howto:hambasics:temp
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howto:hambasics:temp [2019/11/25 18:25] – [Amplitude, Wavelength, Period, and Frequency] ve7hzf | howto:hambasics:temp [2019/11/25 18:31] – [Old] ve7hzf | ||
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- | Look at the following two waves. | ||
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- | {{wave1.png? | ||
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- | At first sight: | ||
- | - the first one is " | ||
- | - the first one is also " | ||
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- | These two observations can be quantified very precisely as: | ||
- | - the // | ||
- | - the //period//: **horizontal** length of one complete cycle. | ||
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- | {{ wave3.png | ||
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- | So the previous two waves have: | ||
- | - Amplitude = 2, Period = 0.05 ms | ||
- | - Amplitude = 1, Period = 0.02 ms | ||
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- | {{wave1.png? | ||
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- | The amplitude is normally related to the strength of the signal (like the volume for sound). | ||
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- | Since the period (//T//) is the amount of time it takes to complete one cycle, and the frequency (//f//) is the number of cycles in one second, the period and the frequency are inverses of each other: | ||
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- | < | ||
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- | <box 80% blue> | ||
- | In this course, we'll see a few formulas and it'll be tempting to memorize them but let's instead understand what they really mean... | ||
- | </ | ||
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- | For example: | ||
- | * if the period is half a second, we can fit 2 full cycles in one second. | ||
- | * If the period is a quarter of a second, the frequency is 4. | ||
- | * If the period is a tenth of a second, the frequency is 10. | ||
- | * If the period is T seconds, the frequency is $\frac{1}{T}$ ( $\frac{1}{0.5} = 2, \quad \frac{1}{0.25} = 4, \quad \frac{1}{0.1} = 10$ ) | ||
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- | Right? | ||
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- | So for the previous two waves, the frequencies would be: | ||
- | * < | ||
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- | * < | ||
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- | Recall that //Hz// means "cycle per seconds" | ||
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- | Let's now look at three different ways to encode a signal on a radio wave. | ||
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- | FIXME: add $f=\frac{c}{\lambda}$ | ||