The Electromagnetic Spectrum is a finite resource and its use is rapidly expanding. Unencumbered access to spectrum has been, and continues to be, critical to many government and commercial systems. As existing RF systems evolve and new communication systems are deployed, the need for additional spectrum bandwidth continues to grow. With federal mandates and initiatives, such as the 500 MHz of federal spectrum released for commercial use by 2020, the impact to spectrum monitoring equipment and the role of spectrum management also must evolve.This article will cover the different functions of the traditional RF measurement instrument architectures and their role in spectrum monitoring. The basic spectrum analyzer architecture is discussed as well as the modern digital monitoring receiver.