HDMI Wireless Video Transmitter and Receiver COFDM-908T

Q. What is the video resolution?
A: HDMI 1080P.

Q. Does the transmitter power current is high?
A: For Transmitter, the different PA (power amplifier) inside, the current is different. 20W 6-7A, 10W 5A, 5W 3A, 1-2W 1.6A

For Receiver, the current is only 0.3A (300mA)

Q: Like we only need 10km, how much PA is recommended?
A: Considering that your transmitter and receiver are used on the ground, unlike drones, the heights of the transmitter and receiver are very different. It is recommended to use a 10W PA transmitter for 10 kilometers. You also need to consider that your receiver is installed on the car, and it keeps moving at high speed at any time. Only a high-power transmitter can ensure the signal stability at the receiver.

Q: What frequency is better? 2.4G or 5.8G?
A: The frequency range of Cofdm is 170~860Mhz.
We also have products that use 2.4G or 5.8G, but the range of these two intervals is the same as the frequency of WiFi, which will cause the transmission to be greatly interfered by WiFi, and the transmission distance will be greatly shortened.
If there are digital TV DVB-T signals locally, try to avoid frequencies in these ranges when selecting frequencies.

Q: Can customers adjust the frequency by themselves? If sometimes the frequency is occupied.
A: The default center frequency is 595Mhz, generally there is +/-15Mhz bandwidth, which is 30Mhz, and the frequency range can be adjusted. (580-610Mhz).
Beyond this range, it is necessary to change the antenna and PA customized according to this center frequency.

Q:How does the customer adjust the frequency of the transmitter or receiver? Is there any software to change the frequency?
A:It's very easy, the transmitter can use the assistant board next to the picture, and the receiver's assistant board is on the fuselage, with a screen and buttons.

But it is not recommended for customers to adjust, because sometimes he changed the parameters of the transmitter but did not change the parameters of the receiver, saying that he could not receive the signal.

Q: Can I adjust the power amplifier on the transmitter?
A: The user can reduce the actual output power by increasing the impedance of the high power, but cannot increase the transmitter of the low power PA.
For example, 10W PA can change to 5W PA, but can not change 5W PA to 10W.

1. No one can tell you the exact transmission distance. Because the transmission distance depends on the height of your transceiver antenna and the type and thickness of obstacles, whether the transmitted signal can be diffracted, whether there is interference in the current frequency, etc.
2. There are trees or a mountain in the middle, and the transmission distance is different.
3. It is difficult to tell you an accurate transmission distance, even the walls have thickness, generally 500-1000 meters.
4. Please watch our test video, if you think it is suitable, you can buy a sample for testing, if you are not satisfied, you can return it to us.
5. Here is a form for COFDM PA and LOS and NLOS transmission distance for your references.

Now COFDM-908T supports H.264, not H265.

Max support 1080 50P. We have actually tested that at 1080P60, the frame will be stuck, or the recognition will be incomplete

1. Power consumption is equal to current times voltage. For example, for a 10W transmitter, the current is 5.5A, and the voltage is 12V, so its power consumption is 66W.
2. If you prepare a 1000W rechargeable battery and use a 10W PA transmitter, it is estimated that you can use 1000W divided by 66W, which is equal to 15 hours.

1. Whether the link between the transmitter and receiver is good or the signal strength can be seen on the small screen at the COFDM receiver.
2. Not on the transmitter. Because COFDM is a one-way transmission, only the receiver can receive the signal strength of the transmission and show them on the screen. If the transmitter needs to see these signals, it is necessary to add a set of data transmission devices to transfer the status signal from the receiver to the transmitter and display them by the signal light.
3. The transmitter and receiver of two-way transmission can have this function, and it is recommended to choose a bidirectional transmission device.

1. First of all the frequency is correct.
2. In order to achieve the best performance of the transmitter, power amplifier and antenna, they are generally customized according to a central operating frequency point, and they can all work within a working frequency range, generally ±15Mhz. That is to say, when the central operating frequency is 290Mhz, the working range of the transmitter is 275Mhz~305Mhz. So it meets the frequency range of 280~300Mhz required by customers.

1. Yes, the wireless video signal reception is improved by using Yagi and omni-directional antennas.

2. 

3. 

1. Yes, we can build the transmission of telemetry and video in COFDM-908T.

2. The below model of transmission of telemetry is recommended.

   https://ivcan.com/p/digital-data-link-for-drones-and-robotics/

   

1. First, the 10-watt RF linear amplifier and the 20-watt RF linear amplifier use the same cavity, which is machined by a CNC mill.
2. CNC milling machines are not only expensive but also take a long time to process. The 20W and 10W cavities are universal, so they can be used with each other. For faster delivery, this character was not changed and used directly.
3. This product actually has 20 watts. We used special instruments to test it before shipment. Please see the video below. （The instrument shows 3.04dBm plus the black attenuator 40dBm equals 43.04dBm）
4. Test video at youtube: https://www.youtube.com/shorts/jfNoZeb1BIA
5. Here are some correspondences between the output power and the dBm parameters displayed by the instrument.
6. 20mW is 13dBm
   200mW is 23dBm
   1 Watts is 30dBm
   2 Watts is 33dBm
   5 Watts is 37dBm
   10 Watts is 40dBm
   20 Watts is 43dBm
   50 Watts is 47dBm
   100 Watts is 50dBm

Normal Four HDMI Video input and One HDMI output box

If it is just a simple splicing of four camera videos into one video, you can add a box with four HDMI inputs and one HDMI output in front of the transmitter. This means that the monitor on the receiver will always display each video on a quarter of the screen.

Yes, our dual antenna RF input receiver supports diversity. You can use two yagi directional antenna on our cofdm wireless video receiver.

For better signal reception, it is recommended to have one Yagi directional antenna and one omnidirectional antenna installed on the receiver.