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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, хүн ам шигүү суурьшсан, газарзүйн хувьд алдартай газрууд, болон дохио тархсан газрууд.
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, Ганц бүдгэрч эсвэл хөндлөнгийн оролцоо нь бүхэл холбооны холбоосыг бүтэлгүйтэхэд хүргэдэг, 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
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15км 30км 80км 150км холын зайн утасгүй видео дамжуулагч хүлээн авагч дамжуулах дамжуулагч PA 2W 5W 10W
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10W PA 150KM агаарын видео өгөгдөл дамжуулах холын зайн UAV утасгүй дамжуулагч хүлээн авагч өргөн зурвасын тактикийн бариул
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80KM утасгүй дамжуулагч-хүлээн авагч Видео өгөгдөл RC дамжуулах систем HDMI SDI урт хугацааны бага хоцрогдолтой Vcan1702
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IP торон түр хүлээн авагч OFDM дамжуулагч хүлээн авагч Дрон IP камерт зориулсан утасгүй видео өгөгдөл дамжуулах
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SDI or HDMI To IP encoder modulator CVBS H.265 H.264 encoding board pcba Ethernet RSTP UDP for UAV Drone Robotic
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IP торон видео мэдээллийн сүлжээ дамжуулагч дамжуулагч Ad hoc сүлжээний өргөн зурвасын радио
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7KM утасгүй видео өгөгдөл RC дамжуулах систем нь урт хугацааны бага хоцрогдолтой HDMI SDI 15 км OFDM Vcan1643
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Mini хэмжээтэй HDMI кодлогч самбар IP Ethernet RJ45 гаралтын модулятор H.265 HTTP RSTP UDP ONVIF TCP
COFDM Technology Introduction
COFDM is coded OFDM (Кодлогдсон 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 (Дижитал видео нэвтрүүлэг), LTE (4G), and WIFI.
Early COFDM wireless image transmission equipment mostly used improved DVB solutions, but there were problems such as two-way transmission, давтамж хамтлаг, cost, гэх мэт, 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 (зөвхөн 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.
Conclusion
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
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Шилдэг FPV видео дамжуулагч модуль 3W PA 50km FPV камерт зориулсан 170-860Mhz утасгүй RF аудио видео дамжуулагч
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30км холын зайн COFDM HDMI утасгүй видео дамжуулагч хүлээн авагч нь UAV Drone 1080P 908T-д зориулсан иж бүрэн аудио видео TX RX
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Камерт зориулсан утасгүй видео дамжуулагч ба хүлээн авагч, HDMI HD H265 264 кодлогч 1W / 2.5W ТХГН-ийн 1080P60 Vcan1726
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30-миллисекунд Drone UAV HDMI Утасгүй видео дамжуулагч Хэт бага хоцролттой утасгүй дамжуулах систем Vcan1729
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COFDM модулятор демодулятор модуль кодлогч декодер HDMI CVBS AV оролт AES 256 FHD RF дамжуулалт
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COFDM утасгүй видео дамжуулагч ТУЗ-ийн кодчилдог
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COFDM утасгүй Ethernet ил тод дамжуулах модуль 100Mbps RJ45 FDD видео өгөгдөл дамжуулагч ба хүлээн авагч
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COFDM дижитал видео дамжуулагч утасгүй HD видео дамжуулагч хүлээн авагч нь нисэх онгоцны аюулгүй байдлын камерын бүрэн багц дамжуулалт юм
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Гар утасгүй хүлээн авагч 7 инчийн мэдрэгчтэй дэлгэц COFDM хүлээн авагч дижитал видео хүлээн авагчтай 7 инчийн дэлгэц