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#1
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Can anyone direct me to some good understandable references on single
sideband frequency modulation? I have no real practical reason for wanting to know about this. It is interesting to me in a "mathetical" sort of way. Of course, that is dangerous for me because my brain gets very stubborn when I try to do math. Such ideas as "negative frequency" kind of send my mental faculties into total shutdown. But I read schematic very well. It is a visual language I can usually understand. Seems like years ago there was an article on SSB FM in Ham Radio. That would probably be a good start. If anyone can send me a copy of that article I would be much appreciative. Thanks in advance Bruce kk7zz www.elmerdude.com |
#2
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No such thing that I have ever heard of.
For an easy explanation of the modulation modes -- see URL: http://www.williamson-labs.com/480_mod.htm Perhaps you were thinking of commercial FM broadcasting -- there is a baseband FM signal, a 19kHz pilot carrier, and a DSB suppressed signal at 38kHz. All this yields stereo FM Baseband is left plus right channel the DSB signal is left minus right -- so after demodulation, adding them gives Left and Right channels -- 73 From The KeyBoard In The Wilderness "Bruce Kizerian" wrote in message om... Can anyone direct me to some good understandable references on single sideband frequency modulation? I have no real practical reason for wanting to know about this. It is interesting to me in a "mathetical" sort of way. Of course, that is dangerous for me because my brain gets very stubborn when I try to do math. Such ideas as "negative frequency" kind of send my mental faculties into total shutdown. But I read schematic very well. It is a visual language I can usually understand. Seems like years ago there was an article on SSB FM in Ham Radio. That would probably be a good start. If anyone can send me a copy of that article I would be much appreciative. Thanks in advance Bruce kk7zz www.elmerdude.com |
#3
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No such thing that I have ever heard of.
For an easy explanation of the modulation modes -- see URL: http://www.williamson-labs.com/480_mod.htm Perhaps you were thinking of commercial FM broadcasting -- there is a baseband FM signal, a 19kHz pilot carrier, and a DSB suppressed signal at 38kHz. All this yields stereo FM Baseband is left plus right channel the DSB signal is left minus right -- so after demodulation, adding them gives Left and Right channels -- 73 From The KeyBoard In The Wilderness "Bruce Kizerian" wrote in message om... Can anyone direct me to some good understandable references on single sideband frequency modulation? I have no real practical reason for wanting to know about this. It is interesting to me in a "mathetical" sort of way. Of course, that is dangerous for me because my brain gets very stubborn when I try to do math. Such ideas as "negative frequency" kind of send my mental faculties into total shutdown. But I read schematic very well. It is a visual language I can usually understand. Seems like years ago there was an article on SSB FM in Ham Radio. That would probably be a good start. If anyone can send me a copy of that article I would be much appreciative. Thanks in advance Bruce kk7zz www.elmerdude.com |
#4
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W7TI ) writes:
On 21 Oct 2003 10:06:26 -0700, (Bruce Kizerian) wrote: Seems like years ago there was an article on SSB FM in Ham Radio. __________________________________________________ _______ In the April issue? :-) Bill, W7TI No, the January 1977 issue of Ham Radio magazine, it was the cover article. (I knew it was a January issue, and around that time, but I used the online index at http://webhome.idirect.com/~griffith/hrindex.htm to find it, though it took a few tries to figure out which category it was in.) I could never really make sense of the article. My recollection is that it didn't do a good job on conveying the theory to the average ham, or even the purpose of such a mode, and then went into some stuff about implementing using some circuits out of a textbook and not a complete circuit. One or the other would have been fine, but in straddling both theory and practical it did neither well. Michael VE2BVW |
#5
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W7TI ) writes:
On 21 Oct 2003 10:06:26 -0700, (Bruce Kizerian) wrote: Seems like years ago there was an article on SSB FM in Ham Radio. __________________________________________________ _______ In the April issue? :-) Bill, W7TI No, the January 1977 issue of Ham Radio magazine, it was the cover article. (I knew it was a January issue, and around that time, but I used the online index at http://webhome.idirect.com/~griffith/hrindex.htm to find it, though it took a few tries to figure out which category it was in.) I could never really make sense of the article. My recollection is that it didn't do a good job on conveying the theory to the average ham, or even the purpose of such a mode, and then went into some stuff about implementing using some circuits out of a textbook and not a complete circuit. One or the other would have been fine, but in straddling both theory and practical it did neither well. Michael VE2BVW |
#6
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Michael Black wrote:
No, the January 1977 issue of Ham Radio magazine, it was the cover article. I could never really make sense of the article. My recollection is that it didn't do a good job on conveying the theory to the average ham, or even the purpose of such a mode, I would think it would be for the same reason as SSB for AM? To achieve half the bandwidth utilization for a given signal? (But at the expense of 3dB poorer SNR...) I suspect that going through the math for the 'direct generation' means of SSB-FM would be pretty gnarly, but the 'first generate FM, then add a sharp filter' approach should work (although this will really generate vestigal sideband modulation...). ---Joel Kolstad |
#7
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Michael Black wrote:
No, the January 1977 issue of Ham Radio magazine, it was the cover article. I could never really make sense of the article. My recollection is that it didn't do a good job on conveying the theory to the average ham, or even the purpose of such a mode, I would think it would be for the same reason as SSB for AM? To achieve half the bandwidth utilization for a given signal? (But at the expense of 3dB poorer SNR...) I suspect that going through the math for the 'direct generation' means of SSB-FM would be pretty gnarly, but the 'first generate FM, then add a sharp filter' approach should work (although this will really generate vestigal sideband modulation...). ---Joel Kolstad |
#8
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Joel Kolstad wrote:
I would think it would be for the same reason as SSB for AM? To achieve half the bandwidth utilization for a given signal? (But at the expense of 3dB poorer SNR...) ^^^^^^^^^^^^^^ It occurs to me that this part of my comment is non-sense given the machinations one has to go through to compute SNR through an FM channel anyway. Sorry. One wonders what the SNR degradation _would_ be, however. ---Joel Kolstad |
#9
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Joel Kolstad wrote:
I would think it would be for the same reason as SSB for AM? To achieve half the bandwidth utilization for a given signal? (But at the expense of 3dB poorer SNR...) ^^^^^^^^^^^^^^ It occurs to me that this part of my comment is non-sense given the machinations one has to go through to compute SNR through an FM channel anyway. Sorry. One wonders what the SNR degradation _would_ be, however. ---Joel Kolstad |
#10
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"Joel Kolstad" ) writes:
Michael Black wrote: No, the January 1977 issue of Ham Radio magazine, it was the cover article. I could never really make sense of the article. My recollection is that it didn't do a good job on conveying the theory to the average ham, or even the purpose of such a mode, I would think it would be for the same reason as SSB for AM? To achieve half the bandwidth utilization for a given signal? (But at the expense of 3dB poorer SNR...) It's been quite a few years since I looked at the article. There was just something about the article that seemed like I'd been dropped into something. Maybe the style was different from most articles in the magazine, maybe because it didn't really seem to be a practical article. There just seemed to be something missing. Yes, it would take up less space, but then why not go to some other mode? It's the only time I've seen something on the subject, and I think it could have better been handled. Michael VE2BVW |
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