Tabla contenidos
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, densely populated and geographically prominent places, and areas where signals are spread.
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, a single fading or interference can cause the entire communication link to fail, 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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15km 30km 80km 150km maa mbi inalámbrico transmisor vídeo receptor transmisión transceptor PA 2W 5W 10W
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10W PA 150KM enlace datos video aerotransportado UAV ar ya'bu̲ ntsoni ngatho transmisor ar transmisión inalámbrica receptor ar 'me̲i ancha táctica 'ye̲
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80KM transmisor-receptor inalámbrico Video Data RC ko ya transmisión HDMI SDI ya'bu̲ ntsoni ngatho ne xí hñets'i'i latencia Vcan1702
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Transceptor ad hoc malla IP Receptor transmisor OFDM Transmisión inalámbrica ar datos vídeo pa cámara IP ar dron
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Modulador codificador SDI wa HDMI IP CVBS H.265 Placa ya nt'ot'e Ts'ut'ubi H.264 PCBA Ethernet RSTP UDP pa UAV Drone Robotic
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IP mesh video data network transmitter transceiver 自组网宽带电台
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7KM inalámbrico datos vídeo RC ko ya transmisión ya'bu̲ ya ntsoni ngatho ya xí hñets'i'i latencia HDMI SDI 15km OFDM Vcan1643
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Mini tamaño HDMI Encoder Board Over IP Ethernet RJ45 Output modulator H.265 HTTP RSTP UDP ONVIF TCP
COFDM Technology Introduction
COFDM is coded OFDM (Coded 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 (Radiodifusión vídeo 'bede), Lte (4G), and WIFI.
Early COFDM wireless image transmission equipment mostly used improved DVB solutions, but there were problems such as two-way transmission, frequency band, cost, etcetera., 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 (Ho̲ntho 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
Jar resumen, 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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Mäs xi hño módulo transmisor ar video FPV 170 — 860 Mhz Transmisor inalámbrico audio ne video RF pa cámara FPV 3W PA 50km
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30Km xi maki mbi COFDM HDMI Wireless Video Transmitter Receptor Full Set Audio Video TX RX pa UAV Drone 1080P 908T
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Transmisor ne receptor vídeo inalámbrico pa cámara, HDMI HD H265 264 codificador 1W yá 2.5W PA 1080P60 Vcan1726
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30-milisegundos Drone UAV HDMI Transmisor ar video inalámbrico ko ya transmisión inalámbrica latencia ultrabaja Vcan1729
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COFDM Modulador Demodulador Módulo Codificador Decodificador HDMI CVBS AV Entrada AES 256 Transmisión FHD RF
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Placa ya nt'ot'e Ts'ut'ubi pa transmisor vídeo inalámbrico COFDM
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COFDM módulo transmisión transparente Ethernet inalámbrico 100M bps RJ45 FDD transmisor ne receptor ar datos vídeo
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Cofdm Digital Video Transmitter transmisor ar vídeo HD inalámbrico receptor ar vídeo full set transmisión pa cámara ntsuni drones UAV
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Receptor inalámbrico portátil 7 inch Pantalla táctil RECEPTOR COFDM Receptor ar vídeo 'bede ko 7 monitor pulgadas