I have flown many, many hours with the ELRS, flying both freestyle, cinematic and LR for 8+ km and never had a problem until this weekend when I had the failsafe. I was in a valley in the mountains in the middle of nowhere, about 300 m from me there was only one building of a cottage. I flew a distance of about 3 km for more than 15 minutes, no problem. I took off from myself and flew far away from that building. When returning from the flight, I was returning from the other side of the building about 500 m apart. The moment I got a little closer to the building, when the building was between me and the drone, I fell into failsafe st1 and then the GPS Rescue was activated. The drone climbed high, flew over the building, and then I was back under control. It was very scary, even though I deliberately tested GPS rescue several times.
I think the building had wifi with a significantly boosted wifi power because it was isolated and when the building got between the drone and me the background noise in the 2.4 GHz band was more than acceptable and the receiver was overwhelmed. The problem is that I didn't have telemetry logging activated in the transmitter for this flight, so I can't confirm the RSSI, SNR, etc numbers.

What's annoying is that it happened at a distance of about 300 m and that no one can guess in advance if someone has amplified wifi outside the allowed limits in their building. I also fly inside buildings where I shoot promo videos. There are an extreme number of wifi APs in those buildings and I've never had a problem with failsafe.

Regarding the flight configuration, I had FS on EP1, the transmission power of the module was dynamic, the FS came suddenly immediately, the telemetry did not even have time to report the increase in transmitting power. Therefore, I think the RSSI was fine, but the SNR was critical.

I am writing this because V-22 wrote in this thread ExpressLRS 915Mhz failsafe into lake | IntoFPV Forum that the SNR problem is in the 900 MHz band and that it is not a problem in the 2.4 GHz band. Well, I report that the problem is also in this band.

Glad your GPS rescue worked properly! Do you have any DVR of the flight? The FHSS nature and LoRa modulation of ELRS are usually minimally affected by WiFi, as it is unlikely you'd have wideband interference over the entire frequency range used for hopping. That said, ELRS is not magic and still must obey the laws of physics. If the building was directly between you and the drone it certainly could have blocked the signal.

What equipment were you using? What firmware version? What ELRS settings? Without a little more info it will be difficult to figure out why you experienced the failsafe, but my bet is that the building simply blocked the signal.

Hi MomoBrut!!

I did some more reading and researching.
Yes this "jamming" can affect any signal, and is especially bad when its between you and drone.

in my thread I flew easily past trees 1km out, but failsafed 200m near me. On 2.4Ghz the ELRS 3.0 Deja Vu can help. But... little else can help.

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MomoBrut.. please send details about your setup.

How are you ablevto achieve 8km out.. thats very impressive.

(25-Jul-2022, 09:47 AM)V-22 Wrote: Glad your GPS rescue worked properly! Do you have any DVR of the flight? The FHSS nature and LoRa modulation of ELRS are usually minimally affected by WiFi, as it is unlikely you'd have wideband interference over the entire frequency range used for hopping. That said, ELRS is not magic and still must obey the laws of physics. If the building was directly between you and the drone it certainly could have blocked the signal.

What equipment were you using? What firmware version? What ELRS settings? Without a little more info it will be difficult to figure out why you experienced the failsafe, but my bet is that the building simply blocked the signal.

Unfortunately, I have neither a DVR nor a telemetry log. It was just an ordinary flight. I was just searching the terrain, where I will fly afterwards to shoot with the GoPro. Given the experience and the current terrain, I did not expect any problem at all.

Personally, I can't explain it other than that I flew into a directional wifi connection, some outcasts here still use it as a connection to the provider. And to increase the range and capacity, they will simply increase the transmission power above the permitted limit. They don't care because they are in the middle of nowhere.

And when FS came, I was at a height of about 20 m +, i.e. above the building, so it could not shade. And just to remind you, in this configuration I fly without any problem to or behind a building with a large RSSI reserve, I have never had a problem with FS.

TX: HM Pro with standard T-dipole vertical pol.
RX: EP1 with standard T-dipole vertical pol.
ELRS v2.2
150 Hz, TLM ratio 1:8
25 mW, dynamic mode

And I will add that there was absolutely no hitch in the image of DJI Googles in the time of FS, the video signal was absolutely clear at 50 Mbps, if the quad was in the shade, the video would not work that good either.

(25-Jul-2022, 11:06 AM)romangpro Wrote: Hi MomoBrut!!

