I just did my experiments (which implies that Raul's bitrate thing is done).
No luck.
I checked the region codes of all Tellos around: 3x "US", 1x "DE" and my brand new one which has not yet received any firmware updates reports "FF".
DE would make sense, everything else not so much. I have deleted and reinstalled a couple of times. It asked me for "activation", and access to my location. I tried with and without granting the app access to the location. I tried ecverything I could. Not once was the region set.
My brand new
Tello still says "FF". The only thing thats left to try is a firmware update but I am not going to do this.
Because this
Tello with old firmware has a few nice features:
It is much faster in slow mode, it has better attitude angles in low altitude, Sport mode seems unaffected by altitude, and the best thing: More flight time!
My first flight with this
Tello the drone initated autolanding once but this can be cancelled. After cancellation it does not enforce autolanding a few seconds later like the current firmware does. It just keeps flying until it starts to behave erratically at around 2% battery.
Cool !
But bottom line: This is a dead end for now
Thank you for your big big contribution to the investigation. In order the properly interpret the results from you I would like some help to clear up some terms you use.
1. What do you mean by query location? Do you query the oem app or
tello?
2. What do you mean by "set
tello to a region"? Does
tello get told a region by the oem app and keep that info onboard but does not show any signs of altering transmission protocol?
3. How did you end up with 3 US and 1 DE assuming
tello does store region info on itself?
4.
Interesting. So somehow I missed this "set wifi power" message duing startup. I will check again.
Did you follow up on this? If
tello does change transmission power, it maybe possible that "set wifi power" message on startup is doing something?
I doubt if a 3rd party app has the control over phone's RF hardware too, besides the transmission compliance in the manual was for
tello clearly. I will continue with Ryze support to find out what they know about the matter (oh the frustration haha).
For
@raulvolador , I have seen repeated F in color code when it is undefined so FF probably means null.
I read the
FCC report for
tello. They made a test program on page 6 for the compliance test to stream data at test frequencies (1,6,11channel). Only 11 channels were provided since it was the FCC test. Chain 1/0 means horizontal/vertical polarization. On page 11 they show
tello's calculated max antenna gain which is 2.96dbi. On page 44 they show the test result for the program (
tello was running the program with antenna removed and RF spectrometer connected via low loss cable). All this gave us an EIRP of 2.96 + 16.83 (max avg conducted power in g mode wifi which
tello operates on) = 19.79dbm. Fairly close to what the manual claims for FCC (20dbm). I am seeking the CE report now (from Ryze) which isn't open accessible on the internet like the FCC report.
I found the Chinese certification on Chinese authority CMIIT
website after checking the certification IDs printed in the battery bay of
tello. They got two records for
tello for some reason but they are identical. If you click into one of them you see. (Also I found cert ID for Korea, Taiwan, Brazil, Cananda and unknown code 2T1-180101 printed on
Tello)
The EIRP quoted here has a max of 20 compared to 19dbm the manual claims under SRRC (FCC/CE equivalent of China).
I organised some countries 2.4Ghz wifi tranmission power limit and linked relevant documentation for evidence.
As we can see from the table,
Tello clearly is well under the FCC limit given the test program even with the max EIRP. Both China and EU has the same max limit at 20dbm. I argue that since Ryze claimed 20dbm for FCC which is close to their average report figure. They would have gone with the average report figure for EU and SRRC as well. In fact in both
CE (Page 49) and
FCC (d), a maximum average (RMS) conducted output power is to be used for digital modulation transmitter (WiFi is). I have reasonable ground to believe
tello meets the CE and SRRC test limits with the more power liberal FCC report test. In the FCC test we also witness Ryze has the ability to tune the transmission power via software. There is a very small chance that Ryze utilized different output power program in the CE test (if it took event at all), but to prove it Ryze must agree to offer me a CE test report. So this wild goose chase seem to have most likely been caused by an innocent typo made by whoever compiled the manual at Ryze. I am gonna wait and see if the CE report says something interesting if they give me.