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Data Hacking

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62 Part I — Hardware Hacks<br />

FIGURE 4-1: The Garmin III receiver<br />

The debate as to which is best is a complex one, and there are pros and cons to each:<br />

Patch antennas are smaller.<br />

Patch antennas draw less power.<br />

Quad-helix antennas are usually bulky and generally protrude from the unit.<br />

Quad-helix antennas are less prone to having the signal from the satellites blocked<br />

(or masked, to use the technical term) by the receiver and the person holding the GPS.<br />

The surface of the GPS over the patch antenna is prone to catching rain and losing the<br />

signal (simply because it is a flat surface).<br />

A lot of myth and rumor surrounds antennas. Many people believe that quad-helix antennas<br />

offer greater performance under tree cover and are less prone to signal loss in valleys and in<br />

urban areas. However, based on personal experience, I’ve not found this to be the case. Usually,<br />

such phenomena can be attributed to the particular GPS unit, assuming that your course and<br />

speed are unchanged and retaining a false signal lock.

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