of a sinewave at Fc, a sinewave at Fc+20kHz, and a sinewave at Fc-20kHz. If Fc20kHz then one of the components becomes a "negative" frequency. So the carrier must be greater than the baseband signal to prevent this. I'm afraid that this is not correct. The 'laws of physics' don't suddenly stop working if the carrier is lower than the modulating frequency. However, there's no need to get into complicated mathematics to illustrate this. Here is a simple example: (a) If you modulate a 10MHz carrier with a 1MHz signal, you will produce two new signals (the sidebands) at the difference frequency of 10 minus 1 = 9MHz, and the sum frequency of 10 plus 1 = 11MHz. So you have the original carrier at 10MHz, and sideband signals at 9 and 11MHz (with a balanced modulator - no carrier - only 9 and 11MHz). (b) If you modulate a 1MHz carrier with a 10MHz signal, you will produce two new signals (the sidebands) at the difference frequency of 1 minus 10 = minus 9MHz, and the sum frequency of 1 plus 10 = 11MHz. The implication of the negative 'minus 9' MHz signal is that the phase of the 9MHz signal is inverted, ie 180 degrees out-of-phase from 9MHz Actually there would be no phase flip. cos(-a) = cos(a) produced in (a). So you have the original carrier at 1MHz, and sidebands at 9 and 11MHz (again, with a balanced modulator - no carrier - only 9 and 11MHz). The waveforms of the full composite AM signals of (a) and (b) will look quite different. The carriers are at different frequencies, and the phase of the 9MHz signal is inverted. However, with a double-balanced modulator, you will only have the 9 and 11MHz signal so, surprisingly, the resulting signals of (a) and (b) will look the same. A double-balanced mixer is a multiplier. A * B = B * A [Note that, in practice, many double-balanced modulators/mixers put loads of unwanted signals - mainly due the effects of harmonic mixing. However, the basic 'laws of physics' still apply.] Finally, although I have spoken with great authority, when I get a chance I WILL be doing at test with a tobacco-tin double-balanced mixer, What's a tobacco-tin double-balanced mixer? a couple of signal generators and a spectrum analyser - just to make sure that I'm not talking rubbish. In the meantime, I'm sure that some will correct me if I'm wrong. You did pretty good. Ian. -- -- rb |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
Jeff Liebermann wrote:
40KHz thru 285Khz? Great idea. Just one minor problem. A 1/4 wave antenna at about 100Khz frequency is 750 meters long. That's going to be a rather large antenna for literally dragging behind you. Well, your math is correct. However, the so-called "atomic" wrist watches receive their time signal from WWVB which transmits at 60kHz. How do they get that 1250 meter long antenna ( 1/4 wave at 60 kHz) inside that itty bitty wrist watch case? ;-) |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
Don Bowey wrote:
AM is a process of frequency multiplication. Now you tell me where you think such multiplication takes place on a phone line, and I'll follow-uo by telling why you're full of crap. SIMECS! It is all right before your eyes, if you can't see it by now, forget it .... perhaps at a later date. I know your frustration, I have seen the mentally handicapped attempt to deal with the real world and it end only in frustration ... perhaps a change of meds is in order ... JS |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
Radium wrote:
... You and your buddies are a hopeless mess, a thread plonk is in order here. PLONK! JS |
AM electromagnetic waves: 20 KHz modulation frequency on anastronomically-low carrier frequency
On 7/1/07 2:57 PM, in article , "John Smith I"
wrote: Don Bowey wrote: AM is a process of frequency multiplication. Now you tell me where you think such multiplication takes place on a phone line, and I'll follow-uo by telling why you're full of crap. SIMECS! It is all right before your eyes, if you can't see it by now, forget it ... perhaps at a later date. I know your frustration, I have seen the mentally handicapped attempt to deal with the real world and it end only in frustration ... perhaps a change of meds is in order ... JS I see..... You finally admit you don't understand AM at all and can't justify your statement. It's what I expected. Now, run off and play in the street with your tinker toys. |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
Ian Jackson wrote:
In message , cledus writes Radium wrote: Hi: Please don't be annoyed/offended by my question as I decreased the modulation frequency to where it would actually be realistic. I have a very weird question about electromagnetic radiation, carriers, and modulators. No offense but please respond with reasonable answers & keep out the jokes, off-topic nonsense, taunts, insults, and trivializations. I am really interested in this. Thanks, Radium The fundamental answer is no, it is not possible to generate AM where the baseband signal is a pure 20 kHz sinewave and Fc20kHz. The reason is that the modulated waveform consists of the sum of a sinewave at Fc, a sinewave at Fc+20kHz, and a sinewave at Fc-20kHz. If Fc20kHz then one of the components becomes a "negative" frequency. So the carrier must