lightbridge on SE?

[PhantomFlyer3SE]

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This guy went 4,250 meters - that's nearly 14,000 feet - in Italy - which means CE mode, but he also has the most ideal conditions flying from a mountain over water...

The mysterious video is the last one, all others was FCC territory, where 4000 meter is the promised behavior of SE.
This last one is strange, because many Italian guys complains too, that they can't overtake even 300 meters.

I can only think, that Sardinia is quite away from the continent, the south coast is less than 200 km from Africa. Phantoms decide the wifi regulation based on GPS coordinates. May be that aircraft was flown not with CE, but with FCC regulation...

 

[Mark The Droner]

An admin on the other site has just confirmed something I wasn't clear on. And that is, that the freq used between the AC and the controller for both control and FPV is always in the same band, whether it be 2.4 or 5.8.

2.4 and 5 Ghz - DJI Phantom 3 SE

This strengthens the case that the SE uses at least some form of lightbridge since that's how the other lightbridge phantoms work.

 

[VonMacher]

I really can't tell whether P3 SE runs on lightbridge or not. But what I'm sure of is it uses the same frequency band for both FPV/telemetry and control signals.
One more thing, that little stick antenna is used just for WiFi link RC - mobile device, that's for sure. Tested inflight without that antenna, no range difference. System uses just two internal flat antennas (those appears to be dual band). If I disconnect one of those, signal will drop a bit but drone is still under my control with slight video degradation.
So yes, I believe it is enhanced (40 MHz or whatever channel wide) link to drone. It is obviously not strict WiFi since it is not visible within WiFi environment, but its frequency will block designated channel for itself. Clearly visible on WiFi analyzer when 2.4 GHz link with certain channel is chosen, previously visible weaker WiFi signal will disappear from screen, but drone link is not visible on that frequency.
Furthermore, if I choose exactly the same channel as my home WiFi runs on, RC will have hard time connecting to drone, and my home WiFi will be hardly usable, off course.

About that Sardinia flight, as mentioned above, I can't believe this flight was under CE environment with stock system. Stock system maybe, but FCC for sure...

 

[PhantomFlyer3SE]

I really can't tell whether P3 SE runs on lightbridge or not. But what I'm sure of is it uses the same frequency band for both FPV/telemetry and control signals.
One more thing, that little stick antenna is used just for WiFi link RC - mobile device, that's for sure. Tested inflight without that antenna, no range difference. System uses just two internal flat antennas (those appears to be dual band). If I disconnect one of those, signal will drop a bit but drone is still under my control with slight video degradation.
So yes, I believe it is enhanced (40 MHz or whatever channel wide) link to drone. It is obviously not strict WiFi since it is not visible within WiFi environment, but its frequency will block designated channel for itself. Clearly visible on WiFi analyzer when 2.4 GHz link with certain channel is chosen, previously visible weaker WiFi signal will disappear from screen, but drone link is not visible on that frequency.
Furthermore, if I choose exactly the same channel as my home WiFi runs on, RC will have hard time connecting to drone, and my home WiFi will be hardly usable, off course.

About that Sardinia flight, as mentioned above, I can't believe this flight was under CE environment with stock system. Stock system maybe, but FCC for sure...

Hi, thank you for sharing your experineces! It means, that an windsurfer reflector on stick antenna has absolutly no sense in case of P3SE controller. I already ordered one, if I get it, I will give a try to confirm the result of your test

 

[VonMacher]

Hi, thank you for sharing your experineces! It means, that an windsurfer reflector on stick antenna has absolutly no sense in case of P3SE controller. I already ordered one, if I get it, I will give a try to confirm the result of your test

I used one home made windsurfer at the beginning. No improvements what so ever. Even more, I think wide windsurfer area has blocked a little bit two inside antennas, so I experienced some signal degradation.

 

[MarcoFan]

Hello people, this video is mine

that result is awesome for me to, no antenna mods or amplifier, i dont understand if my Ph3 SE during the tests was in FCC or CE (i live in Italy, Sardinia)
in my android device the situation was:
-Original DJI Go 3.1.18 (used with this test)
-DJI Go 4 Mod for FCC (usually used with my Mavic)
that's all....... you think my DJI GO 4 modded.. can influence to the other app DJI GO?

