Demystifying the DJI 4G dongle 2 and DJI enhanced transmission.

[Deleted member 191071]

Hey everyone,

I recently got my hands on the DJI 4G Dongle 2 for my DJI Air 3s, and honestly, it's been a game-changer for connection reliability, especially in areas where I used to experience signal drops. I know the concept of "Enhanced Transmission" and how the dongle integrates can be a bit confusing, so I wanted to share a simple breakdown to help anyone who's considering it or just wants to understand it better.

The reason why I like it so much is beacause I live high up on a hill with very lush trees and shrubbery that just eats radio waves for breakfast. Also I am within the outer control zone of an airports forcing me to stay below 50m / 150ft above ground level. Transmission swaps often between ocusync and DJI enhanced transmission over internet and more so with lower altitudes.

I've seen a lot of questions about whether the dongle replaces OcuSync, or if it's just for internet access. Let's clarify!

Understanding DJI Enhanced Transmission with the 4G Dongle 2

First and foremost, it's crucial to understand that the DJI 4G Dongle 2 does NOT replace OcuSync. OcuSync is always the primary, low-latency, and high-bandwidth connection between your DJI RC 2 controller and your drone (e.g., DJI Air 3s). The 4G system acts as a smart, secondary, and redundant layer.

Here’s how it works, step-by-step:

1. The Primary Link: DJI OcuSync (Controller ↔ Drone)
   • This is the direct, real-time radio signal (usually 2.4/5.8 GHz) that your RC 2 uses to control the drone and receive its video feed. It's designed for low latency and high reliability over shorter to medium distances.
   • Analogy: Think of this as a direct, dedicated cable connecting your controller to the drone. It's super fast and responsive.
2. Internet for Your Drone: The 4G Dongle 2 (Drone ↔ DJI Servers)
   • When you plug the 4G Dongle 2 into your drone (e.g., DJI Air 3s), the drone gets its own independent internet connection via a cellular network.
   • The drone uses this 4G connection to send its video feed and telemetry data directly to DJI's Enhanced Transmission Servers in the cloud.
   • Analogy: The drone now has its own mobile phone, constantly streaming data to a central hub.
3. Internet for Your Controller: Your iPhone's Hotspot (RC 2 ↔ iPhone ↔ DJI Servers)
   • Your DJI RC 2 controller (with its built-in screen) needs its own internet connection to access the DJI Enhanced Transmission Servers.
   • The simplest way to do this is by connecting your RC 2 to your iPhone's personal hotspot (Wi-Fi tethering). Your iPhone uses its 5G/4G cellular connection to connect to the internet, and then shares that connection with your RC 2.
   • The RC 2 then uses this "Internet Connection" to communicate with the same DJI servers where your drone is sending its data.
   • Analogy: Your RC 2 is also like a mobile phone, accessing the same central hub through your iPhone's data plan.
4. The "Enhanced Transmission" Magic (DJI Servers orchestrate everything!)
   • This is where it all comes together! The DJI Enhanced Transmission Servers act as a central bridge.
   • If your OcuSync signal between the drone and RC 2 becomes weak or interrupted (e.g., you fly behind an obstacle, or too far away), the system seamlessly switches to using the internet connections.
   • The drone is streaming its video to the DJI servers via 4G, and your RC 2 is pulling that video from the same servers via your iPhone's internet connection.
   • It's a smart fail-safe and range extender: the server "relays" the video and control signals.

I tried to generate an image with AI help, it's not perfect but it's something. It's basically a question of making sure both your drone and your remote controller has a connection over internet to the DJI Enhanced Transmission relay servers. The DJI dongle with a 4G subscription nano-SIM (physical) plugged into the drone via USB-C fixes the drone side. To access the DJI relay on the controller side you just have to hook up your RC though wifi, either by mobile router, tethered to your phone or simply your home wifi, just as if you're updating your firmware








Why is this a game-changer?

• Redundancy: You have a backup communication path. If OcuSync temporarily struggles, the 4G link keeps you connected, giving you a video feed and the ability to control (though with slightly higher latency).
• Extended Range (Indirectly): While the 4G doesn't directly extend OcuSync's range, it provides a functional connection far beyond what OcuSync alone could manage, as long as both the drone and your controller have cellular signal.
• Confidence: Knowing you have this robust backup significantly boosts confidence, especially when flying in complex environments or at the edges of OcuSync's range.

I hope this helps clear things up for anyone on the fence or just curious! Feel free to ask any questions.

Happy flying!


Some more detailed pictured of the dongle, sim card, USB-C and slot in the Air 3s.



Also, for DJI's official deep dive:

Introducing 4G Connection for Drones with DJI Cellular Dongle

Introducing DJI Cellular Dongle for enhanced 4G connection in drone operations, boosting range, safety, and data quality for diverse missions.

enterprise-insights.dji.com

 

[Deleted member 191071]

A little FAQ:

• What countries in Europe support DJI Cellular Dongle Enhanced Transmission?Austria, Belgium, Bulgaria, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Monaco, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland, United Kingdom.
• What is DJI Cellular Dongle Enhanced Transmission?DJI Cellular Dongle Enhanced Transmission combines traditional OcuSync transmission with 4G automatic enhancement technology. When the traditional OcuSync signal strength is high, the 4G link maintains a basic connection but does not activate 4G for data transmission, which maximizes a high-quality and low-latency experience while minimizing data consumption. When the OcuSync transmission encounters signal interference, obstacles, or long-distance scenarios, the DJI Cellular Dongle automatically activates the 4G network for data transmission, which is called an enhanced transmission phase. If the OcuSync transmission is completely disconnected, data transmission relies entirely on the 4G network to transmit images from the drone to the ground and commands from the ground to the drone.
• How much data does DJI Cellular Dongle use?With full use of the DJI Cellular Dongle for transmissions, the drone will consume a maximum of approximately 1 GB of data during a 30-minute flight. The remote controller will consume a similar amount of data. So double it if your RC is though a cellular plan.
• Which drones support DJI Cellular Dongle 2?DJI Air 3S, DJI Mini 4 Pro, and DJI Air 3.
• How do I activate Enhanced Transmission in DJI Fly?The drone must have the DJI Cellular Dongle 2 with a nano-SIM card (eSIM is not supported).Check that the DJI Cellular Dongle's indicator is a solid green or blinking green.Connect 4G between the drone and the remote controller, and activate the function via the 4G icon or the "..." menu in DJI Fly.
• How can I check the activation date of the DJI Cellular Dongle and where do I find the serial number?You can find the serial number on the back of your DJI Cellular Dongle 2, where it is shown as an IMEI code. Enter the full IMEI code on the device information page to check the activation date.
• Why is a subscription fee required?The subscription fee covers the costs of renting servers and cloud services that enable low-latency and high-quality 4G video transmission. When you purchase the DJI Cellular Dongle 2, a one-year free subscription to the Enhanced Transmission service is included. First year is free, after that about €30 per year.
• How do I renew the subscription when it expires?The DJI Fly app will notify you when the subscription expires. Follow the instructions in the app to renew.
• Are there any restrictions on mobile operators?No, it is recommended to use SIM cards from local operators.
• Can I get a refund if I cancel the subscription?No, as the subscription is a digital product that takes effect immediately upon payment.
• How much latency is there when using Enhanced Transmission?Transmission via the LTE link is easily affected by network signals. Under optimal signal conditions, the minimum latency is approximately 200 ms. If the signal is weak, the latency can increase to several seconds, which not only affects the video stream but can also impact control of the drone. Be sure to monitor the 4G signal strength during the flight.

 

[Suren]

A very detailed and informative post about how 4G works.