What are the differences between SNR and NNR, and how do they impact the performance of communication systems?

Signal-to-Noise Ratio (SNR) measures the strength of the signal compared to the background noise, while Noise-to-Noise Ratio (NNR) compares the noise level before and after processing. A higher SNR indicates better signal quality, leading to improved communication system performance. On the other hand, a lower NNR suggests that noise has been amplified during processing, potentially degrading system performance.