Sommario
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, luoghi densamente popolati e geograficamente importanti, e aree in cui i segnali sono diffusi.
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, una singola dissolvenza o interferenza può causare il fallimento dell'intero collegamento di comunicazione, 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 30 km 80 km 150 km trasmettitore video wireless a lunga distanza ricetrasmettitore di trasmissione PA 2W 5W 10W
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10W PA 150KM collegamento dati video aereo a lungo raggio trasmissione wireless UAV trasmettitore ricevitore a banda larga maniglia tattica
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80Trasmettitore-ricevitore wireless KM Sistema di trasmissione dati RC HDMI SDI a lungo raggio a bassa latenza Vcan1702
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Ricetrasmettitore ad hoc mesh IP Ricevitore trasmettitore OFDM Trasmissione dati video wireless per telecamera IP drone
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Modulatore encoder SDI o HDMI a IP Scheda di codifica CVBS H.265 H.264 pcba Ethernet RSTP UDP per UAV Drone Robotico
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Ricetrasmettitore trasmettitore di rete dati video mesh IP Radio a banda larga di rete ad hoc
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7KM Wireless Video Data RC Sistema di trasmissione a lungo raggio a bassa latenza HDMI SDI 15 km OFDM Vcan1643
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Scheda codificatore HDMI mini formato Over IP Ethernet RJ45 Modulatore di uscita H.265 HTTP RSTP UDP ONVIF TCP
COFDM Technology Introduction
COFDM is coded OFDM (OFDM codificato). 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 (Trasmissione video digitale), LTE (4sol), and WIFI.
Early COFDM wireless image transmission equipment mostly used improved DVB solutions, but there were problems such as two-way transmission, banda di frequenza, cost, eccetera., 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 (solo 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 sintesi, 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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Miglior modulo trasmettitore video FPV Trasmettitore video audio RF wireless 170-860 Mhz per fotocamera FPV 3 W PA 50 km
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30Km a lunga distanza COFDM HDMI Trasmettitore video wireless Ricevitore Set completo Audio Video TX RX per UAV Drone 1080P 908T
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Trasmettitore e ricevitore video wireless per fotocamera, HDMI HD H265 264 encoder 1W/2.5W PA 1080P60 Vcan1726
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30-millisecondo Drone UAV HDMI Trasmettitore video wireless Sistema di trasmissione wireless a bassissima latenza Vcan1729
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COFDM Modulatore Demodulatore Modulo Encoder Decoder HDMI CVBS Ingresso AV AES 256 Streaming RF FHD
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Codificare Consiglio per COFDM Trasmettitore Wireless Video
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Modulo di trasmissione trasparente Ethernet wireless COFDM Trasmettitore e ricevitore di dati video RJ45 FDD da 100 M bps
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Trasmettitore video digitale COFDM Trasmettitore video HD wireless ricevitore trasmissione set completo per telecamera di sicurezza drone UAV
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Ricevitore wireless portatile 7 Ricevitore video digitale con ricevitore COFDM touch screen da pollici con 7 Monitor da pollici