Choose your personal GPS tracking device for hiking
The most common AGPS application is for cellular phones. Approximate user coordinates are roughly estimated using information about particular cellular network stations used by the host phone. The stations are located with rather high densities in many countries, especially in urban environments where the harsh conditions call for instant positioning and therefore for AGPS applications. A handset position estimate with an accuracy of a couple of kilometers is available from a cell ID. Using the information about a few of these stations allows us to use methods similar to positioning with GNSS to improve the positioning estimate even further. A rather precise time estimate can also be delivered to a user through a cellular phone network.
If this assist information is available, we can use ambiguous code estimates from the acquisition process to find a receiver’s position, using measurements available just a few milliseconds after the receiver is switched on. For snapshot positioning, however, accuracy, would suffer.All positioning estimates are calculated in real time using broadcast ephemerides and with a mobile device front end at a cost of about $6. GPS Tracking Devices permits sub-meter accuracy with code phase measurements. Further improvements in accuracy may be achieved using carrier phase measurements.
A change in the navigation bit polarity interferes with coherent acquisition and coherent tracking algorithms. If a receiver knows the navigation bit in advance, it uses this information to extend the coherency interval, which drastically increases sensitivity. Therefore, a pilot channel is adopted, which has a fixed secondary code instead of a navigation message with data.
Normally, however, receivers are not concerned with this process. Instead, receivers use tracking to obtain the navigation message and resolve code ambiguity. This, however, comes at a price. The receiver would need to have a few seconds of uninterrupted and uncorrupted signal reception to acquire enough of the navigation message to derive a time mark. This would be a disadvantage for many applications, in particular for positioning in urban conditions, in high-multipath environments, and when a quick positioning fix is required. Often, it is not possible for a receiver that either is indoors or has an obstructed sky view to ensure uninterrupted tracking. In this case, a receiver may operate in snapshot mode.
We have defined snapshot positioning as positioning based on code phase measurements from an acquisition process without reading a time mark from the navigation message. As discussed previously, to be able to make a positioning without tracking requires approximations of time and user position. This information is called assist information and is the heart, or rather the blood supply, of Mini GPS Tracker technology. If we don’t achieve a time estimate in the receiver better than 1 ms, we cannot resolve this ambiguity without tracking and reading the navigation data.
Models specifically intended for mounted use in an automobile or on a boat will generally be too bulky and heavy to hold for extended periods. If ou want a GPS intended for handheld use in hiking and backpacking, there are some great models that can work well for you.
Qbit Mini Personal GPS Tracker was lighter and graphically displayed my path as I created it-both features I like. The newly-launched Qbit Personal GPS Tracker will give you a completely new level of awareness and convenience. It stands out by compact, lightweight design for both excellent mobility and reliability. Loaded with GPS, LBS and WIFI positioning, Qbit enables you to view real-time location from the computer, tablet or smart phone. It is capable of withstanding extreme environment. Being stylish, tough and accurate, Qbit is idea for kids, the elder and people with special needs.
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