Common understanding of frequency division multiplexing
Suppose you are chatting with your friends, but friend A wants to chat with you, and friend B wants to chat with friend C. But both want to talk at the same time. If you're all talking loudly at the same time, it's impossible for either of you to hear who's saying what.
At this point, if you each speak in a different pitch, you can speak at the same time without interfering with each other.
Usually girls speak sharply, this is a high pitch; boys speak low, this is a low pitch.
If you listen to a lot of songs, you will encounter the bass and soprano singing their own songs, but it will not affect the audience's understanding of what they are singing.
This is like the method in which multiple signals in frequency division multiplexing are modulated with different frequencies, so that the modulated signals are staggered in frequency position (some people speak with high pitch, some people speak with low pitch, so the frequency of the sound is staggered ), in order to achieve the purpose of transmitting multiple signals simultaneously in one channel (the channel here is the transmission of language at the same time).