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#31
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Telamon wrote:
In article .com, Denny wrote: Snip plonk Anyone who would do that deserves a Bigger SNIP and a Monster PLONK tom K0TAR |
#32
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Telamon wrote:
In article .com, Denny wrote: Snip plonk Do you only post here to plonk people? I guess that could be fun.... ;^) - 73 de Mike KB3EIa - |
#33
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#34
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On Jun 21, 1:08 pm, Michael Coslo wrote:
Telamon wrote: In article .com, Denny wrote: Snip plonk Do you only post here to plonk people? I guess that could be fun.... ;^) - 73 de Mike KB3EIa - Thats about it. Don't mind him. He was abused as a child. He's plonked me twice in the last 5 years or so, and I'm sure this post will bring me up to three.. Which begs the answer... If I was plonked before, how can I be replonked, unless I was unplonked.. I noticed he had to plonk Denny twice.. I guess his plonking device is about as effective as viagra on a 98 year old.. I call him Telaprick... And yes, he has worked hard in the past to deserve the new name I have bestowed upon him. I quit posting to the shortwave group about a year ago, cuz I got tired of dealing with a couple of brain dead morons that think they own the whole show over there. And if you post anything that is even slightly technical, they will whine and complain that it's too much for the average shortwave listener to handle, or comprehend. So I decided, $%&* em if they can't take a joke. The only thing that goes "plonk" around here are the turds that fall into the toilet each morning after I've had my first cup of go juice. Only a whiny bitchette would go around constantly "plonking" people. It adds more clutter than the posts he is plonking.. MK |
#35
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In article ,
Michael Coslo wrote: Telamon wrote: In article .com, Denny wrote: Snip plonk Do you only post here to plonk people? I guess that could be fun.... ;^) Nope. I just figure that if a person will entertain a Troll then they are not worth reading. Plonk -- Telamon Ventura, California |
#36
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In article ,
Tom Ring wrote: Telamon wrote: In article .com, Denny wrote: Snip plonk Anyone who would do that deserves a Bigger SNIP and a Monster PLONK Good for you. Plonk -- Telamon Ventura, California |
#37
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On Jun 20, 1:01 pm, (Mark Zenier) wrote:
In article . com, Radium wrote: On Jun 18, 11:05 am, (Mark Zenier) wrote: 1. What is the energy of a photon at 150 kHz? 6.2 X 10^-10 eV You didn't answer the other questions. How much power does a good radio need to get a listenable signal? Here's some numbers input impedance 50 ohms Noise Figure 5 db Bandwidth 6 kHz signal to noise ratio 40 dB (This would be what some of the newsgroups listeners here would want if they had one of their pretty damn good radios listening to a broadcast station. Really picky ones would probably want a 8-15 kHz bandwidth with a 60 dB s/N ratio). There are equations out there that will give you how much power you need for this signal... I guess the dynamic range needs to be at least 140 dB [to match human ear's loudness perception] and bandwidth at least 40 KHz [to match human's pitch perception]. I am not sure about the input impedance or noise figure. |
#38
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In article .com,
Radium wrote: On Jun 20, 1:01 pm, (Mark Zenier) wrote: In article . com, Radium wrote: On Jun 18, 11:05 am, (Mark Zenier) wrote: 1. What is the energy of a photon at 150 kHz? 6.2 X 10^-10 eV You didn't answer the other questions. How much power does a good radio need to get a listenable signal? Here's some numbers input impedance 50 ohms Noise Figure 5 db Bandwidth 6 kHz signal to noise ratio 40 dB (This would be what some of the newsgroups listeners here would want if they had one of their pretty damn good radios listening to a broadcast station. Really picky ones would probably want a 8-15 kHz bandwidth with a 60 dB s/N ratio). There are equations out there that will give you how much power you need for this signal... I guess the dynamic range needs to be at least 140 dB [to match human ear's loudness perception] and bandwidth at least 40 KHz [to match human's pitch perception]. I am not sure about the input impedance or noise figure. We're not talking about human perceptions, we're talking about a radio. Anyway, how much power does a radio signal to need to be picked up? To start with, there is electronics noise. This comes from temperature of the circuit, and how wide the frequency response. The equation is kTB, where k is Boltzmann's Constant, T it the absolute temperature in Kelvin, and B is the bandwidth in Hertz. This is called the thermal noise power. Next, there's a fudge factor, called either the Noise Factor or the same thing stated in decibels, the Noise Figure. It's determined by the quality of the transistors (or other active amplifying element) and the topology of the circuit. It specifies how much more noise is added in the circuit. The best way to get it is to measure it. (5db, about a factor of 3, would be for a pretty good shortwave radio). Multiply thermal noise power by the noise factor, and you find the "noise floor", or "minimum detectable signal" for a circuit. But that doesn't do you much good, because all you can do with that is, maybe, tell if there is a signal there, or perhaps not. So you need more power in the signal to overcome the noise. For reasonable audio, a factor of 10,000 for power is in the ball park. (This is usually expressed as decibels, ie. 40 dB). So here's a cut and paste from a unix program that does calulations with stated dimensions, along with some comments. [mzenier@localhost mzenier]$ units --verbose 1948 units, 71 prefixes, 28 functions You have: boltzmann * 290 kelvin * 6 kilohertz * 3 * 10000 Boltzmann's constant * room temperature * bandwidth * Noise Factor * 40 dB You want: watts boltzmann * 290 kelvin * 6 kilohertz * 3 * 10000 = 7.2069944e-13 watts This is how much power is needed to receive the signal with a signal to noise ratio of 40 dB in a shortwave radio. You have: 150 kilohertz h frequency * Planck's Constant You want: joules 150 kilohertz h = 9.9391031e-29 joules Energy per photon at 150 kHz You have: (boltzmann * 290 kelvin * 6 kilohertz * 3 * 10000)/(150 kilohertz h) You want: hertz (boltzmann * 290 kelvin * 6 kilohertz * 3 * 10000)/(150 kilohertz h) = 7.2511517e+15 hertz Divide the power needed by the energy in each photon, and you get the number of Photons per second at 150 kHz to give a 40 dB signal to noise ratio in a pretty good quality receiver with a 6 kilohertz bandwidth. 7.2511517e+15 is a lot more than 20,000. (And a good demonstration why they don't use the math for quantum physics for radio frequency calculations.) Mark Zenier Googleproofaddress(account:mzenier provider:eskimo domain:com) |
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