Hi,
Just wondering because I seem to be having a couple of issues around where I fly - basically at some points in the flight I can get a certain distance (say 400m) and my FrSky (2.4) telemetry will start beeping (2 quick beeps which means the signal is around 40% I think) .. at the same time, video (5.8) completely disappears for a second or two.
What sort of radio transmission would cause this?
Or does it sound like its a signal issue (I lean against the car while flying) possibly caused by reflections?
Steve,
Are there any caravan sites close to where this happens, some use (illegal) high power boosters to get wifi out across the site.
I've experienced this when flying with Coyote at one place in one direction (and there's a caravan park there)
I've also heard of some farmers using boosters for the same reason.
PK :)
It's not just campsites and farmers, some residential homes might use Wifi boosters as well. They are indeed illegal if they boost beyond a certain power (not sure what that is), and many of the boosters come from China and have not passed FCC, CE or OFCOM validation for the EU market.
Either that or its Ryan Reynolds testing out BTs "amazing" WiFi signal whilst hanging from a helicopter. I'd give him a ring.
It's weird - and reproducible at the same place every time. I think I'll try to fly in the opposite direction just to check it's not a problem with my gear but it seems weird that the picture simply disappeared suddenly as if there was no signal, plus the 2.4 beeping as well - although it did not wipe out my control.
Hi Steve, Just to add my tuppence worth, When I flew back up in Scotland I often flew out pretty long distances with 2.4 Frsky while sat inside my car avoiding the bloody midges.
I didn't get any issues either.
Also I did use a 2w Wifi Sunhans booster which certainly didn't cause any issues with my 5.8 video.
Infact the booster never caused even the most minutest problems to my mates flying around me on 2.4 rc.
This is just my experience with boosters but perhaps there are other's out there not quite so good as Sunhans perhaps? ;)
Don't make sense to me Steve...
If your plane flew into a noisy spot, I could understand it losing 2.4 reception, but nothing out there could prevent it from transmitting 5.8 back to you.
So I would have said something close to where you are sat, like WiFi from ya phone or a GoPro or something, wiping out both your 5.8 vid RX and 2.4 telemetry RX.
But if it always happens in the same flight spot?
Stumper >:(
A few months ago I was on holiday on a chalet site in the Highlands. On powering up the P3Pro I got the error message
"Intensive electromagnetic interference nearby please make sure no magnets or metal objects are near the compass and keep the aircraft above 1 meter off the ground to do recalibration."
I did the recalibration but still got the same message. Noticing a fairly large metal grating not far away I moved, recalibrated and got no more error messages. Then a minute into the flight I started to get control glitches and freezing of the video signal so I landed. Next outing was at the club field where everything was OK again. I've never had that error message again.
However I recall that walking back to the chalet I noticed each unit had a UHF yagi pointed at the clubhouse which was certainly too far away for a normal router signal to provide wi-fi in the chalets.
I suspect interference from a 2.4 booster serving the whole chalet site.
So if that's close to you to wipe out both ... how come it happens at the same place in the plane's flight?
Maybe just appears to be so?
Here's a couple of examples - two different planes:
Mini Talon (2.4 Frsky, 5.8GHz IRC channel 1)
Skywalker (2.4 Frsky, 5.8GHz IRC channel 4)
See about 250-400m out in the same location it's noisy as. It doesn't really bother me that much because I tend to simply motor through it but I'm interested:
a) what would cause it?
b) how come it doesn't affect it if I go further out? Must be a directional "beam" of interference in that case swamping Rx telemetry signal (but receiving signal is fine), and 5.8GHz transmission.
! No longer available (http://www.youtube.com/watch?v=tX5DTzrS3xY&feature=youtu.be#)
Is that a tower on the left at 24 seconds and later at 1:43 ?
Might have those directional microwave link things (look like white hat boxes or dustbins) on it and these would put out a strong directional signal ?
PK :)
Hi Steve, it could be the signal bouncing off the car, so next time, stand away from it.
My money is on your vrx or the Goggle skew..have you checked the SMA fitting..?..Is it correct..?...Same fizzing crap on both planes at a mere 400mtrs suggests the problems are at the video recieve end.
I dont buy into the Wi Fi beam of interference myself, but try the same test in the opposite direction...My guess is, it will be the same and its distance related....I loath 5.8g video myself, its so picky, although I have been out to 2kms using 14dbi antennas with a good image.
:vulture:
Quote from: English Turbines on July 04, 2017, 08:54:07 AM
Hi Steve, it could be the signal bouncing off the car, so next time, stand away from it.
My money is on your vrx or the Goggle skew..have you checked the SMA fitting..?..Is it correct..?...Same fizzing crap on both planes at a mere 400mtrs suggests the problems are at the video recieve end.
I dont buy into the Wi Fi beam of interference myself, but try the same test in the opposite direction...My guess is, it will be the same and its distance related....I loath 5.8g video myself, its so picky, although I have been out to 2kms using 14dbi antennas with a good image.
