Змест
OFDM Technology Introduction
OFDM (Orthogonal frequency-division multiplexing, orthogonal frequency division multiplexing) is a multi-carrier digital modulation technology.
OFDM differs from AM/FM because it can transmit multiple high-speed signals using different frequencies at the same time. The result is bandwidth-efficient use of burst communications amid noise and other interference.
Traditional FDM (frequency division multiplexing) divides the bandwidth into several sub-channels, with guard bands in the middle to reduce interference, and they send data simultaneously. Tuning your receiver to the right station is necessary to watch cable TV or analog wireless broadcasts.
Using interference-free technology makes the use of available spectrum more efficient because guard bands aren’t needed. OFDM systems require much less bandwidth than traditional FDM systems.
OFDM Technical Characteristics
Anti-multipath fading and efficient use of frequency band resources
Based on the cyclic prefix, multipath interference is converted into useful signal multipath reception, reducing the impact of self-coherent interference and inter-symbol interference, and improving the channel’s ability to resist multipath fading. It is particularly suitable for use in high-rise buildings, густанаселеныя і геаграфічна прыкметныя месцы, і вобласці, дзе распаўсюджваюцца сігналы.
Efficient use of frequency band resources
OFDM technology uses FFT/IFFT algorithms to transform frequency domain signals, allowing multiple sub-carrier signals to be transmitted in parallel on a broadband channel, thus improving spectrum utilization efficiency. This is particularly important in wireless environments with limited spectrum resources.
Strong resistance to narrow-band interference
In a single-carrier system, адно заміранне або перашкода можа прывесці да збою ўсяго канала сувязі, but in a multi-carrier system, only a small portion of the carriers will be interfered with. Error correction codes can also be used for error correction on these sub-channels. This technology can automatically detect which specific carrier under the transmission medium has high signal attenuation or interference pulses, and then take appropriate modulation measures to enable successful communication on the carrier at the specified frequency.
High flexibility
OFDM technology can adjust the number and spacing of sub-carriers in different application scenarios to adapt to different bandwidth requirements and has good flexibility.
OFDM Feature Products
-
15км 30 км 80 км 150 км міжгародні бесправадной відэаперадатчык прыёмнік трансівер PA 2W 5W 10W
-
10W PA 150KM бартавая відэаканал перадачы даных БПЛА далёкага радыусу бесправадной перадачы перадатчык прыёмнік шырокапалосная тактычная ручка
-
80KM бесправадны перадатчык-прыёмнік Сістэма перадачы відэаданых RC Сістэма перадачы дадзеных HDMI SDI з нізкай затрымкай на далёкія адлегласці Vcan1702
-
IP mesh ad hoc прыёмаперадатчык OFDM перадатчык прыёмнік Бесправадная перадача відэа даных для IP-камеры беспілотніка
-
Мадулятар кадавальніка SDI або HDMI да IP CVBS H.265 Плата кадавання H.264 pcba Ethernet RSTP UDP для беспілотніка Robotic
-
IP mesh сетка відэа перадачы дадзеных трансівер Спецыяльная шырокапалосная сетка радыё
-
7Бесправадная сістэма перадачы відэаданых KM KM з далёкай далёкасцю затрымкі HDMI SDI 15 км OFDM Vcan1643
-
Плата кадавальніка HDMI міні-памеру праз IP Ethernet RJ45 Мадулятар выхаду H.265 HTTP RSTP UDP ONVIF TCP
COFDM Technology Introduction
COFDM is coded OFDM (Кадаваны OFDM). Some channel coding is added before OFDM modulation (error correction coding and guard interval are added before orthogonal modulation) to make the signal more reliable and effective transmission.
Applications of COFDM
OFDM, as a high-speed transmission technology that can effectively combat interference between signal waveforms, is more widely used in the field of broadband mobile communications. Pure OFDM wireless transmission systems are rarely used in actual systems, and are basically based on COFDM technology, such as DVB (Digital Video Broadcasting), LTE (4G), and WIFI.
Early COFDM wireless image transmission equipment mostly used improved DVB solutions, but there were problems such as two-way transmission, паласа частот, cost, і г.д., and it is rarely used in the current market. The bottom layer of common ad hoc network technologies on the market is mostly improved from LTE or WIFI technology.
WiFi technology is mainly used in stationary short-range and common applications. Its pilot subcarriers used for channel estimation are relatively sparse (толькі 4 pilots under 20Mhz bandwidth). It is not effective in mobile scenarios such as UAV image data transmission and emergency communications. ideal;
LTE is designed for complex high-speed mobile long-distance scenarios, has a high pilot density (200 pilots under 20Mhz bandwidth), has stronger signal recovery capabilities, and is more suitable for areas such as occlusion and high-speed movement.
Заключэнне
In summary, COFDM is coded OFDM, which adds channel coding to OFDM to provide communication system bit error performance. Our ad hoc network is based on LTE underlying technology (channel coding technologies such as OFDM multi-carrier, convolutional coding/TURBO coding) and is optimized and designed for complex scenarios such as drones and emergency communications.
COFDM Feature Products
-
Лепшы модуль відэаперадатчыка FPV 170-860 МГц Бесправадны радыёчастотны аўдыё-відэа-перадатчык для камеры FPV 3W PA 50km
-
30Км на вялікія адлегласці COFDM HDMI бесправадной відэа перадатчык прыёмнік поўны камплект аўдыё відэа TX RX для БПЛА Drone 1080P 908T
-
Бесправадны відэаперадатчык і прыёмнік для камеры, HDMI HD H265 264 кадавальнік 1 Вт/2,5 Вт PA 1080P60 Vcan1726
-
30-мілісекундны Дрон БПЛА HDMI Бесправадны відэаперадатчык Сістэма бесправадной перадачы з ультранізкай затрымкай Vcan1729
-
Модулятар COFDM Дэмадулятар Модуль кадавальнік Дэкодэр HDMI CVBS AV Уваход AES 256 FHD RF струменевае
-
Кадзіраваць савет для COFDM бесправаднога перадатчыка відэа
-
Модуль бесправадной празрыстай перадачы Ethernet COFDM 100M біт/с RJ45 FDD перадатчык і прыёмнік відэададзеных
-
COFDM Digital Video Transmitter бесправадной прымач HD відэа перадатчыка поўны набор перадач для камеры бяспекі беспілотнага беспілотніка
-
Ручны бесправадны прыёмнік 7 цалевы сэнсарны экран COFDM-прыёмнік Лічбавы відэапрыёмнік з 7 цалевы манітор