Aloft Forums
Welcome to Aloft Forums. Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!
Archer R4 with very short range
- Thread starter Gizmo6
- Start date
I have been using the internal until today when I used the T type from a RadioMaster module for the second round of radio checks and a short flight.
INAV BlackBox logs indicated several signal losses but never showed a failsafe flag, with both 2.4GHz and 900MHz being fed to the flight controller via SBus I am not sure if INAV can tell which signal is lost or just indicates combined signal quality. I just started using the logging functions when this issue started and the volume of info INAV collects is a bit overwhelming.
Landru
Strong User
Wow! What a whopping difference. The link with internal antennas fails or verges on failure throughtout. On the other hand, with external antennas, the link is strong. (That said, RSSI did drop noticeably in the last third of the test, which may indicate an orientation-dependent issue.)
A few questions:
- Were both those tests made with the same power setting on the transmitter? I assume the internal antennas were tested with range test power. Could the externals have been tested with full power?
- As you walked the circle, did you maintain the transmitter in a more or less constant orientation to the model? Sorry, I forgot to suggest that earlier.
- Can you post a pic of how you arranged the external 2.4GHz antennas on the transmitter?
The 2.4GHz link on that flight varies from perfectly acceptable to worse than marginal. That could suggest an intermittent hardware fault, a reception issue due to antenna placement or orientation, or possibly other issues which we might or might not need to consider.
The coincidental flat lines in the plots for VFR and RSSI suggest loss of link. It's not an absolute certainty. Still, I wouldn't expect to see such a result in a properly functioning and configured system at 200 yard range. A few questions:
- Was the flight made with internal or external antennas for 2.4GHz?
- Did you get any impression that the reception problem was related to model orientation, height, or distance?
The 2.4GHz data from those flights looks fine to me. Were they made with internal or external antennas for 2.4GHz?
What to make of all this? I think that depends on the answers to the questions posed above.
Last edited:
Both sets of ground tests were conducted using the range check setting.
Tx orientation for the internal antenna was constant, I did rotate the Tx 90 degrees to position the T horizontal vice vertical a couple of times to see if it would effect the signal strength when it started to fall off.
The flight was with the external 2.4 GHz antenna.
The reception seems to be problematic when above and left of the Tx which would put it roughly in line with the end of the T antenna.
Flights on the non problematic models were using the internal antenna.
I have another R4 and a R-XSR that I have ACCESS FW for, I think its time to try another Rx and see if the results change.
Tx orientation for the internal antenna was constant, I did rotate the Tx 90 degrees to position the T horizontal vice vertical a couple of times to see if it would effect the signal strength when it started to fall off.
The flight was with the external 2.4 GHz antenna.
The reception seems to be problematic when above and left of the Tx which would put it roughly in line with the end of the T antenna.
Flights on the non problematic models were using the internal antenna.
I have another R4 and a R-XSR that I have ACCESS FW for, I think its time to try another Rx and see if the results change.
Landru
Strong User
It's looking pretty clear now that the Altus performs much better with the external 2.4GHz antenna, which also happens to be at right angles to both the internals.
By any chance do you happen to fly with the transmitter held more or less vertical? If so, that could put the model in the null of the T antenna in some positions other than directly overhead.
Or do you perhaps fly off to the side of the transmitter without turning to face the model? In recent remarks posted on RCG, crashes due to antenna nulling were attributed to that technique. Right or wrong, my assumption was that every LOS pilot turns to keep the model more or less directly in front of the transmitter. Actually, it sounds very much like my assumption was wrong. For reference, I very rarely fly in a flight line situation. Rather, I'm used to following thermals in any and every direction around myself.
Yes, that seems like a good idea. I wonder if one of the antennas is out of order on your 'problem' R4.
Last edited:
Transmitter is usually held at something more like 30 to 40 degree angle so If I look down I will be looking at the end of the T antenna. When flying LOS I try to face the model, when flying FPV I just try to keep it some where in front of me.
I will try and get to the field in the morning and do some testing with the new Rx. Need to print a new nose and reinstall the camera so I can get the telemetry data from OSD and overlay the BlackBox data.
Makes troubleshooting much easier as all flight mode changes are displayed along with signal issues / failsafe and time stamps that can be cross checked with the Tx telemetry, would be really helpful if that could be played back and added to the video feed.
I might try replacing the antennas and doing a range check with just the problem R4 and a battery, if that shows an improvement I can reinstall it in the Altus and flight test it.
I will try and get to the field in the morning and do some testing with the new Rx. Need to print a new nose and reinstall the camera so I can get the telemetry data from OSD and overlay the BlackBox data.
Makes troubleshooting much easier as all flight mode changes are displayed along with signal issues / failsafe and time stamps that can be cross checked with the Tx telemetry, would be really helpful if that could be played back and added to the video feed.
I might try replacing the antennas and doing a range check with just the problem R4 and a battery, if that shows an improvement I can reinstall it in the Altus and flight test it.
Landru
Strong User
Yeah, I had wondered about that, too, but it doesn't seem to be an issue. See post no. 15.
Plus, unless I'm missing something, the good flight results for the OV10 and the Turbo Timber using the internal antennas seem to show that things are in good order on the transmitter side.
