this paper describes the prototype spectrum analyzer simulation using Software Defined Radio technology. The use of this technology continues to grow very rapidly, this is what drives researchers to develop this system. SDR is a radio communication system where the modulation system contained in the hardware is replaced by implementing software on a computer or embedded system. The SDR system commonly used is GNU Radio. The use of SDR is very cheap (around $ 20), and is small in size so that it offers cost effectiveness and portability requirements added by GNU radio software that is open source. In this experiment, there were several parameters measured including power and signal to noise ratio (SNR) measured using GNU Radio and compared with measurements using the Spectrum Analyzer GSP-730 which was applied to prototype simulations using 60 MHz to 80 MHz frequency inputs from generator frequency. From the experimental results show the average GNU radio power is -15.28 dBm and the average spectrum analyzer power is -15.2 dBm, so the accuracy level of the power measurement on GNU Radio reaches 99.47%, while the average SNR spectrum analyzer is 54, 2 and GNU radio SNR 54.32 so the accuracy of SNR measurement in GNU Radio reaches 99.78%.