THE PROBLEMS OF GPS.
It's well known that a GPS location device works poorly (if at all) inside buildings and through other obstructions. A radio's GPS antenna requires a clear line of sight to lock on to at least three satellites before the radio's electronics can be made to calculate its position in latitude and longitude. This can take minutes for the calculation. And to achieve proper altitude or height calculations, the unit must be able to communicate clearly with not three, but at least four satellites. GPS performance is also hampered in automobiles with tinted windows, heavy smoke, or atmospheric conditions like torrential rain. If a radio is clipped to an officer's belt, or buried under a coat, or placed close to the ear, an unobstructed line of sight to the minimum three satellites necessary for location is compromised. And with GPS, even after signal lock is achieved, the information is not yet in the hands of the dispatcher or in the radio network database. That requires an additional communication channel between the radio and the network over which the information is passed. In other words, the radio knows where it is, but 'home base' does not unless another channel is made available.


 

 

HOW SAFEPOINT WORKS.
In a way, SafePoint operates exactly the opposite of GPS. It does not calculate where it is (something the radio user probably already knows), but instead enables the dispatcher or database to monitor the location of the radio, which is far more valuable than the radio's "self-knowledge" of its own location. Instead of receiving signals from satellites and calculating its own location, the radio's regular transmission is picked up by at least three ground-based receivers, which integrate with Time of Arrival (TOA) technology to calculate the radio's position.

SafePoint's received signal far exceeds the power of the standard GPS satellite signal, permitting it to penetrate more easily through obstructions. SafePoint can also detect and locate transmissions without the addition of any device to the mobile or portable radio. SafePoint sensors overlay the radio network's infrastructure, feeding the sensor from the network's antenna couplers - a great advantage for "painless" installation.

The timing information from the transmission is passed to a Central Analysis Processor (CAP) that performs the calculations, determines the radio location, and relays the radio ID into a database. The information can then be presented on a local CAD display or on the SafePoint "TrackerX" mapping monitors. Decoding inbound information, is simple for SafePoint.

Radio diagnostics software constantly monitors transmissions and can identify unstable radio transmissions from radios - a valuable maintenance tool all by itself. This data can be used as a tool for debugging failing radios. Preventive maintenance can then be scheduled before the radio fails.

Should a SafePoint system irregularity occur, the problem can be analyzed by remote communications. In addition, software updates can be downloaded to upgrade and improve system performance.

ADDITIONAL INFORMATION ABOUT HOW SAFEPOINT WORKS.
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