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Wish I had not asked now.

lissforester

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This afternoon whilst playing with the video settings on my drone, Ie: shutter speed and frame rates.
Hovering at about 70 to 80 feet up directly above my head in my back garden/yard, I flew the drone back behind me only about 15 to 20 feet and completely lost signal between the drone and the controller, the screen went grey and connection was lost.
I rapidly spun around (heart thumping) to look up and there it was still at 70 to 80 foot up and 15 to 20 foot away, as I spun around so the drone was now in front of me again and the signal came almost instantly and control was gained.

Later while enjoying a beer, I was puzzled as to why this should happen with the drone in such close proximity, here are some thoughts,
I put this to you just as a thought and will be more than happy to have others thoughts on this.

My drone a Mini 2 with the standard controller, both controller and drone were about 75% charged. I am using the latest DJI Fly App 1. 4.12, I have a Lenovo M10 Gen 2 tablet as my screen.

I have read on here that the ideal for signal strength is 'Line of Sight' or VLOS for the best transmission and distance, now the transmitter and receiver ariel on my controller with a phone in the place is completely visible and uncovered at all times whether the drone is in front or behind you, because the top of the ariel is above the phone, with a 10inch tablet with a metal extension bracket in place, the top of the areil is at least 3 inches below the top edge of the tablet, effectively shielding the ariel, another thing to consider is the back of the tablet is metal, could this metal back be acting as a partial shield? Now throw in possible interference from the tablets Wi Fi signal into the mix could this be what caused my signal loss until I turned around 180 degrees and the ariel is now visible to the drone.
 

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eEridani

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That pair of black knobs on the end of the phone holder rods are the antennas. The antennas are directional. They need to point at the drone. Metal blocks the signal, too, like the frame of the phone or tablet. So any incidental lobe radiation from the antenna will be suppressed.

Lesson is: always keep the pointy end towards the drone.

This isn't the controller gain pattern, but is representative of how antennas radiate energy in one direction, and not all directions.
antenna-gain-pattern.png
 
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MAvic_South_Oz

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It's puzzling, Occusync 2.0 should handle that no problems.
With my M1P, I can fly behind me for as far as I can see and have great reception, the only time it diminishes is where there is nearby vegetation, tree foliage etc, that gets between, then I just turn and face flats of my antenna to the drone position and all good again.

I can only relate it to the new controller antenna design, not flexible / orientatable like the old controllers, perhaps that's the difference between my M1P controller (and other models following) to the new design of the most recent controllers.

As mentioned above, ANYTHING, even tree leaves etc as you fly further distant / lower LOS can reduce signal strength.
 

ElRubio

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This afternoon whilst playing with the video settings on my drone, Ie: shutter speed and frame rates.
Hovering at about 70 to 80 feet up directly above my head in my back garden/yard, I flew the drone back behind me only about 15 to 20 feet and completely lost signal between the drone and the controller, the screen went grey and connection was lost.
I rapidly spun around (heart thumping) to look up and there it was still at 70 to 80 foot up and 15 to 20 foot away, as I spun around so the drone was now in front of me again and the signal came almost instantly and control was gained.

Later while enjoying a beer, I was puzzled as to why this should happen with the drone in such close proximity, here are some thoughts,
I put this to you just as a thought and will be more than happy to have others thoughts on this.

My drone a Mini 2 with the standard controller, both controller and drone were about 75% charged. I am using the latest DJI Fly App 1. 4.12, I have a Lenovo M10 Gen 2 tablet as my screen.

I have read on here that the ideal for signal strength is 'Line of Sight' or VLOS for the best transmission and distance, now the transmitter and receiver ariel on my controller with a phone in the place is completely visible and uncovered at all times whether the drone is in front or behind you, because the top of the ariel is above the phone, with a 10inch tablet with a metal extension bracket in place, the top of the areil is at least 3 inches below the top edge of the tablet, effectively shielding the ariel, another thing to consider is the back of the tablet is metal, could this metal back be acting as a partial shield? Now throw in possible interference from the tablets Wi Fi signal into the mix could this be what caused my signal loss until I turned around 180 degrees and the ariel is now visible to the drone.
You’re absolutely correct on the shading from the tablet. Maybe you can find an extension for the antennas, a bracket to place the tablet below the controller.
 
