Devo 12S DSMX Range and Telemetry Questions

Hi Everyone,

I am having some range issues(?) with my Devo 12S, I would be very grateful if someone could help to answer my questions. My story is a bit long, but I just want to don’t miss any details of my findings, so here’s my story:

I am a helicopter pilot and I have been flying all my helis with a Devo 12S and Walkera Rxs for almost 2 years now and I have had no problems whatsoever. I have installed Deviation 4.01 a few months ago, so I could fly my new Terx 150 with a DSMX satellite. Everything worked perfectly (with both my Trex 150 (DSMX) and Walkera Rxs) and I love the flexibility of Deviation.

Last month, I added a Trex 700E HV version to my fleet and I wanted to use a 2S LiPo to power the servos and electronics, but according to the Specifications, Walkera Rxs can only handle up to 5V. I am worried I would blow up the Walkera Rx if I just power it with a 2S LiPo, so I decided to run 2 DSMX satellites with my Vbar. The binding process with my Devo 12S went smoothly and I went out for a maiden flight. I made sure my transmission power was 150mw and Voilà! The maiden went great and I didn’t notice any issues at all.

When I got home, I checked my Vbar log, to my surprise; I found hundreds of “antenna switched” entries. So I checked on the internet, “antenna switched” is similar to “Fades” in Spektrum term, and it could be caused by placing the satellites at undesirable locations on the heli, shielding the reception of the satellites. I thought “OK, I will move both satellites to open areas and I will be ok!” and so I did. I went out again for another flight, and no improvement was found, there were still hundreds of “antenna switched” in my Vbar log. I understand occasional “antenna switched” is normal, but hundreds of them looks worrying to me. So I decided not to touch my Trex 700 again until I figure out problem.

To rule out the possibility of having faulty Vbar or DSMX satellites, I borrowed 4 different DSMX satellites from my friend and tested them on my 450 heli, and the same results were found – a full page of “antenna switched” entries in my vbar log.

I started to think there could be something wrong with my Devo 12S, but I still didn’t give up then, as I thought it could be a compatibility issue between Vbar + DSMX Satellites and Deviation. So I bought a Spektrum AR6210 receiver and a TM1000 telemetry module to make sure it is a transmitter problem. This time I didn’t hook up the receiver to a Vbar, but I just watched the telemetry data shown on my 12S as I walked away from the receiver. I tried to do a range test, I turned the transmission power of my 12S down to 100µw and at about 10 meters away, I already had over 100 FadesA and FadesB , 40 Loss and no Holds. When I reached about 13 meters, FadesA and FadesB shoot up to 255 (maximum that could be displayed?), 200 Loss and no Holds. If I walked any further away from that, I got Holds and the telemetry module lost connection. So my questions are:

1.) Am I correct to say Deviation should give the same range regardless if DEVO or DSMX protocols were used?

2.) Do you think the above range issue is a DSMX-only issue or there is something actually wrong with the hardware of my Devo 12S?

3.) If my problem is hardware, what would be the most likely cause? Could it be a faulty Antenna? Or could it be the transmission module?

4.) Has anyone tried to supply Walkera Rxs with a voltage higher than 5V? Anything bad happened?

5.) If I want to try replacing my Tx antenna, what is the most suitable antenna gain for a Devo 12S? What is the antenna gain of the Devo 12S stock antenna? 2dB? 3dB?

6.) What is the proper way of range testing a Deviation Tx? Am I right to assume similar procedures to other brands Tx? Turn the power down to 100µw and walk 30 meters away from the aircraft, and if I still have full control, then I am good to go?

7.) As I only fly helicopters, I never really exceed a range of 200 meters. So even if the signal of my Tx is weaker than it should be, I would not have noticed it if I never use DSMX Sats and check the Vbar log. Has anyone encountered similar issues? And could it be resolved?

If I cannot resolve this problem, I would have to dump this Tx (this is the last thing I would ever want to do), crashing a heli is one thing, but the possibility of hurting somebody is a lot more serious. Thanks for reading this and any help or input are very much appreciated.

