Re: OPLink signal range - Revo vs Mini
« Reply #15 on: December 08, 2018, 08:24:41 pm »
IMPORTANT
Good omnidirectional antennas will get you hundreds of meters on 1.25mw.  When you have hundreds of meters at 1.25mw, and have increased to 100mw and still need more, then consider the RFM23BP.  See post on 433mhz antennas tested.
https://forum.librepilot.org/index.php?topic=4199

There are 8 non-zero power levels controlled by 3 bits in the OpLink configuration.  They are given names like 1.25mw and 100mw, but those are really just names and those two really mean "lowest power" and "highest power", so if you change rfm22b to rfm23bp and set it to 100mw you actually get 1000mw.

Several things to be aware of:
- 1W OpLink needs a 5V-6.00V power supply.  You must power the RFM23BP with 6V to get a full 1000mW but the rest of the OpLink needs to be powered by the OpLink 3.3V regulator.  That means you can't just connect the RFM23BP power (5V-6.00V) connection where the RFM22B power (3.3V) was connected.
- Due to the design of the RF section of the RFM23BP, the power level does not modulate very well.  That is why lower power levels on RFM23BP are not defined in the datasheet.  You can reduce the power setting, but don't expect it to follow any nice linear scheme.  I also don't know if the RF splatters when you do this.  I would suggest RF filters and an RF power meter if you you intend to run reduced power levels.  Really... don't be an RF hog and splatter on legal users.  ;)
https://www.ebay.com/itm/RF-Power-Meter-27-2400-5800-mhz-arduino-ad8319-5-8Ghz-2-4Ghz-antenna-tool-FPV/253921388053
https://www.readymaderc.com/products/details/low-pass-filter-for-433mhz-sma-antennas
- The RFM23BP pinout is the same as RFM22B even though it looks like one of the signals is inverted
- The RFM23BP is physically longer than the RFM22B, so you will probably be soldering one side and running wires for the other side.
- For just control, you can have a modded OpLink on the ground and a stock OpLink in the air, but for bi-directional communication, you need both ground and air OpLinks (or Revo or Sparky2) modified.
- Someone was making 1W OpLinks a year or more ago.  Kind of expensive, but worth it if you aren't expert at de-soldering, don't have the equipment, or don't consider the tedious upgrade to be a fun part of the hobby.
« Last Edit: December 14, 2018, 05:35:27 pm by TheOtherCliff »

jdl

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Re: OPLink signal range - Revo vs Mini
« Reply #16 on: December 09, 2018, 02:37:40 pm »
Few things to add:

Some useful info here:

http://www.itluxembourg.lu/site/modding-the-orangerx-1w-modules-for-full-power/

http://www.itluxembourg.lu/site/2-5w-narpat-mod/

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.
« Last Edit: December 09, 2018, 02:46:22 pm by jdl »

Re: OPLink signal range - Revo vs Mini
« Reply #17 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.
« Last Edit: December 10, 2018, 09:51:25 am by TheOtherCliff »

ekrem

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Re: OPLink signal range - Revo vs Mini
« Reply #18 on: December 14, 2018, 08:28:29 am »
so,
when I change Tx out power 100mw (via GCS) rfm23 module is setup to 30dbm (1watt)   (answer is yes :)  )

and
when I change ground tx to rfm23 module,  air module must change to same rfm23b
« Last Edit: December 14, 2018, 08:49:12 am by ekrem »

jdl

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Re: OPLink signal range - Revo vs Mini
« Reply #19 on: December 14, 2018, 09:13:53 am »
when I change ground tx to rfm23 module,  air module must change to same rfm23b

Not obligatory. Unless you plan to fly with control and telemetry far away (more than 10km in RF clear environment) with plain omnidirectional antennas.

ekrem

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Re: OPLink signal range - Revo vs Mini
« Reply #20 on: December 14, 2018, 02:28:57 pm »
thanks

only my flight plan whit in 2-3 km (so no need change to air side rf module)

jdl

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Re: OPLink signal range - Revo vs Mini
« Reply #21 on: December 14, 2018, 04:53:30 pm »
thanks

only my flight plan whit in 2-3 km (so no need change to air side rf module)

For such short distances you really do not need more than standard 100mW OpLink on both sides. On the other hand, extra transmitter power can help in very noisy environment, like near radio towers. Although, flying in such areas is generally not a good idea.  :)

Re: OPLink signal range - Revo vs Mini
« Reply #22 on: December 14, 2018, 05:14:09 pm »
You should be able to get around 2km on 100mw with good (omnidirectional) antennas and clear Line Of Sight.

