A software-defined GPS receiver includes a hardware-oriented front end for down converting and digitizing the signals received from GPS satellites. The GPS signal processing functions, such as acquisition/tracking and navigation computing, can be performed by software running on the receiver central processing unit (CPU), rather than by firmware in a custom hardware device such as an ASIC. The signal processing capabilities of the receiver can therefore be readily reconfigured (e.g., upgraded) to accommodate changes in the satellite signal transmissions. Moreover, by utilizing an operating environment architecture and application programs that are compliant with the Software Communications Architecture (SCA) specification, a distributed positioning system of scalable, portable, and compatible SCA-compliant software-defined GPS receivers can be realized.