Hi John,
I run a Devo8S with Devention 4.01, different Helis (Mini Cp, T-rex 450, Compass 6HV & 7HV)
On the 7HV I have the same Setup 2 DSMX Satelites & VBar. I have the same issue with the Antenna switching. transmission power is 100mw. I have not done a range test with lower transmission power, but with 100mw I loose control after 200 meters on Ground test in the worst case. I have about 50 flights on this heli now, but had never any issues in flight. (up in the air the range should be better since it's a 2.4GHz)
I guess I should do a range test with the satelites on a different place, but to answer your questions:

2+3: I don't think there is something wrong with your transmitter hardware, since it's the same on mine.

4: I run Walkera RX up to 6V

6: I'm sure u r right, but I don't know the transmission power @ a spektrum transmitter range test

7: it would be interesting what's a occasional antenna switching, i think I read somewhere in the VBar forum that antenna switching every second is normal?? So I'd probably figure out how often is occasional.

I will probably do a range/flight test with a Spektrum transmitter the next days & let u know the results.

I've had ~ 250 flights with the devention firmware (~100 with Devo Protokoll, ~150 with DSMX) and everything worked fine until yesterday.

I hope I figure out what went wrong, but so far I can say that either the Software crashed or the TX output PCB failed.
I was flying the Trex 450 (Devo RX701) & suddenly the motor switched off at low altitude (must have been failsave) the heli crashed into a field and had no visible damage, that's why I wanted to check the servos and spool it up just a minute later. but I had no control! I replaced the Lipo of the heli, same thing. then I realized the Microbeast doesn't boot up and also the ESC doesn't initialise. so I switched the transmitter off & on and finally the heli was initialising! that's why I'm sure there was something wrong with the transmitter.
Since it was the 450, I had 2 more flights everything fine. at home I checked the error log: no entry

that's why I'm really worried now! I'd say the range is enough if you fly only helis and no FPV. but crashing a 600 or 700 heli at the wrong moment can cause some serious injury!

so if I figure out what's wrong or if there is a difference in the antenna switching to a Spektrum transmitter I'll let u know.

attached the Vbar log file



all the best
Markus

Hi Markus,

Thanks very much for your reply. Your vbar log looks very similar to mine, but mine is just slightly better as I did get a few “good health” messages, maybe I was flying closer than you were?

I have been reading on different forums, many heli pilots reported for a 4-5 minute flight, they are getting less than 20 “antenna switched” messages with their Speckrum transmitters. So our Vbar logs are very worrying indeed. On top that, my range test results was only 13 meters at 100µw before I lost connection. (FYI, I changed the antenna of my Devo 12S, I got same results.) Yes, I have not lost control for the last 2 years, but still, I am not inclined to fly my larger birds with the Devo 12S until I get this sorted.

As I do not have access to a Spektrum Transmitter, do you own a Spektrum Transmitter? I would be very interested to see your Vbar log again if you fly the same heli with a Spektrum Tx. Thanks.

Hi John,
I opened up my transmitter yesterday to have a look if the connectors and cables are fine & to check if I can see any faulty part, but everything looked good. then I reconnect every every plug to make sure they have a good contact. 3 more flights without any problems with the 450, but I don't wanna fly my bigger helis right now, since I don't trust this transmitter right now.
that's why I decided to buy a DX9, cause I don't wanna spent the whole summer testing the Devo with the Trex.
to make it short: In the future I will fly the Trex450 with the Devo and see what happens and I'll post the Vbar log with the DX9 than we see if there is a difference with exactly the same configuration.

hey John,
I have bound the DX9 to the 7HV, did a range test and had some flights. range test pretty much 30m, when I look to the heli it works @30m, but when I turn around and the signal is blocked by my body it doesn't (I don't know the the Spektrum TX power @ the range test).
now the important thing, the new Vbar log, basically a big improvement, almost no antenna switches! I dont know if u speak german, but the errors @ the beginning and middle of the log file are from binding & range test. some vibrations, mostly spool up & bank switching (rpm change) and some in flight vibrations, probably due to tail gyro too high at flight mode 2 (bank 3)

since it's exactly the same setup the antenna switches must have come from the Devo, I'm sorry for u!
It's a pitty cause I really liked the Devo, especially the sticks compared to the DX9.
but as I said it worked for me for around 50 flights on this heli without any issues, I only switched the TX because of the inflight TX output driver or software crash.

