GR8 Range check reality check

[Mucksmear]

Hello! I just upgraded to an X18 from a Futaba 9cap and am looking for some feedback on my setup and range test results. A week ago I was flying the Alpina at 4 corners and got a “Low RSSI” alert while still fairly close in right after partial fly-by - maybe less than 100’ out.

Today I did a more “proper” range check at the Berkeley Marina (wide open, flat, no obstructions) with the Alpina mounted on a wooden tripod. A lazy-susan bearing allows the model to turn or weathervane.

Installation: Archer GR8 (plus an Archer RS as a redundant rx). GR8 antennas are oriented 90 deg to each other in a vertical plane starting near the fuse bottom centerline and radiating upwards and spanwise towards the elevator/Rudd pushrods. The Alpina fuse is fiberglass but I think there may be a straight 1/4”-3/8” wide run of carbon tow down the length of the fuse on each side. Also, the elevator.rudder pushrods are plastic sheathed music wire running parallel to the suspected carbon tow. See cross section image.

For the test in RANGE mode, I walked away to the rear of the Alpina keeping the TX facing the Alpina. I got “low RSSI” warnings before I reached 90’ - probably around 70’-80’. At 90’ I stopped and my son slowly spun the Alpina on the tripod through 360deg. Then I moved out to 100’ and we spun the Alpina again, then out to 110’ and another spin…

I’ve included 2 graphs from Companion with some notation added for model orientation, etc. On the 1st graph I forgot to put the TX in RANGE mode. The 2nd graph is in RANGE mode.

It looks like the signal gets blanketed the most from the equipment up front. Are these results reasonable for a range check or should I be looking for better results?

 

[Raymond Gaskins]

Hello! I just upgraded to an X18 from a Futaba 9cap and am looking for some feedback on my setup and range test results. A week ago I was flying the Alpina at 4 corners and got a “Low RSSI” alert while still fairly close in right after partial fly-by - maybe less than 100’ out.

Today I did a more “proper” range check at the Berkeley Marina (wide open, flat, no obstructions) with the Alpina mounted on a wooden tripod. A lazy-susan bearing allows the model to turn or weathervane.

Installation: Archer GR8 (plus an Archer RS as a redundant rx). GR8 antennas are oriented 90 deg to each other in a vertical plane starting near the fuse bottom centerline and radiating upwards and spanwise towards the elevator/Rudd pushrods. The Alpina fuse is fiberglass but I think there may be a straight 1/4”-3/8” wide run of carbon tow down the length of the fuse on each side. Also, the elevator.rudder pushrods are plastic sheathed music wire running parallel to the suspected carbon tow. See cross section image.

For the test in RANGE mode, I walked away to the rear of the Alpina keeping the TX facing the Alpina. I got “low RSSI” warnings before I reached 90’ - probably around 70’-80’. At 90’ I stopped and my son slowly spun the Alpina on the tripod through 360deg. Then I moved out to 100’ and we spun the Alpina again, then out to 110’ and another spin…

I’ve included 2 graphs from Companion with some notation added for model orientation, etc. On the 1st graph I forgot to put the TX in RANGE mode. The 2nd graph is in RANGE mode.

It looks like the signal gets blanketed the most from the equipment up front. Are these results reasonable for a range check or should I be looking for better results?View attachment 13239View attachment 13240View attachment 13241View attachment 13242View attachment 13243View attachment 13244

I have had this same issue with low RSSI with this same receiver and a similar setup using the latest version of Open Tx on my FrySky 10s express Tx. I now use VFR (valid frame rate) to help me decide if I have a critical RF link instead of RSSI. Others on the forum have discussed this issue in great detail. I think you will be fine. I don’t think you can turn off the RSSI but you can adjust the sensitivity threshold and just ignore it.
Raymond Gaskins

 

[2xWhiskey]

I've had a similar experience where I had gotten a couple instances of RSSI warnings where in flight and about 80' out, and the LiPo pack was in direct line between by radio and the RX antenna placements. I lost the plane when the aircraft was in this orientation to where it augured in, but I believe system power was lost due to the poor technique of not securing an ESC to extension connection with a second mechanical means. But who knows if that occurred inflight, or because of the crash?

My takeaway and recommendation would be to relocate one the antennae as far as you can from the other so that only one can be blocked by the battery at a time (line of sight). The 90 degree off orientation is good technique too.

