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ee:hydrophones:start [2018/01/28 10:41] Ryan Summers |
ee:hydrophones:start [2018/01/28 10:45] Ryan Summers |
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| ===== Introduction ===== | ===== Introduction ===== | ||
| - | The purpose of this page is to describe how the arrival times are acquired on a number of hydrophone channels. This documentation does //not// describe how that information is turned into bearings or how it is used in localization. | + | //Note: The purpose of this page is to describe how the arrival times are acquired on a number of hydrophone channels. This documentation does //not// describe how that information is turned into bearings or how it is used in localization.// |
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| The arrival time calculations tend to be complicated by noise, which means that it is not possible to trivially detect rising edges. The ping can be thought of as an identical signal arriving slightly later on each of the hydrophones. In order to accurately calculate the time differences between each signal, a [[https://en.wikipedia.org/wiki/Cross-correlation|cross correlation]] is used. A cross correlation essentially slides one signal over the top of another, and at the point where the signals maximally overlap, the amount of shifting needed is equal to the time delay of the signal. An education GIF of a cross-correlation is available [[https://media.giphy.com/media/VVPKOXc6aY1Lq/source.gif|here]]. | The arrival time calculations tend to be complicated by noise, which means that it is not possible to trivially detect rising edges. The ping can be thought of as an identical signal arriving slightly later on each of the hydrophones. In order to accurately calculate the time differences between each signal, a [[https://en.wikipedia.org/wiki/Cross-correlation|cross correlation]] is used. A cross correlation essentially slides one signal over the top of another, and at the point where the signals maximally overlap, the amount of shifting needed is equal to the time delay of the signal. An education GIF of a cross-correlation is available [[https://media.giphy.com/media/VVPKOXc6aY1Lq/source.gif|here]]. | ||
