Translate the following passages into Chinese 1. The modulator has two main functions. First, it converts the electrical message into the proper format. Second, it impresses this signal onto the wave generated by the carrier source. Two distinct categories of modulation format are analog and digital. An analog signal is continuous and reproduces the form of the original message quite faithfully. In this case, the modulator need not change the format of the signal. It could be appropriate to amplify this signal, however, so that the signal will be strong enough to drive the carrier source.