OFDM and COFDM technology, although the name is only one letter difference, but it allows wireless audio and video transmission applications have more possibilities. COFDM is a combination of OFDM and channel coding, and it is very good at eliminating the effects of flatness fading and Doppler shift. It is very suitable for installation on mobile platforms such as vehicles, ships, helicopters, and drones.
Application of COFDM Technology in Education Live Broadcast
What is OFDM
Orthogonal Frequency Division Multiplexing (OFDM) is an orthogonal frequency division multiplexing (OFDM) technology. Actually, OFDM is a type of MCM (Multi Carrier Modulation), a kind of multi-carrier modulation.
The main idea of ​​OFDM technology is to divide a given channel into many orthogonal sub-channels in the frequency domain, use one sub-carrier for modulation on each sub-channel, and transmit each sub-carrier in parallel. Thus, although the total channel is non-flat and frequency selective, each sub-channel is relatively flat. Narrow-band transmission is performed on each sub-channel, and the signal bandwidth is less than the corresponding bandwidth of the channel. Therefore, the signal waveform can be greatly eliminated. Interference.
What is COFDM
Coded orthogonal frequency division multiplexing (COFDM) is short for Coded Orthogonal Frequency Division Multiplexing (OFDM). The basic principle is to transfer high-speed data streams through serial-to-parallel conversion and allocate them to several sub-channels with lower transmission rates.
COFDM is based on the idea of ​​spreading information in the frequency domain and the time domain. By encoding, the fading of each unit's code signal during transmission can be considered statistically independent, thereby eliminating the effects of flatness fading and Doppler shift. COFDM wireless monitoring equipment has strong diffraction and anti-jamming capabilities. It is generally applicable to government enterprises such as *,*, and fire protection. Meanwhile, COFDM equipment can realize fixed-mobile and mobile-mobile rooms without any additional equipment. The use of this equipment is ideal for installation on mobile platforms such as vehicles, ships, helicopters, and drones.
Vision Crystal Wireless Helicopter/Droneless Wireless Audio and Video Transmission Products
Visual Crystal Wireless PRO 800 Wireless Audio and Video Transmission Products
The application of COFDM technology in wireless video transmission has the following advantages:
1 It is suitable for non-communication and blocking environments in suburban areas and buildings, and has excellent “diffraction” and “penetration” capabilities.
2 It is suitable for high-speed mobile transmission and can be applied to transmission equipment such as vehicles, ships, helicopters, and drones.
3 The transmission equipment using COFDM technology can realize fixed-mobile, mobile-mobile and other equipment transmission without any additional equipment. The transmission has the characteristics of strong phase stability, long transmission distance, flexible application, etc. COFDM transmission equipment generally shows high performance-to-price ratio.
4 used for high-speed, large data transmission, the rate is generally greater than 4M bps, to meet the high quality video and audio transmission.
5 Strong anti-interference, can transmit data smoothly in complex electromagnetic environment.
6 It has excellent performance in combating frequency selective fading or narrowband interference and interference between signal waveforms. Through the joint coding of each subcarrier, it has strong anti-fading capability.
COFDM and OFDM technology, although the name is only one letter difference, but it allows wireless audio and video transmission applications have more possibilities.

Waterless Diffuser

LED Colorful Egg Aromatherapy humidifier/Aroma Diffuser

Function: Aromatherapy/humidification /clean & reflash air.
Purify & reflash indoor air, keep healthy in the room/indoor
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* Input voltage: DC24V, Power:12W,Ultrasonic frequency:2.4HZ
* Tank:200ML,Spay time: 6-8hrs,Effective area: 10-20㎡ Noise Ratio< 35dB
* Spray quantity: about 30ml/hr; 10s Intermittent spraying, 1hr/2hr setting.
* LED colofur lighting,manual or automatic switch to ligh,7 color change
* When no water,it will power-off automatically,Timed work
* Warm night lamp, air humidification, charming fragrance, purify the air.
* Egg-shaped,eco-friendly ABS & PP,Frosted surface,shell resistant to row.

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* Function: Aromatherapy/humidification /clean & reflash air.
* Purify & reflash indoor air, keep healthy in the room/indoor
* The humidfy effect to remove dust and static electricity.
* To add some essential oil into the humidifier,clean air.

* Operation and function,Press the spray button
1st press: to start continuous spray, "ON" indicator.
2nd press: to be modes of spray for 1s and stop 10s, "10s" indicator.
3rd press: to 1-hours working mode. "1H" indicator.
4th press: to 2-hours working mode. "2H" indicator.

5th press: long press over 2s to stop working.


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