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FrSKY Taranis X9d Plus and X8R Telemetry Signal Lost Problem

rijun034

New member
Hi!

I'm using **FrSKY Taranis X9D Plus with X8R receiver.** After resetting the transmitter, I have completed Stick calibration and configured Fail-safe.

I created a model for **Fixed-wing** and bonded X8R successfully.

But the problem is that now when I'm using the TX-RX, several times the **TX announces that Critical range problem and Telemetry signal lost**. After a matter of seconds, it will **connect again.**

This issue **repeats again and again**. I don't know what and where I missed.

I cannot test my flight in this condition.

I'm new to FrSKY Taranis and X9D.

Anyone faced similar problem and If solved, please share the solution (troubleshoot or setting problem).
 

Wayne

Administrator
Staff member
Does it just say telemetry lost, than telemetry found? If so, just keep the transmitter a little further away from the receiver. Should solve this issue. Basically when they are too close together the telemetry signal is lost as it is too strong. It is like someone yelling directly into your ear.. You hear them, it hurts, but you probably didn't understand what they yelled.
 

romeoletor

New member
I found the same problem and in addition an other issue: The channel 2 of the RX8R was going to end point for a short time and after returning back in the right position. When this happens , I get a telemetry lost and telemetry recovered message. This phenomenon happened also during a test flight with the model at 100m distance. The seller sent me an other Rx8R with the same issue. I also left the RX and TX on for about 3 Hours and this behaviour arised for about 4 times. The phenomenon is random and appears with all possible conditions. Even when TX is OFF and RX8R is in fail safe. I am waiting an answer from the seller
 

Konrad

Well-known member
Just spit balling here,.
But how's your power supply? Most BEC's are not rated for continuous use much past 20 minutes. This is particularly true of linear BEC. And true for linear and switching BECs with no air flow over them. The fact that a servo goes to an end point is indicative of a power interrupt. The fact that you still get these resets even with the TX off indicates to me that the issue is not RF related, as with the TX off there should be no RF link.
Try running your tests again with a large 4 cell (4.8v nominal) battery.

Not sure what the reseller has to do with this. I normally put technical compliance on the shoulder of the equipment OEM, FrSky! But as the retail seller did try to do right by you in giving you another RX it might be nice to acknowledge their effort even, if it didn't addresss the technical issue.
 

Tim Callahan

New member
Good luck getting this fixed. i have been complaining about this issue for a long time. Two years ago i swiched to the GRX8 receiver and the problem got worse. the problem is like you say its intermittent. I like the GRX8 becaus of the fearures, swiching chan 7 to allow a normal receiver hook up, selecting Telemetry or not, and it's capsability to be used in a redundant receiver sitiuation, but most i like the size. i have been flying my Kappa 3 and two others with this issue and its not limited to take off, being to close, happens all through flight. its so annoying to listen to her say " telemetry lost telemetry found" over & over & over. through all these warnings i have yet to lose contact from the plane in flight. i have had flights where she says "telemetry lost" and then over a min or min1/2 she comes back with "telemetry found. Now all i do is turn her off, then turn up when i want altitude. It would be great if sombody could figure out a solution or cause.
Help Konrad, Help Wayne
 

Konrad

Well-known member
Tim,
I'm sorry to say that I'm just like you, an end user of the product (a customer). I have no pull with Fr Sky (or anybody else).

Now I will say it is up to us to document as well as possible the failure modes we have with products. Unfortunately I'm not aware of a vehicle to report technical issues directly to Fr Sky. I do know that Wayne does make an effort to let Fr Sky know of issues and that he tries to leverage them to come out with a solution to technical issues. Aloft Hobbies is also very good at supporting the product should there be a manufacturing issue (warranty).

The issue might be as simple as antenna impedance matching. It might be a issue with the firmware's trip point. As a field support engineer in a previous life I know a lot of issues are with the integration of sub systems (servo drain, antenna placement, power supplies, component mounting etc.). So the more data we can give Fr-Sky the more likely they can duplicate the problem and hopefully come up with a solution.

