How to Setup DJI O4 Pro Air Unit and Best Settings for Camera/Transmission

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In this tutorial, I’ll guide you through setting up the DJI O4 Air Unit Pro in any FPV drone. This includes connecting the wiring to the flight controller, configuring Betaflight OSD, and sharing useful tips and best transmission/camera settings to get the optimal performance for your specific needs.

Still debating whether you should get the DJI O4 Pro? Check out my review: https://oscarliang.com/dji-o4-air-unit-pro/

Where to Buy?

You can purchase the DJI O4 Air Unit Pro at the following retailers:

• AliExpress: https://s.click.aliexpress.com/e/_ooZCvq5
• GetFPV: https://oscarliang.com/product-6ugi
• RDQ: https://oscarliang.com/product-22l1
• Amazon: https://amzn.to/3Cb5xjh
• FPV24 (EU): https://oscarliang.com/product-zklr

The complete O4 Pro package, including the camera and antenna, retails for US$229. Individual spare parts can also be purchased separately, allowing you to replace damaged components without buying a new unit:

Connecting O4 Pro to FC

The DJI O4 Air Unit Pro uses the same 6-pin connector and pinout as the O3, making it plug-and-play with flight controllers designed for existing DJI Air Units.

Pinout of the 6-pin connector:

• VCC: Power supply
• GND: Ground
• RX/TX: Required for OSD and telemetry (e.g., displaying battery voltage)
• GND and SBUS: For DJI Remote Controller (optional)

If you are not using a DJI Remote to control the drone, and are instead using your own radio receiver, it’s recommended to remove the SBUS wire (DJI HDL) from the connector. This can prevent potential conflicts. Use a sharp tool, such as a needle, to lift the tab in the connector and pull the wire out. In this case you may also remove the additional ground wire (brown).

Powering the O4 Pro

The O4 Pro can be powered directly from a 2S to 6S LiPo battery (7.4–26.4V). However, whenever possible, power it via a 9V BEC on the flight controller for added protection against voltage spikes.

Power requirements:

• Max power consumption: ~10.5W
• Current draw: 1.15A at 9V
• Recommended BEC: Rated for at least 1.5A at 9V

Disconnecting Camera and Antenna

It’s possible to disconnect the camera or antenna if it makes installation easier.

Loosen the four M2 screws at the corners of the Air Unit.

Carefully lift the bottom plate without pulling on the ribbon cable. Disconnect the UFL connectors for the antenna and camera.

Mounting Camera and Air Unit in Frame

When mounting the Air Unit, ensure the DJI logo is facing up. Use M2 screws to secure the transmission module.

Activation

Once the O4 Pro is connected to the flight controller (FC), it’s time to activate it. If the Air Unit has been previously activated, this step is not required.

Download DJI Assistant 2 (Consumer Drone Series):  https://www.dji.com/nl/downloads/softwares/dji-assistant-2-consumer-drones-series.

If you have previously installed it, it’s a good idea to download and install the latest version. Note: Activation cannot be done via the DJI Fly App.

Important: The O4 Air Unit must be powered by a battery or a correctly rated power supply during activation. Unlike the O3, it cannot be activated using just the USB-C cable. Although the USB-C cable is not included, any USB-C data cable will work.

Firmware Update

While connected to DJI Assistant 2, check if new firmware is available for your O4.

Pro Tip: For firmware updates, you can unplug the battery during the process to avoid heating.

Pairing DJI Goggles 3 with O4 Air Unit Pro

Before pairing, ensure your Goggles 3 firmware is updated to the latest version. Without this update, the O4 Pro and O4 options will not appear in the menu. Follow these steps:

Update Firmware

• Turn on the Goggles 3 and connect them to your computer using a USB-C data cable.
• Update the firmware via DJI Assistant 2.

Pro Tip: If the Goggles 3 does not appear in DJI Assistant 2, navigate to the goggles menu:
Settings → About → OTG Wired Connection and enable it.

Select O4 Air Unit Pro in the Goggles Menu

• Go to the goggles menu, navigate to Status → Switch, and select “DJI O4 Air Unit Pro.”

Enter Bind Mode

• Press and hold the power button on the goggles until they start beeping, indicating they are in bind mode.

Power on the O4 Air Unit

• Wait for the LED on the Air Unit to turn red.
• Use tweezers to press the bind button on the Air Unit. The red LED will begin flashing slowly, indicating it is in bind mode.

Complete Binding

• Binding is successful when the LED on the Air Unit turns solid green, and the goggles display the camera feed.

