This work presents the realization and analysis of narrow-band Spectrum Sensing based on energy detection using the Universal Software Radio Peripheral (USRP) transceiver, GNU radio Digital Signal Processing (DSP) platform and Python scripts. A description of the conceptual steps behind the implemented system is presented. Receiver Operational Characteristics (ROC) curves comparing experimental, simulated and analytical results are given demonstrating good agreement between the realized system and the theoretical models. Future work related to more complex systems and spectrum sensing schemes are also discussed.