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Indoor FM boost with no cables?
Jerry Stuckle wrote:
I never said that, either. But like the troll you are, you can't get anything straight. Your memory is failing Jerry. |
Indoor FM boost with no cables?
Jerry Stuckle wrote in news:lrgjen$ao4$1@dont-
email.me: I know EXACTLY what a picowatt is. And I also know what portable receivers are capable of. Sure, if you feed a picowatt directly into the front end of a receiver, a good receiver will hear the signal. But what field strength do you need at the antenna for a portable FM receiver to hear that signal? And most of your inexpensive portable receivers will not hear much of a signal (if at all), even if you do feed a picowatt directly into the front end (not that you can without major surgery on the receiver). Which begs the question of whether that front end is a high resistance input or not. I don't know if it's 50R, 75R, or whatever, but I do know that if it's a high resistance then talk of power means nothing, it needs spelling out in volts. I think one reason this thread got so long is that context is everything, and people (including me) didn't say enough about it from the off. Cranking the numbers means little in a case where a smarter question might well be 'how long is a pice of string?'. What is helping me a lot here is the direct accounting of people's experience with various powers, in specific buildings and such, using specific antennas.. Thanks for those, they give me the quickest grasp of the scale I need to work with. |
Indoor FM boost with no cables?
Jerry Stuckle wrote in news:lrgjen$ao4$1@dont-
email.me: Sure, but you're also talking a 5Khz deviation (actually about 12Khz bandwidth). Commercial FM uses 75Khz deviation (typically around 180Khz bandwidth). A huge difference. Does that degrade the signal quality compared a really good FM broadcast? (If it does so a lot, it amazes me how little people are willing to accept from their portable MP3's and DAB radios, but that's another matter...) Whatever I end up doing, I want to avoid things like catching the FM, truning to audio, rebroadcasting with all the losses involved, then back to audio yet again! Sounds to me like a disaster, I'd likely end up with bigger problems than I'm trying to fix now. :) |
Indoor FM boost with no cables?
Jerry Stuckle wrote in news:lrglvk$ub7$1@dont-
email.me: And as a matter of fact, I train the people who work with me. I've been in the electronics business for over 40 years, working on everything from $40 dollar CB sets to multi-million dollar computer mainframes. I doubt you've even touched a soldering iron. Sorry about the tad bit of schadenfreude I'm getting here, but you two remind me of the Lone Gunmen in that amazing X-Files episode, just before Signy Coleman showed up. I think we need Signy Coleman in here. :) |
Indoor FM boost with no cables?
On 01 Aug 2014 17:48:22 GMT, Rob wrote:
Oh yes I do! dBm, meaning dB over a milliwatt. And in the cable industry, dBuV, meaning dB over a microvolt. Also dBmV for cable and OTA TV (into 75 ohms): http://www.tselectronic.com/tech_notes/db.php For FM tuners, it's dBf (dB over 1 femtowatt) usually into 300 ohms but sometimes into 75 ohms: http://mail.audiokarma.net/forums/showthread.php?t=29525 http://community.crutchfield.com/car_audio_and_video/f/27/receivers/t/3088/fm-sensitivity#13128 Plenty more to choose from: http://en.wikipedia.org/wiki/Decibel#Suffixes_and_reference_values In America, where everything is bigger, probably dB over a millivolt, but not expressed as dBm! Bigger is better. FCC broadcast EIRP specs are most often expressed in dBW (dB over 1 watt) but sometimes dBk (dB over 1 kilowatt). My own version for data sheets and press releases is dBr (dB better than reality). -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Indoor FM boost with no cables?
Jeff Liebermann wrote in
: For FM tuners, it's dBf (dB over 1 femtowatt) usually into 300 ohms but sometimes into 75 ohms: The Tecsun PL-390 uses dBµ (micro). Most of this is new to me, but I read that Tecsun's dB referencing makes them useful to EMI and RFI engineers, and one related radio beign especially useful for tracing noise, having a plug-in rotatable magnetic loop antenna as well as a long(ish) whip. At this point pouring scorn or praise on Tecsun radios is interesting to me either way, because for the first time in a while I have found a radio I care enough not to be indifferent to it. |
Indoor FM boost with no cables?
On 8/1/2014 2:58 PM, Lostgallifreyan wrote:
Jerry Stuckle wrote in news:lrgjen$ao4$1@dont- email.me: Sure, but you're also talking a 5Khz deviation (actually about 12Khz bandwidth). Commercial FM uses 75Khz deviation (typically around 180Khz bandwidth). A huge difference. Does that degrade the signal quality compared a really good FM broadcast? (If it does so a lot, it amazes me how little people are willing to accept from their portable MP3's and DAB radios, but that's another matter...) Whatever I end up doing, I want to avoid things like catching the FM, truning to audio, rebroadcasting with all the losses involved, then back to audio yet again! Sounds to me like a disaster, I'd likely end up with bigger problems than I'm trying to fix now. :) I won't get into the math here, but due to the sidebands (yes, FM has sidebands, also - the number and strength of the sidebands is proportional to the deviation and modulating frequency), frequency response of the modulated signal is proportional to the bandwidth of the channel and deviation. A 5 kHz deviation can theoretically pass up to about 5Khz of audio, but in practice it's limited to about 3 kHz (to avoid adjacent channel interference). This is fine for voice, but does not work well for music (try listening to music on the AM band, for instance). A 75 kHz deviation can easily be modulated at 15 kHz, providing for better quality music. Back in the late 60's and early 70's, there were some hams on 2 meters running 15 kHz deviation. It's amazing how much better the audio quality was, even with just voice. But that's back when there were few repeaters; I'm glad it didn't catch on. Here in the Washington, D.C. area, it's impossible to get coordination for a 2 meter repeater and difficult on 440 Mhz. I can't imaging what it would be like with 1/3 of the channels available! -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Indoor FM boost with no cables?
