Hello everybody,

I have set up an Trex 450L with Spirit II and an SRXL2-Receiver SPM4651T. I have an question about the signal strength of my Setup (Spektrum DX18 Gen1 and SRXL2-Receiver SPM4651T). All funktions are working like it should but I have an question about the displayed signal strenth of my DX18 Gen1 - here I am very unsure if that is an problem - In the Display of my DX18 Gen1 I see an signal strength of -22dBm, and here is the heli and receiver placed in an distance of only 0,5m. No matter how the heli is placed obove/below front or behind the displayed signal strength is not more than -22dBm - I have an Blade-Heli 230S V02 and there I get an signal strength of 0 dBm (max) like it should be - What is wrong with my configuration ? Is the SRXL2-Receiver SPM4651T possibly defective ? The firmware of the SPM4651T is the newest 2.40 -
Additional information: My Dx18 Gen1 has the airware 2.05
I haven't done a range test yet with this heli -

I'm afraid my helicopter could crash with this current equipment (failsave) - Has anyone an similar equipment and can look what the signal strength look like ?

Any help is appreciated -
Thanks in advance !

Best regards
Matthias

On my DX9 all my stuff read like -44db all the time so I probably wouldn't worry about it

Do a range check by putting your TX into the range check mode and see how far away you can get. Make sure the heli isn’t on the ground, raised up a few feet and not anything metal. I think 30 feet is good? I forget the number. Your manual will have the info.

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Find me on HeliFreak, username Xoexoe

Hello Guys !
Thanks for your answer ! Today I have made an Range check... I have putted an carton and additional plastic climbing aid fot the range test. Height: 103 cm or 3,38 ft.
I put my helicopter on it and did a range test in all four directions (the helicopter rotated 4x90 °). The distance was about 28 m. In the transmitter I set the range test, held the bind button and read the displayed values. I always used the spark's Aileron and elevator levers. A friend registered whether everything was running smoothly - Everything went as it should - The following values were then obtained Antenna A: 6; F: 6, H: 0 - The lowest value of the received power was at -86 dBm or 21% R - To be honest, I don't find the result great. However, I'm not sure what that ultimately means for the range (how many meters), I don't know - what do you think about it ?
Shall I try another receiver, I have an antennaless SRXL2 receiver too -

I would have expected more from SRXL2 now -

Best regards
Matthias

Hi Matthias,

i have used the single 4651T on a Logo 400SE - so a bigger heli than your Rex 450... it's a 'real' 470/480. i had the Rx & antennas mounted very similar to yours, just a little bit higher (Logo 400 lower Gyro platform, ~ where your tail servo is). no problem with the Logos plastic frame.

i would not be worried... just try it in flight... do not fly to far first and check what happens during really slow piros or flips. log the antenna results for later check in detail and set alarms to be warned if frame losses are getting critical. then increase the distance and watch. it is clear - if you read the rcgroups post of Miguel Alvarez and other Spektrum developers - they clearly advise to use the 4651T plus additional Sat on anything 500+... and they personally would even use additional Sat on 400+ if i remember correctly. following that advice your setup should be safe... officially mine was not

the 4651T telemetry readings have not been reliable before the last update on my iX12... after the last update (June?) there was no more problem for me. you can find attached the first test flight after the update of my 4651T where i tested exactly like this... in the end there was a huge loop ~100m away.

result: no frame losses, no problems at all in the following 2-3 normal flights. but the antenna dBm readings where still strange for me: you can see the point of landing - heli landed (short before motor off) and next to ground the signal % is falling as to be expected, then you can see me walking to pick up the heli and signal going back to full. then signal is again falling during carrying the heli to the bench... Tx in left hand, heli in right hand. this was the last flying day with Spektrum before my system change - but i would not have any doubt to fly like this from signal quality point of view...

Ciao
Michael

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cheers
Michael

Hi Michael,
thanks for your reply ! Yesterday I have tested a couple of helis with one satellit and an Spektrum serial telemetry receiver with diversity SPM4649T. At a distance of 0.5 m between heli and remote control, the display was by all helis at -40 dBm. As a reminder, the 4650t had a signal strength of -22dBm at this distance - I hadn't done a real range test because I didn't have the time -
I think the possibility of a second satellite, either a SLRX2 capable or a normal DSMX satellite, could improve the situation if that could be possible with Spirit, maybe Tomas could say somthing about that...

