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Hardware / Re: OPLink signal range - Revo vs Mini
« Last post by TheOtherCliff on December 10, 2018, 12:51:29 am »
When I first built one, I only did power output testing using a simple field strength meter.  My testing showed the first few GCS settings were all about the same, but that power did reduce significantly for the lower values.

I have since bought an ExpertRC power meter and I just now tested the RFM23BP OpLink power vs. GCS configured power level.  RFM23BP is powered with a 3A Hobbywing switching BEC that has a jumper for 5V or 6V.  I currently have it set for 5V (I thought I had it set for 6V) and measures 5.13V at the RFM23BP under load.

I have a second power option because my circuit has a diode from USB power to RFM23BP power so I can run it with just USB and get a measured 3.95V (long USB cable and diode both reduce the voltage) at the RFM23BP under load.

There are some things that don't add up, like at the 100mw setting, the 3.95V power is less than half of the 5.13V power, but at the 1.6mw setting, the 3.95V power is more than half of the 5.13V power.  I suspect that the 3.95V voltage increases at reduced loads.

Code: [Select]
  GCS    Power    Power
 Power    at       at
 Level   3.95V    5.13V
 100mw   407mw   1016mw
  50mw   380mw   1007mw
  25mw   380mw    989mw
12.6mw   380mw    955mw
 6.3mw   331mw    851mw
3.16mw   245mw    566mw
 1.6mw   112mw    214mw
1.25mw    68mw    129mw

The actual values could be a bit lower than shown in this table.  My research makes me think it should be less than 1W for 5.13V.  The important thing is that for this batch of RMF23BP in this circuit, the actual power levels produced are nearly identically high for several of the top programmed power levels but the actual power levels drop significantly for programmed power levels below those top levels.

Note that this table is quite a bit different than JDL's.  There is a reason that the lower power levels are undefined in the datasheet and this may be part of it.  On the other hand, JDL discussed some Narpat mods.  My RFM23BP is stock and came from eBay for about $7 a few years ago.  Moral of the story is that you probably need to measure your own circuit.  You probably want to do that anyway to make sure your output power is as expected.
Then I followed the advice of F5soh, and I tried setting the Air data rate to maximum (256000) in both sides finally the OPLink communicates with the revolution!
- data rate must match on both sides; sometimes it helps to increase to the next higher data rate on both sides

But why did I have these problems?
Two reasons: the solder blob, and the source code for the default data rate should probably be changed to a higher number.  Or instead of increasing source code data rate default value, we could change the source code to disable some unneeded messages to decrease the amount of data that is sent, so higher data rate is not needed.  The user can also disable these unneeded messages, but it is easier to just tell the user to increase the data rate.

Do I still have a bad FC board ??
At lowest power, you should get 10's of meters even with bad antennas; hundreds of meters with good antennas.
If you use good antennas as tested in the linked thread, and you get solid, constant connection (not dropping and reconnecting every few seconds) to hundreds of meters at lowest power, then everything is working well.
Previous bad solder will make a short between antenna pad and ground...
If you want to improve the range a little you try to reduce the Air data rate to 100000.

256000 data rate allow connecting when Rf modules are not well tuned : look AFC correction value (should be around 0) and adjust the Xtal capacitor if needed.
I found an imperfect solder on the RF module of the Revolution (see red circle attached photos), I tried to restore the solder (green circle), I tried the OPLink again and it still does not work ..
Then I followed the advice of F5soh, and I tried setting the Air data rate to maximum (256000) in both sides .......................... ...................... finally the OPLink communicates with the revolution! Hallelujah!

But why did I have these problems? do I still have a bad FC board ??

