Range problem with Devo10 and LemonRX DSMX Sat

I’m actually flying multiple larger Quadcopters in size from 160mm to 360mm with an Devo10 transmitter loaded with Deviation firmware. As receivers I use mostly LemonRX DSMX satellites and one Deltang RX71 (diversity DSM2). I also fly many smaller copters with the DSM2/DSMX protocol but here the range is not really a problem. Most of the copters using different FC’s running Cleanflight firmware in different versions.

Over the last week I had some unexplainable crashes. With some more investigation and testing last days I found the root of the problems. I made some range tests and it looks to be I have an range problem with my gear. I get already issues in 30-40m distance (the quad and me between the antennas). The LemonRX Led starts already flickering. In 60-70m distance I can already produce a full disconnect if I move the copter in an certain position and failsafe will be triggered. I have reproduced this with multiple copters. I’m transmitting with 100mW but I have also tried with 150mW without real better results. I have also tried an second Devo10 with the latest nightly build but the range is nearly the same. Telemetry is always switched off. I also tried the range check of the nightly build of the Devo10 and here the RX Led starts to flicker already in about 6-7 meters and signal is already lost above 10-12m distance.

Having the Devo10 antenna pointing to the sky will give some better range. This makes sense since the signal will be very weak in the direction the antenna is pointing to. If the RX antenna is pointing into same direction and the copter is in an spot where the antenna is pointing the signal is easily lost even with relative short distance. If you let the antenna point to the left or right you may already have some dead spots very left and right from you. You very unlikely fly directly on top of your head so have the antenna pointing straight up is the best option. Next days I will try to get someone with an original Spectrum TX to make additional range checks and see if this is going better. I also did not have done test with DSM2 protocol and different number of channels.

May be the new diversity satellite RX are useful upgrade. I ordered some of them already. I may need to shorten the aerials or need to be creative to hide them from the propellers.

www.lemon-rx.com/shop/index.php?route=pr...th=72&product_id=135

If there is someone out there who have also experience with this kind of RX/TX combinations I’m interested in your findings. I will advice everyone who is using such an combination to do range an checking.

BTW: have the sam post in the RCG forum for a couple of days already. Likely today I will do some range test with an Spectrum DX8 transmitter. Will see what comes out of this.

It is reported that the nightly build solved this problem:

www.deviationtx.com/forum/7-development/...lease?start=20#38014

You may try out mwm's build in the following link:

www.deviationtx.com/downloads-new/category/212-mwm-newnighlyt

As already mentioned in my initial post I run the latest nightly (from the link you referenced) and range range test results are not really different then with 4.0.1 release. I did some testing today with an Spektrum DX6i transmitter and the range test results are even worse? The LemonRX satellite was already start flickering in about 20m distanced. and I could get and complete disconnect stepping between the transmitter an receiver and move the quad in an specific position.

So the spektrum transmitter had worse range than the devo? Could you post a picture of your receiver mounted in the quad? I am getting about 20 meters range test (100uw) line of site since moving to the nightly linked above, not sure what I should get. I just have the short wire version of the lemonrx satellite mounted to the top of a cf 250 quad frame. I too think the diversity(long wire) version would help with a cf frame. You can use zio ties and shrink tube to mount the antennas.

In this thread you can find some pictures how the sat is mounted:

www.multiwii.com/forum/viewtopic.php?f=12&t=6456

www.multiwii.com/forum/download/file.php...10f4c78197&mode=view

www.multiwii.com/forum/download/file.php...10f4c78197&mode=view

i am running lemon dsmx also and i mounted the sat on the bottom of the rear on my 250 mini and i seem to get decent range as long as i keep it LOS ...

Quick question tho is the sat supposed to have a LED light when powered up cause mine don't? I'm not even sure my sat is working...lol luckily i am running APM so if it looses connection it fail safes into RTL

Carbon fiber frame?
You probably would need then longer antennas / sats which are not faded and stick out of the chassis.

IMHO you need to track range problems with Spektrum FlightLog and telemetry (fades, holds, framelosses) and see how e.g a AR6210 behaves on 30/45/60m distance (Holds >0, FrameLosses >40, Fades >100/255).
Therefore you would need a Spektrum genuine receiver with supported DataPort.
It will also tell WHAT antenna (main, SAT) has higher fades and need to be re-oriented.
I do not advise to use SAT-only solutions if you have any problems.

