To solve this problem by coding, adding "who am I" to the sent information has the advantage of not being easy to make mistakes, but the disadvantage is that the information is lengthened and inefficient. I don't know that all their messages are based on "who am I", and they don't always judge who sent them by whistling. Otherwise, at least when Mabond blew the news that "Big Brother is dead", everyone should be able to judge that this is the message sent by the whistle of Lao Qi, or get the sender's information from the message. In fact, although several brothers are together, it is just a proof. Although they have doubts about the content of the message, they don't know who sent it.
By expressing different information at different frequencies, the channel can be maximized and the transmission efficiency is high, but it is really difficult to do this. Besides sending information to control the frequency, it is also difficult to receive it, because many people can't easily distinguish absolute audio. For example, people who have never studied music can rarely judge scales accurately. The existence time of frequency and the relative height of frequency are relatively easy to judge.
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