Inhoudsopgave
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, dichtbevolkte en geografisch prominente plaatsen, en gebieden waar signalen worden verspreid.
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, een enkele vervaging of interferentie kan ervoor zorgen dat de hele communicatieverbinding mislukt, 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 lange afstand draadloze video zender ontvanger transmissie transceiver PA 2W 5W 10W
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10W PA 150KM video-dataverbinding in de lucht lange afstand UAV draadloze transmissie zender ontvanger breedband tactische houvast
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80KM draadloze zender-ontvanger Videogegevens RC-transmissiesysteem HDMI SDI lange afstand lage latentie Vcan1702
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IP mesh ad hoc transceiver OFDM zenderontvanger Draadloze videogegevensoverdracht voor drone IP-camera
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SDI of HDMI Naar IP encoder modulator CVBS H.265 H.264 coderingskaart pcba Ethernet RSTP UDP voor UAV Drone Robotic
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IP mesh videodatanetwerk zender transceiver Ad hoc netwerk breedbandradio
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7KM draadloze videogegevens RC-transmissiesysteem lange afstand lage latentie HDMI SDI 15km OFDM Vcan1643
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Miniformaat HDMI-encoderkaart Over IP Ethernet RJ45 Uitgangsmodulator 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 (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, frequentieband, cost, enz., 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 (alleen 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.
Conclusie
samengevat, 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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Beste FPV-videozendermodule 170-860Mhz Draadloze RF-audiovideozender voor FPV-camera 3W PA 50km
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30Km lange afstand COFDM HDMI Draadloze Video Zender Ontvanger volledige Set Audio Video TX RX voor UAV Drone 1080P 908T
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Draadloze videozender en -ontvanger voor camera, HDMI HD H265 264 encoder 1W/2,5W PA 1080P60 Vcan1726
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30-milliseconde Drone UAV HDMI Draadloze videozender Ultra-low-latency draadloos transmissiesysteem Vcan1729
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COFDM Modulator Demodulator Module Encoder Decoder HDMI CVBS AV Ingang AES 256 FHD RF-streaming
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Coderen van Commissarissen voor COFDM draadloze video zender
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COFDM draadloze Ethernet transparante transmissiemodule 100M bps RJ45 FDD videogegevenszender en -ontvanger
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COFDM Digital Video Transmitter draadloze HD video-zender ontvanger volledige transmissie voor UAV drone beveiligingscamera
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Handheld draadloze ontvanger 7 inch touchscreen COFDM-ontvanger Digitale video-ontvanger met 7 inch-beeldscherm