Receivers are generally categorized by their physical characteristics, the elements of the GPS signal they can use with advantage, and by the claims about their accuracy. But the effects of these features on a receiver’s actual productivity are not always obvious. There are receivers that use only the C/A code on the L1 frequency and receivers that cross-correlate with the P code, or encrypted Y code, on L1 and L2. There are L1 carrier phase tracking receivers, dual-frequency and multi-frequency carrier phase tracking receivers, receivers that track all in view, and GPS/GNSS receivers. The more aspects of the GPS signal a receiver can employ, the greater its flexibility, but so, too, the greater its cost. It is important to understand receiver capabilities and limitations to ensure that the systematic capability of a receiver is matched to the required outcome of a project.
As shown in the illustration, it is possible to divide receivers into three categories. They are; recreation, mapping, and surveying. These categories can be further divided by the observables they are capable of tracking. Again, the contribution of these capabilities to the levels of possible systematic precision and accuracy are given from lower (L1 Code alone) to higher (GPS + GLONASS), that is, from left to right in the illustration.