On 8/1/2014 1:58 PM, Lostgallifreyan wrote:
Jerry Stuckle wrote in news:lrgjen$ao4$1@dont- email.me: Sure, but you're also talking a 5Khz deviation (actually about 12Khz bandwidth). Commercial FM uses 75Khz deviation (typically around 180Khz bandwidth). A huge difference. Does that degrade the signal quality compared a really good FM broadcast? (If it does so a lot, it amazes me how little people are willing to accept from their portable MP3's and DAB radios, but that's another matter...) Whatever I end up doing, I want to avoid things like catching the FM, truning to audio, rebroadcasting with all the losses involved, then back to audio yet again! Sounds to me like a disaster, I'd likely end up with bigger problems than I'm trying to fix now. :) Not really a disaster, I do it daily. The drawback is, if I want to change stations, I need to run to my bedroom where the internet radio is and push buttons. One of these days, I'll breakdown and get myself a portable internet radio. Mikek PS, I'll bet both of you stations stream on the internet. If you have wifi, that will eliminate your noise problem. Mikek --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
Indoor FM boost with no cables?
Jerry Stuckle wrote:
I won't get into the math here, but due to the sidebands (yes, FM has sidebands, also - the number and strength of the sidebands is proportional to the deviation and modulating frequency), frequency response of the modulated signal is proportional to the bandwidth of the channel and deviation. A 5 kHz deviation can theoretically pass up to about 5Khz of audio, but in practice it's limited to about 3 kHz (to avoid adjacent channel interference). This is fine for voice, but does not work well for music (try listening to music on the AM band, for instance). A 75 kHz deviation can easily be modulated at 15 kHz, providing for better quality music. You keep amazing me, Jerry! Keep on going, I need some fun going into the weekend! |
Indoor FM boost with no cables?
Jerry Stuckle wrote in news:lrgvk8$5er$1@dont-
email.me: I won't get into the math here, but due to the sidebands (yes, FM has sidebands, also - the number and strength of the sidebands is proportional to the deviation and modulating frequency), frequency response of the modulated signal is proportional to the bandwidth of the channel and deviation. A 5 kHz deviation can theoretically pass up to about 5Khz of audio, but in practice it's limited to about 3 kHz (to avoid adjacent channel interference). This is fine for voice, but does not work well for music (try listening to music on the AM band, for instance). Thankyou, that's great help. I'll have to be careful about buying one of those widgets... I did suspect that something that had a narrower bandwidth would reduce frequency response (based on playing with the AR-3000 on narrowband FM). That's one reason I was wondering about boosting the broadcast signal directly for low level rebroadcast in a building, to keep what fidelity I can as best possible. |
Indoor FM boost with no cables?
amdx wrote in :
PS, I'll bet both of you stations stream on the internet. If you have wifi, that will eliminate your noise problem. I get capped at 10GB per month, and that costs far too much. If I saw the costs of the bandwidth to do this I might scream loud enough that even my neighbours might have a noise problem. :) Besides, good FM totally beats all internet quality. Radio 3's best HD sound falls well short, equivalent to a 192 kbps MP3 at best, from what I have read and heard about it. FM in the UK is extremely good quality, nothing else has been any better yet. Which is probably why obituary after obituary gets written for broadcast FM radio, btu it never dies, the 'swicth-off date' is forver being set back, and it likely won't happen once peoplerealise the costs of allocating bandwidth foe that kind of quality ona per-person basis! That's a mind-stunning financial and technical calculation no matter how we look at it. |
Indoor FM boost with no cables?
On Fri, 01 Aug 2014 15:22:10 -0500, Lostgallifreyan
wrote: Jeff Liebermann wrote in : For FM tuners, it's dBf (dB over 1 femtowatt) usually into 300 ohms but sometimes into 75 ohms: The Tecsun PL-390 uses dBµ (micro). Yep. The Tecsun PL-390 uses a Silicon Labs SI4734 DSP chip. I've done some work with similar chips and think they are wonderful. http://www.kaitousa.com/PL390.htm https://www.silabs.com/Support%20Documents/TechnicalDocs/Si4730-31-34-35-D60.pdf One of the chief benefits to all an all digital receiver is the nearly "brick wall" IF filter, which works nicely at keeping HD Radio crap out of the receiver. I'm not sure if you have that problem in UK: http://www.telegraph.co.uk/technology/8071209/BBC-launches-HD-radio.html but if you do, the SI4734 should remove the junk from the adjacent channel. Note that the HD Radio occupied bandwidth is about 400 KHz, while conventional FM is a bit less than 200 KHz. http://802.11junk.com/jeffl/crud/KCSM.jpg Too bad the PL-390 won't do synchronous AM or SSB. The chip can do it, but it's only available in the later PL-880 receiver. http://www.kaitousa.com/PL880.htm I'm not sure where the dBf stuff came from, but my guess(tm) is that it was used to simplify the sensitivity specs so that the numbers came out positive integers. Most of this is new to me, but I read that Tecsun's dB referencing makes them useful to EMI and RFI engineers, We call it EMC (electromagnetic compatibility) in the US. http://www.fda.gov/Radiation-EmittingProducts/RadiationSafety/ElectromagneticCompatibilityEMC/default.htm I don't think using dBµ will make much difference as I'm constantly converting from various field strength units to voltages and powers. If you're into this, you might want to save this page: http://802.11junk.com/jeffl/coverage/VZW-water-plant/Field%20Intensity%20and%20Power%20Density.pdf I forgot which book I stole it from. and one related radio beign especially useful for tracing noise, having a plug-in rotatable magnetic loop antenna as well as a long(ish) whip. Direction finding is fine for finding the general area. However, for close up, one needs a "sniffer". For that, I use an Alinco DJ-X2 AM receiver with the stock 17 cm antenna. It's not very sensitive but good enough for finding unwanted emitters. Your Tecsun PL-390 would probably work equally well. At this point pouring scorn or praise on Tecsun radios is interesting to me either way, because for the first time in a while I have found a radio I care enough not to be indifferent to it. I guess that means you like it. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Indoor FM boost with no cables?