Tnk so much to everyone!!  :)
Try setting the Air data rate to maximum (256000) in both sides.
Tnks F5soh,
ok then I disabled those ports (see attached image).
My OPLink still does not work, I posted all my settings here in this post, they seem to be correct, I do not understand where the problem is ...
Perhaps the problem is related to the fact that I made only "vehicle setup wizard" ??
There is no need to change something in HW page, except if you want to use auxiliary stream.
All the Oplink configuration (Ground Oplink and Revo) is done in OPlink tab.
Thank you very much TheOtherCliff for your precious and fast support!
I changed the power settings to 1.25mw, but the OPLink does not communicate with the Revolution.
I also checked the RF boards, but for me it does not seem to be the faulty model (see attached photo).
I followed your directions but everything seems to be okay, but there is no communication.
I repeat that I have absolutely no idea how to set the ports in "HW settings" to run the OPLink.
Can someone explain how to set the ports (these I highlighted in red in the attached file) to make the OPLink work ?? I do not see anything written on the internet page about configuring these ports to make OPLink work ...
Thank you
Hardware / Re: OPLink signal range - Revo vs Mini
« Last post by jdl on December 09, 2018, 02:37:40 pm »
Few things to add:

Some useful info here:

Consider powering an *unmodified* RFM23BP module with slightly less than 6V. I use a Shottky diode to drop the voltage down to 5.8V that still gives 1W RF output and does not stress its onboard 3.3V LDO regulator .

I've found info in rcgroups that tests/measurements on RFM23BP modules conform their stated spec and do not emit more than expected/desired in harmonics when working in 1W mode. No tests made with RFM23BP modified for higher than 1W RF output.

I just did a series of measurements how the output of a modified for 1W OpLink (RFM22B replaced with RFM23BP and separately powered with 5.8V instead of 3.3V) changes according different Max Power settings in GCS:

100   -   30.1dBm      1.0W
50   -   30.1dBm      1.0W
25   -   30.0dBm      1.0W
12.6   -   30.0dBm      1.0W
6.3   -   30.0dBm      1.0W
3.16   -   29.8dBm      962mW
1.6   -   29.7dBm      940mW
1.25   -   29.2dBm      836mW
0   -   0.0dbM      0.0mW

So just set Max Power to 100. RF output power can be modified by changing power supply voltage of RFM23BP in the range 3.3V - 6V (or higher - up to 10V, if you dare to try "Narpat" mod or similar).

If you run a modified OpLink on the ground and a stock OpLink in the air, the one on the UAV hugely benefits from the fact its antenna is high above the ground and not affected by it, so the difference in link quality of control packets and back telemetry is not that noticeable.

P.S. A small comment on the "Narpat" mod: I believe the useful changes are just adding a second R25 transistor in parallel with the existing one and cutting the trace/adding 100nF capacitor to provide a separate power supply for RF MOSFET.
GCS General / Re: Ubuntu 18.04 compiling "next" fails
« Last post by TheOtherCliff on December 09, 2018, 08:08:00 am »
Here is a list of my libusb stuff that is installed or not.

I see there are 2 dev packages and there are both i386 and amd64 architectures.  Obviously I am running a 64bit distro.  :)

Code: [Select]
[email protected] ~ $ dpkg -l *libusb*
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name               Version        Architecture   Description
ii  libusb-0.1-4:amd64 2:0.1.12-23.3u amd64          userspace USB programming library
ii  libusb-1.0-0:amd64 2:1.0.17-1ubun amd64          userspace USB programming library
ii  libusb-1.0-0:i386  2:1.0.17-1ubun i386           userspace USB programming library
ii  libusb-1.0-0-dev:a 2:1.0.17-1ubun amd64          userspace USB programming library developm
un  libusb-1.0-doc     <none>         <none>         (no description available)
ii  libusb-dev         2:0.1.12-23.3u amd64          userspace USB programming library developm
un  libusb0            <none>         <none>         (no description available)
ii  libusbmuxd2        1.0.8-2ubuntu1 amd64          USB multiplexor daemon for iPhone and iPod

[email protected] ~ $ cat /etc/lsb-release
DISTRIB_DESCRIPTION="Linux Mint 17.2 Rafaela"

[email protected] ~ $ uname -a
Linux i925 4.4.0-139-generic #165~14.04.1-Ubuntu SMP Wed Oct 31 10:55:11 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
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