hwh

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Re: OpLink trouble
« Reply #90 on: December 20, 2016, 10:43:45 pm »
Regulations about number of hopping channels aside, IIRC limiting the channel range to something like 0->15 doesn't limit the frequencies to the low range.  There is a translation table that is basically random, so you are actually getting 16 random channels spread evenly throughout the full range?...

If you select 0-15 you get 16 channels spread between 430.0 and 430.6 MHz.  There's no advantage to limiting the number of frequencies it hops on.  Only to limiting the actual frequencies to comply with regulations or avoid known interference.

...As an aside, the higher the baud rate, the larger the group of adjacent channels it uses simultaneously when broadcasting.  I don't remember how this relates to the translation table.

It doesn't use multiple channels with higher rates, the channels just get wider.  The wider channels tend to make it more tolerant of off frequency modules since the AFC will automatically fine tune if the transmitter and receiver channels overlap even a little.
« Last Edit: December 20, 2016, 10:52:46 pm by hwh »

karla

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Re: OpLink trouble
« Reply #91 on: December 21, 2016, 06:32:09 am »
Thanks all

Maybe you can upgrade to 16.09 and try to reproduce the "dropouts" ?
Since one year, there is some fixes related to the Rssi and connect/disconnect state for OSD.

Thats one good reason to upgrade.
Without a stable, reliable control link with good range, its really not possible to move on to more advanced functions. This has to be resolved.
Thanks for the scope table, that provides more useful information than using the Link Meter. I would anticipate my RSSI will move up and down not because of different locations in my house, they just sit still, but for some other reason.

... and for hwh, I might just experiment with using the standard number of channels again since it should not give any benefits. Problem should be elsewhere...

Best

karla

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Re: OpLink trouble
« Reply #92 on: December 22, 2016, 10:39:20 am »
Good news.
I have upgraded the OPlink board used as ground transmitter to software from Openpilot 15.05.2 to Librepilot 16.09 and also the same upgrade of software on the Revo board used on the 180 quad.
I am unable to reproduce the dropouts while doing 3 times 5 min connection = 0 dropouts.
Will continue to put it on one full hour using the scope of f5soh.
K

karla

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Re: OpLink trouble
« Reply #93 on: December 22, 2016, 12:40:53 pm »
Not a full hour but 30 min I think and no drop out.
So what was the solution?
. Fix the OPlink short on the antenna connector
. Replace a bad RFM22b chip   
. Upgrade to LP 16.09
I will take this to the field and try more ...
 

karla

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Re: OpLink trouble
« Reply #94 on: January 02, 2017, 12:38:13 pm »
Hi, just some feed back on the latest field tests.

Converting both my 180 and 240 quads to LP 16.09 from OP, plus the fact of fixing the short circuits of the antenna on the OPLM seems to work so well now.
Both quads run Revolution boards with one OPlink board for control and telemetry on the ground side. I am still only flying some 30 m out but at radio max power set at only 25 mWatt and putting the setting of max channels back to default of 250, I have a really steady and strong signal with the Link meter showing 30+. Really happy with this and confidence in the hardware and SW is growing.
Also did run the Autotune function on both of them and its really impressing, they came up with way much better tuning than myself did on manual tuning.
I Would love this feature on Helicopters :)

f5soh

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Re: OpLink trouble
« Reply #95 on: January 02, 2017, 05:21:25 pm »
Like Hank already say some posts later, setting a 0-250 range is not a guarantee of quality but you should adjust Chanel spectrum to complies with local regulations or antennas that may works better in lower or higher frequencies.

karla

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Re: OpLink trouble
« Reply #96 on: January 03, 2017, 03:28:48 am »
Got it, thanks Laurent.
Karl

Tongala

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Re: OpLink trouble
« Reply #97 on: January 19, 2017, 04:24:32 am »
Thanks for this thread lots of useful information.
 
Am only using oplink for data not control. LP16.09
Measured resistance at zero had less than 3M range at 100mw on two different quads. Followed advice here, removed 5 pin connector, drilled out center pin and soldered on a pigtail. Now open circuit and range at 25mw about 17M would have expected more. Then again perhaps frequencies are out no way for me to check.
My questions are because I had been using the oplink for more than 3 months with zero resistance could I have damaged the RF module the same as can happen if not using antenna ?
I have oplink as coordinator. Would it improve range if revo was coordinator?

Thanks

 

Re: OpLink trouble
« Reply #98 on: January 19, 2017, 04:39:14 am »
I expect way more than 17m at 25mw.  It could be your antennas though.  Do you have another one or another set that works well?  Try other antennas or antennas from units that work well, so it is known they are correct and good.

Damage from use when "shorted out" is possible, but I would not assume it was damaged until proven.  I have run some after the antenna came off with no damage.  Hwh developed the "drill it out" procedure and his were OK after the repair.

Cheap clone OpLinks can be badly off frequency.  I recall that there is a new adjustment available in LP if you can get and build the version that has it.  It may be in 'next' or it may just be in a dev branch so far.

Tongala

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Re: OpLink trouble
« Reply #99 on: January 19, 2017, 05:28:45 am »
Thanks for reply was not expecting one so quick.

Your advice worked, changed antennas and now at 40M about -65db very good. Never thought of that.
At the moment cannot check further distance but I am happy with this as I only use link for tuning and to check gps.

Thanks again to you and the LP team.

hwh

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Re: OpLink trouble
« Reply #100 on: January 19, 2017, 07:23:19 am »
...Cheap clone OpLinks can be badly off frequency.  I recall that there is a new adjustment available in LP if you can get and build the version that has it.  It may be in 'next' or it may just be in a dev branch so far.

It was merged into next around the beginning of January.   It shows how far the AFC is auto tuning and lets you fine tune the frequency.

karla

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Re: OpLink trouble
« Reply #101 on: January 19, 2017, 10:53:54 am »
It was merged into next around the beginning of January.   It shows how far the AFC is auto tuning and lets you fine tune the frequency.
fantastic! must try that.