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Pumpkin drop event

Help! 2.4Ghz Signal Issues

#1
Greetings,
I hoping someone can help. I've been flying DTFB airplanes for about 3 years, mostly in urban areas (in parks and abandoned lots) near my house. My first radio was the flysky CT6B which worked great most of the time, however i started to notice signal dropouts in certain places at the parks I fly. I took that radio apart and found the antenna connection had come undone from the board, I re-soldered it and flew a bit more but still had intermittent problems. I then upgraded to the Turingy 9x, it in general has been good, but I still have glitches at the same points in the sky that I did before.

My Setup
Turnigy 9X (stock w/ stock receiver)
Fatshark 250mw video transmitter (stock dipole antenna)
Turnigy cheapo servos
30amp red brick esc (most commonly used)
Variety of brushless motors

I have the video transmitter spaced away from the Rx and the ESC as far as possible from the Rx as well. The problem occurs with or without the FPV gear.

The Problem
The fields I fly aren't that big, about the size of a soccer field, so I am never very far away. I also follow the FAA guidelines for altitude so 400ft is the maximum, but I rarely go over 200'. The fields are typically lined with houses or buildings that I fly near but not over. The problem will occur at the same point in the sky (or near ground) every time as I fly around, and those points haven't changed in years even with many different airplanes and two different radios. When it happens I will lose all control for 1-2 seconds.

My Question
Is this something normal for flying in urban areas on the 2.4ghz band? This is my biggest question, I have looked into possible issues with the BEC becoming overloaded and shutting down, my antenna position and so on fruitlessly. What are the possible solutions, should I go to 433mhz, change antennas or change my stock 2.4 module? Thank you guys for any help you can give me, its frustrating when my 5.8Ghz video signal on stock dipole antennas is much more robust than my 2.4Ghz for control.
 

Craftydan

Hostage Taker of Quads
Staff member
Moderator
Mentor
#2
Most WIFI routers runs at 2.4GHz . . . that's probably your culprit. Digging up an old used 72MHz radio or switching over to an LRS could help by getting off the band, but at least in the case of the LRS, you don't know what the frequency spectrum looks like in an urban environment.

The 433 band could also be heavily used locally for municipal communications (and your use would be reported to the FCC if you interfere -- be sure you have your HAM license).

Alternatively . . . fly from a spot closer to the interference point. There's a fair chance a house VERY nearby has an illegal signal booster running on their wifi -- hard to prove without the right gear, but if it's picked a channel, from the other side of the field your radio may think that channel is OK, but as your RX gets farther away from you the closer/louder Wifi drowns it out. If you're nearer the source of the interference, your radio will do a better job of picking a clear channel, and as you move the RX away from you, the interference source gets quieter at an even faster rate.
 
#3
Most WIFI routers runs at 2.4GHz . . . that's probably your culprit. Digging up an old used 72MHz radio or switching over to an LRS could help by getting off the band, but at least in the case of the LRS, you don't know what the frequency spectrum looks like in an urban environment.

The 433 band could also be heavily used locally for municipal communications (and your use would be reported to the FCC if you interfere -- be sure you have your HAM license).

Alternatively . . . fly from a spot closer to the interference point. There's a fair chance a house VERY nearby has an illegal signal booster running on their wifi -- hard to prove without the right gear, but if it's picked a channel, from the other side of the field your radio may think that channel is OK, but as your RX gets farther away from you the closer/louder Wifi drowns it out. If you're nearer the source of the interference, your radio will do a better job of picking a clear channel, and as you move the RX away from you, the interference source gets quieter at an even faster rate.
Thanks Craftydan, didn't think of powering up nearer to the point of interference thats a good idea. Maybe its time to pick up a spectrum analyzer as well or cheap 433mhz (orange rx) just to try it out and see if its better.
 
#4
I had terrible results with my 9x stock module and receiver. I would get glitches even at arms length if I flew in the neighborhood of a cell tower and under the best of circumstances, I wouldnt ever get more than 500 meter. Some people have reported far better results than that, but just plug a ACCST (frsky) module in your bay and pick up some compatible receivers. You'll get a pretty solid link, far more choice in receivers and you'll have telemetry, for, if nothing else, early warning for low RSSI. Well worth the money.

