Cordless telephone power-on encoding and decoding circuit diagram

When the mobile phone goes off-hook, it first sends out a password signal, and the desktop computer starts working after receiving it. However, other mobile phones with the same frequency cannot generate a power-on action due to inconsistent passwords, thus preventing others from making phone calls. The requirements for R and C of the peripheral components of the encoding circuit and the decoding circuit are consistent, and the error does not exceed 1%. Usually R chooses 220k ohms, C chooses 0.015uF.