Tartalomjegyzék
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, sűrűn lakott és földrajzilag kiemelkedő helyek, és olyan területek, ahol a jelek terjednek.
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, egyetlen fading vagy interferencia a teljes kommunikációs kapcsolat meghibásodását okozhatja, 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
-
15km 30km 80km 150km távolsági vezeték nélküli videó adó vevő adás adó-vevő PA 2W 5W 10W
-
10W PA 150KM légi video adatkapcsolat nagy hatótávolságú UAV vezeték nélküli átviteli adó vevő szélessávú taktikai kapaszkodó
-
80KM vezeték nélküli adó-vevő Video Data RC átviteli rendszer HDMI SDI nagy hatótávolságú, alacsony késleltetésű Vcan1702
-
IP mesh ad hoc adó-vevő OFDM adó vevő Vezeték nélküli videó adatátvitel drone IP kamerához
-
SDI vagy HDMI-IP kódoló modulátor CVBS H.265 H.264 kódoló kártya pcba Ethernet RSTP UDP UAV Drone Robotichoz
-
IP mesh videó adathálózati adó adó-vevő Ad hoc hálózati szélessávú rádió
-
7KM vezeték nélküli Video Data RC átviteli rendszer nagy hatótávolságú alacsony késleltetésű HDMI SDI 15km OFDM Vcan1643
-
Mini méretű HDMI kódolókártya IP-n keresztül Ethernet RJ45 kimeneti modulátor 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, frekvenciasávban, költség, stb., 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 (csak 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.
Következtetés
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
-
A legjobb FPV videó adó modul 170-860Mhz vezeték nélküli RF audio-video adó FPV kamerához 3W PA 50km
-
30Km távolsági COFDM HDMI vezeték nélküli videó adó vevő teljes készlet Audio Video TX RX UAV Drone 1080P 908T
-
Vezeték nélküli videó adó és vevő fényképezőgéphez, HDMI HD H265 264 kódoló 1W/2.5W PA 1080P60 Vcan1726
-
30-ezredmásodperces Drone UAV HDMI Vezeték nélküli videó adó Ultra alacsony késleltetésű vezeték nélküli átviteli rendszer Vcan1729
-
COFDM modulátor demodulátor modul kódoló dekódoló HDMI CVBS AV bemenet AES 256 FHD RF streaming
-
Kódolás Board COFDM Vezeték nélküli video adó
-
COFDM vezeték nélküli Ethernet transzparens átviteli modul 100M bps RJ45 FDD videó adat adó és vevő
-
COFDM digitális videó adó vezeték nélküli HD videó adó vevő teljes körű átvitel UAV drone biztonsági kamerához
-
Kézi vezeték nélküli vevő 7 hüvelykes érintőképernyős COFDM vevő Digitális videó vevő 7 hüvelykes monitor