:vulture:
It's the same result on my goggles (bignose skew to nextwave rx module) and the groundstation (bignose 3 turn helical to Uno Rx), they're both connected properly to their receivers.
Quote from: pk-surfing on July 04, 2017, 07:43:49 AM
Is that a tower on the left at 24 seconds and later at 1:43 ?
Might have those directional microwave link things (look like white hat boxes or dustbins) on it and these would put out a strong directional signal ?
PK :)
Nope, It's a church
Quote from: Steve W on July 04, 2017, 10:00:19 AM
It's the same result on my goggles (bignose skew to nextwave rx module) and the groundstation (bignose 3 turn helical to Uno Rx), they're both connected properly to their receivers.
Hi Steve,
Well the UNO vrx and the 3 turn should be good for 3kms easy, provided you point it and take it out of the car of course.
Get it on a Tripod so you can aim it is my advice, it's no good in the car, that will kill it.
Next time out, I suggest you try it and fly in the opposite direction, with your DVR recording directly out of the spare video port on the UNO....because that's a very good 5.8G receiver.
You can fly it on the goggles of course, and record it there as well..?
Still dont buy into the interference theory myself, but I dont suppose it's impossible. You could also try a different frequency, some VTXs have crap output on some of the channels.
:vulture:
Yea. I know the gear is fine, I was just wondering what would cause it to knock both frequencies out at the same time in the same place. It has to be some sort of router doesn't it? I mean they're the only things that use both frequencies, so it must be. If you look in the video next to the water tower there's a "square" of trees - in that square is a small holding - I wonder if they have a booster set up so that they have WiFi in all of their outbuildings?
Having said that I've flown over their house many times when landing and never had an issue, but there's always been a spot halfway down the field where it just wipes out - sometimes worse than others, but it's always noisy there. It was particularly bad last time. Above a certain altitude it doesn't happen, say ~100m up. It's weird though simply because the location it happens in is basically at least 400m from any other structure in all directions - maybe there's a beacon buried under the soil. Ever seen War of the Worlds?? ;D
Intersecting ley lines. Try wandering around the spot with a twig.
Have you done the sums to see if it's the fresnel zone your breaking? Just a thought as you said it doesn't happen if flying higher over the same spot
Quote from: Brucey on July 04, 2017, 02:51:18 PM
Have you done the sums to see if it's the fresnel zone your breaking? Just a thought as you said it doesn't happen if flying higher over the same spot
I haven't, no - I did think it could be the close proximity of myself to the car, but it is just weird that it happens on 2 different frequencies at the same time - plus the 2.4 dropping so low to trigger a telemetry warning so close in I figured that it had to be some kind of local interference.
I'll sit a bit away next time and see if it still does it. I've sat inside the car before and flown out much further with no issues though so not sure.
Guess I'll never know really, just wondered if anyone had any theories about what it could be - I can fly through it as I say but yea.. I see it all the time at that point in space.
Here's my two additional penneth. The church (St. Oswalds) is out on a limb, down a long track from Luddington. From what I can make out, theres a farm/buildings on the corner or Garthorpe Road and Carr Lane. if you drew a line between those two buildings, that's almost where your plane would be at 250-400m from the road which you launch from.
Alternatively draw a line from the middle of Luddington through the church and its almost the same line. If the church has a Yagi/directional antenna and either of the other locations provides a WiFi signal across that land, it could affect your 2.4 and 5.8? As others have mentioned, try flying out to the North West and see if the same happens.
Edit for clarification: As the Church is out on a limb it may accept a WiFi signal from either Luddington or The building on the corner.
...and to add to my outlandish theory, there is a directional antenna on the top of the School at Luddington too, which seems to point between the houses and has a clear view of the church from what I can see.
https://www.google.co.uk/maps/@53.6432109,-0.7478646,3a,75y,275.09h,76.06t/data=!3m6!1e1!3m4!1shfIsdlDghOvVwtSWjAKHHg!2e0!7i13312!8i6656 (https://www.google.co.uk/maps/@53.6432109,-0.7478646,3a,75y,275.09h,76.06t/data=!3m6!1e1!3m4!1shfIsdlDghOvVwtSWjAKHHg!2e0!7i13312!8i6656)
Good catch krikey, I've never noticed that antenna before (never really looked, I think I'll have a gander tonight while I walk the dog).
The school providing the church with WiFi would make sense actually because the parish council is tightly interwoven with the school / village hall here, and it would certainly explain why the signal is so localised if it is directional towards the East from the school to the church .. and into the field behind it.
Interestingly enough there's a point from my launch point where the signal gets terrible on my quad as well if I fly from it towards the church (which is 400m from my launch point). It would be in the same cone of signal.
So they must be using dual-band for it to affect both my frequencies. Would they transmit with a directional antenna though? Surely it would make more sense to have a high-gain receiver antenna on the church pointing towards the school, instead of the school transmitting to the church?
I guess it depends on what (if anything) the school are providing to the community and also how focussed the beam is. For the school to provide WiFi to the village, a 180 degree beam would be needed I think which might not fit in with my wild idea!
