[ShadowOfGed]

Originally Posted by DaveGee When you broadcast you do so in RADIO WAVES yes junior even TV is broadcast via radio waves. A wave (by its very definition) travels from one frequency to ANOTHER. You saying 802.11A runs at 5.00GHz is just stupid and shows how little you know when it comes to radio. If something did communicate at 5.00GHz it wouldn't be a **wave** I WOULD BE A FLAT LINE!!!!!!!! … bizarre world where radio signals are NOT waves but single values and straight lines

Ok, smartypants.

From now on, for every reference you make to a frequency band, you are REQUIRED to list the range in full. In writing, in speech, or any other medium. Simply saying "5.0GHz" is clearly not enough for you, so every time you talk about your 2.4GHz phone, you'll instead have to say "2.400GHz - 2.417GHz." No exceptions.

Oh, not up to the challenge? Didn't think so. It would be absolutely ridiculous to expect everyone to always reference common frequency bands by listing both the upper and lower bounds. Thus, it has become common in technological venues to reference common bands by a frequency close to their range. We know these as 2.4GHz and 5.8GHz. These references are typically understood to mean "the band around 2.4GHz" or "the band around 5.8GHz," but clearly that is not sufficient for the likes of you.

Also, I assume you're not an engineer. Or, if you are, I will not buy anything you're making. Some simple terminology: a frequency is just that—a single fixed frequency. Congratulations, you've got that down pat. I see here, however, that you've had trouble upgrading to the more advanced vocabulary we have to offer.

Your definition of "wave" is incorrect. A wave is any signal that traverses space. We have gravity waves, electromagnetic waves, compression waves, and more. Sure, a wave typically oscillates, but it doesn't have to. Let's go to someone who knows what a wave is, like the Oxford Dictionary. A wave is "… (5) a periodic disturbance of the particles of a substance which is propagated without net movement of the particles, as in the passage of undulating motion or sound, or (6) a similar variation of an electromagnetic field in the propagation of light or other radiation." Note that these definitions make no reference to the need for a range (band) of frequencies, because a fixed-frequency wave is still a wave.

What you were calling waves, you really meant to call frequency bands. A band is any range of frequencies. Please note that the IEEE references "the 5GHz band," which could very well include 5.8GHz if they mean "5-6GHz band."

Thus, that means that neither chucker nor the IEEE are "incorrect;" their specification of "5GHz band" was merely misinterpreted by you. Perhaps should be a little more flexible and a little more forgiving of mistakes, and maybe then you would have realized it was merely a difference in specificity. You only needed to say that 5.8GHz is a more *accurate* specification of the band used by 802.11a. Had you done it civilly, and in that manner, I wouldn't feel compelled to smack down your post.

And yes, you're right, it does appear that 802.11a uses 5.8GHz. Look, that took me 11 whole words. You could have said it without being an asshat and making a fool of yourself. You won the battle but lost reputation. I hope it was worth it.

Originally Posted by DaveGee Hell, I'm done here...

Yep, because 'tudes like that aren't welcome.



And now to what I really wanted to say after this thread was so rudely derailed:

I was at WWDC on Monday and saw the 5.8GHz network show up on my coworker's MacBook. It's not a fake screenshot, but it did leave me wondering what they (will?) ship that supports it…

[ShadowOfGed]

Originally Posted by DaveGee Now I've wasted way WAY too much time on your stupidly and pigheaded attitude.

And I've wasted even more reading your inflammatory posts. Consider a more civil tone next time. People are generally more receptive. You'd be amazed how it works.



EDIT: Yeah, I know I'm the pot calling the kettle black… seemed necessary to make my point.

[chucker]

Originally Posted by ShadowOfGed I was at WWDC on Monday and saw the 5.8GHz network show up on my coworker's MacBook. It's not a fake screenshot, but it did leave me wondering what they (will?) ship that supports it…

WMU already posted a link to TS's article on this matter.

(FWIW, I was rather rude in some posts as well, and for that I apologize.)

[Engine Joe]

Originally Posted by ShadowOfGed And I've wasted even more reading your inflammatory posts. Consider a more civil tone next time. People are generally more receptive. You'd be amazed how it works.

