Servers by jDrones

Telemetry connection doesn't work in a sunny day

Dear community,

I’m using the Sik telemetry to connect my rover with the Mission Planner.
Inside of the room, it works perfectly fine. However, when I do the field test outside under the sun in a sunny day, sometimes the telemetry will stop working suddenly and the connection will be also interrupted. So is it because all the telemetry has the same problem and I should avoid drive my vehicle under the sun ? Or I need to purchase a better telemetry that can work under the sun ?

@Mirko_Zhou, I’ve never heard of a telemetry radio failing in the sun before. I guess it’s overheating so perhaps mount it on the bottom of the vehicle or something similar. I’m afraid that’s the limit of my advice but I’ve ping’d some other devs to see if they have any ideas.

@Pedals2Paddles, FYI just to keep you in the loop re any GCS failsafe issues.

While it is sitting there on the ground? Or while in flight? If while in flight, you could just be flying out of range. Otherwise, I agree with Randy that this probably a hardware problem.

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Thank you. So telemetry has the capacity to work under the sun ?
Is there any good quality telemetry you recommend that can be connected with Pixhawk 1 ?

I would look at these here, great range and also support ppm passthrough and s. bus passthrough. These are very user friendly and have many options the user can set. They do get a bit hot but have never had one fail even when ambient temp. is 105°F and very little airflow over it on the ground.


I am assuming that because he posted this in the rover section that it more than likely was sitting on the ground or water, not sure just a hunch!

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Thank you so much.
So I need to buy two units and also the cables for connection with Pixhawk ?

Yes, they have newer versions called the 900ux which is compatible with the 900x units, they also have 868x units and I have been told they will come out with 868ux units. I have used the 900x,900+, and the 900u version. The units with x after the number support ppm or s bus passthrough. The nice thing about the ux units are they have a jst-gh connector instead of the larger servo pins. Do note that these radios must be powered from a bec and not the power coling from the telem/serial ports. They could cause brown out issues when powered via the telem/serial ports. You will not regret getting a set of these! I know I haven’t!

I found a telemetry kit based on RF900 including all necessary cables:

Can I use this one ?
Also how can I power the component from BEC ? What I thought is that we can use the cable they provided to connect directly with the Telemetry port from Pixhawk

I’d get their 900x version as this supports encryption also and the ppm and s bus passthrough which are quite nice features and not a heck of a lot more to be honest, if you can swing it.

I see.
Could you please explain more regarding how can I power the radio modem from BEC ? What hardware do I need to buy and how to wire the connection ? Can I just use the BEC output from ESC ?

I personally wouldn’t use the esc and dont even use the bec that often comes with esc just because they are quite flight critical and any less loaf on it the better. Any 5volt bec that supports 1amp will do often times most 5volt becs are 5 volt 2 amp. At max power the rfd should pull close to 800mA. To hook it up just pull the power and ground off the df13 or jst-gh whichever flight controller your working with and hook them to the bec. Make sure your bec can support the voltage you supply from your battery. I will try and dig up some photos.

The battery on my vehicle is currently connected with the power module, providing power to Pixhawk and the motor. So I’m not sure how can I connect BEC with the battery ? Do I have to cut the cable and solder them together ?

Could you provide a picture of the setup?

you could solder in the bec right off the voltage and current sensor, just cutoff the plastic cover and solder the bec directly off there. I would also provide the M+ with power from the bec as well.

Thank you so much. Do you have any recommended BEC unit ?

Not really, all kind of depends on where you are and whats available. Just make sure its the right voltage and has enough amps to power what you are running. any 5volt 2amp bec will work for powering both the m+ and the rfd, could bump up the amps a bit just to be safe but that should cover your needs. You might also want to look at adding a ground plane to that m+ antennae, emlid recommends a min. of 70mm copper or aluminum. It will greatly reduce your multipath errors, I have found that a cd with copper tape has worked fairly well and isn’t to expensive.

Thanks Matt. Can I just cover the mental plate with copper tape and use it as ground plate ?

How big is that metal plate? That little rib on the front is the only thing I would be worried about, can you perhaps turn that over so its flat then it shouldn’t be much of an issue mounting it there, might improve quality if you mounted it up higher but it may be so minimal you’d never know the difference. Just some thoughts!

Servers by jDrones