User Segment (GPS-Receiver)
This will be a short chapter only giving rudimentary information since the receiver market is highly dynamic market with various models changing every few months.
Modern GPS satellite receivers can be built in such a compact way,
that they even can be integrated in wrist watches. Most of the commercially
available instruments today have about the size of a cell phone. All
receivers today have at least 12 channels, meaning that they can receive
and process the signals of at least 12 satellites in parallel. Earlier
instruments had to process data in series, making them considerably
slower and less accurate and more sensitive against disturbances. Todays receivers can follow up to 66 GPS signals (more than are currently available) and deal with multipath and reflected signals as well as are sufficiently senstive to work indoors.
Instruments for the professional use (military and land survey) typically are bigger and considerably more precise.