Pairing Goggles 2/Integra with O4 Pro

To use the O4 Air Unit with Goggles 2 (or Integra), you’ll need to update the firmware on both devices. And don’t worry, you will still get compatibility with the O3 Air Unit, as well as older DJI FPV Air Units and the Vista system.

Pro Tip: If you’re using a Mac and encounter connection issues (e.g., Goggles 2 not appearing in DJI Assistant 2), this is a known problem. Unfortunately, there isn’t a reliable fix. A workaround is to update using the DJI Fly App on your smartphone or switch to a Windows PC for the firmware update.

After the update, go to the goggles menu and select either O4 Air Unit or O3 Air Unit under the settings.

Press the link button between the lenses on the Goggles 2 to enter bind mode.

Power on the O4 Air Unit and wait for the LED to become red. Press the bind button on the Air Unit (e.g., using tweezers). The red LED will flash, indicating bind mode. Binding is successful when the LED turns solid green, and the camera feed appears in your goggles.

Switching Between Pro and Lite

If you use both the O4 Pro and O4 Lite, remember to switch between them in the goggles menu before flying. Each time you fly with a different unit, you’ll need to manually select the corresponding Air Unit in the goggles settings.

Unlock FCC Mode

If your Goggles 3 are shipped with CE mode (to comply with European regulations), they will be limited in terms of output power (only 25mW) and channels. There will be only 1 available channel in the 40MHz mode and 3 available channels in the 20MHz mode.

In FCC mode, you should have the maximum 1200mW output power option, and there should be 7 available channels in the 20MHz mode, and 3 available channels in the 40MHz and 60MHz mode.

For goggles in CE mode, it’s possible to perform the “FCC hack” to unlock higher output power (more range and signal penetration) and more channels (allows more pilots in the air at the same time), but only do this if it’s legal where you fly.

To switch to FCC mode, simply get the file “ham_cfg_support”, unzip it to the root directory of the SD card and put it in the goggles, power on goggles, that’s it.

Download file here: https://drive.google.com/file/d/1ug2U_i5kdrKQQ2I17NLJBXm2tKQeNj5Q/view?usp=share_link

To check if you are in FCC mode, go to Settings => Transmission => Channel Mode, switch to Manual, under 40MHz or 60MHz bandwidth, you should see 3 channels available in FCC mode. If it will only show 1 channel there, you are in CE mode.

Once FCC mode is unlocked, you won’t have to do it again. You can go back to CE mode by factory reset the goggles (in the menu Settings => About).

Setup OSD in Betaflight

The DJI O4 Air Unit fully supports the Betaflight OSD, including the Betaflight OSD menu and all available OSD elements.

Go to the Presets tab, and search for “dji”, the “FPV.WTF MSP-OSD” preset should pop up. In options, select the UART you have connected to the O4 Pro Air Unit.

To enable HD OSD, go to the settings menu in the goggles, Settings > Display > Canvas Mode, and select HD OSD.

This allows you to display the OSD with smaller fonts and drag OSD elements all the way to the edges of the screen. If you select Normal Mode, the font will appear much larger.

Finally, go to the OSD tab in Betaflight Configurator. Under Video Format, ensure HD is selected.

Setup DJI Remote Controller

If you’re using a third-party radio link, you can skip this section.

Using DJI’s remote controller eliminates the need to wire a separate radio receiver to the flight controller, as the DJI O4 Air Unit also serves as an RC link. This simplifies the setup process. However, there are a few downsides to consider:

• Basic functionality: DJI’s remote controllers lack the advanced features and control precision offered by more sophisticated systems like ExpressLRS.
• Failsafe dependency: Since the video and radio signals share the same link, losing the video signal also results in a failsafe, which isn’t the case with advanced RC links like ExpressLRS that typically outperform video links significantly.

Compatible DJI Remote Controllers:

• RC2: Works exclusively with the Goggles 2 and Integra.
• RC3: Works exclusively with the Goggles 3 and N3.

Pairing the DJI Remote Controller 3:

1. Power on your goggles 3 and RC3.
2. Long-press the power button on both the goggles and remote controller to enter linking mode.
3. Once the devices are successfully linked:
   • The goggles will stop beeping and display the live view.
   • The remote controller will stop beeping.

Configuring Betaflight:

1. In the Ports tab, enable Serial RX for the UART connected to the SBUS wire.
2. In the Receiver tab, set the protocol to SBUS (via UART).

