The signal generator has the function of signal modulation. What is the signal modulation? The signal modulation refers to the in the modulating signal, frequency change inset the LF signal into the HF carrier signal. The the signal can transfer any information from data to video. The signal modulation can divide into analog modulation and digital modulation. The analog modulation like AM and FM are often applied in the broadcast communication; while the digital modulation is on account of two states, and allow the binary data.