1 mile from a 10KW long wave transmitter, would you fly ? SOLVED.. I'm not risking it

[Tony Weller]

This monster which is pumping out banal shite across UK shores at 909MHz 909khz (sorry for confusion)along with being close to an airport has curbed my enthusiasm for flying round here, it's a mile away and far from the 2.4GHz used for my expensive toy. Would you even bother trying? at that power there could be some nasty harmonics. I am a keen SDR-play user with a amplified magnetic induction loop antenna for short wave listening and this pisses all over it up to about 5MHz.

 

[PhantomPilotuk]

View attachment 82101
This monster which is pumping out banal shite across UK shores at 909MHz along with being close to an airport has curbed my enthusiasm for flying round here, it's a mile away and far from the 2.4GHz used for my expensive toy. Would you even bother trying? at that power there could be some nasty harmonics. I am a keen SDR-play user with a amplified magnetic induction loop antenna for short wave listening and this pisses all over it up to about 5MHz.

Personally no but I will follow this thread with great interest

 

[FoxhallGH]

There has been a lot of discussion on this Forum about flying within the influence of RF interference. It's an open book because there are many flyers - especially in the USA, who report that they carry out transmission tower inspections with DJI Drones. Personally, I'm with you on this one and would err on the side of caution, as the transmission power MAY induce electrical currents in the Drone - and also MAY swamp the receiver which would make your controller ineffective.

 

[dannybgoode]

There’s a few of those near me. I fly and have never had an issue. I’ve flown by all kinds of masts without incident.

LW is so far from the GHz range the controller uses I really wouldn’t worry.

Note I’m an advanced amateur radio licence holder so have a good working knowledge of things radio

73 de M0SDB

 

[The Editor]

There’s a few of those near me. I fly and have never had an issue. I’ve flown by all kinds of masts without incident.

LW is so far from the GHz range the controller uses I really wouldn’t worry.

Note I’m an advanced amateur radio licence holder so have a good working knowledge of things radio

73 de M0SDB

Fundamental yes, but third harmonic no.

Although the final stage of the TX on the towers are probably fairly clean, the design of DJI's Chinese front end probably isn't the greatest.
The other thing to always bear in mind is that at 10kw of RF radiating from those masts the UAV's/RC receiver maybe swamped and unable to cope.

 

[dannybgoode]

Fundamental yes, but third harmonic no.

Although the final stage of the TX on the towers are probably fairly clean, the design of DJI's Chinese front end probably isn't the greatest.
The other thing to always bear in mind is that at 10kw of RF radiating from those masts the UAV's/RC receiver maybe swamped and unable to cope.

It’s not going to be 3rd harmonic though. More like the 27000th harmonic (assuming a transmit frequency of 198khz) by which time the power, even with a transmitter power of 10KW will be negligible given power halves with each harmonic.

I’d be very worried about the design of the DJI front end if frequencies in the KHz swamped it regardless of transmit power - of that were the case it’d knock out TV’s across the neighbourhood, satellite transmissions and mobile phones.

Honestly it’s nothing to worry about. I’d be surprised if you even got an interference warning.

 

[The Editor]

It’s not going to be 3rd harmonic though. More like the 27000th harmonic (assuming a transmit frequency of 198khz) by which time the power, even with a transmitter power of 10KW will be negligible given power halves with each harmonic.

I’d be very worried about the design of the DJI front end if frequencies in the KHz swamped it regardless of transmit power - of that were the case it’d knock out TV’s across the neighbourhood, satellite transmissions and mobile phones.

Honestly it’s nothing to worry about. I’d be surprised if you even got an interference warning.

The OP said that the tower transmits at 909mhz. That’s why I said third harmonic.
I’m confused by your comment regarding the front end of the DJI equipment. Swamping the receiver would have no consequence in being able to ‘knock out TVs’ etc.
I’m not talking about the TX side of the DJI equipment.

 

[Tony Weller]

I think I should have said khz, see for yourself, sorry for confusion but you can see what it does to my SDR radio at gains where I can receive and decode FT8, I digress.......

