Clàr-innse
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, dùmhail sluaigh agus àiteachan follaiseach air feadh na dùthcha, agus raointean far a bheil comharran air an sgaoileadh.
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, faodaidh aon crìonadh no bacadh a bhith air an ceangal conaltraidh gu lèir fàiligeadh, 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 astar fada gun uèir inneal-sgaoilidh bhidio glacadair tar-chuir transceiver PA 2W 5W 10W
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10Ceangal dàta bhidio adhair W PA 150KM inneal-sgaoilidh tar-chuir gun uèir UAV fad-raon grèim-làimhe innleachdach bann-leathann
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80KM wireless transmitter-glacadair Dàta Bhidio Siostam Transmission RC HDMI SDI raon-laighe ìosal fad-ùine Vcan1702
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Mogal IP ad hoc transceiver glacadair inneal-sgaoilidh OFDM Tar-chuir dàta bhidio gun uèir airson camara IP drone
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SDI no HDMI Gu IP modulator encoder CVBS H.265 H.264 bòrd còdaidh pcba Ethernet RSTP UDP airson UAV Drone Robotic
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Tar-chuir lìonra dàta bhidio mogal IP transceiver rèidio bann-leathann lìonra ad hoc
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7Dàta bhidio gun uèir KM Siostam tar-chuir RC raon fada latency ìosal HDMI SDI 15km OFDM Vcan1643
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Meud Mini HDMI Bòrd Encoder Thar IP Ethernet RJ45 Modulator toraidh H.265 HTTP RSTP UDP ONVIF TCP
COFDM Technology Introduction
COFDM is coded OFDM (Còd 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 (Craoladh bhidio didseatach), LTE (4G), and WIFI.
Early COFDM wireless image transmission equipment mostly used improved DVB solutions, but there were problems such as two-way transmission, tricead còmhlan, cost, etc., 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 (a-mhàin 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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Modal tar-chuir bhidio FPV as fheàrr 170-860Mhz Tar-chuir bhidio claisneachd RF gun uèir airson camara FPV 3W PA 50km
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30Km astar fada COFDM HDMI Glacadair tar-chuir bhidio gun uèir làn bhidio claisneachd TX RX airson UAV Drone 1080P 908T
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Tar-chuir bhidio gun uèir agus cuidhteas airson camara, HDMI HD H265 264 còdaiche 1W / 2.5W PA 1080P60 Vcan1726
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30-millisecond Drone UAV HDMI Tar-chuir bhidio gun uèir Siostam tar-chuir gun uèir ultra-ìosal-latency Vcan1729
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COFDM Modulator Demodulator Module Encoder Decoder HDMI Cur a-steach CVBS AV AES 256 Sruth FHD RF
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Còdachadh Bhòrd airson COFDM Wireless Video chraobh-sgaoilidh
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Modal tar-chuir follaiseach Ethernet gun uèir COFDM 100M bps RJ45 FDD inneal-sgaoilidh dàta bhidio agus cuidhteas
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Glacadair tar-chuir bhidio HD COFDM Digital Video Transmitter gun uèir làn-sheata airson camara tèarainteachd drone UAV
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Glacadair gun uèir inneal-làimhe 7 òirleach Touch Screen COFDM Glacadair Bhidio Digiteach le 7 òirleach Monitor