Televisiosignaalit

Televisiosignaalit, or television signals, are the electromagnetic waves that transmit visual and audio information from a broadcasting station to a television receiver. These signals can be transmitted via various methods, including over-the-air broadcasting, cable television, and satellite television. The most common types of television signals are analog and digital.

Analog television signals use a continuous waveform to represent the video and audio information. These signals are susceptible to interference and degradation over long distances, leading to poor picture and sound quality. In contrast, digital television signals use a series of discrete values to represent the same information. This allows for better compression, error correction, and resistance to interference, resulting in higher quality images and sound.

Television signals are typically transmitted in the very high frequency (VHF) and ultra-high frequency (UHF) bands of the radio spectrum. The specific frequencies used depend on the broadcasting standard and the country's regulations. For example, in the United States, analog television signals are broadcast in the VHF band (channels 2-13) and the UHF band (channels 14-51), while digital television signals are broadcast in the UHF band (channels 14-51).

Television signals can also be modulated using different techniques to optimize their transmission. Amplitude modulation (AM) and frequency modulation (FM) are commonly used for analog signals, while quadrature amplitude modulation (QAM) and orthogonal frequency-division multiplexing (OFDM) are used for digital signals.

In recent years, there has been a shift towards digital television broadcasting due to its numerous advantages over analog. However, analog television signals are still in use in some countries and regions, particularly in areas with limited infrastructure or where digital signals are not yet available.