Jeff Liebermann wrote in
: If you're into this, you might want to save this page: http://802.11junk.com/jeffl/coverage...%20Intensity%2 0and%20Power%20Density.pdf Thankyou. That's a good looking reference. For now it passes swiftly overhead, but I get the point about converting to SI units ASAP for best anchorage. I did see the Wikipedia page, but I think studying that file you posted will work better for me. About the PL-390, yes, I like it. :) It crashed, locked like a brick within days of buying, but despite that nasty event (and the even nastier twenty minute wait that ensueth before the power fades enough to let me regain control) that small radio impresses me every time I use it. I hope to figure out a fast reset modification though, and I'm also wondering if I can find a TTL serial based board for making my own project radio using the same IC, and allowing me to use the old Psion Organiser II XP as a controller and display, but I think that might be more expensive than I'd like despite the cheapness of those Organisers these days. |
Indoor FM boost with no cables?
Jeff Liebermann wrote in
: I'm not sure if you have that problem in UK: http://www.telegraph.co.uk/technology/8071209/BBC-launches-HD-radio.html but if you do, the SI4734 should remove the junk from the adjacent channel. Note that the HD Radio occupied bandwidth is about 400 KHz, while conventional FM is a bit less than 200 KHz. Not yet, so far as I know, but forewarned is forearmed.. :) I can't help thinking that the extra demand for bandwidth might end up making FM look like the better option... |
Indoor FM boost with no cables?
Jeff wrote in :
The point that Jerry is missing is that the in-car devices that link an MP3 player, and the like, to a car radio are being received by just that, a car radio; so if the deviation were as low as 5 or even 15kHz then the level of audio coming out of the radio would so so low as to be unusable. The deviation of the transmitters must match the bandwidth of the receiver being used, ie the normal FM broadcast band deviation of 150kHz of more. I am not sure what the FCC power limit for such devices is, but in the UK is it is 50nW erp in the FM broadcast band, yes 50 nanowatts. I expect that the devices sold in the US are similar output power. Jerry does not seem to take on board that this is an international group, not a group of ex-US cable technicians who slovenly misuse dBm to mean dBmV, when the rest of the world uses dBm correctly to mean dB relative to a milliwatt. Jeff Thanks, that looks clear, and fits with other things I read, especially the dBm bit and the 50 nW. One thought: Does the bandwidth match have to be exact? Or is there a case for some reduction on the transmitter to allow more of them to make potentially less local competition between each other when lots are used? Is there some compromise that doesn't afflict the sound too much, while reducing both the occupancy of the spectrum and the need for power for some given reach of distance? (I don't intent using one, but they do interest me strangely...) |
Indoor FM boost with no cables?
On 8/2/2014 6:12 AM, Jeff wrote:
On 02/08/2014 00:13, Lostgallifreyan wrote: Jerry Stuckle wrote in news:lrgvk8$5er$1@dont- email.me: I won't get into the math here, but due to the sidebands (yes, FM has sidebands, also - the number and strength of the sidebands is proportional to the deviation and modulating frequency), frequency response of the modulated signal is proportional to the bandwidth of the channel and deviation. A 5 kHz deviation can theoretically pass up to about 5Khz of audio, but in practice it's limited to about 3 kHz (to avoid adjacent channel interference). This is fine for voice, but does not work well for music (try listening to music on the AM band, for instance). Thankyou, that's great help. I'll have to be careful about buying one of those widgets... I did suspect that something that had a narrower bandwidth would reduce frequency response (based on playing with the AR-3000 on narrowband FM). That's one reason I was wondering about boosting the broadcast signal directly for low level rebroadcast in a building, to keep what fidelity I can as best possible. The point that Jerry is missing is that the in-car devices that link an MP3 player, and the like, to a car radio are being received by just that, a car radio; so if the deviation were as low as 5 or even 15kHz then the level of audio coming out of the radio would so so low as to be unusable. Wrong. These are operating in the commercial FM band, and use 75 kHz deviation. I never said otherwise. The deviation of the transmitters must match the bandwidth of the receiver being used, ie the normal FM broadcast band deviation of 150kHz of more. Again, incorrect. The deviation is 75 kHz (deviation is measured from the center frequency). Bandwidth is 150 kHz. I am not sure what the FCC power limit for such devices is, but in the UK is it is 50nW erp in the FM broadcast band, yes 50 nanowatts. I expect that the devices sold in the US are similar output power. Again, incorrect. Jerry does not seem to take on board that this is an international group, not a group of ex-US cable technicians who slovenly misuse dBm to mean dBmV, when the rest of the world uses dBm correctly to mean dB relative to a milliwatt. Jeff Nope. I'm talking about what is commonly used here. But there are some people from the U.K. who think they are experts on everything. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Indoor FM boost with no cables?