 

[dannybgoode]

The OP said that the tower transmits at 909mhz. That’s why I said third harmonic.
I’m confused by your comment regarding the front end of the DJI equipment. Swamping the receiver would have no consequence in being able to ‘knock out TVs’ etc.
I’m not talking about the TX side of the DJI equipment.

There’s no way that transmits at 909MHz. That’s an LW antenna and backed up by the fact the op states it shows up on their sdr radio up to about 5MHz.

A 909MHz Tx antenna would be really quite small. Great big long wire like that is MW at best.

LW harmonics would still have enough poke at 5MHz to show up just about depending on the exact Tx frequency.

The last time I looked TVs were very much receivers. If this would swamp the receiver of the controller it would similarly swamp the receive circuit in a TV and would play havoc with a mobile phone. Again the receive side not the transmit.

As I say I’m an M0 radio amateur. It takes a couple of years study and practical experience to pass all three exams and it is very RF theory heavy.

 

[The Editor]

I think I should have said khz, see for yourself, sorry for confusion but you can see what it does to my SDR radio at gains where I can receive and decode FT8, I digress.......View attachment 82118

Not in you original post you don’t.
You specifically say 909Mhz

 

[Tony Weller]

Not in you original post you don’t.
You specifically say 909Mhz

Yes I did, I'm a **** sorry

Have done a strike through. Interesting discussion but would FLY that was question.

 

[The Editor]

Yes I did, I'm a **** sorry

No worries........ Now you see why I was confused.?

 

[Tony Weller]

Personally, I'm with you on this one and would err on the side of caution, as the transmission power MAY induce electrical currents in the Drone - and also MAY swamp the receiver which would make your controller ineffective.

That's what I was thinking about not so much harmonics but sheer wattage. Also I read it's directional and near the sea so wattage coming my way.

 

[dannybgoode]

Not in you original post you don’t.
You specifically say 909Mhz

The aerial gives it away. It’s just not a uhf antenna.

@Tony Weller. Shear wattage has surprisingly little impact on things when the frequencies in question are so far apart. As I say we have the same transmitters just up the road from here and they don’t cause any issues when flying close by.

As a test I’m going to fly round the mighty Emley Moor TV mast in the next couple of weeks. Still pretty certain it’ll be fine and that’s much closer frequency-wise and a lot more than 10KW

 

[Tony Weller]

As a test I’m going to fly round the mighty Emley Moor TV mast in the next couple of weeks. Still pretty certain it’ll be fine and that’s much closer frequency-wise and a lot more than 10KW

OK I look forward to seeing the results but until then I'm grounded here
For those who may be interested the banal shite is 5 live and talk sport

 

[The Editor]

A 909MHz Tx antenna would be really quite small. Great big long wire like that is MW at best.

Not if it’s a big tower with a 33cm stub at the top of it! ?

The confusion has been cleared up now (OP has edited his post - so we are talking about kHz).

However, I’m not talking about the RX in the Remote. I mean if you fly near the mast, the RX in the UAV could be swamped by EIRP of that magnitude.

At best, the AGC could shut down the sensitivity of the UAV RX and you could lose link with your ground based RC transmitter.
Or....packet/frame loss could occur within the FHSS data stream causing connection loss.

Personally, I wouldn’t risk it but each to their own. The same reason I always operate with my phone/tablet in airplane mode.

I know a little bit about this technical stuff - I operate commercially and hold PfCO (previously PFAW) for a number of years and have a degree in electronic engineering.
I held a G6 license many years ago but could never be bothered to learn Morse so left it there.

 

[Tony Weller]

For the radio people, here it is breaking through up to 7 Mhz !!! slightly higher than FT8 reception !!! **** it is.

 

[Tony Weller]

Particularly nasty one here.....Think I need to move...

 

[The Editor]

Particularly nasty one here.....Think I need to move...
View attachment 82127

And take your green headgear off and replace it with tin foil (just to be safe).

 

[Tony Weller]

And take your green headgear off and replace it with tin foil (just to be safe).

I'm not that bad honestly just want don't want to lose my Mavic...