Bandwidth is a gateway drug. It leads to other drugs such as Everything2 and porn. At first, when you have a slow connection, say a dialup, you can't really be exposed to major online addictions, but once your bandwidth increases, you see how other addictions come to light. They don't seem that harmful at first, but look what broadband has done to some of these noders.

It is a popular misconception that what internet users crave above all else is bandwidth. This is not true; low latency is also very important! You will never surpass the bandwidth of having a UPS truck packed with CD-ROMs drive across town and drop them all at your house. But the latency is not so good.

Bandwidth can also be defined as the frequency difference between two arbitrary attenuation values.

For example: The 3 dB bandwidth of my audio amplifier is 20 kHz. Translation: The difference between the highest and lowest frequency of interest that is 3 dB (half power) is 20 kHz. 3 dB is how far down from maximum (or whatever you choose) that you allow for the signal to be acceptable to you. If the low frequency is 30 Hz then the upper 3 dB frequency is 20,030 Hz.

You can specify whatever attenuation factor you want for your system but generally an unmarked bandwidth will assume 3 dB.

This definition also holds true for EM waves.
I hear a lot about companies getting the rights to certain bandwidths, so that they can in turn sell it to other providers, since bandwidth is something apparently everyone is going to need at some point, whether it's for a connection for a computer or a phone. For someone ignorant of all things bandwidth, this idea seems to me like trying to buy the rights of the moon's gravitational pull. I mean, it's air, charged with different levels of electrical and cell power but still, it's just air. Now our air has become a market, a place to monopolize. I mean, how many natural resources do we have left? Is there a monopoly on polar ice? Well, I guess we want the ice to stay where it is. Never mind.

I only wish bandwidths were visible to the naked eye. I would like to be able to look up in the sky and see bands in the various stratospheres, perhaps color coded to whatever corporation owns them. Nokia, Sprint, Acme, Intel. What have you. Wouldn't that be like seeing the Matrix, or what? But then, if we could see them, maybe we'd be disgruntled as to how little of our small world is free anymore. It would become the true glass ceiling, the snow globe effect we only want to reserve for the photographs of the Earth taken from the safe distance of outer space.

Earlier this week, I saw, on a friend's email forward, a photograph of the Earth at night. All those lights sprinkled like jimmies on an ice cream sundae. Even in my ignorance of geography and without the aid of the color codes of atlases, I would point like a child witnessing fireworks for the first time. Ooh, that must be Russia. That's Africa, and that, I point to the United States, is us. All of us. Ooh ahh.

In a general sense, this term describes information-carrying capacity. It can apply to telephone or network wiring as well as system buses, radio frequency signals, and monitors. On a more human level, the term can describe a person's capacity for dealing with multiple projects ("I'd like to update this database, but I don't have the bandwidth.").

Bandwidth is most accurately measured in cycles per second, or hertz (Hz), which is the difference between the lowest and highest frequencies transmitted. But it's also common to use bits or bytes per second.

banana problem = B = bang

bandwidth n.

1. [common] Used by hackers (in a generalization of its technical meaning) as the volume of information per unit time that a computer, person, or transmission medium can handle. "Those are amazing graphics, but I missed some of the detail -- not enough bandwidth, I guess." Compare low-bandwidth; see also brainwidth. This generalized usage began to go mainstream after the Internet population explosion of 1993-1994. 2. Attention span. 3. On Usenet, a measure of network capacity that is often wasted by people complaining about how items posted by others are a waste of bandwidth.

--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.

The following are some formulae to calculate the required bandwidth for many kinds of common modulation techniques:

  • Amplitude Modulation: 2 * Signal Frequency
  • Single Sideband Modulation: 1 * Signal Frequency
  • Vestigial Sideband Modulation: 1.20 to 1.30 * Signal Frequency
  • Narrowband Frequency Modulation: 2 * Signal Frequency
  • Wideband Frequency Modulation: 2 * Modulation Ratio * Signal Frequency
  • Pulse Amplitude Modulation: 0.5 * Pulse Frequency
  • From this, it can be seen that pulse amplitude modulation is the most bandwidth efficient. However, it cannot carry analog data. Single sideband modulation is the most bandwidth efficient for analog data, and wideband frequency modulation is the least. Even though it uses a lot of bandwidth, wideband frequency modulation has superior noise resistance, making it a good choice for some applications.

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