This is simple! Your understanding of terrestrial digital TV is actually very close, but the receiving equipment is not a TV set, but a digital set-top box, and the signal demodulated by the set-top box can be sent to the TV. Satellite digital TV uses pan antenna to receive satellite signal, which is decoded by satellite receiver and sent to TV. Cable digital TV receives satellite signals and enters the satellite receiver. The signal from the receiver is sent to the encoder, then to the multiplexer, then to the digital broadband modulator, and then to the mixer (one program corresponds to one receiver, one encoder; One to eight programs correspond to one multiplexer). After the mixer comes out, it enters the optical transmitter and is sent to all user cells. After the digital TV signal is received by the optical receiver, it can directly enter the user's digital TV set-top box and then enter the TV set.

Supplementary note: at present, there is no real digital TV in China, and it must be decoded by digital set-top box. Only by integrating the functions of set-top box into TV can it be called digital TV. I hope what I said can help you. I'm just communicating, not your grades.