Videos Recording

To start recording using the goggles, swipe down from the top to access the Record button in the on-screen menu. Alternatively, you can configure the goggles and the O4 Air Unit (AU) to start recording automatically when you arm the quad. Navigate to Settings → Camera → Advanced Camera Settings to enable this option, which many pilots find more convenient.

You may find the video files get split in the O4 when it gets to about 4GB. This is due to the FAT32 format of the SD card, which has a 4GB file size limit. There is no work around to this unless you record at a lower resolution or frame rate which leads to smaller file size.

However, here’s the silver lining. When these split files are imported into a video editor sequentially, they should play back seamlessly. There shouldn’t be any skips, stutters, or overlaps. It means that while you might have multiple files for a single recording session, your final edited video can still be one smooth, continuous clip.

If you need to stablize these videos in Gyroflow, the program actually allows you to import these clips first before applying stabilization to ensure consistency.

Video bitrates under different resolution/frame rate:

• 4K 60fps: 130Mbps
• 4K 50fps: 120Mbps
• 4K 30fps: 90Mbps
• 2.7K 60fps: 100Mbps
• 2.7K 50fps: 90Mbps
• 2.7K 30fps: 70Mbps
• 1080p 120fps: 80Mbps
• 1080p 100fps: 70Mbps
• 1080p 60fps: 50Mbps
• 1080p 50fps: 40Mbps
• 1080p 30fps: 25Mbps

Download Video

To download videos, plug in the USB cable. There’s no need to remove the SD card. For the O4 AU, you’ll see two separate external drives—one for the SD card and one for the internal memory. To download video off the Goggles, you should power them on first, otherwise connecting the USB cable does nothing.

If you plan to record videos directly on the O4 Air Unit, you might want to get a micro SD card for expanded storage. Note that not all SD cards are compatible. For example, I encountered a slow SD card warning with the Sandisk Extreme Pro 64GB U3 A1 card. Switching to a Samsung 256GB Evo A2 resolved this issue. You can find that card here: https://amzn.to/3B8JplQ

For best performance, format the SD card inside the Air Unit using the Format option in the goggles’ camera menu.

Video Stabilization

The O4 Air Unit supports two stabilization methods: Rocksteady and Gyroflow.

Rocksteady is built-in and can be enabled in the goggles’ menu. It stabilizes your footage automatically during recording, offering results that are good enough for most users. To use Rocksteady, set Recording Stabilization to On.

Gyroflow is a free software-based stabilization tool. It provides more flexibility, allowing you to fine-tune stabilization levels to meet your preferences. With Gyroflow, the raw footage remains unstabilized, and you decide how much stabilization to apply during post-processing.

To use Rocksteady, simply set Recording Stabilization to On.

If you want to use Gyroflow and make the most out of it, set

• Aspect Ratio: 4:3
• Camera FOV: Wide
• Recording Stabilization: OFF

To use Gyroflow, you need to download it, which is free. You just need to drag and drop your footage in the software and the stabilized footage ready to be exported. You can fine tune the stabilization settings, which I explained in my Gyroflow tutorial: https://oscarliang.com/gyroflow/

How to Avoid Jello and Vibration

The O4 camera is highly sensitive to vibrations, making it crucial to isolate the camera from vibration sources or eliminate vibrations altogether.

Avoid using a 24kHz PWM frequency on your ESC. Similar to the O3, the O4 performs poorly with low ESC PWM frequencies due to increased vibration and noise. Using a higher frequency, such as 48kHz, is recommended for optimal stabilization performance.

Mounting the O4 camera directly on carbon fiber or CNC aluminum is not advisable, as vibrations can transfer directly from the motors to the camera, leading to jello effects in your footage. Instead, mount the camera on a soft material that provides vibration dampening.

Many modern frames come equipped with silicone or rubber inserts or spacers specifically designed for mounting FPV cameras, which can reduce vibrations. These materials act as a buffer, preventing direct transmission of motor-induced vibrations to the camera, thus enhancing video clarity and reducing jello.

Best O4 Pro Settings

Recommended Camera Settings for the Best FPV Experience (For those who prioritize low latency and don’t care much about recording quality):

• Aspect Ratio 4:3
• Video Quality: 1080p 100fps (offers lowest latency)
• Camera FOV: Wide
• Auto ISO Limit: 6400
• Color: Normal
• Auto Mode

Recommended Camera Settings for the Best HD Recording (For those Using ND filter, Gyroflow stabilization, and Color grading):

• Aspect Ratio 4:3
• Video Quality: 4K 60fps (30fps might be better for low light, but it can increase latency, making accurate flying harder.)
• Camera FOV: Wide
• Recording Stabilization: OFF
• Color: D-Log M
• Sharpness: -1 (you can increase sharpness in post-editing if needed)
• Noise Reduction: 0 (or +1 in low-light situations to reduce noise in dark areas)
• Camera Mode: Manual
• Shutter Speed: 1/120
• Auto ISO
• Auto ISO Limit: 200 – (set this as low as possible to avoid graininess; however, too low might make the image too dark.)
• White Balance: Put White Balance on Auto first and see what the system choose, then lock in with that value, so WB is fixed during flight
• Display Assist: On (restores contrast and saturation in the goggles feed when using D-Log M but does not affect recorded footage.)

