👉 In digital signal processing, an "upband" refers to a subcarrier used in amplitude modulation (AM) and frequency modulating (FM) systems. It is often referred to as a "high-pass filter". In AM systems, it serves as a high-pass filter to remove low-frequency components from the carrier wave, while in FM systems, it acts as a bandpass filter to separate the audio signal into different bands of frequencies for better signal discrimination and separation.
