Troubleshooting Poor Video Link Signal

User Guide

4/23/20244 min read

  1. Antenna and Cable Check: Ensure antennas and cables are properly installed and not damaged.

  2. Obstacle Assessment: Identify any obstacles between ground and air units during testing.

  3. Parameter Verification: Review and check parameter settings are correct.

  4. Interference Evaluation: Determine if interference is present in the testing area.

Troubleshooting Poor Signal Testing: Essential Steps

V Series Video Link (V21/ V31)

  • Ground Antennas: Install at maximum height for stability.

  • Air Antennas: Avoid blockage by fuselage or wings.

1.Antenna Installation Guidelines:

  • Review DRPR Log for insights during flight testing.

  • Simulate testing environment by adjusting RF values to [-20~-40] on both air and ground units.

2.Pre-Troubleshooting Preparation:

Accessing DRPR Logs and Setting RF Values:

a. Visit the IP Address: Enter the designated IP address in your web browser's address bar.

  1. V series IP address Air: Ground:

b. Log In: visit as Management Login.

And then enter the RF value setting interface. For more setting instructions, pls refer to Support- User Manual-<V Series Video Link Module Settings Manual>.

Key Data Sections: Focus on RSRP, SNR, and DISTANCE

3. Analyzing DRPR Log:

SNR (Signal-to-Noise Ratio) shows the current signal quality. The bigger the SNR value is, the better the signal quality. Take the the picture below as an example: SNR > 19 section means the best signal quality.

Troubleshooting SNR Discrepancies: Address antenna or feeder line issues based on SNR differences.

High absolute difference (> 7) between two SNRs suggests potential antenna installation or feeder line issues, particularly on the side with the smaller SNR. Adjust the direction for one antenna and observe changes in the DRPR log. If no improvement, inspect feeder lines or consider replacements. Referring to the provided images, it's evident that there are issues with the Second Antenna side based on the Center Node DRPR Log.

Interference Detection: Use Background Noise formula to assess environmental interference.

In the Access Node DRPR Log, both antenna SNRs are below 7, indicating poor signal quality from both antennas. Meanwhile, in the Center Node DRPR Log, the SNR for the Main antenna is also below 7, with an absolute difference of over 10 between the two SNRs. This suggests issues with the Main Antenna for the center node, necessitating adjustments and corrective actions, such as changing the antenna angle while monitoring DRPR log changes. This systematic troubleshooting approach allows for the identification and resolution of antenna and feeder line issues for both center nodes and access nodes, step by step.

Once the antennas and feeder lines are confirmed to be in good working condition, the next step is to assess the flying environment for potential interference. Start by checking if the SNR is less than 15. If it is not, consider adjusting the distance between the ground unit and air unit, or reducing the RF power. To determine if there is environmental interference, use the formula: Background Noise = RSRP – SNR No environmental interference is present when the Background Noise is less than -118.


a. The noise primarily originates from the surrounding flying area, but it could also stem from the antennas circuit or other devices such as screens, FPC, high-speed data cables, power supplies, and so on.

b. It's important to reset the devices to factory default settings if there are any special configurations during testing, to ensure they do not impact their actual usage.


Based on the Center Node DRPR Log image provided, the Background Noise Value for the Main Antenna is -120, while for the Second Antenna it's -118. This indicates the absence of environmental interference. However, environmental interference is detected for the access node, as indicated by the Access Node DRPR Log.

Center Node DRPR Log

Access Node DRPR Log

Center Node DRPR Log

Access Node DRPR Log

Center Node DRPR Log

Access Node DRPR Log