Telemetry data on the active receiver antenna sure could come in handy for debugging an issue like this. Some systems provide that. One example is the UNI firmware for ACCST.
Plus, unless I'm missing something, the good flight results for the OV10 and the Turbo Timber using the internal antennas seem to show that things are in good order on the transmitter side.
Telemetry data on the active receiver antenna sure could come in handy for debugging an issue like this. Some systems provide that. One example is the UNI firmware for ACCST.
Last edited:
Landru
Strong User
Testing the receiver on its own is a good idea. You might consider testing it before and after swapping antennas. And who knows, you might find obvious damage as soon as you get it out of the model.
Landru
Strong User
A second 2.4GHz receiver?
After taking another look at the telemetry logs, I have another question: Does the model programming for the ZOHD Altus have a second 2.4GHz receiver bound?
I ask because both ZOHD-Altus-2025-08-05-08-14-54.csv and InternalAntennaRadioCheck.csv show the presence of RX0, RX1, and RX2. Presumably one of those three is the 900MHz receiver. Or am I wrong about that? In any case, none of the other telemetry files posted show more than two receivers, not even Flight200YardsMaxDistance.csv, which I thought was for the Altus.
I'm certainly no expert in EthOS, quite the contrary. If a third receiver is bound to a model but not actually present, could it cause the problem we're seeing? My quick digging on the Internet didn't turn up any definitive info. I'm not even sure why all the telemetry files include two entries for the "RX" sensor. Perhaps that's expected when both 2.4GHz and 900MHz are in use?
After taking another look at the telemetry logs, I have another question: Does the model programming for the ZOHD Altus have a second 2.4GHz receiver bound?
I ask because both ZOHD-Altus-2025-08-05-08-14-54.csv and InternalAntennaRadioCheck.csv show the presence of RX0, RX1, and RX2. Presumably one of those three is the 900MHz receiver. Or am I wrong about that? In any case, none of the other telemetry files posted show more than two receivers, not even Flight200YardsMaxDistance.csv, which I thought was for the Altus.
I'm certainly no expert in EthOS, quite the contrary. If a third receiver is bound to a model but not actually present, could it cause the problem we're seeing? My quick digging on the Internet didn't turn up any definitive info. I'm not even sure why all the telemetry files include two entries for the "RX" sensor. Perhaps that's expected when both 2.4GHz and 900MHz are in use?
Last edited:
This mornings testing pretty much points to a bad R4, I swapped in a RX6R and only used the internal antennas as the range check was much better than the R4. the one large dip in signal quality was due to vehicles parked between the Tx and Rx at one point in the 360° arc.
The flight was without any audible warnings and I got much further away both in altitude and distance.
The Tx only shows two active Rx in the RF System page, RX6R and R9MINI-O, RX3 is unassigned. I am even less of an ETHOS expert so I don't know a missing Rx would do more than throw RSSI / VFR warnings.
I will take the Bare R4 to the field next trip and complete a range check with the existing antennas then put some new ones on and check again, could prove educational.
Now it's time to fire up the 3D printer and print a new nose so I can put the FPV gear back in.
Thank you for all the help sorting this out.
The flight was without any audible warnings and I got much further away both in altitude and distance.
The Tx only shows two active Rx in the RF System page, RX6R and R9MINI-O, RX3 is unassigned. I am even less of an ETHOS expert so I don't know a missing Rx would do more than throw RSSI / VFR warnings.
I will take the Bare R4 to the field next trip and complete a range check with the existing antennas then put some new ones on and check again, could prove educational.
Now it's time to fire up the 3D printer and print a new nose so I can put the FPV gear back in.
Thank you for all the help sorting this out.
Yes the back has been off, once to replace a RTC battery and recently to check the antenna cables. Will be going in a 3rd time to replace the power board as the rudder trim right is now inop.
Landru
Strong User
Yep, today's results are in a completely different league. There was no in-flight switch to 900MHz. Nice. It's looking like your initial hunch on the R4 being wonky was on the money.
What seems particularly weird is that the non-existent receiver actually become the "active" receiver at several points in two different logs. As you said, it could be that there was no significant impact. Still, it's hard for me to imagine that any of that is intended behaviour.
Edit
Could it be that the receiver ID for the R4 is used for another receiver in another model? I believe those ID are supposed to be unique.
Last edited:
Landru
Strong User
Is that last connector on the right possibly canted a little bit? It's hard to be sure from the photo.
That is a possibility that I will investigate when the new power board arrives. The logs would seem to indicate good power out when not trying to communicate with a bum Rx but while the Tx is open I will have a close look at all connections.
The mystery Rx is something I will have to ask FrSky about, for all I know it could be a glitch in the OpenTx companion when reading ETHOS files.
I just looked at the spread sheets for all posted logs and only Rx 0 & 1 are listed, perhaps someone more versed in decoding logs could shed some light on where the third nonexistent Rx info is coming from.
Last edited:
Guess I'm going blind, yes once I looked by row number I see the same thing. I will send this to the guy I know that works at the service center and see if he can make sense of it.
Are you sure all the antennae are connected? In the image the white one on the right looks not flat, though it could be an illusion.