be greater than the baseband signal to prevent this. I'm afraid that this is not correct. The 'laws of physics' don't suddenly stop working if the carrier is lower than the modulating frequency. However, there's no need to get into complicated mathematics to illustrate this. Here is a simple example: (a) If you modulate a 10MHz carrier with a 1MHz signal, you will produce two new signals (the sidebands) at the difference frequency of 10 minus 1 = 9MHz, and the sum frequency of 10 plus 1 = 11MHz. So you have the original carrier at 10MHz, and sideband signals at 9 and 11MHz (with a balanced modulator - no carrier - only 9 and 11MHz). (b) If you modulate a 1MHz carrier with a 10MHz signal, you will produce two new signals (the sidebands) at the difference frequency of 1 minus 10 = minus 9MHz, and the sum frequency of 1 plus 10 = 11MHz. The implication of the negative 'minus 9' MHz signal is that the phase of the 9MHz signal is inverted, ie 180 degrees out-of-phase from 9MHz produced in (a). So you have the original carrier at 1MHz, and sidebands at 9 and 11MHz (again, with a balanced modulator - no carrier - only 9 and 11MHz). The waveforms of the full composite AM signals of (a) and (b) will look quite different. The carriers are at different frequencies, and the phase of the 9MHz signal is inverted. However, with a double-balanced modulator, you will only have the 9 and 11MHz signal so, surprisingly, the resulting signals of (a) and (b) will look the same. [Note that, in practice, many double-balanced modulators/mixers put loads of unwanted signals - mainly due the effects of harmonic mixing. However, the basic 'laws of physics' still apply.] Finally, although I have spoken with great authority, when I get a chance I WILL be doing at test with a tobacco-tin double-balanced mixer, a couple of signal generators and a spectrum analyser - just to make sure that I'm not talking rubbish. In the meantime, I'm sure that some will correct me if I'm wrong. Ian. Ian, I believe your analysis is correct. But if you expect to build a receiver that uses a filter centered at 1 MHz with a BW of 20+ MHz to recover a DSB AM signal, I don't believe that the DBM approach will accomplish this. With your approach, you could filter out the sidebands by centering a filter around 10 MHz (the baseband freq). This could be used to recover the baseband 10 MHz signal. But the OP asked about AM of a carrier at very low frequencies. Good explanation of what happens when using a DBM, though. Regards, -C |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
In article ,
cledus wrote: Snip Would you please have the decency to snip rec.radio.shortwave and other groups from the newsgroup header. Thanks. -- Telamon Ventura, California |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
"John Smith I" wrote in message ... Listen to a "strong--pure am signal" on an fm receiver, turn up the volume on the fm receiver, something is responsible for that ... repeat experiment with the reverse ... "imperfect world theory" proof! What is responsible for that is not that AM somehow also produces FM, but simply that the type of demodulator used by the FM receiver in question will also demodulate AM to a usable degree. Ditto the reverse (look up "slope detection" for an example of how a very common AM demodulator can also demodulate FM). Bob M. |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
Jeff Liebermann wrote:
I found a photo of the insides of a watch. See: http://tf.nist.gov/general/pdf/1877.pdf on page 11-12. It's a small 2cm internal rod antenna. A ferrite loop that small for VLF must be very inefficient. I guess they used a high gain RF stage to make the VLF signal usable. |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
Jeff Liebermann wrote:
Watch antennas: http://www.c-max-time.com/products/productsOverview.php?catID=5 See the photos of the various antennas. Too bad there's no specs. I'll grind out the field strength numbers later. I've been living in the microwave region for so long, that I'm having problems with LF calcs. http://www.c-max-time.com/downloads/getFile.php?id=423 Gives dimensions,No of turns,Inductance etc. |
AM electromagnetic waves: 20 KHz modulation frequency on anastronomically-low carrier frequency
Jeff Liebermann wrote:
Conventional TV is VSB (visidual side band) Vestigal Sideband -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
AM electromagnetic waves: 20 KHz modulation frequency on anastronomically-low carrier frequency
On 7/2/07 6:45 AM, in article , "John Smith"
wrote: Don Bowey wrote: ... Would you please come and ask nicely. I don't like how you put your order. Get back on your meds and cease and desist from bothering the other mental patients--else you get the straight jacket next! grin JS Your attempts at presumed humor, are as bad as your AM knowledge. :^) |
AM electromagnetic waves: 20 KHz modulation frequency on anastronomically-low carrier frequency
On 7/2/07 6:45 AM, in article , "John Smith"
