Binary the way micros count
A complete cure for electrical noise
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- Thermal noise
- Partition noise
| A complete cure for electrical noise
Sorry, just dreaming. There isn’t one. The small particle-like compo- nents of electricity, called electrons, vibrate in a random fashion powered by the surrounding heat energy. In conductors, electrons are very mobile and carry a type of electrical charge that we have termed negative. The resulting negative charge is balanced out by an equal number of fixed particles called protons, which carry a positive charge (see Figure 5). The overall effect of the electron mobility is similar to the random surges that occur in a large crowd of people jostling around waiting to enter the stadium for the Big Match. If, at a particular time, there happens to be more electrons or negative charges moving towards the Figure 5
Equal charges result in no overall voltage Figure 6
A random voltage has been generated left-hand end of a piece of material then that end would become more negative, as shown in Figure 6. A moment later, the opposite result may occur and the end would become more positive (Figure 7). These effects give rise to small random voltages in any conductor, as we have seen. Figure 7
The opposite effect is equally likely Binary - the way micros count Thermal noise The higher the temperature, the more mobile the electrons, the greater the random voltages and the more electrical noise is present. A solution: High temperature = high noise so: Low temperature = low noise. Put the whole system into a very cold environment by dropping it in
Let’s return to the Big Match. Two doors finally open and the fans pour through the turnstiles. Now we may expect an equal number of people to pass through the two entrances as shown in Figure 8 but in reality this will not happen. Someone will have trouble finding their ticket; friends will wait for each other; cash will be offered instead of a ticket; someone will try to get back out through the gate to reach another section of the stadium. As we can imagine, the streams of people may be equal over an hour but second by second random fluctuations will occur. Electrons don’t lose their tickets but random effects like temperature, voltage and interactions between adjacent electrons have a very similar effect. Figure 8 The fans enter the stadium A single current of, say, 1 A can be split into two currents of 0.5 A when measured over the long-term, but when examined carefully, each will contain random fluctuations. This type of electrical noise is called partition noise or partition effect. The overall effect is similar to the thermal noise and, between them, would cause too much noise and hence would rule out the use of a 10-digit system. Download 115.46 Kb. Share with your friends:
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