I will test it on the weekend as you suggested with increasing the distance and height and slowly pirouettes.
Did you have the telemetry saved on the SD card? What did you use to open the file, is there a viewer? A tip from you would be great!

Have you switched to Jeti? For the sake of interest, what does the range test look like on the Jeti DS-16, is it better? What experience have you been able to gain so far?

Tanks a lot in advace !

Best regards
Matthias

Hello Matthias,

in fact yes: i did have the 4649 before on the same heli, same positioning... yes, ~-40dBm was the starting point... and in the end i did have 150-300 frame losses per flight (the 4649 did report all antenna fades as frame loss iirc). in my opinion no good idea to securely fly it without additional sat (and i did mount one - but do not forget: the 4649T will not know about this additional sat and signal quality will be reported the same, even Spirit will use the additional data from the Sat). anyhow this was the reason to switch to 4651T. much better then... in the end signal quality was absolutely ok after the last update - as said.

i was using a iX12 where the log is stored on internal memory... DX radios do store it on external accessible SD card (at least my DX9 did 2-3 yrs ago). the program to be used is Spektrum TLM viewer (by Mike Petrichenko)... it is the "one & only" for Spektrum telemetry logs.

i've attached a signal quality log of the same heli (red=signal quality, A1/A2 are the 2 antennas - 9 being max), nothing else changed, just Jeti Rex3 (again 1:1 same position of antennas) as a receiver. of course this cannot be compared 1:1... we do not know how Jeti is calculating the signal strength plots. but i guess the result is clear... the same on all of my helis... including Diabolo 700... only 1 Rex3 and all logs look the same for antenna quality.

i do clearly prefer light radios... so i am using a Jeti DS-12 since mid June... the Spirit Edition. my wife does have a DS-12 too... but a blue one that was/is unfortunately not available as Spirit Edition simply a perfect radio for me... especially telemetry features & alarms are what i've been searching for. i do not like to hear "battery 1.987 maH power used", but "battery 75%", "...50/25/10%". and no alarms if there is nothing special. easy to program most features, but really powerful... if you consider Jeti the Spirit Edition is really worth a closer look! once familiar with the new radio, the switch on the helis took 5-10 minutes per heli... at least in my case for Spirit and NEO. we are (both) perfectly happy with the DS-12...

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cheers
Michael

Hello Michael, hello Guys !

Today I have trusted me to make an "Range-Check" in the air with my TREX 450L with SpiritII and new configuration with SRXL2-Receiver SPM4651T...
In my DX18 Gen1 I have programmed warnigs for signal level at -61dBm and Framelosses greater than 20 -
With a little palpitation, I took off...and the tail of the helicopter was directed to me. I was about 5 m away than I got a warning of the signal level below -61dBm ! I was really surprised and landed immediately. I checked my radio but there was no Fade, no Frameloss and no Hold - I looked in the TLM-File and there I saw that the signal level was really under -61 dBm, but as discribed no frameloss and no hold.. In the flightlog I set the warning level of signal strength to -85 dBm and the framelosses as described greater than 20 -
Then I made an second flight also with a little palpitation - I got no warning about the signal level again - I made some pirouettes, fly farther away and higher also with pirouettes.
After, I did not know exactly, about 5 Min I landed without any warnings. After that I looked in the TLM-File and here are no Fades, no Framelosses and no Holds - The signal level swayed quite strong in numerical value (-dBm), look in the added files -

What I have learned from this is, that the signal level does not seem to play a major role, at least with Spektrum, since I have not seen any fades, frame losses or holds in my remote control or in the TLM file. I assume that as long as I have got none excessive framelosses my range is absolutely fine - what do you think about that conclusion ?

Enclosed the two Scrennshots (files) -

Best wishes
Matthias

same conclusion i made... looks just like mine (above) did... i would have no problems to fly like this. i had set my frame loss warning to 10 iirc... never reached it with this setup. even on my bigger helis where i've used AR7700 + additional sat i've only once scratched the warning threshold - the sat in the front of a 700 died... it was flying with main receiver only.

.. enjoy your heli!

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cheers
Michael

Hi Michael,

thanks a lot for your support and I am very appreciated for your help !
Now I can fly my T-Rex 450L without feeling uncomfortable -

Greetings
Matthias