Position location systems use triangulation techniques with radio signals to determine the geographical location of an object. Examples of satellite systems include GPS in the US and Glonass in Russia. Private systems such as the Qualcomm Omnitracks also exist.
Many applications make use of the satellite based Global Positioning System (GPS) at 1.675 MHz; applications are as varied as tracking stolen automobiles, navigating unfamiliar streets, returning to a particularly successful fishing spot, or positioning troops. Private commercial tracking systems also exist; an example is Qualcom's Omnitrax which keeps track of trucking fleets, improving efficiency and security.
These systems use a few high powered transmitters and many, many receivers. Typical GPS receivers consist of the LNA followed by two or more down conversions and appropriate gain. Receivers in private systems have similar architectures.
Discrete GaAs FETs and BJTs provide the sensitivity for the front end amplifier; the remainder of the system may use discrete GaAs FETs or BJTs, amplifier ICs, other RFICs, or even LSI depending on the application's requirements.