Multiple frequencies, a number of signal types, and the new binary offset carrier (BOC) modulation makes working on the production of Galileo-capable receivers a challenge. Starting off with a prototype design before a finalized signal specification is handed down will reduce the design risk for the future. The Galileo System Test Bed version 2 (GSTB-V2) satellites are scheduled to launch in late 2005 or early 2006. These initial test satellites will broadcast the first Galileo signals in space, and will furnish a representative signal to drive initial testing, and secure frequency filing. Over the next few years up to four In-Orbit Validation (IOV) satellites will follow the GSTB-V2s. The reception of signals from both constellations will bring user benefits that include enhanced accuracy, availability, and reliability. Currently, the signal path to the satellite constellation can be obstructed by bridges, buildings, trees, and other types of signal blockage. Because there will be twice as many satellites available in the sky, it will be less likely that signal blockage will cause interference with the navigation solution. Right now there is no signal-in-space available to allow for testing of prototype receivers, and Galileo signal simulators are still in development. However there are several possible solutions for receiver design challenges including signal generation and receiver modeling done entirely via software.