It's also possible that as I've found things that support such a theory, it's just as likely to be debunked by people who can identify what type of antenna is on the school roof (and indeed if it is an antenna), or even a quick call to the school to ask if they provide WiFi to the Church :)
Edit: if the school are indeed providing this, I suspect that it would need to be official as it would potentially affect other home Wifi, so maybe OFCOM would have records?
In the video we see drop outs into noise on 5.8GHz ..from a pure radio point of view this would indicate a reduced signal arriving at the ground station This could be due to:-
1 The on board battery masking the signal back to the ground station
2 The car getting in the way of the signal path
3 Fresnel Zone issues
The reduction of 2.4 GHz telemetry which is being transmitted from the airframe at a lower level than the 2.4GHz control signal could equally be explained by the above.
The wireless router explanation, I don't believe holds water, as this the router would have to be close to the ground station and the chances of 2.4 AND 5.8 being effected at the same time by an external source are extremely unlikely.
So I would suggest mounting the 5.8GHz antenna in the bottom of the plane where nothing can get in the way of a line of sight signal back to the ground station.
Similarly ensure that the telemetry antenna is similarly placed ..well away from other servo wiring etc
No idea ... to be honest I would have thought that if it was an antenna it'd be higher up, but then again I've used inter-building IR/laser-links for networking before which are below gutter-level so nothing would surprise me.
I also can't see why the church would need wifi really .. it rarely opens and when it does it's for jumble sales, tea mornings etc.
I think I'll just fly and expect the deadzone.
Quote from: g4uvz on July 04, 2017, 06:09:04 PM
In the video we see drop outs into noise on 5.8GHz ..from a pure radio point of view this would indicate a reduced signal arriving at the ground station This could be due to:-
1 The on board battery masking the signal back to the ground station
2 The car getting in the way of the signal path
3 Fresnel Zone issues
The reduction of 2.4 GHz telemetry which is being transmitted from the airframe at a lower level than the 2.4GHz control signal could equally be explained by the above.
The wireless router explanation, I don't believe holds water, as this the router would have to be close to the ground station and the chances of 2.4 AND 5.8 being effected at the same time by an external source are extremely unlikely.
So I would suggest mounting the 5.8GHz antenna in the bottom of the plane where nothing can get in the way of a line of sight signal back to the ground station.
Similarly ensure that the telemetry antenna is similarly placed ..well away from other servo wiring etc
Well, the VTXs are mounted on the wing (skywalker) and the underside of the fuselage (mini talon) away from any other components (especially the Skywalker)
The FrSky receivers I use are diversity ones, D8RII+ with the antennas in a V shape, plus I have a 5dBi antenna on my transmitter. They should definitely not only be reaching 300m before I get telemetry warnings ... but maybe that's because the onboard transmission is being blocked when the plane tries to send the RSSI back to me? It is only in that specific place and I have never failsafed - so maybe it can receive fine, but not transmit telemetry back to me due to the interference?
Does anyone know how many mw the FrSky D8RII+ transmits telemetry back at? Or am I mistaken in how the RSSI works?
I don't get this...
Are we suggesting that the WiFi is so strong that it disables the VTX on the plane as it passes over?
Stops it from transmitting?
How could that happen?
Some WiFi routers use 5.8GHz so if it's a strong enough directional signal it could swamp the VTX if the plane is within the RF cone.
Quote from: Dillwhacker on July 04, 2017, 08:12:41 PM
I don't get this...
Are we suggesting that the WiFi is so strong that it disables the VTX on the plane as it passes over?
Stops it from transmitting?
How could that happen?
Presumably if a relatively low powered VTx transmitting on 5.8Ghz enters another cone of transmission also on 5.8Ghz but is much more powerful, would this not interfere with the VTxs own transmission? I'm thinking laymans terms here which might be very wrong, but if a small wake from a boat crosses a larger wake on the ocean, doesn't the small wake get corrupted/distorted by the time it exits the other side?
No, radio waves don't 'mix' like that. Broadcast radio FM signals don't corrupt each other.
If the goggles and the wifi are fixed, then the wifi signal into the goggles is fixed.
If the plane's signal is too weak to overcome the wifi interference at 400 metres, it shouldn't matter whether the plane is North or South , the planes signal strength will be the same.
And why is it OK further out?
Beats me...
(?)
It could be a WiFi link Steve, as I said, simply fly the same distance and height in the opposite direction to test the theory....Some of those (directional) WiFi routers use 5ghz in order to get the Bandwidth higher. The giveaway would be a similar directional receive antenna at the other end, so maybe drive over to the Church for a look to see if you can see any antennas and, where they are pointing?. These type of routers are very directional.
You were flying at 70mtrs, so what happens if you go a little higher?....It could just be the Freznel zone in both cases. As for the beeping FRSky TX Module you are using, try setting the Ducky at 90 degrees to the TX Module, that should make it work better for you. Remember, the telemetry downlink is not as powerful as the control uplink.
:vulture: