Efnisyfirlit
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, þéttbýlir og landfræðilega áberandi staðir, og svæði þar sem merki dreifast.
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, ein dofnun eða truflun getur valdið því að allur samskiptatengillinn bilar, 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 þráðlaus þráðlaus myndsendi móttakari sendandi senditæki PA 2W 5W 10W
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10W PA 150KM loftborinn myndbandsgagnatengil langdrægur UAV þráðlaus sending sendandi móttakari breiðband taktísk handfang
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80KM þráðlaus sendir-móttakari Myndgögn RC sendingarkerfi HDMI SDI langdræg lítil leynd Vcan1702
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IP möskva ad hoc sendimóttakari OFDM sendandi móttakari Þráðlaus myndbandsgagnasending fyrir dróna IP myndavél
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SDI eða HDMI til IP kóðara mótara CVBS H.265 H.264 kóðun borð pcba Ethernet RSTP UDP fyrir UAV Drone Robotic
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IP möskva vídeó gagnanet sendandi senditæki Ad hoc net breiðbandsútvarp
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7KM þráðlaust myndbanda gagnaflutningskerfi langdrægi lágvöntun HDMI SDI 15km OFDM Vcan1643
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Mini Stærð HDMI kóðara Board Over IP Ethernet RJ45 Output modulator H.265 HTTP RSTP UDP ONVIF TCP
COFDM Technology Introduction
COFDM is coded OFDM (Kóðað 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 (Stafræn myndútsending), LTE (4G), and WIFI.
Early COFDM wireless image transmission equipment mostly used improved DVB solutions, but there were problems such as two-way transmission, tíðnisviði, cost, o.fl., 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 (aðeins 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.
Niðurstaða
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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Besti FPV myndbandsendirinn 170-860Mhz þráðlaus RF hljóðmyndsendir fyrir FPV myndavél 3W PA 50km
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30Km langa vegalengd COFDM HDMI þráðlaus myndsendandi móttakari fullt sett Audio Video TX RX fyrir UAV Drone 1080P 908T
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Þráðlaus myndsendir og móttakari fyrir myndavél, HDMI HD H265 264 kóðari 1W/2,5W PA 1080P60 Vcan1726
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30-millisekúndu Drone UAV HDMI Þráðlaus myndsendir Þráðlaust sendikerfi með ofurlítil biðtíma Vcan1729
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COFDM Modulator Demodulator Module Encoder Decoder HDMI CVBS AV Input AES 256 FHD RF streymi
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Umrita stjórn til COFDM Wireless Video Sendandi
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COFDM þráðlaus Ethernet gagnsæ sendingareining 100M bps RJ45 FDD myndbandsgagnasendir og móttakari
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COFDM Stafrænn myndbandssendi þráðlaus HD myndbandssendir móttakari fullur sending fyrir UAV drone öryggismyndavél
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Handheldur þráðlaus móttakari 7 tommu snertiskjár COFDM móttakari Stafrænn myndmóttakari með 7 tommu Skjár