Troubleshooting COFDM Transmitter Flash Issues

Introduction

COFDM transmitters are widely used for wireless video transmission in drones, cameras, and other applications. Occasionally, users may encounter an issue where parameter changes cannot be saved. This guide explains how to identify and troubleshoot such issues, using a real-world example.

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Customer Case

A customer purchased two sets of a COFDM transmitter system. Here’s what they observed:

• Transmitter Set 1: Works perfectly. Settings can be adjusted via the configuration tool or PC serial port, and all changes are saved after power cycling.
• Transmitter Set 2: Settings can be adjusted and appear to work, but after powering off and on, the changes are lost and previous settings are restored.

The customer confirmed that the same configuration works correctly on Set 1 but cannot be stored on Set 2.

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Step 1: Identify the Flash Chip Issue

Based on the reported symptoms, the problem is likely hardware-related, specifically the flash chip. To confirm:

1. Connect the transmitter to a PC using a serial port tool, such as Serial Debug Assistant.
2. Send the AT command:

ATGSN_

3. Take a screenshot of the response and share it with the support team. This helps verify the flash chip model and determine whether a replacement is needed.

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Step 2: Important Safety and Compliance Tips

While troubleshooting, keep the following points in mind:

• Always connect an antenna before powering on the transmitter. Running it without an antenna may damage the PA.
• Use legal bandwidth settings. In the example video, the transmitter bandwidth was set to 10 MHz, which exceeds the legal limit. Ensure it does not exceed 8 MHz.

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Step 3: Next Steps

Once the flash chip is confirmed, the likely solution is replacing the chip. After replacement, the transmitter should store settings normally, just like the working unit.

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Conclusion

Flash chip issues in COFDM transmitters are uncommon but can prevent settings from being saved. By following the steps above—checking the chip with AT commands, adhering to safety guidelines, and using legal bandwidth—you can identify the problem and take the necessary corrective action.