Too many threads active about 3rd party receivers...you do not know what is going on below...

With my AR6210 I got ~60m distance on 1mw without holds and not that many FrameLosses.

With DX8 it was on ground test menu ~60m.

20m only? Try some new (genuine) full receiver (not SAT only) and make ground FlightLog detail tests:

My 2cents

Thomas

Antenna orientation got mentioned briefly, and might be an issue. I know I see as much as 20dB drop in signals strength with bad orientation.

The cheap dipoles that come on the Rx's and most Tx's have a doughnut-shaped radiation/sensitivity pattern, with the antenna proper oriented through the "hole" of the doughnut. So you want the two antenna's oriented parallel to each other. The worst thing you can do is point your Tx antenna at the aircraft. My intuitive behavior is to point the Tx at the aircraft, which is a bad idea . On the 10, I orient the antenna parallel to the ground pointing along the flight line so the aircraft will be inside the doughnut.

If you have two antennae - a diversity Rx or an Rx & sat - you want the two antenna pointed at 90° to each other, so that you never have both of them pointed at the Tx.

magic_marty wrote: i am running lemon dsmx also and i mounted the sat on the bottom of the rear on my 250 mini and i seem to get decent range as long as i keep it LOS ...

Quick question tho is the sat supposed to have a LED light when powered up cause mine don't? I'm not even sure my sat is working...lol luckily i am running APM so if it looses connection it fail safes into RTL

The LemonRx DSMX sat will have the red LED on if it is getting an valid TX signal. It will start flickering on lost frames and will go of if signal is list.

Thomas.Heiss wrote: Carbon fiber frame?
You probably would need then longer antennas / sats which are not faded and stick out of the chassis.

IMHO you need to track range problems with Spektrum FlightLog and telemetry (fades, holds, framelosses) and see how e.g a AR6210 behaves on 30/45/60m distance (Holds >0, FrameLosses >40, Fades >100/255).
Therefore you would need a Spektrum genuine receiver with supported DataPort.
It will also tell WHAT antenna (main, SAT) has higher fades and need to be re-oriented.
I do not advise to use SAT-only solutions if you have any problems.

Too many threads active about 3rd party receivers...you do not know what is going on below...

With my AR6210 I got ~60m distance on 1mw without holds and not that many FrameLosses.

With DX8 it was on ground test menu ~60m.

20m only? Try some new (genuine) full receiver (not SAT only) and make ground FlightLog detail tests:

My 2cents

Thomas

Yes this are all carbon frames. I don't own original Spektrum gear fro doing more testing. I only can relay on my buddy's in the club. Full receivers (with satellites) are likely much to big for my Quads and also don't provide an good signal. The PPM and PWM output will generate some jitter during the generation and measuring in the FC. The serial output is more accurate since the transfer is completely digital and what you receive is exactly what the transmitter sends. I may test an original spectrum satellite but the components inside are identical to the LemonRX only the firmware is different. also the construction is very similar. Anyhow the satellites are advertised as full range receivers.

Thomas.Heiss wrote: IMHO you need to track range problems with Spektrum FlightLog and telemetry (fades, holds, framelosses) and see how e.g a AR6210 behaves on 30/45/60m distance (Holds >0, FrameLosses >40, Fades >100/255).
Therefore you would need a Spektrum genuine receiver with supported DataPort.

You also get Flightlog telemetry from the latest generation of OrangeRx receivers. They're actually a better choice than Spektrum Rx's for small craft because the telemetry Tx is built into the Rx instead of needing a second box. They're also diversity Rx's, so you should get more reliable reception (but not more range) out of them. For use on a quad with a flight controller, the OrangeRx Rx's also offer CPPM output, or better yet SBUS, which doesn't have the frame length issues that CPPM does - so more channels and much less delay. Spektrum has a serial protocol of their own, but I don't know if there's a flight controller that it works with, and it's only available on their high-end (many channels, so big and heavy and expensive even for Spektrum) Rx's.

Carbon fiber frames are so cool. And so problematic. I've not used one, and keep shying away.

The whole frame is conductive and has to be dealt with as part of the antenna system. Or rather a ground plane for it. Which could be a good thing. But seems like it's crying for a completely different approach. It's not just reflective. It's opaque to radio signals. I imagine four separate antennas with coax feeds to better deal with the problems of communicating from any orientation and escaping the 'shadows'. Certainly not taking a traditional, short antenna receiver, and slapping it on.

