new ccna 200-301 cost

new ccna 200-301 cost.From earlier in this chapter, you have learned that amplitude enables waves to travel farther. This is an advantage because you are able to cover a wider range, and for wireless deployments, it means eliminating or reducing the amplitude of the wave with fewer APOs, effectively reducing the distance the wave can travel. The factor that affects wireless transmission by reducing the amplitude is called absorption ( absorption).One result of absorption is the generation of heat. When an object absorbs a wave, it generates heat regardless of what kind of wave it absorbs. A good example of this is a microwave oven. The wave produced by the microwave oven is absorbed by the food and as a result heats the food. The problem you may run into is that if a wave is completely absorbed, the wave stops. While this effect reduces the distance the wave can travel, it does not change the wavelength or frequency of that wave. Neither of these two values change when the wave is absorbed.What are the possible sources of absorption you may ask. Walls, the human body and carpets are all capable of absorbing signals. Using sound as an example, if you have some really loud neighbors who are having a barbecue outside your bedroom window, how do you dampen those sounds? You can hang a blanket over the window or block the window with a board. These same things that absorb sound waves also absorb data waves.How does this affect your wireless deployment? Take a look at Figure 3-2, where you can see an office that has just been leased and is ready to move in. After a brief site survey, it was determined that placing 4 APs would provide sufficient coverage. But you didn't take into account the effects of absorption. Of course there is nothing in the room that would cause this problem.Now look at Figure 3-3, which shows the same office but with furniture, wall cabinets, and other items moved in. Note that with all this furniture, wall cabinets, and other objects, the signal will be absorbed and the 4 APs initially considered adequate will therefore not provide proper coverage. This is an example of absorption.3. Understanding ReflectionAlthough the absorption bow I causes some problems, it is not the only obstacle you will encounter that affects wireless deployment. Another obstacle is reflection, which occurs when a signal bounces off of an object and travels in a different direction. This can be 27 Chapter 3 Wireless LAN RF PrinciplesExplained by shining a flashlight at an angle on a mirror that reflects the beam of light onto the opposite wall. This conceptual principle is the same as that of the wireless waveform. This effect can be seen in Figure 3V, where the angle of reflection of the signal is the same as the angle of incidence of the signal reaching the mirror. It is also possible to relate this to sources of interference in the office environment. Although mirrors are not always placed in offices, there are other objects with similar reflective effects, such as monitors and framed art paintings with glass surfaces.Figure 3.3 Absorption in the office after moving in furniture, wall cabinets and other objectsReflections are frequency dependent. Some frequencies are not reflected as readily as some others. This is because objects that reflect certain frequencies may not reflect other frequencies.