Assessment of L5 receiver performance in presence of interference using a realistic receiver simulator

In the frame of the GPS modernization program, a third civil GPS signal, called L5, will be broadcasted by the first Block IIF satellites launched in 2005. The signal band is located in an ARNS band so that it is of particular interest for users such as civil aviation. It is expected to increase accuracy, availability, integrity and continuity of service. A receiver dedicated to this signal requires special design. Signal modulation is different from that used on the L1 signal in that there are two components, in phase quadrature with each other, available to the user. The first carries data while the second, called the pilot component, does not. Different tracking configurations may be considered either combined or not. Moreover, the spectral environment in this band is different from what can be found around L1. For instance, the L5 band is expected to face a strong interference environment mainly because of pulsed DME/TACAN signals. The aim of this paper is to present a visual and realistic L5 signal generator and receiver simulator that implements various tracking schemes. In addition, a complete front-end performing digital pulse blanking is simulated. It is based on a previously validated L1 simulator and has been developed under the Labview environment. This development software enables a very visual tool with, for instance, code and phase error stresses, integrate & dump prompt samples but also ADC bins distribution are visualized in real-time. It helps to understand how the receiver behaves in various cases. This tool is used to estimate tracking performance in normal conditions of use but also in presence of different types of interference that can be generated.