Markus

When does the receiver switch antenna? Is it based on signal strength RSSI threshold?

Or is based on decoding of frames, so if corrupt frame checksum etc, Rx try the other antenna and you loose one frame? In this case if deviation sometime transmits a faulty frame, then antenna might switch?

Hi Fernadez,
in my opinion it's not based on signal strength, because when you look at the first log there is antenna switching every second, so it's more likely that deviation transmits faulty frames.
as I wrote before, I have never had problems with the signal strength or anything else during a flight, the only problem was the inflight TX output- or software crash.

Markus

Hi Markus,

Your vbar log looks much better now! At least we have now confirmed the frequent antenna switches were in fact related to "our" Devo transmitters. However, I am not so sure if we have a strong enough case to confirm and tell everybody "Devo + DSMX = Range Problem (or frequent antenna switches)" as we could just be the unlucky ones who got a Devo with faulty hardware (Walkera is not famous for their quality control).

I just bought a Futaba 14SG and I am only using it for my Trex 700E. In comparison, I still prefer my Devo 12S, the grip, the sticks and the flexibility of the deviation firmware. Not to mention carrying an extra Tx to the flying field.

I really hope others who are using DSMX could also share their experience, or even better if PB would share his view on our issues. So the deviation community can decide if DSMX is suitable for their larger models. Thank you.

I am having this range issue too on lemonRX, orange & spektrum dsm2 flying FPV with about 200m distance and signal lost everytime. I have been trying to find out what happen but end up suspecting all walkera radio not only limit to devo12. I have tested with devo 6, 8s & 12s all with very poor range & all tested with devention and also defaut walkera firmware...

Hello,

Has anyone been able to test for frame errors using DSMX? I want to use my 12s with my big planes but now I'm shy to do so....

Been having all kinds of Spektrum equipped Mcpx BL and 130x flights with no radio problems at all. I know I don't go out as far and so I can't testify to range issues...

Thanks

John L.

Hi John,
Hi Markus,

@max.hof
Your 450-crash reminds me to my V120d02s crash which was definitely related to telemetry in conjunction with a defective TX-module.

Watch out for random implausible telemetry values!

I don't have any experience withe DSMX or V-bar, but it would be interesting to see, if switching telemetry off would change anything.

greetings
Manfred

Hi Manfred,

Thanks for the input, but I don't think our issue is related to telemetry. The frequent "antenna switches" happened regardless of whether telemetry is on or off. For me, it seems to be a signal strength problem, when the Tx is close to DSMX sat, no antenna switches were found.

Interestingly, another user reported he was able to get a range of 35 meters with a DSMX sat on his Devo 10. ( www.deviationtx.com/forum/6-general-disc...10-antenna-mod#24690 ) Whereas, I only had 13 meters before I lost bind.

Cheers,


John

I have DEVO8s with 4.01 firmware, DSMX sat connected to MSH Brain system and DSMX reciver AR6210.

I maked a test:
- DSMX sat (power 100mW) - about 180m (after 180m sat was temporary blinking)
- reciever AR6210 without SAT (power 100mW) - about 50m (after 50m reciever show 1 lost signal)

Telemetry OFF.

I don't know where problem is. I will check a range with DSM2 and RX802 tommorow.

johnho100 wrote:
However, I am not so sure if we have a strong enough case to confirm and tell everybody "Devo + DSMX = Range Problem (or frequent antenna switches)" as we could just be the unlucky ones who got a Devo with faulty hardware (Walkera is not famous for their quality control).

Hi.
I have the same problem with my Devo 8S. I got only ~10m at 100uW under perfect line of sight condition. If I put the receiver into a form, I got only ~5m at 100uW. Then, I will get only ~150m at 100mW at most.

While the devo is quite convenient for me, the range issue is very critical. If this range issue is only for my faulty radio, I'll buy another devo. However, if my device is normal, I need to consider another radio for the range issue.

