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WIFI test using the wifi Analyzer app
2834 13 2016-8-5
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wmcvey
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[size=14.6667px]As we all know the Standard using wifi to communicate between the controller and your device (cell or tablet) and also between the controller and the drone for the video feed and telemetry. Many are also aware of an app called "Wifi Analyzer" to check for interference in the area. I decided to use the app to check on what channel my P3S was using on 2.4G wifi. The controller on my setup is using channel 10. I say the controller because it seems that's the only reading I'm getting, from the RC. When I turn on the RC I get a good strong reading on channel 10, but don't get any (none) from the drone itself. Turn on the controller, there's the signal. Turn RC off, signal goes away. Turning the drone on or off does nothing, no wifi signal that I can tell. Does this seem right??
2016-8-5
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Geebax
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It is probable, the Standaard uses 5.8Ghz, not 2.4Ghz.
2016-8-5
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wmcvey
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Geebax Posted at 2016-8-5 20:53
It is probable, the Standaard uses 5.8Ghz, not 2.4Ghz.

5.8Ghz is only for the RC controls (sticks) to drone and maybe the S1 and S2 switches. All the download, video and telemetry should be wifi on the 2.4Ghz band. Even though during my test I didn't have the drone's props turning, that shouldn't be a issue I don't think. As I'm viewing the image from the camera, and that data has to be coming from the drone on wifi somehow.
2016-8-5
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DJI-Ken
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The RC is 5.8 and the video is 2.4
2016-8-5
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wmcvey
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Ken, would you have any thoughts to way this is? That I get a 2.4Ghz signal from the RC when it's turned on, but don't get any reading from the drone when it's on, via the app I'm using?
2016-8-5
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wmcvey
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One thing that just came to mind is it possible that the wifi signal I'm getting for the RC is the wifi for the device (cell or tablet) connection. And the reason I'm not getting any reading from the drone is because even though DJI is saying it's a wifi signal from the drone, it's not a traditional wifi signal and the "Wifi Analyzer app" is not picking up on it.
2016-8-5
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Geebax
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wmcvey Posted at 2016-8-6 12:08
One thing that just came to mind is it possible that the wifi signal I'm getting for the RC is the w ...

'One thing that just came to mind is it possible that the wifi signal I'm getting for the RC is the wifi for the device (cell or tablet) connection. '

Correct, it is the connection from the RC to the mobile device as you suspected.

'And the reason I'm not getting any reading from the drone is because even though DJI is saying it's a wifi signal from the drone, it's not a traditional wifi signal and the "Wifi Analyzer app" is not picking up on it.'


No, is it not a normal WiFi signal at all, it just uses the same frequency band as WiFi. So if the analyser is designed to recognise WiFi communication protocol, it will not understand the communication betqween the RC and Aircraft.

And I am not sure why DJI would choose to use 5.8Ghz uplink and 2.4Ghz downlink, especially seeing they are using the same antenna.



2016-8-5
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cloudycante
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wmcvey Posted at 2016-8-6 04:08
One thing that just came to mind is it possible that the wifi signal I'm getting for the RC is the w ...

Consider that the RC acts like a Access Point, broadcasting the SSID Wifi network: AC and Tablet only connect to it.
It is normal that you don't see any activity when you power on only the drone.

Now, if your tablet is only 2.4ghz, then the app won't be able to see the 5.8ghz signal.

Did you verify that your tablet can actually see other 5.8ghz wifi networks?
2016-8-5
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cloudycante
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By the way, I just tried with my P3S, and my computer, scanning the wifi signals. I too only see the 2.4ghz, but I can see other 5ghz signals. That make me think - plain and simple - that the 5.8ghz signal is not a wifi signal.
After all DJI says they use 5.8ghz, not 5ghz, which is the wifi standard.
2016-8-5
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OrlyP
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The 5.8GHz signal on the P3S is not standard WiFi. Though it uses the same band as WiFi (ISM band), but it talks quite differently and no WiFi equipment including the WiFi Analyzer app will be able to see it.
2016-8-5
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wmcvey
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Geebax Posted at 2016-8-6 01:45
'One thing that just came to mind is it possible that the wifi signal I'm getting for the RC is the ...

There's really two antennas, the external one is the 5.8 for drone control and the 2.4 Wi-Fi antennas are internal.
2016-8-6
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wmcvey
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cloudycante Posted at 2016-8-6 02:08
Consider that the RC acts like a Access Point, broadcasting the SSID Wifi network: AC and Tablet o ...

I think you hit the nail on the head, meaning the RC is acting as a access point and broadcasting its ID. And the Drone and tablet are just client Wi-Fi devices not broadcasting an ID and invisible to the app I was using.
2016-8-6
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MD_Icarus
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In general Radar applications:

High Uplink Frequency = Higher Power to achieve greater distance
(RC can afford it but not the p4)

Lower Downlink Frequency = Lower Power to achieve sufficient distance
(P4 conserves energy using lower frequency)

Although the frequencies and distance in this case are not high enough for the following radar law to apply, DJI may have considered it:

Lower frequencies tend to penetrate better when they have to go through interference or attenuation due to atmospheric effects. Higher frequency are the opposite.

Another important consideration is having higher frequency circuits next to mechanical devices is not an easy task.  The lower mechanical circuit frequency components leak into the high frequency circuits (and vice versa) so the design, especially the isolation/sealing/external filtering needs to be a major design consideration.

When I was younger I recall an application when the entire design had to be scrapped and re-done after initial field testing of a radar system which worked great in the lab. Once in the real environment, the external interference caused the system to fail repeatedly due to cross frequency interference and harmonics, which exceeded the allowed power level of the receiver.
2016-8-6
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Mike-the-cat
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MD_Icarus Posted at 2016-8-6 05:57
In general Radar applications:

High Uplink Frequency = Higher Power to achieve greater distance

Thanks for the informative post.
I'd agree with everything you said here except for the practical aspects of power consumption and what they mean for choice of frequency on the drone.

Keeping the bird aloft is far more energy consuming than any of the electronics on board by probably two orders of magnitude.
2017-4-22
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