On 8/2/2014 6:27 AM, Lostgallifreyan wrote:
Jeff wrote in : The point that Jerry is missing is that the in-car devices that link an MP3 player, and the like, to a car radio are being received by just that, a car radio; so if the deviation were as low as 5 or even 15kHz then the level of audio coming out of the radio would so so low as to be unusable. The deviation of the transmitters must match the bandwidth of the receiver being used, ie the normal FM broadcast band deviation of 150kHz of more. I am not sure what the FCC power limit for such devices is, but in the UK is it is 50nW erp in the FM broadcast band, yes 50 nanowatts. I expect that the devices sold in the US are similar output power. Jerry does not seem to take on board that this is an international group, not a group of ex-US cable technicians who slovenly misuse dBm to mean dBmV, when the rest of the world uses dBm correctly to mean dB relative to a milliwatt. Jeff Thanks, that looks clear, and fits with other things I read, especially the dBm bit and the 50 nW. One thought: Does the bandwidth match have to be exact? Or is there a case for some reduction on the transmitter to allow more of them to make potentially less local competition between each other when lots are used? Is there some compromise that doesn't afflict the sound too much, while reducing both the occupancy of the spectrum and the need for power for some given reach of distance? (I don't intent using one, but they do interest me strangely...) In an FM transmitter, the amount of deviation is proportional to the amplitude of the modulating signal. That is, the louder the audio, the greater the deviation. Transmitter bandwidth cannot be greater than receiver bandwidth without loss of signal and distortion. Transmitter deviation can be less than receiver bandwidth; this only results in lower audio. This is why commercial FM receivers typically have a bandwidth of 170-180 kHz, when deviation is only 75 kHz. It makes things less critical. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Indoor FM boost with no cables?
Jeff wrote in :
The bandwidth does not have to match exactly, but it it is too much then it will distort as it exceeds the Bandwidth if the IF filters in the receiver, and if it is too low the volume out of the receiver will be low, so you would have to turn up the volume control when you used the device. If it were extremely low then the audio would be very quiet indeed, and if the signal strength were also too low you would loose everything in noise. The nominal max deviation in the FM broadcast band is +/-75kHz (150kHz total). Thanks. It looks like matching is best for compromise then, not some value for transmission lower than reception, because what you gain in RF reach you lose in SNR on output so striving for anything but a good match looks like a game of diminishing returns. |
Indoor FM boost with no cables?
Jerry Stuckle wrote in news:lriogq$kba$1@dont-
email.me: In an FM transmitter, the amount of deviation is proportional to the amplitude of the modulating signal. That is, the louder the audio, the greater the deviation. Transmitter bandwidth cannot be greater than receiver bandwidth without loss of signal and distortion. Transmitter deviation can be less than receiver bandwidth; this only results in lower audio. This is why commercial FM receivers typically have a bandwidth of 170-180 kHz, when deviation is only 75 kHz. It makes things less critical. Ok, so a kind of 'headroom' exists then, but is there some agreeable degree of reduction on transmitter bandwidth to gain a significant reach in RF propagation and reduction in intrusion across the band, before the whole exercise fails due to poor SNR on output? My guess is that there may be, but the decision could be very different depending on whether speech or music (let alone stereo) is wanted. |
Indoor FM boost with no cables?
Jerry Stuckle wrote in news:lrio4f$fs4$1@dont-
email.me: Nope. I'm talking about what is commonly used here. But there are some people from the U.K. who think they are experts on everything. To be fair to him, I'm in the UK and he may well have aimed that point at me, knowing this from the message header or some earlier post of mine. I'm also interesed in how the US conventions differ from ours. |
Indoor FM boost with no cables?
Lostgallifreyan wrote:
Jerry Stuckle wrote in news:lriogq$kba$1@dont- email.me: In an FM transmitter, the amount of deviation is proportional to the amplitude of the modulating signal. That is, the louder the audio, the greater the deviation. Transmitter bandwidth cannot be greater than receiver bandwidth without loss of signal and distortion. Transmitter deviation can be less than receiver bandwidth; this only results in lower audio. This is why commercial FM receivers typically have a bandwidth of 170-180 kHz, when deviation is only 75 kHz. It makes things less critical. Ok, so a kind of 'headroom' exists then, but is there some agreeable degree of reduction on transmitter bandwidth to gain a significant reach in RF propagation and reduction in intrusion across the band, before the whole exercise fails due to poor SNR on output? My guess is that there may be, but the decision could be very different depending on whether speech or music (let alone stereo) is wanted. Deviation is something different than bandwidth. To receive an FM signal, as a rule of thumb you require a receiver with a bandwith of about twice the deviation plus twice the maximal audio frequency. So to receive a signal with 15kHz audio and 75kHz deviation, you require a bandwitdh of about 180kHz. This is not "to make things less critical". It is a requirement because of the characteristics of FM modulation, where sideband frequencies are determined by a Bessel function. The ratio between deviation and maximal audio frequency, the modulation index, determines the signal/noise ratio after demodulation for a strong signal. So for music transmissions on the FM broadcast band a larger modulation index (about 5) is used than for communication (usually 1 or a bit less). That means at typical signal strengths encountered in broadcast use, the signal/noise ratio is better than for small modulation index. (for weak-signal work, where you are looking for an intelligible signal and not for lowest noise, a smaller modulation index performs better because you can use a narrower receiver bandwidth) |
Indoor FM boost with no cables?
