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 influence on 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.