| | 5 | == Background |
| | 6 | === General Background |
| | 7 | If two signals are sent at the same frequency, they can conflict with each other. Therefore, there are spectrum licenses in each country which are earmarked for specific purposes, such as TV or phone use. Each user must stay within their allotted bandwidth (the portion of the spectrum which they own the license to) on the power-frequency plot, but as they are wave shaped, they do not naturally fit perfectly. Ideally they would appear rectangular, so as to maximize the amount of power that could be sent while staying within the intended bandwidth. In lower frequency signals, this issue is solved by having license owners designate the edges of their spectrum to be buffer zones according to FCC rules (in the United States), but this could be less effective at higher frequencies where waves will likely have a greater amount of spillover or leakage. |
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| | 9 | This issue is particularly coming to a head with the advent of 5G, which is relying on using higher frequencies to have enough spectrum. Weather prediction technology analyzes waves at about 23.8 GHz, and could be disrupted by leakage from 5G. This project aims to get a general idea about how much potential leakage there might (or might not) be. |
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| | 11 | === Difficulties with the Study |
| | 12 | There are low level signals in the electromagnetic spectrum emanating from a variety of natural causes. This forms a "noise floor" level at frequencies across the spectrum. Transmissions (by human or natural causes) generates a jump of power (in dbm/Hz) at the frequencies which they are sent. However, this noise floor is not constant but is actually an ever changing low level wave. Therefore, calculating what value to judge as noise floor (and any amount of power above that line to be leakage above the noise floor) can be tricky. |
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| | 14 | Licenses identify the amount of spectrum which can be used by a company/owner, within limits set by the FCC. However, it was difficult to tell in this study how to asses what should be considered spectrum within the intended bandwidth vs what is leakage. |
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| | 16 | ===Note about Frequencies and Bandwidth |
| | 17 | There are multiple important values involving frequency which are relevant to this project. Center Frequency is the central frequency at which a transmission is sent and received, and tends to be where the peak of the wave is. The sampling rate (or transmission bandwidth) is the amount of spectrum/frequencies which the signal is sent at. However, the actual signal wave may be wider than this. The receiving bandwidth is the amount of spectrum analyzed by the receiver of the transmission, and is important that it is the correct width to receive the entire wave in all its width. |
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| | 19 | == Weekly Progress |