Lostgallifreyan wrote:
Jerry Stuckle wrote in news:lrio4f$fs4$1@dont- email.me: Nope. I'm talking about what is commonly used here. But there are some people from the U.K. who think they are experts on everything. To be fair to him, I'm in the UK and he may well have aimed that point at me, knowing this from the message header or some earlier post of mine. I'm also interesed in how the US conventions differ from ours. I think you should be careful not to mistake Jerry's conventions for US conventions. It looks a lot like Jerry makes many assumptions that are not based on signal theory or common practice, but mainly on his own experience as a cable fitter. |
Indoor FM boost with no cables?
On 8/2/2014 4:11 PM, Lostgallifreyan wrote:
Jeff wrote in : The bandwidth does not have to match exactly, but it it is too much then it will distort as it exceeds the Bandwidth if the IF filters in the receiver, and if it is too low the volume out of the receiver will be low, so you would have to turn up the volume control when you used the device. If it were extremely low then the audio would be very quiet indeed, and if the signal strength were also too low you would loose everything in noise. The nominal max deviation in the FM broadcast band is +/-75kHz (150kHz total). Thanks. It looks like matching is best for compromise then, not some value for transmission lower than reception, because what you gain in RF reach you lose in SNR on output so striving for anything but a good match looks like a game of diminishing returns. I probably missed something in this thread, but where are you going to get an FM transmitter that isn't designed to work with FM radios? Mikek |
Indoor FM boost with no cables?
On 8/1/2014 6:32 PM, Lostgallifreyan wrote:
amdx wrote in : PS, I'll bet both of you stations stream on the internet. If you have wifi, that will eliminate your noise problem. I get capped at 10GB per month, and that costs far too much. If I saw the costs of the bandwidth to do this I might scream loud enough that even my neighbours might have a noise problem. :) Besides, good FM totally beats all internet quality. Radio 3's best HD sound falls well short, equivalent to a 192 kbps MP3 at best, from what I have read and heard about it. FM in the UK is extremely good quality, nothing else has been any better yet. Which is probably why obituary after obituary gets written for broadcast FM radio, btu it never dies, the 'swicth-off date' is forver being set back, and it likely won't happen once peoplerealise the costs of allocating bandwidth foe that kind of quality ona per-person basis! That's a mind-stunning financial and technical calculation no matter how we look at it. Ok, high fidelity is not important for what I listen to which is mostly speech. I listen to old time radio programs on Old Time Radio, All Time Radio Oldies Radio Theater, and 20th Century Radio (OTR). I also listen to a lot Science 360 and then other talk radio programs. For those interested this is where you set up the stations for an internet radio. I think you can check the station list (19,000 stations), possible you need to put in your internet radio info to search, I don't know. https://radios.reciva.com/ Mikek |
Indoor FM boost with no cables?
On 8/2/2014 5:53 PM, Rob wrote:
Lostgallifreyan wrote: Jerry Stuckle wrote in news:lrio4f$fs4$1@dont- email.me: Nope. I'm talking about what is commonly used here. But there are some people from the U.K. who think they are experts on everything. To be fair to him, I'm in the UK and he may well have aimed that point at me, knowing this from the message header or some earlier post of mine. I'm also interesed in how the US conventions differ from ours. I think you should be careful not to mistake Jerry's conventions for US conventions. It looks a lot like Jerry makes many assumptions that are not based on signal theory or common practice, but mainly on his own experience as a cable fitter. Cabling is not the only thing I do - nor the only thing I have done in the past. It is just one of the things my company does. But like other trolls, you think you know everything, when you actually know nothing. So much for the anonymous troll who uses a fake email and probably doesn't even have a call sign. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Indoor FM boost with no cables?
Jerry Stuckle wrote:
On 8/2/2014 5:53 PM, Rob wrote: Lostgallifreyan wrote: Jerry Stuckle wrote in news:lrio4f$fs4$1@dont- email.me: Nope. I'm talking about what is commonly used here. But there are some people from the U.K. who think they are experts on everything. To be fair to him, I'm in the UK and he may well have aimed that point at me, knowing this from the message header or some earlier post of mine. I'm also interesed in how the US conventions differ from ours. I think you should be careful not to mistake Jerry's conventions for US conventions. It looks a lot like Jerry makes many assumptions that are not based on signal theory or common practice, but mainly on his own experience as a cable fitter. Cabling is not the only thing I do - nor the only thing I have done in the past. It is just one of the things my company does. But like other trolls, you think you know everything, when you actually know nothing. So much for the anonymous troll who uses a fake email and probably doesn't even have a call sign. I do have a college degree as an electronics engineer, so I do have the theoretical background that you so sorely lack. I have posted for many years under my full name, callsign and e-mail address, but I have chosen to stop doint that. Many know who I am. |
Indoor FM boost with no cables?
