مواد جو جدول
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, گنجان آبادي ۽ جاگرافيائي لحاظ کان نمايان جايون, ۽ علائقا جتي سگنل پکڙيل آهن.
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, ھڪڙي ھڪڙي ڀڃڻ يا مداخلت سڄي رابطي واري لنڪ کي ناڪام ٿيڻ جو سبب بڻائي سگھي ٿو, 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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15ڪلوميٽر 30km 80km 150km ڊگھي فاصلي واري وائرليس وڊيو ٽرانسميٽر وصول ڪندڙ ٽرانسميشن ٽرانسيور PA 2W 5W 10W
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10W PA 150KM ايئر بورن ويڊيو ڊيٽا لنڪ ڊگھي رينج UAV وائرليس ٽرانسميشن ٽرانسميٽر رسيور براڊ بينڊ ٽيڪٽيڪل هينڊ هولڊ
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80KM وائرليس ٽرانسميٽر وصول ڪندڙ وڊيو ڊيٽا RC ٽرانسميشن سسٽم HDMI SDI ڊگھي رينج جي گھٽ ويڪرائي Vcan1702
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IP ميش ايڊهاڪ ٽرانسيور OFDM ٽرانسميٽر رسيور وائرليس وڊيو ڊيٽا ٽرانسميشن ڊرون IP ڪئميرا لاءِ
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SDI يا HDMI کان IP انڪوڊر ماڊلٽر CVBS H.265 H.264 انڪوڊنگ بورڊ pcba Ethernet RSTP UDP UAV ڊرون روبوٽ لاءِ
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IP ميش وڊيو ڊيٽا نيٽورڪ ٽرانسميٽر ٽرانسيور ايڊهاڪ نيٽورڪ براڊ بينڊ ريڊيو
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7ڪي ايم وائرلیس ويڊيو ڊيٽا آر سي ٽرانسميشن سسٽم جو ڊگهو سلسلو گهٽ ويڪرائيسي HDMI SDI 15 ڪلوميٽر OFDM Vcan1643
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ننڍي سائيز HDMI انڪوڊر بورڊ مٿان IP Ethernet RJ45 آئوٽ پٽ ماڊلٽر 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 (ڊجيٽل ويڊيو براڊڪاسٽنگ), LTE (4ز), and WIFI.
Early COFDM wireless image transmission equipment mostly used improved DVB solutions, but there were problems such as two-way transmission, ات ٽولي, cost, وغيره., 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 (صرف 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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بهترين FPV وڊيو ٽرانسميٽر ماڊل 170-860Mhz وائرليس آر ايف آڊيو وڊيو ٽرانسميٽر FPV ڪئميرا 3W PA 50km لاءِ
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30ڪلوميٽر ڊگهو فاصلو COFDM HDMI وائرليس ويڊيو ٽرانسميٽر وصول ڪندڙ مڪمل سيٽ آڊيو وڊيو TX RX لاءِ UAV ڊرون 1080P 908T
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وائرليس ويڊيو ٽرانسميٽر ۽ ڪئميرا لاءِ رسيور, HDMI HD H265 264 انڪوڊر 1W/2.5W PA 1080P60 Vcan1726
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30-مليسيڪنڊ ڊرون UAV HDMI وائرليس ويڊيو ٽرانسميٽر الٽرا-لو-ليٽسي وائرليس ٽرانسميشن سسٽم Vcan1729
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COFDM ماڊلٽر Demodulator ماڊل انڪوڊر ڊيڪوڊر HDMI CVBS AV ان پٽ AES 256 FHD آر ايف اسٽريمنگ
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COFDM وائرليس وڊيو Transmitter لاء Encode بورڊ
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COFDM وائرليس ايٿرنيٽ شفاف ٽرانسميشن ماڊل 100M bps RJ45 FDD وڊيو ڊيٽا ٽرانسميٽر ۽ وصول ڪندڙ
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COFDM ڊجيٽل ويڊيو ٽرانسميٽر وائرليس HD ويڊيو ٽرانسميٽر وصول ڪندڙ مڪمل سيٽ ٽرانسميشن UAV ڊرون سيڪيورٽي ڪئميرا لاءِ
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هٿ واري وائرليس وصول ڪندڙ 7 انچ ٽچ اسڪرين COFDM وصول ڪندڙ ڊجيٽل وڊيو وصول ڪندڙ سان 7 انچ مانيٽر