The subject of this book is to analyze, design and implement a digital front-end that converts the high-speed digital IF samples from a RF-board into a complex, decimated base-band sample stream (signal conditioning). The realization shown in this book is based on the needs for a high-end combined Galileo/GPS receiver. However, the presented algorithm is independent of the usage in a GNSS receiver environment. There are many other possible applications. The part of the receiver described in this book uses a sample rate of 300MHz, the base-band sample stream has a rate of 100MHz. To minimize the cost and complexity of the conditioning section described in this book, the sample rate of the signal is reduced by a factor of 3 and optimized to decrease the necessary number of filter operations. Additionally, the real signal is converted to a complex signal (real and imaginary part) for later processing. This conversion and the decimation of the sample rate has no significant influenceon the signal information. Because of the complex representation, a bandwidth of around 100MHz is possible. Thus, the receiver can handle the Galileo-signal E5ab with a bandwidth of about 71MHz.