On 8/2/2014 7:10 PM, Rob wrote:
Jerry Stuckle wrote: On 8/2/2014 5:53 PM, Rob wrote: Lostgallifreyan wrote: Jerry Stuckle wrote in news:lrio4f$fs4$1@dont- email.me: Nope. I'm talking about what is commonly used here. But there are some people from the U.K. who think they are experts on everything. To be fair to him, I'm in the UK and he may well have aimed that point at me, knowing this from the message header or some earlier post of mine. I'm also interesed in how the US conventions differ from ours. I think you should be careful not to mistake Jerry's conventions for US conventions. It looks a lot like Jerry makes many assumptions that are not based on signal theory or common practice, but mainly on his own experience as a cable fitter. Cabling is not the only thing I do - nor the only thing I have done in the past. It is just one of the things my company does. But like other trolls, you think you know everything, when you actually know nothing. So much for the anonymous troll who uses a fake email and probably doesn't even have a call sign. I do have a college degree as an electronics engineer, so I do have the theoretical background that you so sorely lack. I have posted for many years under my full name, callsign and e-mail address, but I have chosen to stop doint that. Many know who I am. So you claim. But you're just an anonymous troll with no call sign and an invalid email address. As for the degree - IF you ever had one (which I doubt), it was probably mail order from one of the diploma mills. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Indoor FM boost with no cables?
Jerry Stuckle wrote:
On 8/2/2014 7:10 PM, Rob wrote: Jerry Stuckle wrote: On 8/2/2014 5:53 PM, Rob wrote: Lostgallifreyan wrote: Jerry Stuckle wrote in news:lrio4f$fs4$1@dont- email.me: Nope. I'm talking about what is commonly used here. But there are some people from the U.K. who think they are experts on everything. To be fair to him, I'm in the UK and he may well have aimed that point at me, knowing this from the message header or some earlier post of mine. I'm also interesed in how the US conventions differ from ours. I think you should be careful not to mistake Jerry's conventions for US conventions. It looks a lot like Jerry makes many assumptions that are not based on signal theory or common practice, but mainly on his own experience as a cable fitter. Cabling is not the only thing I do - nor the only thing I have done in the past. It is just one of the things my company does. But like other trolls, you think you know everything, when you actually know nothing. So much for the anonymous troll who uses a fake email and probably doesn't even have a call sign. I do have a college degree as an electronics engineer, so I do have the theoretical background that you so sorely lack. I have posted for many years under my full name, callsign and e-mail address, but I have chosen to stop doint that. Many know who I am. So you claim. But you're just an anonymous troll with no call sign and an invalid email address. As for the degree - IF you ever had one (which I doubt), it was probably mail order from one of the diploma mills. I see you have been in that business, so you probably consider that normal. But this is not the US, and those practices are not that common here. (certainly not when I got my degree) |
Indoor FM boost with no cables?
Jerry Stuckle wrote:
On 8/2/2014 5:53 PM, Rob wrote: Lostgallifreyan wrote: Jerry Stuckle wrote in news:lrio4f$fs4$1@dont- email.me: Nope. I'm talking about what is commonly used here. But there are some people from the U.K. who think they are experts on everything. To be fair to him, I'm in the UK and he may well have aimed that point at me, knowing this from the message header or some earlier post of mine. I'm also interesed in how the US conventions differ from ours. I think you should be careful not to mistake Jerry's conventions for US conventions. It looks a lot like Jerry makes many assumptions that are not based on signal theory or common practice, but mainly on his own experience as a cable fitter. Cabling is not the only thing I do - nor the only thing I have done in the past. It is just one of the things my company does. But like other trolls, you think you know everything, when you actually know nothing. So much for the anonymous troll who uses a fake email and probably doesn't even have a call sign. And here he goes off into his usual "stupid troll" rant with yet a person who had the umitigated audacity to imply Jerry Stuckle does not know everything about everything. You ignorant peasants just don't understand; Jerry Stuckle has done everything, knows everything and is NEVER, EVER wrong about anything. To even hint otherwise is blasphemy and you shall be severely reprimanded and totally disparaged as you well deserve. -- Jim Pennino |
Indoor FM boost with no cables?
On 8/2/2014 7:38 PM, Rob wrote:
Jerry Stuckle wrote: On 8/2/2014 7:10 PM, Rob wrote: Jerry Stuckle wrote: On 8/2/2014 5:53 PM, Rob wrote: Lostgallifreyan wrote: Jerry Stuckle wrote in news:lrio4f$fs4$1@dont- email.me: Nope. I'm talking about what is commonly used here. But there are some people from the U.K. who think they are experts on everything. To be fair to him, I'm in the UK and he may well have aimed that point at me, knowing this from the message header or some earlier post of mine. I'm also interesed in how the US conventions differ from ours. I think you should be careful not to mistake Jerry's conventions for US conventions. It looks a lot like Jerry makes many assumptions that are not based on signal theory or common practice, but mainly on his own experience as a cable fitter. Cabling is not the only thing I do - nor the only thing I have done in the past. It is just one of the things my company does. But like other trolls, you think you know everything, when you actually know nothing. So much for the anonymous troll who uses a fake email and probably doesn't even have a call sign. I do have a college degree as an electronics engineer, so I do have the theoretical background that you so sorely lack. I have posted for many years under my full name, callsign and e-mail address, but I have chosen to stop doint that. Many know who I am. So you claim. But you're just an anonymous troll with no call sign and an invalid email address. As for the degree - IF you ever had one (which I doubt), it was probably mail order from one of the diploma mills. I see you have been in that business, so you probably consider that normal. But this is not the US, and those practices are not that common here. (certainly not when I got my degree) Yea, when you got your "degree". Which diploma mill did you get from - the University of Golden Knowledge? Fat chance. If you did have a degree, you would be able to read. You've shown multiple times you cannot. But you are just an anonymous troll who's afraid people will find out he doesn't have ANY of the things he claims. And you're afraid your boss will find out how little you know and fire you from your dishwashing job. Once again you can have the last word. I know trolls have to have it. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Indoor FM boost with no cables?
