FAQ for wireless video transmission

1. Can I change the transmitter and receiver frequency? Can it work on 260 MHz band?
  1. Yes, the frequency range can be changed from 170Mhz (better from 220Mhz) to 860Mhz. So it can work well at 260Mhz band.
  2. The frequency should be modified to the same on the transmitter and receiver. Of cause, the Power Amplifier and antenna frequency should modify the same frequency. (You need to buy a power amplifier and antenna for the transmitter and receiver to meet your changed frequency).
  3. In order to improve the sensitivity of transmitting and receiving, the frequency bandwidth is generally made very narrow (center frequency ±15Mhz, so bandwidth should be 30Mhz). The power amplifier of the transmitter and the frequency of the antenna are specially customized according to the frequency you need.
  4. It is best when you place an order, please tell me what kind of working frequency you need. Our engineers will modify the frequency of the transmitter and receiver, and also modify the PA and custom antenna according to this frequency range to ensure the best sensitivity and support the longest transmission distance.
  5. The default frequency is 590Mhz, With 30Mhz (+/-15Mhz), you can change it without modifying the Power Amplifier and antenna. For example, 578Mhz, 584Mhz, 590Mhz, 596Mhz, and 602Mhz.
  6. If you need to modify the transmitter frequency and bandwidth, you need a special tool of the parameter configure board, please see the below picture, it is not a default accessory, please buy it at an extra cost or contact us before ordering.

parameter configure board tool for transmitter

Yes, it supports to send the video and UART data from the transmitter and receiver.
As it is one-way transmission, so it can not send the control command from the receiver to the transmitter.

If you need to send control commands or other data from the receiver to control other devices such as cameras or drones at the transmitter, you can add a set of cheap digital transmission equipment, contact us, and we can customize it for you.

Simplex-half-Duplex-full-duplex-wireless-video-data-Transmissions-method-one-two-way-transmitter-receiver

Please check the UART define on the transmitter and receiver at the below link. Please tell me if you want to have a lead cable. (default is no)

Drone wireless video transmitter UART connection define for data transmission

drone wireless video receiver UART connection define for data transmission

The transmitter default Power Amplifier is 2 Watts, so it can support 30 KM at line-of-sight.

The below picture is our tested distance from the mountain to the seaside.

If you want to transmit a longer range, you can increase the power amplifier. In addition to one watt and two watts, we can also make 5 watts, 10 watts, and 20 watts for your choice. Larger amplifiers also require larger batteries and current support.

For 20W PA, the power supply should be 24~28V. Only at 28 volts can the power amplifier achieve the best workability.

Our engineer can change the frequency to 300Mhz from the default 590Mhz, The antenna, and PA in the warehouse are 590Mhz, 300Mhz needs two weeks to customize, so the delivery time needs longer than our default 590Mhz.

Yes, it support 720P CVBS video input on the transmitter and 1080P HDMI video ouput on the receiver.
If your camera is HDMI connector, you can use one HDMI to CVBS video convertor box, it will be much cheaper than you used one wireless video transmitter.
If you still need HDMI input on the transmitter, then the below model is recommended.
COFDM-908T is also recommended.

Step 1: Please press OK and the right button at the same time, a menu of whether to save appears on the screen.

COFDM Wireless Reciever save parameter

Step 2: Please press OK to choose Yes to save.

wireless video receiver adjust parameter

Yes, you can change the frequency to 300Mhz, but this is not recommended.
Why?
1. Our wireless video transmitter and receiver both support AES128 encryption and decryption. The password can be changed on the configuration board at any time. It is safe for your video.
2. If you change the frequency on the transmitter and receiver to 300Mhz, the antenna and Power Amplifier frequency should be changed to 300Mhz also.
For a small number of special frequency antennas, maybe the antenna factory will not agree to special produce.
3. Maybe the antenna problem is solved. The power amplifier in the transmitter is preset, and we also send you the test video before the delivery. If the end-user modifies the power amplifier frequency, it is easy to be burned. Without a power amplifier, then this system can not be working well the long distance. The buyer has to send it back to the China factory for repair, Although our repair is free, but the buyer has to pay all the shipping costs.
4. Please tell us what frequency the buyer wants to have, we will modify and test its quality in the factory. after QC passed, we will send you.
COFDM-912T is a one-way wireless transmission system.
That means it only downloads the video or data from the transmitter to the receiver, but it can not upload the UART data from the receiver to the transmitter, for example, it can not control the transmitter's camera or drone.
Is it suitable for your project?
Or check the below link, we will understand clearly your project.
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COFDM-912T is a one-way video transmission system.
If you need to control the camera and drone, you need to choose two-way models.
Now we can offer you the smallest transmitter antenna is 13 cm in length.
Remind, please use the bigger or longer antenna if your project allows, it can get better reception performance in the larger range.
13cm length cofdm wireless video transmitter antenna

