NPR measurements on satellite signals

Noise-Power-Ratio (NPR) measurements are a common procedure and a simple but useful tool to characterize the performance of power amplifiers for satellites or other multi-channel communication systems. The main advantage is the use of wideband signals like noise, multi-carrier CW tones or I/Q modulated signals, which leads to a better simulation of the real environment. This application note provides information how to generate these signals with a vector signal generator and perform NPR measurements with spectrum analyzers. With the R&S®SMW200A vector signal generator any desired test signal can be created. The R&S®FSW spectrum and signal analyzer offers an automated function for NPR measurements. The limiting factors of both a vector signal generator and a spectrum analyzer are explained. Measurement examples show the practical results of NPR measurements.