All the best,
Konrad
 

Tim Callahan

New member
there are 4 of us in our group that are using all FrSky equipment, and we all experiance some of these issues. i'll se if we can't start collecting some data on how often, percise issue, weather, and anything else that might fall into the " cause and effect" bucket.
Tim
 

Konrad

Well-known member
I noticed that on the Taranis the user can assign the value for the RSSI alarms.
I wonder if after doing a range test to the point that RX actually goes into fail safe. That the RSSI value seen in this condition should be entered. Maybe add a safety margin by bringing the RX and Tx 85% closer together than the F/S distance and use the resultant RSSI value as the alarm trigger. ( I don't know if the RSSI issue is with the receiver not getting a good signal. Or if the issue is the transmitter not getting a good signal back from the receiver. This is why I place more credence on the physical range test than the RSSI alarm)

I too fly a GRX8 Rx at distances in a 3.2 meter glider. While my eyes aren't as good as they use to be I get OK signal strength to about 3 or 4 km at altitude. This really is at the range of my eyes as the glider is winking in and out of view. All I've done to my Rx is try to keep the antenna at 90° to each other and I've added some stiff heat shrink to the non shielded part of the antenna to keep it straight. This was done to try to keep the RF electrical length as designed. (Bent, bowed or kinked antenna result in an effectively new tuned RF length. Antenna length is the first "RF filter" in helping with the signal selectivity of the RX).
https://alofthobbies.com/frsky-g-rx8.html

I'm now wondering if the receiver's receiving antenna array has the same impedance (Standing Wave) as the receiver's transmitting array. The RF standing wave is a design issue that all RF engineer's need to deal with. The fact that these RX's use the same antenna array to both receive signals and transmit data can be an issue.

Again I need to be clear I have no inside knowledge as to how these RX's are designed. I'm just spit balling (thinking out load) here.

All the best,
Konrad
 
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Robert Smith

New member
Same problems - X9D with GRX8. Always range test fine. Random lost signal for usually about 1 sec - as short as .5 sec as long as about 4 seconds. Problems at distances of 400 to 800 foot altitude and range of 500 feet to over 1200 feet. Range and altitude seem irrelevant. Antennas are mounted external to aircraft and the receiver has been replaced without improvement. My best guess - receiver/transmitter and X9D are not compatible (unlikely) or a design error or failure in RF board (my likely). I need a solution now. Would be happy to return for credit and upgrade to Horus. Tired of continuing problems with a unit that is only a few months old. Also have been unable to get contact with Aloft tech support after trying for a week. Where do I go from here?
Bob Smith
 

RalfH

New member
Is it possible that the battery voltage drops due to high current load from the servos? This could cause a brown out for the receiver and lost telemetry.

Ralf
 

Robert Smith

New member
Using 1100 mah LIFE which is overkill. If it was low voltage induced brownout it would do it upon landing with large flaps and ailerons fully deployed, but that's not when it is happening.
BS
 

Wayne

Administrator
Staff member
I wonder if after doing a range test to the point that RX actually goes into fail safe. That the RSSI value seen in this condition should be entered. Maybe add a safety margin by bringing the RX and Tx 85% closer together than the F/S distance and use the resultant RSSI value as the alarm trigger. ( I don't know if the RSSI issue is with the receiver not getting a good signal. Or if the issue is the transmitter not getting a good signal back from the receiver. This is why I place more credence on the physical range test than the RSSI alarm)
PLEASE do not do the above - very poor idea.

The telemetry lost, telemetry found is not related to RSSI. It simply means the transmitter lost telemetry feed from the receiver. It is interesting that this seems to effect a very small group of folks, and a receiver replacement did not cure the issue.

Are all of you that have this issue using a Taranis or Taranis Plus?
 

Konrad

Well-known member
I agree, not a desired option.
But as the RSSI is a relative index I was thinking that the alarm could be reset with real world finding (range test). There is often a huge difference in distance from when the TX alarm goes off and the RX goes into Fail Safe
Beyond that I'll leave it up to the RF engineers.

FYI: When I do get a premature telemetry loss signal I can usually fix it with proper antenna orientation. This is different from the classic swamping of the Rx front end by having the TX too close to the RX.

Using an early Taranis plus on OpenTX 2.2.3


dBm and RSSI are different units of measurement that both represent the same thing: signal strength. The difference is that RSSI is a relative index, while dBm is an absolute number representing power levels in mW (milliwatts).

RSSI is a term used to measure the relative quality of a received signal to a client device, but has no absolute value. The IEEE 802.11 standard specifies that RSSI can be on a scale of 0 to up to 255 and that each chipset manufacturer can define their own “RSSI_Max” value. Cisco, for example, uses a 0-100 scale, while Atheros uses 0-60. It’s all up to the manufacturer (which is why RSSI is a relative index), but you can infer that the higher the RSSI value is, the better the signal is.

All the best,
Konrad
 
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Konrad

Well-known member
Wayne I'm glad you called me out on this. If you or anybody else thinks I've make a false or dangerous statement please call me out. Safety is everybody concern. I'd rather look foolish than have somebody hurt.

Wayne again thank you.


All the best,
Konrad
 

countryshooter

New member
I have been having the same problem. I solved it by installing a voltage regulator from the battery to the receiver so I get a constant 7.2v to the receiver and cut the power wire from the bec and as of now I have no problems
 
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