Yes and yes. A hardware signal generator will have bandwidth well beyond the audio range. The waveform has not been sampled.
Ed
And I was the guy who, sorry to say when you did all the hard work!, that took advantage of available functionality like "IEEE 802.3ad" in easily managed via web interface (or laptop directly connected to) switches where I would run FOUR gigabit lines between them and servers and even some servers to the switch and then to workstations (some users did work with quite large files even back then and me at home especially with the 'side business' using huge databases, full compact discs in just one ISO file (650MB+), and then HDTV sports events to edit video files 20GB and larger). You did awesome for people like me who just followed the instructions in the Cisco book. Like I said earlier in this thread, I wish I had learned much more electrical engineering. I will try. 🙂
Read the Wikipedia article entitled Rise Time. You'll enjoy their derivation of the formula (Bandwidth x Risetime) = Constant.
Since a circuit which produces an "electrically TRUE square wave" is required to have a risetime of zero femtoseconds (in order to be perfect), it must also have a bandwidth of infinity. Which is not possible currently with the devices we have available.
_
Since a circuit which produces an "electrically TRUE square wave" is required to have a risetime of zero femtoseconds (in order to be perfect), it must also have a bandwidth of infinity. Which is not possible currently with the devices we have available.
_
Attachments
I remember the later 90's when the bands that made actually great music would somehow be convinced to 'loudness brickwall' their final product. The dynamic range was then down to around 3 to 6dBfs then. It was horrible. One of my best examples is Radiohead's "OK Computer". They brickwalled that one to the point of distortion and gave away all of the dynamic range. I'm hoping that a company like MFSL (Mobile Fidelity Sound Labs) gets that master tape and remasters it properly. That outfit has done a great job with other works released on CD some or many years ago and cleaned the sound up.
As for those who complain about the opposite, too much dynamic range, and especially with classical music that starts out quiet but then builds to a thunderous crashing, I tell them to get more powerful amplifiers and better speakers. And, as far as I know, the rule of thumb still is to provide a level of continuous amplifier wattage that is greater than what the speakers (quality ones) are rated for to eliminate electrical clipping and only have to worry about mechanical clipping.
I will do so. That is again exactly along the lines of what I was trying to explain to my friend. But, discussing 'zero femtoseconds' and an 'infinite bandwidth' wouldn't have gone well. (grin)
In the late 1990's Dutch fire brigades, police and ambulances went from using narrowband FM to a digital system, C2000, because the government had decided so. It was a complete disaster: previously, when the reception was poor, the signal to noise ratio was below spec, but they could still understand each other. With the digital system, they would all of a sudden lose contact. Some fire brigades temporarily went back to narrowband FM. Nowadays the C2000 base stations have huge masts for the aerials to get acceptable coverage.
I would also add that a square wave with zero rise time would be "dirty" (i.e. rich in harmonics) to the point that there could be EMC issues with nearby electronics such as receivers and other sensitive components.
Some systems implement slew rate limiting for that very purpose.
Some systems implement slew rate limiting for that very purpose.
Perfect Circle. My 40 watts continuous/channel can't play them very loud.
A partial solution is to use a steep slope high pass filter @20 Hz. Their mixes contain a whole lot of subsonic trash. I imagine DSP could address this issue.
I created "perfect" square wave signal on CD artifically, by editing 0s and 1s into an 1 kHz pattern .wav and converting ot to audio CD format. By playing it back, you get a square wave limited by the analog part of the CD-player. But I understand that even the DAC has its own rise/fall time limits. Anyway, it is good enough for test purposes, because it does not contain the limitations of the recording chain.
That's also the reason why digital wireless communication systems don't use square waves. They have to occupy no more bandwidth than necessary, so they use modulated sine waves with filtered modulating signals.
lcsaszar - That results in aliasing. To avoid aliasing, you have to sum the harmonics only up to fs/2. The resulting waveform is intentionally bandwidth-limited.
If you need real square waves, get a hardware generator.
Ed
If you need real square waves, get a hardware generator.
Ed
FYI, you should not be sharing photoshopped images without at least a warning of substantial editing.
This is the original https://i.kym-cdn.com/entries/icons/original/000/001/296/morans.jpg
Yes. The resulting squarewave in the analog domain contains harmonics way beyond the sampling frequency. That is intentional in my case.
I'd say that neither of you were discussing the same thing and talking at cross purposes!
The friend was saying that digital signals are transmitted with square waves and that's how the 1s and 0s are perfectly received.
Then you replied that you can't make perfect square waves in real life.
Whilst you may be correct in that, that wasn't what you said your friend was getting at, you just happened to pick up on one single aspect of his claim ... which really wasn't the point of it (as is being relayed to us at least).
Even if a square wave were to be the method of transmission, the threashold of conditions needed to switch states is where the accuracy of transmission would be key. The squareness of the wave, the rise time etc, would then only determine the timing of these state changes, a buffer and re-clocking will overcome that.
So - your friend's understanding of digital signal transmission is wrong, but his round-about assertion that the outcome of even a square wave transmission can be perfect, in the sense that the states will switch perfectly in relation to those changes in the signal is correct in theory .... but not becuase the square wave is perfect. At which point, arguing about the possibility of perfect square waves existing is a change of topic.
And then there's probably a lot reasons why square waves are not used to transmit digital signals anyway... so it's all moot.
That's a daft thing to assert. It's not a point of information you're putting across, it's nothing more than an opinion.
If it's the photoshopping that contains the meaningful message then it's there for a reason and is the point being made.
You're kind of daftly saying that people should give an exhaustive history and origin of a photo whenever they use a meme... Do you know how memes come about and are used? They deliberately do not reference original sources of images - that is their point.
You should instead just be saying that you don't like the message that it's perveying and want it known that that message has been created by someone from another photo..
Of course, "should" or "should not" means nothing - I don't have any influence over you, nor you the previous poster - again, it's only an expression of my feelings, not an instruction.
U.S. Navy tech’s course introducing Fiber Optics.
http://www.compatt.com/Tutorials/NEETS/New_PDF/14196A.pdf
I had no idea.
The original picture is no more flattering to stupid Muricans. The stupid is quite close to home for me. As much as I try to get along with people, as an Official Smarty Pants I can't help but out blatant ignorance, and it's not always popular.
I often wonder if I had been born 20 years later whether or not I would have been one of those that slipped on their own slobber. I was inculcated with a strong work ethic and great value for education. I was taught that I could rise above my roots with education, integrity, hard work, and perseverance. And I did. Believe it or not, these used to be bona fide American values.
Sorry if you guys don't like it, but it pains me greatly to see my once great country becoming a shallow parody of its former self. I owe it to my father, who fought in WWII and would be devastated if he saw what's left of the country today.