The signals from L1-band global positioning satellites are among the weakest in commercial and
private wireless applications. The received power at the antenna of a GPS receiver is buried well below the
integrated thermal noise floor. To successfully recover such weak signals, the receiver must have sufficiently
high sensitivity, while rejecting out-of-band interferences. The purpose of this paper is to describe the key system parameters that should be considered when designing a low-cost, low-component-count, unassisted commercial GPS receiver. This system targets a received sensitivity of -139dBm.