Characterization of L5 Receiver Performance Using Digital Pulse Blanking

In November 1999, the Interagency GPS Executive Board (IGEB) endorsed a set of recommendations for implementation of the third civil GPS frequency (L5) that included specific measures to be taken within the United States to ensure that L5 can coexist with government systems operating at the same or nearby frequencies. The L5 frequency (1176.45 MHz) is located in a band that includes many pulsed emitters. To minimize the impact of L5 on existing systems, the IGEB has recommended that GPS L5 receivers incorporate increased receiver sensitivity and pulse blanking. Further the IGEB sponsored the development of a prototype L5 receiver implementing digital pulse blanking in order to test and evaluate practical implementation issues for this approach. The goal of this effort was to establish design criteria for successful implementation of digital pulse blanking. This paper describes those design requirements along with results characterizing the prototype receiver performance. Testing included laboratory testing under controlled conditions and also tests in simulated environments expected to present the most difficult scenario for the pulse blanker. Furthermore, implementation of digital pulse blanking is independent of the Radio Frequency (RF) and thus can provide benefits to GPS receivers operating at frequencies other than L5, in particular L2 with its known dense pulsed environment.