QFT.

What's with the attitude?

[ShadowOfGed]

Originally Posted by DaveGee A wave (by its very definition) travels from one frequency to ANOTHER.

So, I was taking a look at this once more, and this statement jumped out at me.

Not only is it wrong, it's physically impossible.



When a signal is emitted into free space, its frequency is fixed. Period. In space, it will always remain the same. A signal, of its own free will, cannot travel "from one frequency to another." Powered, non-linear devices can receive the signal and do frequency shifts and other frequency-modifying tasks, but no linear system can. That is, to modify a signal's frequency, you must have devices like diodes and transistors (or even tubes).

I hate to break it to you, but free space (and most of the universe) are linear systems. It is mathematically provable that the output of a strictly linear system will have precisely the same frequency composition as its input. Your computer, television, and wireless devices are all non-linear systems. So yes, they can move signals from one band to another. For example, your phone uses its battery to power the non-linear system that takes signals in the voice band (0-4kHz) and shifts them up to the 2.4GHz band for transmission. The base station then does the reverse, and sends the signal across the wire.

However, once on the wire, or in free space, those frequencies cannot change until some other device receives the signal and does its own processing. Get your facts straight, or know your terminology better. I don't know which is the case, but your above statement, at face value, is blatantly incorrect.

If you're not an expert, don't act like one. You'll get burned by someone who is.

Are you an electrical engineer?

Originally Posted by Mark Twain It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so.

QED.

[CoolToddHunter]

Originally Posted by ShadowOfGed We have gravity waves...

Has this been proven? Am I behind the times? [/thread derailment]

[Doxxic]

Originally Posted by ShadowOfGed So, I was taking a look at this once more, and this statement jumped out at me. Not only is it wrong, it's physically impossible. When a signal is emitted into free space, its frequency is fixed. Period. In space, it will always remain the same. A signal, of its own free will, cannot travel "from one frequency to another." Powered, non-linear devices can receive the signal and do frequency shifts and other frequency-modifying tasks, but no linear system can. That is, to modify a signal's frequency, you must have devices like diodes and transistors (or even tubes). I hate to break it to you, but free space (and most of the universe) are linear systems. It is mathematically provable that the output of a strictly linear system will have precisely the same frequency composition as its input. Your computer, television, and wireless devices are all non-linear systems. So yes, they can move signals from one band to another. For example, your phone uses its battery to power the non-linear system that takes signals in the voice band (0-4kHz) and shifts them up to the 2.4GHz band for transmission. The base station then does the reverse, and sends the signal across the wire. However, once on the wire, or in free space, those frequencies cannot change until some other device receives the signal and does its own processing. Get your facts straight, or know your terminology better. I don't know which is the case, but your above statement, at face value, is blatantly incorrect. If you're not an expert, don't act like one. You'll get burned by someone who is. Are you an electrical engineer? QED.

Watch your tone, SOG. Although it's not true that all waves change frequencies by definition, their freqency doesn't have to remain the same either. Just look at a picture of most audio samples and see how the frequency varies over time.

Moreover, FM signal carrier waves do have varying frequencies by definition (if there's data being transmitted), and that's the kind of waves DaveGee refers to.

FM signal carrier waves carry information by changing the frequency slightly over time according to the displacement in the original signal. This change in signal frequency is translated to a change in signal amplitude again by the receiver.
For one reason or another, this is very efficient... Don't know why - I'm not an expert!

[ShadowOfGed]

Originally Posted by Doxxic Watch your tone, SOG.

Yeah, I was a bit crass. Pot calling the kettle black and all that… I know.

Thanks for toning it down; I was getting a bit out-of-hand.

Originally Posted by Doxxic Although it's not true that all waves change frequencies by definition, their freqency doesn't have to remain the same either. Just look at a picture of most audio samples and see how the frequency varies over time.

Right, but that's because the frequency composition of the signal is being varied at the source.

If you decompose an output signal at any instant in time, and watch that portion of the signal propagate through space, it will ALWAYS have the same composition. Even when traveling through different media, the wavelength will change, but the frequency will not.

Originally Posted by Doxxic Moreover, FM signal carrier waves do have varying frequencies by definition (if there's data being transmitted), and that's the kind of waves DaveGee refers to.

