Odd problem with GR6 telemetry

[CurtD]

This is a new Archer GR6 with the variometer and altimeter telemetry. It's been updated to the latest firmware (but I had to use the S.Port as OTA upgrade would not work) and works fine as far as the receiver goes with good range and no control problems. The problem is the telemetry is really sketchy. I've set it up per the manual as far as I can tell. The altimeter works but it's erratic and inaccurate. I'll see it a '0' on the telemetry display on the ground and when I first launch. I'll also see the aircraft's altitude displayed and changing as I climb and descend. When I finally land and look at my altimeter display in the TX it's no longer '0' but some seemingly random altitude, not '0'. Makes me think that it's not giving me accurate altitude readings. The variometer does not work at all. I never see (or hear from the audio) a change in ascent or descent rate, even when the plane is under power and climbing rapidly.

Am I missing something in the setup or do I have a defective receiver I need to send back to Aloft?

TX is Taranis X9D Plus (2019) with latest firmware.

 

[HENNY]

The altimeter is actually an air pressure gauge. As such it is affected by direct wind blowing on it as well as air pressure changes during a flight. When I fly and leave the ground with zero Alt indication, on landing it could vary by a couple of meters (6 feet) from lift off, this is normal. There is a setup procedure to get the Vario audio indication operational, secondly you can also setup a special function to read out Alt as well as warn when you are too high. Here is a Youtube video for that.

When you indicate the X9D+ has the latest firmware which version is it. OTX v2.3.14?

 

[CurtD]

Thanks for the reply. I understand about how the altimeter works as I'm also a full-scale pilot. The receiver is under a cover that creates a "dead air" space to reduce internal air flow affecting the sensor. Generally, I'm not looking for perfect accuracy, just altitude numbers I can believe. I didn't say in my original post how far off the "zero" was when I landed but it was in the range of 30 to 35 meters. Small errors (a few meters) would be acceptable but this is not a small error.

I have been through the setup procedure for the vario several times with no change in results. It says it's working and returns telemetry but it obviously is not functioning. I'll check the Youtube video to see if there's something different that I should try.

RF module firmware is 2.1.6FCC
OpenTX firmware is 2.8.11-otx. The latest for this TX is 2.8.12 but it appears to only enable Racing mode so I haven't updated to that, and don't plan to.

 

[Flying Dutchman]

Does the altitude reading eventually stabilize? I understand that these sensors need to warm up for a while until they do.

I have a couple of GR8's, and they always require a zero reset before I launch (have now automated that), but I have not seen much drift over the course of even long (40-60 min) flights. Of course here in AZ warming up is generally not necessary , but if you live in colder areas it may be an issue.

And did you get the vario beeper to work? If not, what settings have you used so far?

 

[HENNY]

RF module firmware is 2.1.6FCC
OpenTX firmware is 2.8.11-otx. The latest for this TX is 2.8.12 but it appears to only enable Racing mode so I haven't updated to that, and don't plan to.

The latest OTX version is v2.3.14. version v2.3.12 had some bugs. I agree with the Flying Dutchman in that the GR8 and other FRsky such receivers are very accurate. One thing to perform is a Alt reset to AGL before taking off. This can be achieved using the throttle cut switch if you are using it and a special function setup.

 

[Wayne]

Yep - Reset the telemetry before flight. But keep in mind that the vario sensors take a bit of time to get dialed in, so you may see some bigger errors like 20 or 30 feet at first. Also, if your weather is actively changing at your location, this will also throw things off.

 

[CurtD]

Right on the OpenTX version. The '8' was suppose to be a '3'. I will update the TX soon. I also understand about setting the altimeter to '0' at start and I've been doing that manually but that's not the issue as I've already posted. It's showing SIGNIFICANT (30-40 meters) error when I land which leads me think the altimeter is erratic.

The variometer simply doesn't work. I get the tone and it displays a 'slightly' varying signal (0.1 or so) when I move the aircraft quickly up and down as I've seen demonstrated in YT videos. In the air, I get no change in variometer reading or tone even when I'm under power and climbing rapidly. On the "Telemetry' page in the model setup, "Vspd" is displaying data on the transmitter so the telemetry signal is being received. It's just doesn't change.

 

[Wayne]

In stock form the vario settings in OpenTX work pretty well, but they can be "tuned" to work better or not work at all. So you may need to check those settings for the vario tones, there are a number of videos and web sites that talk about setting these up. But yes, it is possible you have a bad unit, but I'd play around a bit first as the chances of a bad unit are pretty darn low.