wrote: Don Bowey wrote: ... Would you please come and ask nicely. I don't like how you put your order. Get back on your meds and cease and desist from bothering the other mental patients--else you get the straight jacket next! grin JS By the way, I looked at the wiki link you posted and I can see why you are misinformed by it; it's author was either simply not clear in his own mind, or he did not understand that the "undulations" on the telephone line DC voltage is NOT amplitude modulation in the multiplier sense. It is not AM as it is being discussed in this thread of Radium's original post. If you prefer the math proof, multiply the DC voltage frequency (0) by the audio frequency (pick a number between 200 and 3000 Hz), and the product is zero - No new frequencies are present. There's more to it than that but I probably already lost you. |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
In message , Michael A. Terrell
writes Jeff Liebermann wrote: Conventional TV is VSB (visidual side band) Vestigal Sideband Better still, Vestigial Sideband! -- Ian |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
kev hath wroth:
Jeff Liebermann wrote: Watch antennas: http://www.c-max-time.com/products/productsOverview.php?catID=5 See the photos of the various antennas. Too bad there's no specs. I'll grind out the field strength numbers later. I've been living in the microwave region for so long, that I'm having problems with LF calcs. http://www.c-max-time.com/downloads/getFile.php?id=423 Gives dimensions,No of turns,Inductance etc. Thanks. I downloaded that yesterday and got a file with no extension. I eventually figured out it's a PDF file and renamed it. The site also has a rather sketchy article on antenna design at: http://www.c-max-time.com/tech/antenna.php I also found the chip sensitivity somewhere at 0.5uv typical 0.8uv max with a field strength range of: 15-20 uV/m using a 10mm x 60 mm rod. I'm currently slogging through the NIST web pile trying to find the historical or estimated field strengths for the left coast area. http://tf.nist.gov/timefreq/stations/lflibrary.htm Ah, foundit: http://tf.nist.gov/timefreq/general/pdf/1383.pdf Table 2.4 shows signal strength in San Diego varying from 180 uV/m to 1000 uV/m. Now all I need to do is figure out how much S/N ratio is required at the receiver input to properly decode the time signals. All the information needed is probably there, scattered among an assortment of documents, but I'm at a loss on how to estimate the actual field strength sensitivity given the rod antenna specifications. The formula #1 at: http://www.c-max-time.com/tech/antenna.php has all the right parameters, but I keep getting insane results when I try to plug in real and estimated values. Maybe some coffee will help. I'll work on it more during the next few daze. It should be easy (famous last words). However, paying work comes first. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
"Michael A. Terrell" hath wroth:
Jeff Liebermann wrote: Conventional TV is VSB (visidual side band) Vestigal Sideband Ummm... How about Vestigial Sideband instead? http://www.javvin.com/hardware/VSB.html http://whatis.techtarget.com/definition/0,,sid9_gci332235,00.html The last vestige of spelling abilities disappeared long ago and was replaced by a spellin chequer that lacked the term. Sorry. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
On Mon, 2 Jul 2007 16:41:01 +0100, Ian Jackson wrote:
In message , Michael A. Terrell writes Jeff Liebermann wrote: Conventional TV is VSB (visidual side band) Vestigal Sideband Better still, Vestigial Sideband! You're both wrong. It is VIRTUAL SIDEBAND because it isn't completely real and the other sideband which isn't virtual carries the missing high frequency modulation info. Once it gets into your second detector then it becomes real due to the laws of product modulation. Next, you will be telling people that VGA doesn't stand for "virtual graphics array." -- Posted via a free Usenet account from http://www.tarrnews.net |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
Don Bowey wrote:
... Yeah, idiot, lot a proof there. NO modulation at all, krist, the guy on the other end is only carrying on a "virtual conversation!" Excellent use of logic, keep up the good work ... JS |
AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-lowcarrier frequency
John Smith wrote:
[stuff] And, by the way, when using plate modulation on a transmitter, the DC input to plates of the transmitter has a modulated signal impressed upon it by a modulation transformer (simply an audio transformer), every watt of power to the xmitter is so impressed ... The DC voltage/current to the xmitter contains the voice data--indeed, the exact same data which is impressed onto the DC on a telephone line (voice/modulation.) However, the real importance of this will only become clear to you when you come out from under the influence of whatever it is you are smokin' ... JS |
AM electromagnetic waves: 20 KHz modulation frequency on anastronomically-low carrier frequency
On 7/2/07 10:53 AM, in article , "John Smith"
wrote: Don Bowey wrote: ... Yeah, idiot, lot a proof there. NO modulation at all, krist, the guy on the other end is only carrying on a "virtual conversation!" Excellent use of logic, keep up the good work ... JS The problem is, you are too ignorant to understand the terms being used. |
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