 

[HornPlayer]

I think we tend to bombard ourselves with too much in-flight information. My pre V2.x.x. Frsky X and SR series receivers give the occasional low RSSI or RX Signal Critical warning when flying close in or directly overhead but have never had an incident where the plane became uncontrollable before, during, or after such a warning. When losing a glider due to soaring too high/out of sight the subsequent ground search for it can be carried out after it has soft-landed by cross referencing the signal from up to 300 meters away. This is much more than normal flying distance and under far more adverse condition. I still throw the odd plane in the air using my old Futaba 6EX TX and I am blissfully unaware of any RSSI glitches - even to the point that I occasionally fly beyond the limitations of my ageing eyes and still have full control as I try to reorient the tiny speck in the distance and steer it onto a course that will bring it back into a more controllable view.
I am looking forward to seeing if the new Uni FW has alleviated rogue RSSI events as claimed. I experienced a lot of warnings when the X8R/X6R started arriving with the paddles on the antennae until I learned to align not just the antennae at 90 degrees but also the boards. I have replaced most of them with the straight whiskers which fixes the problem.

 

[Mucksmear]

Thanks for the informative insights everyone. I will do some more range testing with different antenna placement/orientations and pay closer attention to the VFR.

I forgot to mention that my RSSI thresholds were already set to the lower values of 35 & 32 for ACCESS rx. Also, during the range test I could also see control surfaces intermittently going into their fail-safe positions, starting around probably 70’-80’ distance.

Also,

 

[Raymond Gaskins]

Thanks for the informative insights everyone. I will do some more range testing with different antenna placement/orientations and pay closer attention to the VFR.

I forgot to mention that my RSSI thresholds were already set to the lower values of 35 & 32 for ACCESS rx. Also, during the range test I could also see control surfaces intermittently going into their fail-safe positions, starting around probably 70’-80’ distance.

Also,

Based on additional information you provided, it sounds as if you are really experiencing signal loss.
Raymond

 

[Mucksmear]

Thanks Raymond. I will also do an RX only range test on the tripod, no airframe

 

[Mucksmear]

Ok, I did an RX only test on the tripod. Test location was at a local park instead of the Berkeley Marina, so there are whatever unknown differences with that...

I believe I'm now getting more normal results, but again, this is my 1st time using ACCESS receivers so please share your thoughts. I did a comparison range check with an Archer R4 in a small balsa fuselage and it looks to me like the range test performance was pretty similar.

With the GR8, I got a single RSSI Low warning in the 1st quarter of rotation at 80 feet. There were no other warnings on this test and no warnings on the R4 test. There are many noticeable drops in the VFR and RSSI graphs, but all still above their respective thresholds except for the one instance just mentioned
.
The GR8 graph has been annotated with fuzzy magenta ranges to highlight when the initially end-on antenna was oriented optimally wrt the X18 internal 2.4 antenna that runs horizontally in the top of te TX, but I could not make a connection between RSSI or VFR fluctuations and the antenna orientations. Telemetry tells me there was no fail-safe incidents

Is this more or less what you guys would expect?

Next task will be to try some other antenna locations/orientations in the Alpina as some of you have suggested.

 

[Raymond Gaskins]

Ok, I did an RX only test on the tripod. Test location was at a local park instead of the Berkeley Marina, so there are whatever unknown differences with that...

I believe I'm now getting more normal results, but again, this is my 1st time using ACCESS receivers so please share your thoughts. I did a comparison range check with an Archer R4 in a small balsa fuselage and it looks to me like the range test performance was pretty similar.

With the GR8, I got a single RSSI Low warning in the 1st quarter of rotation at 80 feet. There were no other warnings on this test and no warnings on the R4 test. There are many noticeable drops in the VFR and RSSI graphs, but all still above their respective thresholds except for the one instance just mentioned
.
The GR8 graph has been annotated with fuzzy magenta ranges to highlight when the initially end-on antenna was oriented optimally wrt the X18 internal 2.4 antenna that runs horizontally in the top of te TX, but I could not make a connection between RSSI or VFR fluctuations and the antenna orientations. Telemetry tells me there was no fail-safe incidents
View attachment 13251View attachment 13252
Is this more or less what you guys would expect?

Next task will be to try some other antenna locations/orientations in the Alpina as some of you have suggested.

I have had numerous flights using this receiver with ACCESS protocol and base my decisions regarding antenna orientation on VFR. I orient the two receiver antennas 90 degrees apart and out of the way of batteries and escs as much as possible and have had no problems with the ranges I have associated with 2.4 txs for years. I simply ignore RSSI since moving to the ACCESS protocol.I did not start using FrSky equipment until ACCESS was released. Fellow pilots at my field who previously used these receivers with the ACCST protocol and paid attention to RSSI also noted that RSSI was unreliable when they switched to the ACCESS protocol.
Hope this helps.
Raymond

 

[Mucksmear]

That helps Raymond - thanks. I have been using ACCST (D8) up until now.

 

[deanboatworks]

Do Frsky work with Hitec receivers

 

[Konrad]

FrSky servos will work with Hitec RX? Yes to servos. No to Hitec RX’s working with FrSky TX’s. Both the RX & TX need to be on the same RF protocols.

 

[tic]

I believe the X20/X18 now have MPM's that will work with hitec rx's but sadly not airtronics