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lissforester

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Sheesh - does no one read the manual anymore? Point the controller at the drone. It is the only way the radio works.
View attachment 136532
Hi eEridani,
Of course you are right about pointing the controller antenna toward the drone, as the manual imagery reinforces your comment perfectly.
My point was though, at 80 feet high and only 15 to 20 feet behind me with the controller in the normal viewing position, the angle of the drone from vertically above the controller was at worse case 14 degrees at 20 foot, and best case, only 10 degrees at at 15 foot.
The imagery from the manual as shown above gives a radiated capture angle from the horizontal at antenna of 60 degrees to 120 degrees, giving a capture cone of 60 degrees.
My drone at that time was 10 to 15 degrees, so was well within that 60 degree capture cone.
Which lead me to believe that the issue was not that the drone was outside of the capture cone, but, that the cone was being interfered with by an obstacle. IE: The metal backed tablet
But I do agree with you that at all times the top of the controller antenna should be pointing toward the drone.
Many thanks to all who have commented, all comments and advice are appreciated as they add tools to our arsenal.
 
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lissforester

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Maybe you had a bad connection on the cable , it happens
That's a good thought, we are talking very low voltages that take very little resistance to interfere with.
As I well remember with the dust that the brushes on my old childhood eclectic train and scalextrix cars picked up and caused connection failure.
A photographers puffer bulb will be used from time to time from this point onwards.
 

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eEridani

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I flew the drone back behind me only about 15 to 20 feet and completely lost signal

You said the drone was above and behind you ... that is a no brainer for signal loss.

If I point my controller 90 degrees off the drone, I lose signal. If I don't position the antenna in the correct position, I lose signal. Heck, on launch or land I need to be cautious because if I don't fold my antenna properly, I'll lose signal directly above me, 100 feet away.

The antenna are directional. I don't know what the radiation pattern is, but the signal drops off sharply (on my SC). A -3dB change is 1/2 power - look at that chart above for a typical antenna: nearly 15dB simply turning 90 degrees. So a 630mW signal is only 20w 90 degrees off axis. Said another way - if the drone is controllable a mile way antenna oriented properly, it is only controllable 165 feet away at 90.

Behind the antenna, -30dB, is twice that dB reduction, 0.6mW, which computes out to a 5 foot range.

ps: dust isn't going to hamper anything here. A totally different form of connections, and totally different form of contamination on the conductors involved. That said, cheap cables aren't your friend here - you need good gold plated terminals that have enough gold on them to work many insertion cycles - with wire and terminal connections that can withstand the bending done when wrapping the cable for storage and unwrapping for use. Unfortunately, finding the insertion cycle or bending spec for a USB cable is impossible these days. So just buy a quality brand cable, not some Chinese pretty looking brand.
 
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lissforester

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You said the drone was above and behind you ... that is a no brainer for signal loss.

If I point my controller 90 degrees off the drone, I lose signal. If I don't position the antenna in the correct position, I lose signal. Heck, on launch or land I need to be cautious because if I don't fold my antenna properly, I'll lose signal directly above me, 100 feet away.

The antenna are directional. I don't know what the radiation pattern is, but the signal drops off sharply (on my SC). A -3dB change is 1/2 power - look at that chart above for a typical antenna: nearly 15dB simply turning 90 degrees. So a 630mW signal is only 20w 90 degrees off axis. Said another way - if the drone is controllable a mile way antenna oriented properly, it is only controllable 165 feet away at 90.

Behind the antenna, -30dB, is twice that dB reduction, 0.6mW, which computes out to a 5 foot range.

ps: dust isn't going to hamper anything here. A totally different form of connections, and totally different form of contamination on the conductors involved. That said, cheap cables aren't your friend here - you need good gold plated terminals that have enough gold on them to work many insertion cycles - with wire and terminal connections that can withstand the bending done when wrapping the cable for storage and unwrapping for use. Unfortunately, finding the insertion cycle or bending spec for a USB cable is impossible these days. So just buy a quality brand cable, not some Chinese pretty looking brand.
I think the dust comment was a different thing altogether, I believe Mazdaman was basically saying that it could have been a mechanical disconnection rather than an direct electrical interference disconnection, a dust provoked mechanical disconnection would manifest exactly the same out come giving me a greyed out screen/disconnection.

Any way thankyou for your comments.
Lissforester
 

eEridani

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Train tracks are contaminated mostly by arcing. The train set wheel to track connection is rolling interface, where dust really can interfere, but the arcing that takes place when the surfaces aren't perfectly smooth creates carbon spatters that cause more arcing. After several circuits around the track, enough carbon is deposited the connect is lost. Part of the problem is that the voltages involved are also small - millivolts when trying to start the train set slowly to mimic scaled operation. It takes a certain voltage to break down even simple oxidation on tin or copper, and why sanding train tracks helps.

