Why is there pre-emphasis in TV audio? What is the role of pre-emphasis?
Pre-emphasis is used in TV audio to improve the signal-to-noise ratio of the audio signal. Signal-to-noise ratio refers to the ratio of useful signal to background noise, and pre-emphasis can improve this ratio.
In television broadcasts, audio signals are often affected by a variety of interference and distortions, including uneven frequency response, losses in transmission, and noise. Pre-emphasis increases the intensity of high-frequency components in the audio signal, making the high-frequency part more significant relative to the low-frequency part, thereby increasing the high-frequency energy in the signal.
There are two main aspects of pre-emphasis. First, it can improve the signal-to-noise ratio of the audio signal. Because pre-emphasis enhances the high-frequency part, useful information in the audio signal is easier to distinguish from background noise. Secondly, pre-emphasis can also reduce the distortion caused by uneven frequency response during transmission. During the transmission process, high-frequency signals are usually attenuated due to limitations of lines and equipment. Pre-emphasis can increase high-frequency energy at the source to offset the loss in the subsequent attenuation process.
It should be noted that pre-emphasis is only a processing technology. It is applied during the transmission process. The receiving end needs to perform corresponding "de-emphasis" processing to restore the original audio signal. This technology is often used in analog audio transmission, while in the field of digital audio, the need for pre-emphasis is relatively small because the digital signal itself has better anti-interference performance.
In commonly used audio system chip manuals, there will be relevant register configurations.