How do electromagnetic waves transmit signals? Does the electromagnetic gravity absorb the signal? What material is the signal sometimes? Ha ha, illiterate

How do electromagnetic waves transmit signals? Does the electromagnetic gravity absorb the signal? What material is the signal sometimes? Ha ha, illiterate

Electromagnetic waves, of course, transmit signals by waves. The frequency, amplitude and wavelength of waves are different, and these can be translated into signals. Let's say, the sound we usually hear is also a kind of wave. Your vocal part causes the vibration of the air. The vibration forms a wave, and the wave spreads out. When it reaches someone's eardrum, the eardrum receives the vibration

Is digital TV transmitted by electromagnetic wave?
Spread that in the air!

I didn't expect that there were so many people pretending to understand
Digital TV is to use digital modulation technology to modulate the image, the specific transmission mode, can be wireless (wireless must be electromagnetic wave), can also be wired and so on
The difference between digital TV and analog TV signal is only the way of signal modulation
Because the digital signal is only 0 and 1, it has strong anti-interference and other aspects
Even optical cable transmission can be regarded as the category of electromagnetic wave, because light is only one kind of electromagnetic wave

In order to use electromagnetic wave to transmit signal, let the electromagnetic wave change with the signal to be transmitted. Why?
The problem of electromagnetic wave transmitting and receiving in Senior High School··

This is called modulation
Modulate the signal to be transmitted to the high frequency electromagnetic wave to make the amplitude or frequency of electromagnetic wave change at different times (i.e. amplitude modulation and frequency modulation). In amplitude modulation, the fluctuation of electromagnetic wave amplitude represents the transmitted information, which can be understood as 0 and 1 of digital circuit. In frequency modulation, the fluctuation of frequency also represents the transmitted information