Aloqa kanali

The sound signal Ovozli signal


TV sound components Televizor tovush komponentlari

The sound program accompanying a television picture signal is transmitted by equipment similar to that used for frequency-modulated (FM) radio broadcasting. In the NTSC system, the carrier frequency for this sound channel is spaced 4.5 megahertz above the picture carrier and is separated from the picture carrier in the television receiver by appropriate circuitry. The sound has a maximum frequency of 15 kilohertz (15,000 cycles per second), thereby assuring high fidelity. Stereophonic sound is transmitted through the use of a subcarrier located at twice the horizontal sweep frequency of 15,734 hertz. The stereo information, encoded as the difference between the left and right audio channel, amplitude modulates the stereo subcarrier, which is suppressed if there is no stereo difference information. The base sound signal is transmitted as the sum of the left and right audio channels and hence is compatible with nonstereo receivers. Televizion tasvir signaliga hamroh bo'lgan ovozli dastur chastotali modulyatsiyalangan (FM) radioeshittirish uchun ishlatiladiganga o'xshash uskunalar orqali uzatiladi. NTSC tizimida ushbu tovush kanali uchun tashuvchi chastotasi rasm tashuvchisidan 4,5 megagerts oraliqda joylashgan va televizor qabul qilgichdagi tasvir tashuvchisidan tegishli sxema orqali ajratilgan. Ovoz maksimal chastotasi 15 kilogerts (sekundiga 15 000 tsikl) ni tashkil qiladi, bu esa yuqori aniqlikni ta'minlaydi. Stereofonik tovush gorizontal supurish chastotasi 15 734 gertsdan ikki baravar yuqori bo'lgan pastki tashuvchidan foydalanish orqali uzatiladi. Chap va o'ng audio kanal o'rtasidagi farq sifatida kodlangan stereo ma'lumot, amplituda stereo sub tashuvchini modulyatsiya qiladi, agar stereo farq haqida ma'lumot bo'lmasa, bostiriladi. Asosiy tovush signali chap va o'ng audio kanallarining yig'indisi sifatida uzatiladi va shuning uchun stereo bo'lmagan qabul qiluvchilar bilan mos keladi.