How does TV receive terrestrial signals?

What is a ground signal? According to the definition of "Terminology of Digital TV Receiving Equipment" (SJ/T1KLOC-0/324-2006) of the Ministry of Information Industry, terrestrial digital TV refers to "a TV system that transmits digital TV signals through terrestrial broadcasting." The "ground" mentioned here has nothing to do with the "ground" under our feet. The TV signal of "terrestrial digital TV" is broadcast into the air through TV tower, and then received by users in the form of antenna. There are two ways to receive terrestrial HD signals, one is antenna+set-top box+TV (including LCD TV, plasma, rear projection TV, etc.), and the other is antenna+digital all-in-one machine, such as Toshiba X3300 and ZF500 series. As you can see, no matter how you use it, you need an antenna. The frequency division of terrestrial signal television broadcasting is divided into four frequency bands, namely I, III, IV and V bands. Band I has a frequency range of 48.5KHz-92MHz and can receive 1-5 channels. The frequency range of band III is 165MHz-223MHz, and it can receive 6- 12 channels. Band III has a frequency range of 470MHz-566MHz and can receive 13-24 channels. The frequency range of ⅴ band is 606MHz-958MHz, and it can receive channels 25-58. I-band and III-band are also called VHF band, and the signal wavelength of VHF band is meter wave. Ⅳ and Ⅴ bands are also called ultra-high frequency (UHF) bands, and the signal wavelength of UHF band is decimeter wave. For example, in Beijing, CCTV HD is channel 33, and 6 sets of SD programs use channel 32. The programs of Beijing TV Station use 14 channel. As can be seen from the above table, digital signals on the ground, whether V-segment or U-segment, need all-band antennas. In general, indoor antennas can be used, and outdoor antennas may be needed in places far away from urban areas.