433 Mhz, I wouldnt do, at least not a cheap (non hopping one) in an urban environment full of garage openers, wireless door bells, baby phones and what have you.
 

makattack

Winter is coming
Moderator
Mentor
#5
As CraftyDan mentions, if you go with UHF/433MHz, make sure you get your ham license first! I have my callsign on both the TX and the airplane (along with contact details).

In addition to Dans great advice of powering up close to the noise, another option before you investigate new hardware is to maybe try a range test with different antenna orientation. If your RX and TX antennas are vertical now, maybe try horizontal polarization. I know it sounds silly, but when I was using a Devo10 modded with DeviationTX on the Spektrum protocols, I had range issues with vertical polarization, but horizontal polarization gave me better range.

While the Orange/HobbyKing LRS stuff is cheap, it also requires you to be comfortable programming the TX and RX modules with a computer and FTDI USB interface so it adds a whole other level of complexity to your flying. Also, I know that IBCrazy/Alex Greves has not been happy with the OrangeLRS hardware and has seen the 1W TX module fail too often.
 

PHugger

Church Meal Expert
#6
I was watching a video from BMSweb and his son(?) was flying FPV with FS goggles and CP antennas.
He said he was trying to practice holding his head more upright. I thought that odd (good posture?).
As he flew he would ask his Dad if his head was down (his signal was dropping).
As he drooped his head, his signal faded.
Take away - antenna orientation is very important.

I've never used the flat patch antennas, but I imagine it's very critical to have a proper orientation with them.



Best regards,
PCH
 
#7
I had terrible results with my 9x stock module and receiver. I would get glitches even at arms length if I flew in the neighborhood of a cell tower and under the best of circumstances, I wouldnt ever get more than 500 meter. Some people have reported far better results than that, but just plug a ACCST (frsky) module in your bay and pick up some compatible receivers. You'll get a pretty solid link, far more choice in receivers and you'll have telemetry, for, if nothing else, early warning for low RSSI. Well worth the money.

433 Mhz, I wouldnt do, at least not a cheap (non hopping one) in an urban environment full of garage openers, wireless door bells, baby phones and what have you.
Thanks for the advice, I'm so happy to hear someone else had issues with the stock module, I was starting to think that there was no way to fly near my house anymore. I like your idea of the FrSky, I had seen them but had no idea that they were different in their protocol from the stock TGY 9x. I think I will try and pick one of those up, fits the budget and allows me to save up for a good LRS in the future.
 
#8
As CraftyDan mentions, if you go with UHF/433MHz, make sure you get your ham license first! I have my callsign on both the TX and the airplane (along with contact details).

In addition to Dans great advice of powering up close to the noise, another option before you investigate new hardware is to maybe try a range test with different antenna orientation. If your RX and TX antennas are vertical now, maybe try horizontal polarization. I know it sounds silly, but when I was using a Devo10 modded with DeviationTX on the Spektrum protocols, I had range issues with vertical polarization, but horizontal polarization gave me better range.

While the Orange/HobbyKing LRS stuff is cheap, it also requires you to be comfortable programming the TX and RX modules with a computer and FTDI USB interface so it adds a whole other level of complexity to your flying. Also, I know that IBCrazy/Alex Greves has not been happy with the OrangeLRS hardware and has seen the 1W TX module fail too often.
Thanks, I started studying for my Ham License exam, had one years ago for long range ship to shore communications but let it lapse, so fear not I will do that. I think your right in the fact that if I'm going to buy into LRS stuff I should save up and get the good stuff down the road, for now change the module and work on antenna position. I really appreciate all the help, thanks again.
 

Craftydan

Hostage Taker of Quads
Staff member
Moderator
Mentor
#10
For what is worth, our rc equipment isn't the only stuff affected by wifi kit:

http://www.bbc.com/news/technology-29445385
Meh. they're probably just forced upgrades to boost sales -- run a unbelievably bad EMI test, cry the sky is falling and watch the $$$ roll in compulsively.

If it was genuinely bad, the airlines still have the right to demand you turn them off and not an airline in the world would put up with the risk for an inconvenience we're already used to.
 

makattack

Winter is coming
Moderator
Mentor
#11
Meh. they're probably just forced upgrades to boost sales -- run a unbelievably bad EMI test, cry the sky is falling and watch the $$$ roll in compulsively.

If it was genuinely bad, the airlines still have the right to demand you turn them off and not an airline in the world would put up with the risk for an inconvenience we're already used to.
True, but heck, you'd have thought the airliner manufacturers would have known to at least pick a LCD screen that doesn't bluescreen on ya!