The default full set

  1. SD Transmitter ( PA 0.5W, 1W, 2W, 5W, 10W, 20W, 50W optional according to your order demand)
  2. SD Transmitter antenna
  3. HDMI CVBS output receiver with parameter control menu and small screen
  4. 0.8-meter Receiver antenna 1 pcs. (There are two types of installing or fixing the antenna: 1. magnetic sucker base antenna, 2. Default U-type clamp FRP fiberglass antenna )
  5. Optional, parameter configuration board for the wireless video transmitter.

(If you need a magnetic sucker base antenna, the express or carrier thinks the magnetic products will interfere with their plane safety, so the shipping cost is higher than a U-type clamp antenna. )

The default full set package dimension

  1. 84*21*12CM
  2. Gross Weight 4.5KG
  3. If you choose over 100cm antenna and magnetic sucker base antenna, Some freight forwarders will charge extra fees, such as extra long fees and extra fees for strong magnetic items.

  1. The transmitter parameter configures board is different from the one on the receiver. The firmware on the parameter configure board was different from the transmitter and receiver, they cannot be used interchangeably.
  2. The transmitter parameter configures board can adjust the signal attenuation on the transmitter. Per 0.3db will reduce the 0.5W PA.
Here is the transmitter parameter configuration board.
parameter configure board tool for transmitter
Here is the receiver parameter configuration board.
COFDM Wireless Reciever save parameter

Question: Is it possible to change the outpout power (internal PA 0,5 w, 1 w, 2 w) via the configuration board?

parameter configuration board tool for COFDM wireless video transmitter

  1. As answered above, you can adjust the output power by setting the parameters of ATTEN through the parameter configuration board tool on the transmitter. (This tool does not include the default package, you need to notify that you want to have this tool when you order)
  2. If you buy 2W PA, then you can set it 0.5W, 1W, but can not change it to 5W.
  3. We also can make it to 5W, 10W, 20W, and 50W if you need to support long-range.

No.

This wireless video transmitter only supports CVBS camera or video input, other type of video camera needs an extra converter box.

No. It is COFDM (DVB-T) technology.

So the COFDM frequency range is 170-860Mhz. It can support 477, 610, 675, 724, 816Mhz, but can not support 970, 1180, 1230 Mhz.

Our special model transmitter can support all the above ranges, but the receiver needs to use the downconverter block.

In order to allow our wireless transmitting system to support a wider range and better signal strength, we generally set the operating frequency to a certain point (170~860Mhz), and its supported range is only plus or minus 15Mhz. For example, the center frequency is 590Mhz, max support frequency range should be 575Mhz~605Mhz, The PA and antenna are specially customized according to this center frequency.

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FAQs

The power supply of this transmitter and battery both are 3A@28V. At the normal time, the battery we used for tested is 7AH, it can work for 2~4 hours. If you buy15AH chargeable battery, it can work continuously for about 4~8 hours.

There is three frequencies to choose from 800Mhz, 1.4G, and 2.4G.
But there is no 10W Power Amplifier for 150km at 2.4Ghz. So if the buyer want to support 150km transmission distance, only 800Mhz and 1.2G can be chosen.

Not only switch the frequency at the web UI parameter easily, after changing the frequency, it also needs to change the Power Amplifier inside and the same frequency transmitter and receiver antenna. So buyer should confirm which frequency you need before delivery. The antenna is customized according to this frequency.

UI Wireless 1.4G

Regarding the RF cable, our engineer doesn't recommend that you used it so long. There will be a reduced 0.5dB for one meter RF cable. For 3 meters RF cable, the signal strength will be reduced by 1.5dB.
In order to support long-distance, It is better that you use the RF cable less than 1 meter?
In fact, the transmitter is very smaller, it is better to keep a short distance from the transmitter to the transmitter antenna. The power supply cable for the transmitter and ethernet cable from the camera to the transmitter can be longer as there are no losses like RF cable.

Yes, the default video input is IP RJ45 ethernet port, if your camera is HDMI or SDI or AHD, just plus one small encoder box to solve this problem. Please check the below model.