At least one antenna on top and another on the bottom.

View your quad from various angles and consider that the frame blocks signals well.

turns out my sat wasn't even working... guess that explains the fail safe yesterday i got when sending it on a planned mission...i placed the bind plug on the rx and rebound it and now its working as it should...

Thomas.Heiss wrote: With my AR6210 I got ~60m distance on 1mw without holds and not that many FrameLosses.

With DX8 it was on ground test menu ~60m.

20m only? Try some new (genuine) full receiver (not SAT only) and make ground FlightLog detail tests:

My 2cents

Thomas

Lemon makes a long wire version for CF frames, but nobody in the US carries it so far. I got close to 20m on 100um (microwatts) los BTW.

Would it be possible to solder longer ones on the rx/sat that has the short wires on them? Can buy the longer antenna wires here in the US

mwm wrote: Antenna orientation got mentioned briefly, and might be an issue. I know I see as much as 20dB drop in signals strength with bad orientation.

The cheap dipoles that come on the Rx's and most Tx's have a doughnut-shaped radiation/sensitivity pattern, with the antenna proper oriented through the "hole" of the doughnut. So you want the two antenna's oriented parallel to each other. The worst thing you can do is point your Tx antenna at the aircraft. My intuitive behavior is to point the Tx at the aircraft, which is a bad idea . On the 10, I orient the antenna parallel to the ground pointing along the flight line so the aircraft will be inside the doughnut.

If you have two antennae - a diversity Rx or an Rx & sat - you want the two antenna pointed at 90° to each other, so that you never have both of them pointed at the Tx.

I'm aware of this. In my understanding the center of the doughnut is the axis of the antenna. If it's pointing to the sky you schould have good signal around you ant the worst spot is over your head. Having the antenna parallel to the ground you will have bad spots left and right from you.

magic_marty wrote: Would it be possible to solder longer ones on the rx/sat that has the short wires on them? Can buy the longer antenna wires here in the US

I haven't found a definitive answer on this, some say yes, some no. Apparently impedence can be a concern.
Theoretically you can solder on a coax, centre to antenna pad and shield to ground, and strip off the appropriate(!) length of shield at the end; allowing for possible material differences between the replacement wire and the original wire. But don't know how far you can extend this before impedence changes have a bad adverse effect.

That's what I was thinking cause I think it's frysky that sells the replacement long antenna wires and they are shielded but have the end shield stripped off for reception. ..they come with the small plug on the rx end tho but might be able to snip it off and solder it directly to the rx pad..?
I will range test my mini to see what kind of distance I am getting now that I got the sat working properly. .The best range I get thus far is with the Devo 8 and 12 ch rx with the long antennas ...I mount them on top of the frame using a home made mount with small plastic tubing holding each antenna wire in a 45 degree V position.But I have not tried them on a carbon frame yet I have them on home made wood frames..

andmiller wrote:

Thomas.Heiss wrote: With my AR6210 I got ~60m distance on 1mw without holds and not that many FrameLosses.

With DX8 it was on ground test menu ~60m.

20m only? Try some new (genuine) full receiver (not SAT only) and make ground FlightLog detail tests:

My 2cents

Thomas

Lemon makes a long wire version for CF frames, but nobody in the US carries it so far. I got close to 20m on 100um (microwatts) los BTW.

Have some of them on order. Need some time from China.

magic_marty wrote: That's what I was thinking cause I think it's frysky that sells the replacement long antenna wires and they are shielded but have the end shield stripped off for reception. ..they come with the small plug on the rx end tho but might be able to snip it off and solder it directly to the rx pad..?
I will range test my mini to see what kind of distance I am getting now that I got the sat working properly. .The best range I get thus far is with the Devo 8 and 12 ch rx with the long antennas ...I mount them on top of the frame using a home made mount with small plastic tubing holding each antenna wire in a 45 degree V position.But I have not tried them on a carbon frame yet I have them on home made wood frames..

The board is not designed for this since the long antennas have an coaxial connection. Anyhow you only can fit one antenna in this case. The active Antena is only the left side the other side is connected to ground and only part of the dipole. The real diversity receiver has an switch after the two antenna's and will forward the strongest signal to the reciver chip. The logic and board layout of this reciver is a bit different (see picture in the link of my initial post).