On 8/2/2014 8:50 PM, Jerry Stuckle wrote:
On 8/2/2014 7:48 PM, wrote: Jerry Stuckle wrote: On 8/2/2014 5:53 PM, Rob wrote: Lostgallifreyan wrote: Jerry Stuckle wrote in news:lrio4f$fs4$1@dont- email.me: Nope. I'm talking about what is commonly used here. But there are some people from the U.K. who think they are experts on everything. To be fair to him, I'm in the UK and he may well have aimed that point at me, knowing this from the message header or some earlier post of mine. I'm also interesed in how the US conventions differ from ours. I think you should be careful not to mistake Jerry's conventions for US conventions. It looks a lot like Jerry makes many assumptions that are not based on signal theory or common practice, but mainly on his own experience as a cable fitter. Cabling is not the only thing I do - nor the only thing I have done in the past. It is just one of the things my company does. But like other trolls, you think you know everything, when you actually know nothing. So much for the anonymous troll who uses a fake email and probably doesn't even have a call sign. And here he goes off into his usual "stupid troll" rant with yet a person who had the umitigated audacity to imply Jerry Stuckle does not know everything about everything. You ignorant peasants just don't understand; Jerry Stuckle has done everything, knows everything and is NEVER, EVER wrong about anything. To even hint otherwise is blasphemy and you shall be severely reprimanded and totally disparaged as you well deserve. And here's one of the other anonymous trolls without a call sign on this newsgroup. If I didn't know some REAL hams in the U.K., I would have a VERY DIM VIEW of the people there. You, "Rob", Gareth and a couple of others - all cut from the same form. But trolls can't stand the truth, can you? Once again, you can have the last word - as trolls need Actually, that statement is unfair - to Gareth. At least he isn't afraid to let people know who he is. So Gareth, I apologize for mixing you in with the anonymous trolls. You're better than that. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Indoor FM boost with no cables?
amdx wrote in :
I probably missed something in this thread, but where are you going to get an FM transmitter that isn't designed to work with FM radios? A CB no-longer-wants-to-be? :) Ok, facetious answer, but there's a point to this, they do exist. For all I know, if the microtransmitters have slightly narrower bandwidth deliberately to reduce encroachment on other signals (wise maybe, given that many of these devices may be built and used), then the loss of SNR and quality for music listening may be acceptable for some, but not to me. I wouldn't use one if they haven't got good quality sound. If intended for use in a car, there's much less likely a demand that they should. |
Indoor FM boost with no cables?
Rob wrote in :
Deviation is something different than bandwidth. To receive an FM signal, as a rule of thumb you require a receiver with a bandwith of about twice the deviation plus twice the maximal audio frequency. So to receive a signal with 15kHz audio and 75kHz deviation, you require a bandwitdh of about 180kHz. This is not "to make things less critical". It is a requirement because of the characteristics of FM modulation, where sideband frequencies are determined by a Bessel function. The ratio between deviation and maximal audio frequency, the modulation index, determines the signal/noise ratio after demodulation for a strong signal. That's useful. It ties in with things I have read about phase modulation synthesis. At risk of opening a wild (but fun) bit of off-topic, I wonder if given a reference carrier at precise fixed frequency, a phase modulation technique might allow advantages to signal transmission that FM lacks. |
Indoor FM boost with no cables?
On 8/2/2014 9:55 PM, Lostgallifreyan wrote:
Rob wrote in : Deviation is something different than bandwidth. To receive an FM signal, as a rule of thumb you require a receiver with a bandwith of about twice the deviation plus twice the maximal audio frequency. So to receive a signal with 15kHz audio and 75kHz deviation, you require a bandwitdh of about 180kHz. This is not "to make things less critical". It is a requirement because of the characteristics of FM modulation, where sideband frequencies are determined by a Bessel function. The ratio between deviation and maximal audio frequency, the modulation index, determines the signal/noise ratio after demodulation for a strong signal. That's useful. It ties in with things I have read about phase modulation synthesis. At risk of opening a wild (but fun) bit of off-topic, I wonder if given a reference carrier at precise fixed frequency, a phase modulation technique might allow advantages to signal transmission that FM lacks. Not really. All phase modulation does is integrate the modulating signal and use that to shift the phase of the carrier (which also requires a frequency change to effect the phase change). The resulting signal is exactly the same as if the carrier were directly frequency modulated. The only difference is how you got there. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Indoor FM boost with no cables?
Jerry Stuckle wrote in
: That's useful. It ties in with things I have read about phase modulation synthesis. At risk of opening a wild (but fun) bit of off-topic, I wonder if given a reference carrier at precise fixed frequency, a phase modulation technique might allow advantages to signal transmission that FM lacks. Not really. All phase modulation does is integrate the modulating signal and use that to shift the phase of the carrier (which also requires a frequency change to effect the phase change). The resulting signal is exactly the same as if the carrier were directly frequency modulated. The only difference is how you got there. Ok. What made me wonder is that I read (in the context of phase modulation for musical audio synthesis) that true FM methods can cause a frequency drift that is avoided completely by using phase modulation. I wondered if that fact might (at some other cost) be useful in signal transmission at RF. |
Indoor FM boost with no cables?