HDMI SDI AV input encoder IP RJ45 Ethernet output

  1. If your area has a DVB-T or DVB-T2 digital television signal, the TV frequency range is 170-860Mhz, it has including 800Mhz, so choose 1.4G is better.
  2. Because the GPS antenna receives the GPS signal and the GPS direction on the drone is up, our transmitter antenna is pointing down to send the signal to the ground. As a result, the 1.4G frequency effect on GPS is negligible.

The package size is 125 x 23 x 11cm. Gross Weight:3.72KG, Volume Weight:7.5KG

long-range wireless video transmitter and receiver for drone package

Here is the full set picture.

15km 30km 80km 150km long-range-wireless-video-transmitter-receiver-full-set

Regarding frequency hopping, the engineer has some suggestions for you.

UI Advance

  1. As the system frequency range is 20Mb, if your bandwidth is chosen 20Mb, then it can not hop (only one point). If the bandwidth is chosen 10Mb, then you have two points to hop, if the bandwidth is chosen 5Mb, then you have 4 points to hop.
  2. If 1410Mhz has jammed, then 1420Mhz also has jammed, as the frequency is too close.
  3. When hopping frequency, the data or video transmission will be disconnected, and your video will be frozen.
  4. At the normal time, it is better to choose hopping is NOT.
  5. If your transmission distance is less than 15~22km, then we have another option to choose from, the frequency has 110Mb, and even if you choose 20Mb bandwidth, it has 5 points to choose from for frequency hopping.

Yes, it supports.
There are two solutions for the multi-transmitter cameras to one signal receiver.
Please check the below test video at youtube
multi-camera transmitter and receiver for ptz surveillance camera
1. 4 IP cameras -> Net Hub -> Transmitter <===> Receiver -> Computer Screen
2. 4 IP cameras -> NVR HDMI output -> HDMI encoder IP output -> Transmitter <===> Receiver -> computer screen.

If you need to support S.bus, then please tell us before shippment, and we will modify our RS232 to TTL.

Our TX900 has three RS232 ports. If you need it to support S.bus, just need plus one small converter from S.BUS to RS232 is ok. ( Mini SBUS Conversion Module Uart to Sbus, Sbus to Uart ).

Mini-SBUS-Conversion-Module-Uart-to-Sbus-Sbus-to-Uart-TTL-RS232

SBUS input UART TTL output and UART TTL input and SBUS output

Please tell us if you need sbus port before delivery. Our engineer will modify the D2 port from RS232 to Sbus.

wireless video transmitter and receiver with sbus from rs232 data port

RSSI wireless link status data requires customers (such as flight controllers) to manually send AT commands to obtain it. It can be obtained in two ways:

  1. Configure UART3 (data port 3rd) as an AT command serial port, and then send AT commands through UART3 (D3) to obtain. https://ivcan.com/change-d3-from-transparent-serial-port-to-at-command/
  2. Update the firmware version 1.5.1 or above, so that there will be an additional TCP server inside for customers to access through TCP to send AT commands to obtain the wireless status.
  3. The LED light is used to indicate the wireless connection status (for example, if the wireless link is disconnected, the light will go out), and there is no dedicated external pin to notify the customer flight control.

Or see the UART AT command list here.

or see https://ivcan.com/how-to-get-the-rssi-and-snr-on-the-drone-transmitter/

  1. The serial port of our wireless video transmission is transparent, and no data is actively sent to the flight controller. This is controlled by the ground station.
  2. It won't send the failsafe command, but you can see the link status light from the signal indicator.
  3. Here is the link status signal strength indicator means
    1. Not Bright: Indicates that the wireless link of the module is not connected
    2. Red: Indicates that the wireless link of the module has been connected, but the wireless signal strength is very weak
    3. Orange: Indicates that the wireless link of the module has been connected, and the wireless signal strength is medium
    4. Green: Indicates that the wireless link of the module has been connected, and the wireless signal strength is very strong
  4. We understand that you hope to have this function, If aircraft loses signal during flight it will not return to home because flight controller will not understand that rc link is lost.
  5. You need to see the link status LED light, if it is Orange or Red, you should control the plane back in advance.
  6. You also can get the RSSI at the below windows

At the normal usage, one node as the transmitter, another node as the receiver. If you need to support long range or over a mountain top, like the below picture, yes, please buy 3rd nord as the reapter.
You just need to put the 3rd node in the middle and set the 3rd node be a 2D3U then ok.

replay repeater for wireless video transmitter and receiver

How to set 3rd node be 2D3U?

