How can DJI uavs get solid telemetry and video signal nearly 2x distance ?

As you might have read reports or seen via utube vids, how can a DJI P4 for ex. fly and have good signals so much further than yuneec (any uav) - especially IF there is a FCC limit to the power (mw) in transmit power ? (like similar in all countries)

Personally i am sure they use more powerful transmitters, even an extra 100mw would make a large diff and likely more amplification of received signals too.

So if true, then why does yuneec use lesser power for transmitters on most/all uavs ?

Anyone have a tech/viable explanation ??

TIA !

 

Thx for reply,
here is a bit more of the OcuSync protocol/system.
https://forum.dji.com/thread-72819-1-1.html

go down a few replies and a guy explains to a degree how the system chooses modes.

I suspect that it is a combination of more complex transmission signaling, both complex to transmit and receive and interpret, plus the payload protocol is likely more robust and redundant, but it could be parallel payload (data) redundancies that would allow for quick recovery of missed packets (bundles) of data, which would allow reliability at the extremes, the more complex transmission signal and mode hopping as well as channel hopping giving improved reliability too - the system simply being a more robust system especially in electrical noisy areas.

unless invented by dji it would cost more to license the protocol and more complex chips too.

i did calculate a dbi tx spec on a dji model and it was a higher power than is supposedly being used by yuneec for any uavs using st16, iirc about 100mw which is significant when you may have only 300mw being used - EU use less wattage than does USA.

wifi (801.11) is so pervasive it is very cheap and even mimo (multiple in multiple out & spread spectrum tx/rx - normal wifi) used most by most wifi versions, a different 'audience/performance' is being attempted, and most wifi is close communication as well, so complex/expensive systems is not necessary.

also signal strength limits of uavs vs wifi, you can buy 2000mw or higher normal wifi adapters for pc use.

of course i do not have all my question answered and will keep looking, will post if i find real implementation details.

i have read elsewhere that the 2.4ghz telemetry is a yuneec specific protocol but may still use a more simple transmission scheme as it barely seems to operate further than does the 5.8ghz and the slightly better performance may simple be due to 2 antennas and maybe nothing more.

I do find it surprising that yuneec did create the 5.8ghz telemetry backup to the 2.4ghz since most of us lose 5.8ghz before 2.4, but is a nice feature which just might never be used or by very few - likely a very busy 2.4ghz band area (or obstructions) and clear channels can not be found !?

also, since a ST16s is used for H520/TH+ is there a new effort to improve transmission quality ? As also likely a faster basic cpu might have been needed - but still just a 16 channel controller.

ps: i did find that for the st16 on TH, there are either 6 or 8 unused channels, and AUX button is unused on the controller thus ...... !!

thx again !

 

we humans seem to always go to the extreme.

also assuming someone who has 2.5mi reliable uav control DOES NOT MEAN THEY WILL EVER OR ALWAYS USE THAT RANGE, does it ?

No the point of having a 2.5mi capability is that it will likely offer a nice reliable thru trees or between/behind a building or such and give a good distance of control.

if a uav gets out of view, and if video fpv is good then possibly can discover location visually and watch how to get back into uav visual range &/or around obstacles.

meaning, a range just gives a more reliable product, more chances to stay in control !

and if you use waypoints/CCC like i do, the uav can get out of sight NOT too far away (you set waypoint height to 10 meters), but if communications is feeble, which yuneec seems to have chosen a feeble video link at least if not limited telemetry, then you can have a costly TOO LOW TO SEE, where the heck is uav, loss of uav and $$$

of course if signal is still avail, then you can hunt down uav and recover, see how it all works to give a MORE RELIABLE PRODUCT/EXPERIENCE !!

and it appears the reason yuneec communications is much less than dji is that for their higher end uavs, they spent MORE $$ on their transmission system and protocols.

and btw, dji did NOT invent the lightbridge, ocusync tech, it has been around a bit in the RC world, this being prior to 2017.

ps: after 1/4mi i can barely see a uav or maybe even not at all in some light conditions, how about you ?