 

[Mark The Droner]

oops... here is the other thread we're discussing the fascinating SE ... CE / FCC

 

[MarcoFan]

 

[VonMacher]

I tried moded DJI Go 4, but can not connect to my RC. It is unlikely that DJI Go 4 interferes with DJI Go 3. I would prefer theory your P3 SE just switched to FCC (27 dBm) mode.
I know it is a different thread Mark, but it is somehow related to this issue we are discussing here.

BTW, great job Marco, I enjoyed your youtube video.

 

[MarcoFan]

thanks

 

[Lugh23]

With the P3SE in CE mode I have already covered a distance of 1.1 km (in open field). But at various (open) locations I regularly have a distance of 700 meters to 900 meters on a high of 85 m. And my P3SE has not been modified
View attachment 91051
I'll never fly in an urban environment. I avoid the attention of the habitants, but sometimes I pass just near a residential area.

You're using Litchi for the SE?? I asked the developers and they said that Litchi doesn't work on the SE as DJI hasn't released the SE specs to them so how do you have it working??

 

[VonMacher]

You're using Litchi for the SE?? I asked the developers and they said that Litchi doesn't work on the SE as DJI hasn't released the SE specs to them so how do you have it working??

This is not Litchi, just AIRDATA UAV, online application for flights logging. Airdata UAV - Flight Data Analysis for Drones
Very nice piece of software.

I have Litchi installed and is not working as well. It can connect to RC, but can not receive video/telemetry from drone. So useless at the moment...

 

[Mark The Droner]

The attachment's notation on the lower left claims he's using Litchi. Maybe it's not correct or up to date...

 

[VonMacher]

The attachment's notation on the lower left claims he's using Litchi. Maybe it's not correct or up to date...

You are right, sorry my bad...

 

[VonMacher]

I just received confirmation about that middle antenna.

"So the phantom 3 SE the middle antenna is local wifi for connecting to you device running the DJi app. Output is very low around 0db. It does nothing else. You can remove the middle antenna and if you device is in the cradle you can fly no problem. The left antenna is in fact the antenna that communicats with the drone. You can fly your drone with only the the left antenna if you are not using an app on a device. It flys fine. The right antenna is the video / flight data down link nothing else.
That is why the internal left and right antennas are a gained dual band patch antenna. The centre antenna is only unity gain."
"Another dead give away is the Mac address sticker on the wifi module the antenna socket is connected to the middle antenna- every wifi AP needs a Mac address the out put is 802.1 wifi standard modulation - left side and drone output modulation us proprietary"

This gentleman actually measured signals with spectrum analyzer and came to that conclusion. What still bothers me is his claim about different role for side antennas. I couldn't see great difference in signal quality after disconnecting either of those antennas.

Conclusion: P3 SE windsurfer is completely useless, except you wanna place your RC far from phone (unlikely).

 

[Mark The Droner]

Who is this gentleman you talked to?

We know that common lightbridge is:

Left antenna transmits

Right antenna receives

So this info is what we suspected and discussed earlier - but it's a nice confirmation.

[incorrect paragraph edited out]

Not sure what you mean by "couldn't see a great difference in signal quality" after disconnecting either antenna. What signal are we talking about?

 

[VonMacher]

Who is this gentleman you talked to?

We know that common lightbridge is:

Left antenna transmits

Right antenna receives

So this info is what we suspected and discussed earlier - but it's a nice confirmation.

However I'm surprised that he seems to be saying you can fly with no right side antenna or incoming signal. I think that is different from the other lightbridge systems. I think it's reasonable to believe he may be wrong. The old P2 series could do that, but this is a completely different system. Technically it could be done, but my understanding is DJI forces fail safe when the controller loses the FPV/telemetry connection.

Not sure what you mean by "couldn't see a great difference in signal quality" after disconnecting either antenna. What signal are we talking about?

Video/telemetry/control signal. I noticed just a slight loss of those signals, but still usable. Will do some more testing, now gets more interesting.