Yep, I'm quite aware. But the need for a frequency band is defined by the FM radio specifications and design. An FM signal's frequency does vary with time, but that's because the source is changing the frequency composition of its output, not because the emitted wave's frequencies change as they travels through free space.

Obviously, if a transmitter could never alter the frequency of its output, we wouldn't have most of the electronic devices we have today. But my point was only that in order to alter frequency, you need some sort of powered device. His definition reads as if a fixed-frequency signal emitted into free space would requisitely shift to another frequency by the time it is received.

Originally Posted by Doxxic FM signal carrier waves carry information by changing the frequency slightly over time according to the displacement in the original signal. This change in signal frequency is translated to a change in signal amplitude again by the receiver. For one reason or another, this is very efficient... Don't know why - I'm not an expert!

If you've ever used an AM radio, you'll notice that it can easily succumb to interference from a myriad of things—power lines, lightning, tunnels, etc. That's because AM radio depends on the actual amplitude of the source signal. So when lightning strikes, it causes the amplitude of signals to be varied unpredictably, which we then hear as static. When you drive into a tunnel, the tunnel itself limits the amplitude of the signal, which is why your AM radio will get quiet in the tunnel.

FM radio is not prone to these maladies. As you said, it emits a very strong signal at a frequency that is dependent on the amplitude of its input signal. Thus, receivers can recreate the original audio merely by looking at the frequency composition of the input signal. FM, by design, is immune to amplitude spikes—even if the amplitude of all frequencies goes up momentarily, the strongest frequency in a band doesn't change. This is why FM is more desirable, despite being a bit more complex.

Disclaimer: this is how they have been explained to me in the past. If anything is incorrect, I apologize. I'm not an expert either, but I'd hope that my ongoing education in EE helps… I keep learning new stuff every time I go back, fancy that.

[Doxxic]

Originally Posted by ShadowOfGed His definition reads as if a fixed-frequency signal emitted into free space would requisitely shift to another frequency by the time it is received.

I too thought the guy was crazy when I read that, and even more when I read the part about 5.0 MHz --> 5.0 MHz = no wave.

But then, I figured he must have some basic mental capabilities (convinced Chucker) and probably only misformulated his statement about waves changing freqs by definition. So in the end, I don't think that part really deserves this amount of attention.

Anyway, you seem quite smart as well!

[ShadowOfGed]

Originally Posted by Doxxic But then, I figured he must have some basic mental capabilities (convinced Chucker) and probably only misformulated his statement about waves changing freqs by definition.

Hence I said "his definition reads like" instead of "he believes." I see your point, though. Perhaps Undoubtedly I was overly harsh… I guess that's how I get sometimes.

Anyhow, the flames have died down, so back on topic: Apple's website now says that the Mac Pro sports 802.11a/b/g, but that Apple only supports 802.11b/g.

[Dorian Gray]

Originally Posted by Doxxic FM signal carrier waves carry information by changing the frequency slightly over time according to the displacement in the original signal. This change in signal frequency is translated to a change in signal amplitude again by the receiver. For one reason or another, this is very efficient... Don't know why

Frequency-modulated waves propagate with a lot of resilience because the frequency doesn't change no matter how much electromagnetic radiation (e.g. weather effects) is bouncing around. Space-time has a certain stubbornness like that. The amplitude can vary all over the shop by external effects but because the amplitude doesn't carry any information that doesn't matter. (DaveGee's assertion that a wave "by its very definition" changes frequency is of course wrong. A 5 GHz wave is not a flat line, but a sinusoidal curve.) Amplitude-modulated waves on the other hand are subject to loss of information when the amplitude is disturbed, because AM signals use the amplitude of the wave to carry information.

I'm not sure "efficient" is the best word to describe FM transmission: it uses a lot of spectrum per channel because of the frequency modulation, and it requires high frequencies due to the nature of the information typically being transmitted (i.e. speech). These high frequencies practically reduce the range to line-of-sight distances and therefore FM transmission requires a large number of transmitters and a lot of electrical power to reach a wide geographical area. Instead, I would call FM transmission "reliable". That's its true forte.