On 8/2/2014 10:52 PM, Lostgallifreyan wrote:
Jerry Stuckle wrote in : That's useful. It ties in with things I have read about phase modulation synthesis. At risk of opening a wild (but fun) bit of off-topic, I wonder if given a reference carrier at precise fixed frequency, a phase modulation technique might allow advantages to signal transmission that FM lacks. Not really. All phase modulation does is integrate the modulating signal and use that to shift the phase of the carrier (which also requires a frequency change to effect the phase change). The resulting signal is exactly the same as if the carrier were directly frequency modulated. The only difference is how you got there. Ok. What made me wonder is that I read (in the context of phase modulation for musical audio synthesis) that true FM methods can cause a frequency drift that is avoided completely by using phase modulation. I wondered if that fact might (at some other cost) be useful in signal transmission at RF. Yes and no... Without knowing the context, I would guess the frequency drift they refer to is caused by a DC bias to the modulator from the incoming signal itself with FM modulation. This would assume the incoming signal is DC coupled, which I would guess it might be in music synthesizers (don't know - never worked with one). Using phase modulation, if there were a DC bias on the signal, it would just old the phase at a constant angle - and since frequency shift is based on the change in the phase angle of the signal (and vice versa, of course), the signal would have zero deviation. It's something I've never encountered in radios, but then you don't normally see radios DC coupling the audio signal to the modulator. But I will admit most of the FM transmitters I've worked with (both commercial FM and VHF/UHF business and ham bands) have been phase modulated. The only time I remember getting deeply into direct FM was back in the early to mid 70's when I was working on a frequency synthesizer of 2 meters (this was back when crystal rigs were still common). It's pretty easy to get FM out of such a circuit since frequency is directly controlled by voltage - all you need to do is feed the modulating signal into the VCO feedback loop. It ended up working pretty well, and I didn't have any problem with frequency drift (but then with a VCO any drift automatically solves itself). -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Indoor FM boost with no cables?
Jerry Stuckle wrote:
On 8/2/2014 8:50 PM, Jerry Stuckle wrote: On 8/2/2014 7:48 PM, wrote: Jerry Stuckle wrote: On 8/2/2014 5:53 PM, Rob wrote: Lostgallifreyan wrote: Jerry Stuckle wrote in news:lrio4f$fs4$1@dont- email.me: Nope. I'm talking about what is commonly used here. But there are some people from the U.K. who think they are experts on everything. To be fair to him, I'm in the UK and he may well have aimed that point at me, knowing this from the message header or some earlier post of mine. I'm also interesed in how the US conventions differ from ours. I think you should be careful not to mistake Jerry's conventions for US conventions. It looks a lot like Jerry makes many assumptions that are not based on signal theory or common practice, but mainly on his own experience as a cable fitter. Cabling is not the only thing I do - nor the only thing I have done in the past. It is just one of the things my company does. But like other trolls, you think you know everything, when you actually know nothing. So much for the anonymous troll who uses a fake email and probably doesn't even have a call sign. And here he goes off into his usual "stupid troll" rant with yet a person who had the umitigated audacity to imply Jerry Stuckle does not know everything about everything. You ignorant peasants just don't understand; Jerry Stuckle has done everything, knows everything and is NEVER, EVER wrong about anything. To even hint otherwise is blasphemy and you shall be severely reprimanded and totally disparaged as you well deserve. And here's one of the other anonymous trolls without a call sign on this newsgroup. If I didn't know some REAL hams in the U.K., I would have a VERY DIM VIEW of the people there. You, "Rob", Gareth and a couple of others - all cut from the same form. But trolls can't stand the truth, can you? Once again, you can have the last word - as trolls need Actually, that statement is unfair - to Gareth. At least he isn't afraid to let people know who he is. So Gareth, I apologize for mixing you in with the anonymous trolls. You're better than that. I beg your pardon, my liege, but it was my understanding I was to have the last word. Obviously I was in error. I was also quite suprised to find I am British, but if your worship says I am British, I must be British as your worship is never wrong. -- Jim Pennino |
Indoor FM boost with no cables?
In message , Jeff writes
Jerry does not seem to take on board that this is an international group, not a group of ex-US cable technicians who slovenly misuse dBm to mean dBmV, when the rest of the world uses dBm correctly to mean dB relative to a milliwatt. I think only a small minority of US cable TV people would misuse dBm when they really mean dBmV. I worked in the industry all my life, 20 years of which were for an American company - and I never found this to be a common practice. -- Ian |
Indoor FM boost with no cables?
On 8/3/2014 5:18 AM, Jeff wrote:
And here's one of the other anonymous trolls without a call sign on this newsgroup. If I didn't know some REAL hams in the U.K., I would have a VERY DIM VIEW of the people there. You, "Rob", Gareth and a couple of others - all cut from the same form. But trolls can't stand the truth, can you? Once again, you can have the last word - as trolls need I do find that rant very amusing; particularly that fact that Jerry misses completely how similar he and Gareth are!! As soon as they are challenged on a subject, rather than carry on a sane argument they both resort first to impugning someone's knowledge and qualifications (without any grounds or knowledge of the person) and then to name calling. It is a startling resemblance. Jeff No, it's just calling unsubstantiated claims by anonymous trolls what they are - pure bull manure! Especially when they repeatedly show a complete lack of the knowledge they claim they should have. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
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