I did some more reading and researching.
Yes this "jamming" can affect any signal, and is especially bad when its between you and drone.

in my thread I flew easily past trees 1km out, but failsafed 200m near me. On 2.4Ghz the ELRS 3.0 Deja Vu can help. But... little else can help.

---

MomoBrut.. please send details about your setup.

How are you ablevto achieve 8km out.. thats very impressive.

It is written in this thread ELRS long range antenna for bigger drones (dipole maybe?) | IntoFPV Forum including all other informations, the range test results see in #65.

I wanted to try elrs so I bought a zorro and some happy model receivers. Over the past couple weeks I’ve has 3 failsafes. So last night I put all my crossfire receivers back in the quads.

Elrs for me is not ready for prime time.

Without telemetry logs or DVR, it's hard to say what happened. There is no reason you should not enable telemetry logging on your radio IMO, as the microSD cards are so large relative to what they need to store it should never be an issue.

(25-Jul-2022, 11:06 AM)romangpro Wrote: On 2.4Ghz the ELRS 3.0 Deja Vu can help.

Again, DVDA will not help if there is wideband interference. The point of DVDA is to maximize the likelihood that you maintain 100% LQ to reduce jitter in the RC signal which helps with feedforward. It will not help increase LQ in marginal cases.

(25-Jul-2022, 01:10 PM)Critterracing Wrote: I wanted to try elrs so I bought a zorro and some happy model receivers. Over the past couple weeks I’ve has 3 failsafes. So last night I put all my crossfire receivers back in the quads.

Elrs for me is not ready for prime time.

If you want help troubleshooting, please start a new thread or hop on the ELRS Discord and I would be happy to help.

Could it be they are using some other 2.4ghz link like a cctv video transmitter (plus an amp) maybe to the end of a long driveway? Reminds me of my Bluetooth failing right outside my condo when I wash the truck. This is the only place I've ever experienced an interference and it might even be my own home automation server that's right near an upstairs window.

(25-Jul-2022, 08:28 PM)V-22 Wrote: Without telemetry logs or DVR, it's hard to say what happened. There is no reason you should not enable telemetry logging on your radio IMO, as the microSD cards are so large relative to what they need to store it should never be an issue.

I zoomed in one of the frames from the 4k video shot on the Go Pro on the following flight. Behind the chimney I noticed a small directional antenna, probably a Yagi with very small, almost tiny elements and about half a meter long. The antenna was pointing more or less in the direction where I was, about 5 meters above. This kind of antenas have about 24 degrees cone and somewhere about +15 dB. I think the problem is solved.

That could just be a TV receiving aerial but only the owner of the cottage actually knows.

Most FPV pilots are breaking the law by transmitting more output power than legally permitted in the location they are flying so I guess we can't really complain if someone else on the ground is doing the same. It's just unfortunate luck if you happen to cross paths with someone who has a bigger power amplifier than you do or who is transmitting on a wider band.

And a question directly for V-22. According to which link parameter is the transmission power of the Tx module switched? Is a combination of parameters used or just RSSI? SNR should definitely be used for switching, maybe even in combination with RSSI and LQ. I assume version 2.2 can't do this. Version 3 already?

(25-Jul-2022, 09:11 PM)SnowLeopardFPV Wrote: That could just be a TV receiving aerial but only the owner of the cottage actually knows.

Most FPV pilots are breaking the law by transmitting more output power than legally permitted in the location they are flying so I guess we can't really complain if someone else on the ground is doing the same. It's just unfortunate luck if you happen to cross paths with someone who has a bigger power amplifier than you do or who is transmitting on a wider band.

The TV Aerial should have wider elements and some grill that will be seen, the wifi antenas can look like there is no grill, like this one ...
https://www.banggood.com/RP-SMA-2_4GHz-2...79563.html

(25-Jul-2022, 09:21 PM)MomoBrut Wrote: The TC Aerial should have some grill that will be seen

Not always true. It depends on the type. My own TV aerial is a Log Periodic type with no reflector grill at the rear like the ones shown at the following link...

https://www.satshop.uk/product-category/...tv-aerials

A man from cottage with log periodic aerial antenna? Well, that will be an engineer. :-)
In any case, the FS occurred at the angle of the antenna, the antenna was oriented between me and the drone at a distance of about 250 to 300 m, so I have no doubt where the FS came from.

The lesson for me personally is that this is much more likely to happen in more remote areas than anywhere else. I have activated the alarm on the RSNR and on the next reconnaissance flights before the final flight with the camera I will do a more detailed survey around such isolated buildings so as not to be surprised during the shooting. A person still has a lot to learn.