This gentleman is from FB ARGtek group, answering to my claim about antennas role.

 

[Mark The Droner]

It's not clear to me what you mean by "slight loss of those signals." One is coming from the AC. One is coming from the controller. Two independent signals from two different sources. So how does fiddling with the controller antennas effect the signal transmitted from the AC?

If you disconnect the left antenna, the control signal will be severely weakened. The FPV/telemetry will be unaffected. If you disconnect the right antenna, the controller's ability to sense the FPV/telemetry signal will be severely compromised, but the transmitting control signal will not be affected. However, the readout on the screen showing the strength of the control signal may give you false info (e.g. DISCONNECTED) because I believe it's programmed to do that when the FPV/telemetry disconnects. But it's just as well because the AC is programmed to RTH anyway. That's my understanding.

Edit: Now that I have more experience, I believe it's possible the FPV signal could be affected by weakening or disabling the control signal as described above. I believe it's possible the "check" which we know doesn't take place in the usual manner as it does on standard wifi signals actually does take place but in a different manner. That is, I believe it's possible the "check" is transmitted via the control signal, and if the check doesn't reconcile, it can cause a perceived weakness in the FPV signal. But this really isn't relevant in the real world in the vast majority of cases because the FPV signal is going to weaken before the control signal anyway.

 

[VonMacher]

It's not clear to me what you mean by "slight loss of those signals." One is coming from the AC. One is coming from the controller. Two independent signals from two different sources. So how does fiddling with the controller antennas effect the signal transmitted from the AC?

If you disconnect the left antenna, the control signal will be severely weakened. The FPV/telemetry will be unaffected. If you disconnect the right antenna, the controller's ability to sense the FPV/telemetry signal will be severely compromised, but the transmitting control signal will not be affected. However, the readout on the screen showing the strength of the control signal may give you false info (e.g. DISCONNECTED) because I believe it's programmed to do that when the FPV/telemetry disconnects. But it's just as well because the AC is programmed to RTH anyway. That's my understanding.

I can't speak about lightbridge functionality, because I don't have it. What I know is based on my observations related to P3 SE WiFi communication RC - Drone (RC - mobile phone communication is completely understood now).

So yes, without one of my side antenna (either one) I can still fly with video/telemetry feed and drone under my control. That is the fact. As I said before, all I can see is a slight drop in signal quality, probably because of some gain loose.
Off course, I can judge that according to DJIGo signal measurement (RC and Video).

Yes, you have two independent signals (lets call them Uplink and Downlink), where Uplink is just RC control signal to drone and Downlink is video and telemetry signal. That telemetry signal gives us (among all other information), to see the receiving quality of control signal sent from RC to drone.
It is clear that RC signal quality is sent back via telemetry to DJIGo so off course if video/telemetry signal is lost, you can't know RC signal status received by the drone - and RTH will engage.If, because of any reason, RC stops to send control signal to drone, it will be visible in related DJIGo field (RC signal quality), since video/telemetry signal still feeds in. Again, it will engage RTH if not set otherwise.

But I'm telling you, while drone hovering 80 meters away I was able to remove and mount back on left antenna (nothing dramatically changed regarding signals), and right antenna as well.

If it would be like you think it is, removing left antenna would cause RC signal lost (visible on DJIGo since telemetry feeds in), removing right antenna would cause total signal loss (since video/telemetry is not received).

 

[Mark The Droner]

...
If it would be like you think it is, removing left antenna would cause RC signal lost (visible on DJIGo since telemetry feeds in), removing right antenna would cause total signal loss (since video/telemetry is not received).

I would agree with you except for one thing: This is what we strongly believe to be a lightbridge signal. And what we know about lightbridge is it travels over amazing distances. 80 meters is not a particularly long distance.

Also, since you have modded your controller with the argtek, when you disconnect that antenna, the cable that leads from your transmitter inside the controller to the coupling which you installed - that cable acts as an antenna. So to claim there is no antenna isn't quite accurate. What you really mean is you have a poor antenna which is the cable.

I suggest, if you're interested, flying out a mile or so, then disconnect each antenna and see what happens.

Thank you for your efforts...