(I think you mentioned you updated the firmware. Please be sure you have the newest firmware if you have a new vario. If you have an old vario of unknown age, the new firmware may not be correct at all as the sensor used did change, thus a new firmware change. That was probably 3 or 4 years ago. I honestly have never seen a reason to update the firmware that comes on a vario, or pretty much any of the sensors.)

 

[CurtD]

I went ahead and updated the OpenTX firmware, SD card, etc. in the TX (X9D+ 2019) to latest version. The receiver (GR6) and Internal RF module were already at the latest version. After updating the TX, the vario still did not work. It showed in the 'live' display on the 'Telemetry' screen (Vspd) where you see all the inputs but not in the 'Vario' configuration. Finally, I tried clearing the vario config, resetting everything to defaults (not configured) and cycled power on the TX. After restarting it, I went back in and re-added the 'Vario' config on the 'Telemetry' (configuration) screen just like I had it before. Now it's working. The only difference was I changed from M/s to ft/s.

I won't be able to flight test the altimeter telemetry until this weekend.

 

[HENNY]

In the vario set up line you need to select Vsp as the source for it work.

 

[CurtD]

Vario and altimeter are now working as advertised. Altimeter seems to be reasonable stable and accurate. The variometer is so nice to have I think I'll probably put this receiver or the GR8 in all my sailplanes. Very nice!

 

[Wayne]

Glad you got everything going!! Thanks for the follow up.

 

[bikexprt]

Hi guys, I am also having an issue with my Archer GR6. The altitude steadily decreases at approx. .9-1.1 m/s, so when I reset telemetry and re-discover sensors, it goes from 0 to -~60 meters in the first minute and keeps going down. If I fly it, it will read steady but only if I climb at a rate of about 1 m/s. So it works, but only with that descent "bias" if you will. Is there a calibration procedure I'm missing?

 

[HENNY]

Hi guys, I am also having an issue with my Archer GR6. The altitude steadily decreases at approx. .9-1.1 m/s, so when I reset telemetry and re-discover sensors, it goes from 0 to -~60 meters in the first minute and keeps going down. If I fly it, it will read steady but only if I climb at a rate of about 1 m/s. So it works, but only with that descent "bias" if you will. Is there a calibration procedure I'm missing?

To reset the Alt use reset Alt not reset telemetry. The receiver finds to additional sensors with the GR6, Alt and Vspd. Are you sure you are monitoring Alt. No calibration is required.

 

[bikexprt]

Hi, thanks for the help. So, I set up a special function to reset the altimeter via a switch on my TX. Now, when I connect to the GR6 the altimeter still begins its steady descent. If I repeatedly reset it to 0 with the switch, it still continues to drop to a negative value albeit more slowly. I'll try to get a video later today and post so you can see what I'm talking about.

 

[HENNY]

Hi, thanks for the help. So, I set up a special function to reset the altimeter via a switch on my TX. Now, when I connect to the GR6 the altimeter still begins its steady descent. If I repeatedly reset it to 0 with the switch, it still continues to drop to a negative value albeit more slowly. I'll try to get a video later today and post so you can see what I'm talking about.

How much is steady decent.

 

[tinkerguy]

Hi, thanks for the help. So, I set up a special function to reset the altimeter via a switch on my TX. Now, when I connect to the GR6 the altimeter still begins its steady descent. If I repeatedly reset it to 0 with the switch, it still continues to drop to a negative value albeit more slowly. I'll try to get a video later today and post so you can see what I'm talking about.

I have two "high precision" varios. They both drift constantly - one keeps going up and the other goes down. Its a rapid change at first but even after 20+ minutes they continue changing. I've learnt to just accept them as simple crude solid state barometers to give approximate altitude, which is probably all that most people need.

 

[HENNY]

I have two "high precision" varios. They both drift constantly - one keeps going up and the other goes down. Its a rapid change at first but even after 20+ minutes they continue changing. I've learnt to just accept them as simple crude solid state barometers to give approximate altitude, which is probably all that most people need.

So how much change are you seeing. 10 of meters or a meter or two.

 

[tinkerguy]

The two can be off by 25 feet or more after about 30 minutes at ground level, one too high and the other too low. If I can combine the output from the two - I can probably average them and get a reasonable value. Its not that big of a deal as these varios are so cheap so you need to moderate your expectations. There are plans out there to make a S-Port compatible DIY altimeter using a mini arduino and a BMP280 pressure sensor - but then again, these cheap off-the-shelf barometers may exhibit lots of drift too.

 

[Wayne]

As I recall the drift will be reduced the longer the vario is powered up. It should be a small error rate. This is why it is a good idea not to use altitude telemetry for major mixes like landing gear deployment.