With a lot of talk around the Mavic 3 and DJI Smart Controller support and some of the confusion on Ocusync 2 and the M3. This should put a bit more clarity on what’s going on and why it’s not as simple as Ocusync 2 on the RC-N1 works and the Ocusync 2 on the SC does not.
A bit of history DJI created Ocusync with the release of the Mavic Pro, before this on previous models we had the Lightbridge system that was a hardware-based radio system. What is known as Ocusync 1 on the Mavic Pro is a software radio (SDR) solution based on off the shelf Leadcore SOCs.
These are Arm A7 chips that have a built-in 4G/LTE RF modem.
Later the Mavic 2 was released with what DJI called Ocusync 2 again based on Leadcore with the White FPV goggles and the Goggles RE and Ocusync Air system all fielding the same Leadcore chipsets.
This was DJI’s move into SDR based video/RC and telemetry link and it was driven by the leadcore LC1806 Series for instance. Regardless of if it was Ocusync 1 or 2 it was all the same Leadcore based system and allowed for up to 1080p video, long-range and latency of around 130ms.
Because this was DJI’s own SDR based link it also meant they were able to actually upgrade earlier hardware with then newer Ocusync 2 protocol on things the White FPV Goggles.
Next came along the DJI Digital FPV System, this took things to a whole new level as while DJI had dabbled in FPV with the Ocusync Air system this was again Leadcore based and suffered from high latency. However, with the Digital FPV system, we had something new we had not seen before. the Leadcore chipset was gone and the system was driven by a new custom P1 SOC.
While there are no published specs on this chip we know it’s a dedicated custom SOC with RC/ Video encoder and built-in dedicated RF modem. This new chipset is used in all parts of the Digital FPV system so the Goggles, DJI FPV RC V1 and Air unit all feature the same SOC with it being used to directly encode and decode the video, RC link and telemetry.
The major benefits of this new chipset compared to the Leadcore solution is much higher bitrates and the sub 30 ms latency link compared to 120 or so ms seen before and it’s lower than anything we have seen before from DJI.
DJI went on to develop a second version of the chipset called the S1, this is a smaller version of P1 with no video encoder on board. This chip is designed to be either used in RC applications where no video output is needed like the FPV Drone remote or in drones/remotes where the encoding is offloaded to other processors such as the main video processing SOC.
Basically, this is a very similar setup to the old Phantom 3 Advanced and Pro models where there was a difference in video recording resolution and frame rates and live feed bitrate as the Advance used the A9 Image processing SOC for both video link encoding and SD recording whereas the P3Pro had a dedicated second TI encoder for the live feed allowing the A9 to be dedicated for the SD recording and as such higher resolutions and frame rates could be had by the user.
The same principle stands for the S1 and P1. One dedicated encoder and one does not and needs an external one. Since the FPV system was released we have seen either the P1 or S1 chipset appear in all the new RTF models from DJI replacing the Leadcore solution.
The first craft was the Air2 using the S1 in both the drone and remote with the H6 camera SOC handling the encoding for recording and live feed, the Mini 2 was released later again with the same setup.
The DJI FPV Drone was released with the P1 onboard like the Air Units and the Air 2S was the first consumer camera drone model to use the P1 aircraft side with the S1 in the RC-N1 RC allowing for higher recording rates and resolutions but 1080p 30 live feed. DJI also called this link O3 for the first time. The new Mavic 3 again uses the P1 craft side, we know the RC-N1 that’s used on the Mini2, Air 2/sand the M3 is based on the S1 however and is classed as Ocusync 2.
However, it’s not clear yet what the RC Pro is using as we don’t have full tear down images yet but as that remote DJI call O3+ when used with the M3 It’s very likely to be the P1 based on that link being 1080P 60 15Mbps and the fact the Enterprise Smart Controller with the M300 also uses the P1.
Here and now it seems DJI is labelling models using the S1 Ocusync 2 but models with the P1 Ocusync 3/3+ in their marketing but it’s worth noting it’s all simply variations of the same thing and the differences are the implementations of the image processing and memory more than anything else.
Now here is where things get a little confusing for the end-user. We actually have two hardware versions of Ocusync 2. The Leadcore implementation on the Mavic 2, P4PV2 and Smart Controller and the custom S1 version on the Mini 2 and Air 2.
Technically while the chipsets are different it’s an SDR and they are compatible with each other without issue as long as DJI allows compatibility via firmware within hardware limits.
However, there is also then the mix of P1 based Ocusync 3 on the Air2S and the Leadcore based Ocusync 2 Smart Controller. While DJI does say they are compatible users have had issues with this combination and this is likely due to the Leadcore solution being maxed out trying to deal with the additional processing overhead.
This also directly feeds into the Mavic 3 not being compatible with the Smart Controller as while the same combination of Leadcore and P1 chipset has been used with the Air2S and SC it’s been problematic and as the Mavic 3 is pushing higher resolution and bitrates than any of the others other than FPV DJI have likely simply decided it’s not going to provide acceptable performance.
While frustrating for users there will always be a point where the hardware limits become an issue. What is interesting in all of this is the DJI Digital FPV system appears to have been a testbed for the custom P1 platform and it’s clearly been a success as DJI have continued to use it in their products including the new Mavic 3.
There has been some noise on the smart controller compatibility it’s a little more complex than just the naming as you can see here. Here and now today it appears it’s not going anywhere and it’s clear DJI build the P1 with an eye to the future as it’s seen wide and varying implementation now in models from the M3 to M300.
This was researched and written by Mads Tech.