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CE transmission power low: 01.05.300 +++
986 18 2018-1-31
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rolsch_p4p
lvl.2
Flight distance : 46834 ft
Germany
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Hello support.

I have access to measuring equipment for EIRP CE and
see problems with the transmission power.

dBm comparison measurement respective RC to the measuring antenna 1m distance:


Graupner mc24 ............. 20dBm

Phantom 2 .................... 14dBm

Phantom 4 pro ................. 8dBm  (firmware 01.05.301)


All RC measured in the 2.4Ghz band.

You see, the 8 dBm are to low.


Here in germany the CE point to max. 100mW EIRP.

So please verify the CE mode in the actual firmware - thanks.
- give this information to our hardware team...



Roland






2018-1-31
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nJo-nJo
lvl.4
Flight distance : 51355 ft
Bulgaria
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Wait patiently...
2018-1-31
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Nebuchadnezzar
Captain
Flight distance : 2720213 ft
Spain
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In fact... It is too low
2018-1-31
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KedDK
Captain
Flight distance : 1133038 ft
Denmark
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Just what i have stated for months, thanks for confirming that something is wrong.
Have you done some measurement on 5.8 GHz?

Also would like to know if you did any measurement prior to the upgrade and at what version(s) my impression is that it won't improve when downgraded even it was better before the upgrade.
2018-2-1
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Siambuddhas Group
First Officer
Flight distance : 116926 ft
Singapore
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Great effort guy....thanks for pointing out their errors..
2018-2-1
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Aardvark
Captain
Flight distance : 384432 ft
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United Kingdom
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This is the output power from the P4P RC which should be about 17dBm ?

If so, can that be compared with another P4P RC so that the hardware can be eliminated.
2018-2-1
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RSS
lvl.3
Flight distance : 5945 ft
Portugal
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Hi, it's possible you rollback to .0602 and do a new RF measurement ?
2018-2-1
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rolsch_p4p
lvl.2
Flight distance : 46834 ft
Germany
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RSS Posted at 2018-2-1 14:36
Hi, it's possible you rollback to .0602 and do a new RF measurement ?

Hi RSS,
at the moment no,
i have not permanently access to the RF equipment.
- i hope for a new test in four weeks.

@Aardvark
Yes,
i has two P4P compared: 01.04.608 (beta for my gimbal issue) = 10dBm and 01.05.301 (beta) = 8dBm
-> only in the 2,4 Ghz range


Remark
I only measure the RC Output but i think i must test the next time both the RC and the P4P!
Then we can analyse the rf transmission and find the issue for the poor CE distance...

But come on DJI, why must the user analyse the firmware issue(s)...


2018-2-2
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nJo-nJo
lvl.4
Flight distance : 51355 ft
Bulgaria
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Because they take your money! Now they sell mavic air...
2018-2-2
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15matjan
Captain
Flight distance : 1158258 ft
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Less transmission power means less flying range and more (hidden) control over avoiding to fly BVLOS. Which is something even DJI does not recognize or admit, they do. Is like with cars, on one hand manufacturers advert for more and more HP, but they, electronically, limit the car' speed.
DJI does want to "bother" EU authorities, so they claim UP TO 2 - 3,5 km CE flying range (depending on model), all of us buy their birds thinking they are right and very little have the chance to access measure equipment to test what they are really selling and controlling.
This way, authorities and DJI are happy, business going well...and owners buy blind.
When and if needed, always one can claim their measures and test are done in ideal condition, no interferrences, lab style in an ivory tower...
Car makers do the same with cars consumption...
Have anyone seen a car manufacturer fined for misleading advertising on car' real consumption ???

Found this table on Wiki: Typical dBm values for electric appliances
Still do not understand why having a tech spec. max 14-17 dBm (depending on frequency, on a P4P) when wirelles LAN (allowed in EU) have 20 to 23 dBm and cell phones ranges from 24 to 30 dBm...

Is what I said on onther topics: pay more, fly less

2018-2-2
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15matjan
Captain
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100mW CE means 20dBm.  P4P's tech spec is 17 dBm and stands for 50mW...This means half than allowed...8dBm is slightly more than 5mW, so you have 10 times less transmission power than on specs, and 20 times less than maximum allowed.
2018-2-2
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KedDK
Captain
Flight distance : 1133038 ft
Denmark
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15matjan Posted at 2018-2-2 09:53
Less transmission power means less flying range and more (hidden) control over avoiding to fly BVLOS. Which is something even DJI does not recognize or admit, they do. Is like with cars, on one hand manufacturers advert for more and more HP, but they, electronically, limit the car' speed.
DJI does want to "bother" EU authorities, so they claim UP TO 2 - 3,5 km CE flying range (depending on model), all of us buy their birds thinking they are right and very little have the chance to access measure equipment to test what they are really selling and controlling.
This way, authorities and DJI are happy, business going well...and owners buy blind.

"can claim their measures and test are done in ideal condition"
No how the test should be performed is part of the specifications and regulations, also i have been wondering why DJI use the limits they do in CE.
In 2.4 GHz, 20 DBm would be allowed and for the 5.8 GHz frequencies used by the Phantom, to my best understanding around 30 DBm should be ok.
2018-2-2
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Nebuchadnezzar
Captain
Flight distance : 2720213 ft
Spain
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This is why i use FCc in Europe... Not more problems of transmision lose...constant signal advice etc etc
2018-2-2
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Mad_Angler1
Captain
Flight distance : 2741657 ft
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20 dbm is the maximum for equipment using full LBT and FHSS compliant, the reason DJI state 17dbm is Lightbridge is not fully FSHH compliant as the ofdm video carrier is not constantly frequency hopping as and such is not allowed to use the maximum output under 2015 regulations , equipment that does not fully comply gets a reduced output accordingly hence the 17dbm.

the RC control link is FHSS but the video is not, it selects a channel at startup but then does not hop unless it detects interference, it also can't fully comply with LBT because of this.

As for your tests did you have the craft on ? these things can not be accurately tested anywhere but in a anechoic chamber and very specelist equiptment.

Sorry but the test is not accurate or proves nothing.
2018-2-2
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15matjan
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Nebuchadnezzar Posted at 2018-2-2 10:42
This is why i use FCc in Europe... Not more problems of transmision lose...constant signal advice etc etc

Really ??? will you teach us how please ???
2018-2-2
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Nebuchadnezzar
Captain
Flight distance : 2720213 ft
Spain
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There are several ways to do that..just search in yt : phantom FCC mode europe.. Anyway ..mavic ..spark users also use these methods.Good luck
2018-2-2
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santofilme
lvl.2
Flight distance : 35758 ft
Brazil
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So that could explain the P4P short range compared to P3P.
2018-2-2
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Steppdroid
lvl.2
Flight distance : 31998 ft
Italy
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Thank for segnalation!!
2018-2-3
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15matjan
Captain
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Nebuchadnezzar Posted at 2018-2-2 14:36
There are several ways to do that..just search in yt : phantom FCC mode europe.. Anyway ..mavic ..spark users also use these methods.Good luck

It works for P4P, but not for P4P+ which is blocked to its own native apps...
2018-2-3
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