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Create: 2025-01-23 Update: 2025-07-01 15:04:23

ПОДНЕСУЩИЕ В OFDM В IEEE 802.11N/AC ПРИ ШИРИНЕ КАНАЛА 20 МГЦ

Сегодня я расскажу о том, из чего формируется OFDM‐сигнал и почему мы видим характерный «провал» в самом центре спектрограммы.

Что такое поднесущие в OFDM
В OFDM (Orthogonal Frequency‐Division Multiplexing) основной диапазон частот разбивается на ряд более узких полос, каждая из которых называется «поднесущей» (subcarrier). Почти каждая из поднесущих несет часть данных, и благодаря особому принципу ортогональности соседние поднесущие не мешают друг другу. Таким образом, весь 20‐мегагерцевый канал «нарезается» на множество небольших подканалов, что помогает эффективно использовать частотный ресурс.

Основные типы поднесущих
*️⃣ DC‐поднесущая (желтая, 1 шт.) находится ровно по центру диапазона и обычно не используется для передачи данных.
*️⃣ Поднесущие с данными (зеленые, 52 шт.) используются для передачи данных.
*️⃣Пилотные поднесущие (синие, 4 шт.) помогают адаптировать приемник и компенсировать возможные сдвиги по фазе и частоте.
*️⃣ Поднесущие защитного интервала (красные, 7 шт.) не используются для передачи данных и выполняют роль «зазора» между рабочим сигналом и граничными частотами, снижая взаимные помехи.

Откуда берется провал в центре
Провал — следствие того, что DC‐поднесущая не несет данных и фактически отключена (амплитуда равна нулю).

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ИП Скоромнов Дмитрий Анатольевич, ИНН 331403723315

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ПОДНЕСУЩИЕ В OFDM В IEEE 802.11N/AC ПРИ ШИРИНЕ КАНАЛА 20 МГЦ

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