Recommended Camera Settings for Decent HD Recording (For those who prefer little to no editing):

• Aspect Ratio 4:3
• Video Quality: 4K 60fps
• Camera FOV: Wide
• Auto ISO Limit: Set as low as possible for your lighting conditions. If unsure, leave it at the default (6400). Note that higher ISO may lead to grainier images in dark areas, but it ensures visibility.
• Recording Stabilization: ON
• Color: Normal
• Camera Mode: Auto
• White Balance: Auto

Recommended Transmission Settings for Solo Flying

• Race Mode: OFF
• Transmission Power: Use the highest power level legally allowed, or set it to Auto.
• Channel Mode: Manual
• Bandwidth: 60MHz (60mbps bitrate)

Recommended Transmission Settings When Flying with Other Pilots

• When flying with other DJI pilots: Consider reducing transmission power and using smaller bandwidth.
• When flying with pilots using other FPV systems (e.g., Analog, HDZero): Enable Race Mode to reduce interference.

Race Mode

Race Mode is a feature designed specifically for FPV racing, available only on the DJI Goggles 3 and N3, but not on the Goggles 2 and Integra due to hardware limitations. It optimizes the system for low-latency performance and minimizes interference in race environments by aligning its channel frequencies to Race band. Here’s what Race Mode offers:

• Lowest Latency: Race Mode forces the system into 100fps with a 20MHz bandwidth, achieving latency as low as 20ms.
• Channel Alignment: Channels align with standard race band frequencies, making it more compatible with other FPV systems.
• Cleaner Signal: The telemetry link now operates on the same static frequency as the video signal, reducing interference with other pilots. When the Air Unit is off, the goggles stop transmitting altogether, allowing pilots to walk around without affecting others.
• Trade-offs: Narrower bandwidth and lower power output reduce range and penetration, making it unsuitable for freestyle, cinematic, or long-range flying. However, these limitations are acceptable for racing, which typically occurs in open fields.

Caution: Avoid powering on your Air Unit while others are in the air, as it momentarily sweeps across the band, potentially causing interference for those who are still in the air. For all other types of flying, normal mode offers better RF performance.

Transmission Power Fine Tune

This feature allows you to fine-tune the output power of your VTX by ±1mW to ±7mW to ensure compliance with racing event regulations. For most users, this setting isn’t necessary unless you’re attending a regulated racing event where precise power levels are required.

Spectator Mode

The Spectator Mode lets you watch other pilots flying with the O4 Air Unit, but it comes with compatibility limitations:

• Goggles 3 and N3 users can only spectate other pilots using G3 and N3.
• Goggles 2 and Integra can only spectate other pilots using G2 and Integra.

Spectator Mode does not work across these two generations, so ensure you’re using the same generation goggles as the pilot you want to spectate.

Replacing Camera and Antenna

The O4 Pro is modular, meaning its camera and antenna can be replaced easily. Disassembly is straightforward, making it convenient for repairs or upgrades.

While the O4 Pro and O4 Lite camera cables are physically the same, the cameras are not interchangeable—if you swap them, no image will display. The O3 camera is not compatible at all with either the O4 Pro or O4 Lite.

If you need a longer camera cable for the O4 Lite, you can use the cable from the O4 Pro, as they are interchangeable in length.

Conclusion: Setting Up the DJI O4 Pro Air Unit

The DJI O4 Pro Air Unit is a cutting-edge FPV system that brings incredible video quality, reliable transmission, and advanced features to your FPV drones. While the setup process may seem intricate at first, this guide simplifies everything from wiring and pairing to fine-tuning settings for optimal performance.

By following this guide, you’ll not only get your O4 Pro Air Unit up and running smoothly but also be equipped with tips and tricks to optimize its performance. Now, you’re ready to enjoy crystal-clear footage, seamless transmission, and an enhanced FPV experience. Fly safe, and have fun exploring what the O4 Pro can do!