There are a couple of components that make an excellent drone: a powerful propulsion system, a high- quality camera, long flight time, and responsive controls. One element of a good drone that is often taken for granted is the transmission technology that allows the remote controller and the drone to communicate. A good transmission system provides a long range of control while minimizing latency and enhancing responsiveness.
True to their reputation, DJI has managed to remain at the forefront of high-end transmission technology. DJI drones are equipped with either one of three options for transmission: Wi-Fi, OcuSync, or Lightbridge. How do these technologies differ and what are the benefits and limitations of each?
The Classic: Wi-Fi
The most basic transmission technology used by DJI is Wi-Fi and is mostly found in consumer-grade drones such as the Spark and the Mavic Air. This is a simple technology where the drone maintains a private Wi-Fi network that the user connects to using the remote controller or a mobile device. Wi-Fi transmission is possible through either one of the 2.5 GHz or 5.8 GHz bands, and the connection can switch between any of the two for optimal control.
The older Spark uses a standard Wi-Fi connection while the Mavic Air is equipped with enhanced Wi-Fi. With the enhanced Wi-Fi, the Mavic Air gains an effective range of 2000m – a huge upgrade to the 500m of the Spark. Either Wi-Fi systems allow streaming of real-time 720p video to the mobile device that is tethered to the controller.
The main benefit of sticking with old-fashioned Wi-Fi transmission is the relative simplicity of the technology. Pairing the drone and remote controller is very easy and does not require any proprietary software. The use of a Wi-Fi transmission system also helps keep the Spark and the Mavic Air two of the most affordable ultra-portable drones out available today.
Simplicity comes at a price, though: drones using Wi-Fi transmission are known to have some of the shortest transmitter ranges. In the case of the Mavic and the Spark, this is not that much of a problem. Considering how small these two drones are, their effective ranges should be just far enough to maintain visual line-of-sight.
Today’s Favorite: Lightbridge
The DJI Lightbridge transmission system is mostly found on their professional-grade drones and is available in two versions. Slightly more affordable brands such as the Phantom 4 Pro and Phantom 4 Advanced are equipped with the standard Lightbridge version, while the upgraded Lightbridge 2 greatly augments the higher-end Inspire 2, Matrice 200, and Matrice 600 drones.
The transmission range of the standard Lightbridge is only slightly better than Wi-Fi, at about 1700m. The Lightbridge 2 is much more powerful, with a range of up to 5000m on FCC-compliant and 3500m on CE-compliant areas. The extended range of the Lightbridge 2 makes it an excellent transmission technology for some commercial drone applications such as aerial mapping, site inspection, or search and rescue.
In terms of flexibility, the Lightbridge 2 version holds the advantage for the ability to switch between 2.4 and 5.8 GHz bands. The standard Lightbridge version only operates on the 2.4 GHz band, which may be restrictive but also helps keep the price of the drones down. Both Lightbridge versions support real-time video streaming with resolutions of up to 1080p.
Aside from its enhanced range, another huge advantage of Lightbridge technology is its ability to set up Master and Slave connections. This allows separate controls over the drone and the camera and gimbal setup, making it easier for professional photography teams to capture unique and captivating drone shots.
Higher-end drones such as the Matrice 200 and the Inspire 2 use Lightbridge 2 technology with the advanced Cendence flight controller. This is a fully customizable remote controller with mappable and assignable functions, making it highly versatile across several industries.
The Future: OcuSync
The OcuSync transmission system debuted along with the Mavic Pro in 2016, quickly becoming the standard transmission technology for many of the prosumer drones from DJI. Its transmission range is up to 7000m, farther than any other transmission technology that DJI has to offer. This is an extremely impressive range that was once believed to be impossible to attain. It was even more impressive considering how small the controller of the Mavic Pro is.
OcuSync technology also has the capability to switch between the 2.4 GHz and 5.8 GHz frequency bands and can stream real-time video up to a resolution of 1080p. The video resolution may change depending on the situation, but OcuSync generally transmits 1080p in short-range distances, and may shirt to 720p when the distance between the drone and the controller grows.
OcuSync inherited the Master and Slave capability of Lightbridge, allowing independent movement of the drone and the camera. Moreover, DJI claims that the OcuSync transmission technology is more resistant to signal interference so pilots should not experience signal drop outs as often. This is a huge benefit for drone pilots who frequently have to conduct commercial drone flights in areas with a high amount of radio signals.
An area that DJI chose to focus on with the OcuSync was latency. This refers to the delay between control response and vide streaming between the drone and the controller. With the OcuSync, latency for remote control commands was kept at only 5ms. This level of latency is near instantaneous and results in very smooth and responsive drone flight. Latency for video data clocked at around 160ms – not bad, but probably not low enough for professional FPV racing.
A unique feature of the OcuSync is its wireless compatibility with the DJI Goggles and DJI Goggles RE. With the low latency and superior FPV video quality that the OcuSync offers, it is by far the best transmission technology for use with high-speed FPV flight. What’s even cooler is that Lightbridge makes it possible to connect multiple DJI Goggles to a single controller so you can have other people act as ‘spectators’ to your flight.
Shortly after the release of the Mavic Pro, the Phantom 4 Pro V2.0 was released. What made this an especially interesting release was that the V2.0 did not come with a lot of upgrades from the original Phantom 4 Pro. The only upgrade that stood out was the use of OcuSync instead of Lightbridge 2. This might be an indicator that DJI will focus on OcuSync technology instead of making further upgrades to the Lightbridge. Only time will tell if there ever will be a “Lightbridge 3” or if we should expect an “Ocusync 2” soon.
Considering all the prosumer drones available today, the proprietary transmission systems of DJI are still probably the best-performing. The OcuSync technology has consistently impressed drone experts worldwide and have all of us excited for what else DJI can come up with. With its impressive range, low latency, and wireless compatibility, it may very well be the foundation that all innovations on transmission technology build upon on.
Experienced drone pilots can recognize the importance of a good transmission system. For professional drone photographers and mappers, a good transmission system may be the advantage that can help cut down the time needed to do a job or to get that perfect drone shot.