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5GHz DFS and OTG
1666 4 2017-8-10
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Matioupi
First Officer
Flight distance : 922569 ft
France
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Hello, about this 5GHz fiasco in europe, I'm wondering :

when used as AP (access point) is the RC wifi hardware only capable of implementing DFS ?
If not, this means that many 5GHz channels will never be useable here (and to use them we'll also need a DFS compatible phone so it will still be nice if there is a setting to prevent using DFS channels at all)

Now when it comes to RC+AC only (or RC+AC + OTG), we have no feedback on the choosen channel.
In those case, how is the channel selection implemented ? Could it happen that with current firmwares, those setups are not following the regulatory domains, eirp and DFS ?

I'm really wondering because here in EU I've been able to fly over 850m several times with RC+AC+OTG and 5.8GHz displayed mode. This is quite over the advertised range in EU which is kind of strange...

In the end, aside of auto mode, letting the user manually choose regdom and channels would be the best way... at least if he choose an illegal setting, he is at fault. That how my home AP (synology 2600ac) works : it let me choose the regulatory domain (and do apply and broadcast it correctly), but tells me that there may be legal implications.

2017-8-10
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ImHereToCrash
Captain
Flight distance : 5381368 ft
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United States
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From what I can work out, the hardware used is identical globally, however in EU, the output power is halved...I doubt anything else changes, and is likely in violation of standards.    as far as OTG permitting greater range in the EU the data is conflicting on this matter, but given how unpolished the DJI go 4 app is, wouldn’t surprise me if it’s flipped to FCC mode when using usb and not WiFi ..  

I totally agree, output is 500mW in FCC mode,  and 250mW in EU mode. For spark RC.    My home WiFi router at 100% power outputs 1200mW and warns me of regulations using more than 1000mW.  I accept I’m in violation and don’t care.   It’s only my fault if I’m arrested for using 200mW more power..   the RC in theory can output 1000mW, most WiFi modules are capable of such.  In fact the FCC allows up to total effective power of 25 watts (25000mW effective)  not output power, that’s effective power..   meaning take antenna gain into effect as well.  The US and EU and any other region should just give us an warning we have to accept if we want 1watt output power and whatever’s else.  We would be at fault..  not DJi.

DjI stop being such a overbearing nanny,
2017-8-10
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Matioupi
First Officer
Flight distance : 922569 ft
France
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ImHereToCrash Posted at 2017-8-10 22:45
From what I can work out, the hardware used is identical globally, however in EU, the output power is halved...I doubt anything else changes, and is likely in violation of standards.    as far as OTG permitting greater range in the EU the data is conflicting on this matter, but given how unpolished the DJI go 4 app is, wouldn’t surprise me if it’s flipped to FCC mode when using usb and not WiFi ..  

I totally agree, output is 500mW in FCC mode,  and 250mW in EU mode. For spark RC.    My home WiFi router at 100% power outputs 1200mW and warns me of regulations using more than 1000mW.  I accept I’m in violation and don’t care.   It’s only my fault if I’m arrested for using 200mW more power..   the RC in theory can output 1000mW, most WiFi modules are capable of such.  In fact the FCC allows up to total effective power of 25 watts (25000mW effective)  not output power, that’s effective power..   meaning take antenna gain into effect as well.  The US and EU and any other region should just give us an warning we have to accept if we want 1watt output power and whatever’s else.  We would be at fault..  not DJi.

I think that this first experience to use an already standardized link (WiFi) vs. proprietary link is quite painfull for DJI...

OTG could solve many things in setups with RC as DJI would only have to do changes on AC+RC where they have source code. On setups with AC+phone only, they have to face phones where 5GHz and DFS implementation is sometimes buggy (especially on Android). Maybe the point would be to reverse and makes phone being the AP instead of Spark being the AP.

Just in case, here is the ETSI document for exacts rules in Europe w.r.t. 5Ghz :
http://www.etsi.org/deliver/etsi ... _301893v020101p.pdf

What's pretty sure is that Spark AC+RC hardware is not localized, the power and channel restrictions are made at software "driver" levels (that's the way it's done in most WiFi dongle Linux drivers and probably other OS too, but I could only have a look to Linux as they are open source). So they could let us do our choices for regdom and channels wherever we live (or in case we travel abroad with devices)

That's 2 month now since Spark is out and this issue has been discovered and still no fix... In my opinion, this is too long with respect to the issue "complexity" and also with respect to product lifecycle...
2017-8-10
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Bradders
Second Officer
Flight distance : 862283 ft
United Kingdom
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I have been using the OTG Cable, http://amzn.to/2wAqX2H and had no issues
2017-8-10
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djiuser_Kf4iPA3
First Officer
Flight distance : 510968 ft
Israel
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Just saw this.
Just to clarify - in the 5GHz unlicensed spectrum range, DJI only uses a sub-section of channels known as UNII-3. They are the channels you see in your Go4 as 149 through 165.
These channels are NOT subject to DFS, in any country that I have checked.
Therefore DFS is of no concern to us.

My guess is that is exactly why DJI chose to use these channels, and only these channels, in the 5GHz spectrum - they didn't want to mess with DFS.
It's a very wise decision in my opinion. DFS channels are not suitable for this kind of job.It adds a level of complexity and means you have to clear your channel (or reduce power immediately) when a radar comes on nearby.

Another reason to concentrate on the UNII-3 channels is that in most countries where they are open to the public, they also allow higher transmit power than UNII-1 and UNII-2 channels (the lower channels in the 5GHz unlicensed spectrum). That's not the case in Europe, though.
2017-10-23
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