I tried to find others.
1) www.deviationtx.com/forum/6-general-disc...10-antenna-mod#24690
~35 m at 100uW
2) www.deviationtx.com/forum/3-feedback-que...t-range-on-dsm#22630
~240m at ??? (maybe 100mW or 150mW ?)
3) www.deviationtx.com/forum/3-feedback-que...range-receiver#24854
~80m at ???? (maybe 100mW or 150mW ?)
4) www.deviationtx.com/forum/3-feedback-que...772-range-test#20163
~30m (30paces) at 100uW

Do you have range issues with DSMX only or you are experiencing range problems with the Devo protocol as well?

harmony96 wrote:
Hi.
I have the same problem with my Devo 8S. I got only ~10m at 100uW under perfect line of sight condition. If I put the receiver into a form, I got only ~5m at 100uW. Then, I will get only ~150m at 100mW at most.

While the devo is quite convenient for me, the range issue is very critical. If this range issue is only for my faulty radio, I'll buy another devo. However, if my device is normal, I need to consider another radio for the range issue.

One thing you could check (I've seen this before) is if the pigtail pulled out of the uFL connector, or it is loose at the radio module. Or, it could be the antenna. Or the uFL connector itself, check the male part on the radio module with a magnifying glass and see if the soldering is all right (easy fix if it's this)

Next test would be to unplug the uFL connector from the module and use a pigtail with a 2dbi antenna and do the range check again. See my antenna mod post for how a pigtail would look like.

Edit:
Some vendors sell used radios, without telling (or maybe even they don't know). I had a Devo 10 working perfectly but when I opened it up the board had signs of repair (some resistors obviously were replaced).

johnho100 wrote: Do you have range issues with DSMX only or you are experiencing range problems with the Devo protocol as well?

I have no receivers that support the DSMX protocol. Because I bought heli + radio package, the devo receiver was not included in the package.

BTW, I tested a range test with a walkera helicopter (mini cp). I got ~10m @ 100uW. As far as I know, the receiver in micro helicopters is not for full range.

sbstnp wrote:
One thing you could check (I've seen this before) is if the pigtail pulled out of the uFL connector, or it is loose at the radio module. Or, it could be the antenna. Or the uFL connector itself, check the male part on the radio module with a magnifying glass and see if the soldering is all right (easy fix if it's this)

Next test would be to unplug the uFL connector from the module and use a pigtail with a 2dbi antenna and do the range check again. See my antenna mod post for how a pigtail would look like.

Thank you for the tips.

When I received my radio, its range was very very short. So, I opened it and found that the uFL connector from the antenna pulled out of the uFL socket from the RF module. At that time, I just thought that walkera QC is bad, but as you mentioned, the seller might send me not the new one but the used one. Anyway, after I connected them, I got the current range. I didn't check the soldering problem at that time. I need to open my radio and carefully double-check from the RF module to the antenna.

For the second test, I need to buy the new antenna.

There you go, that's most likely the issue. Most of the time the crimping on the uFL connector is loose and it can cause the wire to pull out.

harmony96 wrote:

sbstnp wrote:
One thing you could check (I've seen this before) is if the pigtail pulled out of the uFL connector, or it is loose at the radio module. Or, it could be the antenna. Or the uFL connector itself, check the male part on the radio module with a magnifying glass and see if the soldering is all right (easy fix if it's this)

Next test would be to unplug the uFL connector from the module and use a pigtail with a 2dbi antenna and do the range check again. See my antenna mod post for how a pigtail would look like.

Thank you for the tips.

When I received my radio, its range was very very short. So, I opened it and found that the uFL connector from the antenna pulled out of the uFL socket from the RF module. At that time, I just thought that walkera QC is bad, but as you mentioned, the seller might send me not the new one but the used one. Anyway, after I connected them, I got the current range. I didn't check the soldering problem at that time. I need to open my radio and carefully double-check from the RF module to the antenna.

For the second test, I need to buy the new antenna.

@harmony96

What range do you have now?? I have ony ~150m at 100mW, too.