Final answer:
SNR stands for Signal-to-Noise Ratio, and it directly affects the quality of a received signal; a higher SNR usually means better signal quality.
Step-by-step explanation:
The relationship between the Signal-to-Noise Ratio (SNR) and the quality of the received signal is quite direct. SNR is a measure of signal quality that compares the level of a desired signal to the level of background noise. A higher SNR indicates a clearer signal with less noise. As SNR increases, the quality of the received signal generally improves, making it easier to distinguish the actual signal from the noise, which is particularly important in communication systems. Frequency drift due to the relative motion between the source and the receiver (e.g., Doppler shift) does not directly affect SNR but can influence signal reception and quality.