Set up and test Return To Base close by.  Very important to have it set in Flight Mode Switch and in Input->FailsafeSettings.  Test close by, by switching off ground OpLink/Transmitter (not just 2.4GHz transmitter if you use e.g. a 2.4GHz to 433MHz "relay box"!! ) !

Next flight you can fly far out to find out how far it goes.

Edit: @JDL beat me to it.  :)

ekrem

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Re: OPLink signal range - Revo vs Mini
« Reply #23 on: December 15, 2018, 08:12:46 am »
thanks

only my flight plan whit in 2-3 km (so no need change to air side rf module)

For such short distances you really do not need more than standard 100mW OpLink on both sides. On the other hand, extra transmitter power can help in very noisy environment, like near radio towers. Although, flying in such areas is generally not a good idea.  :)

thanks for nicely helps

other thinks;

how I can fly POI flight mode whit revo whit flight mode switch
I was reading some poi flight mode whit revo but not clearly
« Last Edit: December 15, 2018, 08:17:36 am by ekrem »

Re: OPLink signal range - Revo vs Mini
« Reply #24 on: December 15, 2018, 06:31:58 pm »
I have never used POI mode.  This is where I would start:
https://librepilot.atlassian.net/wiki/spaces/LPDOC/pages/84672520/Autonomous+POI+setup

To ask a question about a different subject, it is best to start a new thread in the correct section of the forum.  That way, it can be searched and seen by people interested in that topic.  So for further discussion about this new topic, please start a new thread.   :)
« Last Edit: December 15, 2018, 06:36:58 pm by TheOtherCliff »

ekrem

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Re: OPLink signal range - Revo vs Mini
« Reply #25 on: December 16, 2018, 06:58:28 am »
thanks you are fully right

new post about POI opened

https://forum.librepilot.org/index.php?topic=4509.msg30693#msg30693

ekrem

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Re: OPLink signal range - Revo vs Mini
« Reply #26 on: December 16, 2018, 10:33:08 am »
You should be able to get around 2km on 100mw with good (omnidirectional) antennas and clear Line Of Sight.

Set up and test Return To Base close by.  Very important to have it set in Flight Mode Switch and in Input->FailsafeSettings.  Test close by, by switching off ground OpLink/Transmitter (not just 2.4GHz transmitter if you use e.g. a 2.4GHz to 433MHz "relay box"!! ) !

Next flight you can fly far out to find out how far it goes.

Edit: @JDL beat me to it.  :)

is also setting baud rate to 56000 for telemetry and control

because when I downgrade baud rate to 38400 (for long range tx power)  I got master EVENT alarm

is it normal

Re: OPLink signal range - Revo vs Mini
« Reply #27 on: December 16, 2018, 05:20:39 pm »
It is normal and we sometimes remember to advise to do this.  :)  More information needs higher data rate.

ekrem

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Re: OPLink signal range - Revo vs Mini
« Reply #28 on: December 16, 2018, 06:07:26 pm »
It is normal and we sometimes remember to advise to do this.  :)  More information needs higher data rate.

does it affect flight or stabilization

Re: OPLink signal range - Revo vs Mini
« Reply #29 on: December 16, 2018, 07:05:37 pm »
For me at least, if the data rate (com speed) is set too low it basically doesn't work at all or at least poorly enough that it is obvious there is a problem.  When your link includes Control you would see noticeable control lag or no control.  For data (telemetry) you might notice data dropouts or complete lack of data.

I suppose there are configurations tweaked to have just a little too much control/data for the rate that would work intermittently with some dropouts or delays.

Even with rate set correctly, when you fly far away and start to drop packets, you have basically the same effect as a rate set too low.

Note that for long range flying, where dropouts (control or FPV videol) and lags are possible, you really need to consider using Attitude mode (or really any GPS flight mode).  Imagine loss of FPV video.  You give a roll command and then don't know if you are upside down or sideways or level.  Better to hold the stick for a given attitude than a given roll rate.