Set with AT command:
at+cfun=0
at^dstc=0
at+cfun=1
Restart the link device after the operation

AT command operation postion

UAV Video Link Drone Wireless Video Data Transmitter Receiver new 2023-

On the Web UI parameter mangagment page and debug section,

AT command

Input AT^DGMR?

If you get result is 6602, then it is 15km version.

If you get result is 6603, then it is 30km version.

wireless video transmitter and receiver AT command input section

4K video is supported.
4K video stream generally has more than 8Mbps, and 1080P video generally has more than 2M, so the distance of our wireless video transmission when transmitting 4K video will be shorter than that of 1080P.

In one word, the higher the definition of the video, the shorter the transmission distance.
The video compression is smaller, and the transmission distance is supported farther.

In the process of video transmission, if there is data loss, the picture will appear mosaic or stagnation, freeze and other phenomena.

There will be a limited number of retransmissions at the wireless link level (of course, data errors will also occur if the situation is not good). The upper-layer application on the end will not be aware of it, nor will it ask the sender to retransmit.

If the signal of the wireless link is not good at a certain point after the distance is extended, and there are always bit errors, it is impossible to design it to be retransmitted all the time, so that the end user experience will be very poor.

The wireless link layer has a limited retransmission mechanism. We have tested the tcp protocol for transmission at the video transmission layer (trying to retransmit on the upper layer through the tcp protocol), but the test found that there is no obvious improvement, and it will also lead to uncontrollable delays.

  1. The heat generated by the aircraft side is much larger than that of the ground side. If the fan is running, check whether the air inlet and outlet of the lower fan (the positions of the heat sinks at both ends) are blocked
  2. Try changing the power supply of the air unit transmitter from 24V to 12~18V (the transmit power will be reduced to about 35~36DB)
  3. Slightly reduce the transmit power of the aircraft by the below AT commands: AT^DSSMTP="23" Reboot after setting

Question: Are these settings maximum power of the module? (24 dBm)

Answer: 24dBm is the maximum output power of the link Module, and the gain of the PA (about 14dBm) needs to be added. The actual transmission power after the 24V power supply PA output is about 38dBm.

#

Procurement Specifications

YesNo

Notes

1

The unit shall operate in the VHF BAND and UHF band with its RF transmissions.

UHF

1427.9-1467.9Mhz

2

The unit shall have an RF output power of 27 dBm or more.

Yes

2W 33dBm

5W 37dBm

10W 40-41dBm

3

The unit shall provide Serial (Bidirectional, Fullduplex) as data interface. (RS232 or RS422)

Yes

RS232 bidirectional full duplex

4

The unit power consumption shall not exceed 25W.

Yes

<22W

5

The unit mass shall not exceed 250 grams.

Yes

<150 grams (142grams)

6

The unit shall have a data rate of at least 4.8 Kbps

Yes

RS232:>50kBps

Ethernet:>2M Bps

Lead time: 10 days for small quantity order.

HS code: 8517629900

The difference between the air unit (transmitter) and ground unit (receiver) is two points:

One is the device type: Air unit (transmitter) is the access node and the ground unit (receiver) is the central node.

Two is the rate ratio of the downlink and up link. Over 30km, the best rate ratio is 4:1 or 3:2.

If you don't want to connect the receiver ethernet cable directly to the computer. Then it is not easy to access the receiver at your local network.

Here is two solutions for you.

1. Add the IP address of the 192.168.1.x network segment on the PC side (the PC can be configured with multiple network segment IP addresses)

2. Modify the IP of the wireless video data receiver from 192.168.1.12 to the address of the 10.220.20.x network segment to meet your local network.

For further questions and solutions, please talk with your local area network workmate or engineer, our receiver is like a computer with IP address, it should keep the network segment IP address at the same, for example, 192.168.1.xxx.

Yes, we can change the receiver antenna with a U-shaped clamp bracket to replace the magnetic sucker base.
It is easy to fix on the pole. And magnetic items are charged extra during shipping.
  1. Yes, there are three solutions to do that.
  2. TX900 has three data ports. Distinguish through different transparent serial ports, such as D2 to control relay aircraft and D3 to control mission aircraft. The disadvantage is that the TX900 receiver needs to be connected to two serial ports to send instructions separately.
  3. Use the same transparent serial port to send data in bulk, and then add layer protocols (such as header information) to the data to distinguish which aircraft should receive and process the data. The disadvantage is that the processing of sending and receiving data is complicated.
  4. Or use two receivers: One receiver is for the mission plane (transmitter), and another receiver is for the repeater drone. The connection and operation are easier.

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