Gold connectors don't oxidize, and most electronic connectors these days use a wiping motion, just in case. The wiping action excludes most dust, and allows even silver or tin contacts to provide millivolt useful connections (as long as the gold or silver or tin plate remains, part of the cycle life issue because each insertion removes a bit of the plating). Adding that USB is 3.3 volts, so even a poor connection is generally not an issue unless the spring contact force is worn out (again, part of that cycle life issue mentioned above).
 

lissforester

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You know sometimes in life you can end up wishing you had never asked the question in the first place and had kept it to yourself.
I beginning to feel a bit like that now.
The reason for my question was to hopefully gain some insight into the issue I was experiencing. What little time I have had my DJI Mini 2 and have been viewing these posts I have learned a lot from others experiences and expertise, and I appreciate it, not just the wisdom but also the sympathy and empathy when someone had a loss of a drone, whether that is through stupidity or other circumstances.
And other times in life you meet people who you can take an instant dislike to, because you can end up feeling that whatever you say they are going to know so much more than you, and are going to use this platform to tell the world how smart they are.
I am trying to do is learn about the new hobby I have found.

One would think that the plugs with the 'wiping action' would push dust and fine particles deeper into the sockets as they are inserted?
 

eEridani

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Sorry - I didn't mean my replies to come off that way. I tend to go overboard in explanations because there is so much misinformation out there. The intent is to educate, not demean.

Wiping contacts primarily clean the metal surfaces during insertion. For example, silver is a good conductor, but it oxidizes quickly, aka tarnishes. So switches and connectors that use silver plating are designed to slide during connection. This sliding action removes the thin layer of oxide that forms. Yes, that action pushes any debris aside, or deeper into the socket, but so does pushing any connector plug into a socket. An occasional cleaning removes the accumulation.

Connectors for USB standard take this accumulation into account and the areas inside the sockets have room for stuff to build up, bottoming out would be bad.

Back to the knowledge thing. I've been working around electronics - including a fair bit of time designing things - since about 1973. I even suffered through my train sets not working well as a kid - which helped drive me into the electronics field. So I know a little bit about the technology used here and enjoy answering questions about it.

But ask me about satellite orbits or the stock market or plumbing or crop management or even how to keep my lawn green and I'll just give you a blank stare.

ps: if your controller and phone disconnect, yeah, an entirely different subject. But that wouldn't depend on where the drone is in the sky - so turning around to face the drone wouldn't have fixed the connection.
 
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umanbean

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re: The title of this thread.... at this point I feel I better keep my thoughts to myself.

re: Your problem in post #1, hopefully you'll get some thoughtful, concise replies to help you figure it out.
 
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AZDave

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Hi eEridani,
Of course you are right about pointing the controller antenna toward the drone, as the manual imagery reinforces your comment perfectly.
My point was though, at 80 feet high and only 15 to 20 feet behind me with the controller in the normal viewing position, the angle of the drone from vertically above the controller was at worse case 14 degrees at 20 foot, and best case, only 10 degrees at at 15 foot.
The imagery from the manual as shown above gives a radiated capture angle from the horizontal at antenna of 60 degrees to 120 degrees, giving a capture cone of 60 degrees.
My drone at that time was 10 to 15 degrees, so was well within that 60 degree capture cone.
Which lead me to believe that the issue was not that the drone was outside of the capture cone, but, that the cone was being interfered with by an obstacle. IE: The metal backed tablet
But I do agree with you that at all times the top of the controller antenna should be pointing toward the drone.
Many thanks to all who have commented, all comments and advice are appreciated as they add tools to our arsenal.

I don't think you are reading those images properly.

The middle picture from the manual is a top down view ... it shows a cone left and right of directly in front of you.

The right hand picture is a side view ... it shows a cone angled above and below a horizontal plane.

The right hand picture is the one that is relevant to your case. Your drone being above and in back of you is WAY out of that cone.

Also worth noting is that depending upon the antennas involved, the radiation/reception pattern isn't necessarily (or even very often) a uniform shape. It can have a severe notch at certain angles, particularly in the vertical plane. Notches of 40 dB are not at all unusual even for 2-element antenna arrays such as is the case for our drones, and a negative 40 db would turn a 1 watt equivalent signal into 0.0001 watt (1 ten-thousandth of a watt).

I'm a ham radio operator with antenna modeling software. I just modeled two vertical antennas spaced one half wavelength apart and fed in phase ... at a much lower frequency than used by our drones but the principle is equivalent. The side notch is just over 40 db down from the main lobe, and the overhead notch (although very sharp) is down more than 100 dB!!
 

lissforester

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I don't think you are reading those images properly.

The middle picture from the manual is a top down view ... it shows a cone left and right of directly in front of you.

The right hand picture is a side view ... it shows a cone angled above and below a horizontal plane.

The right hand picture is the one that is relevant to your case. Your drone being above and in back of you is WAY out of that cone.

Also worth noting is that depending upon the antennas involved, the radiation/reception pattern isn't necessarily (or even very often) a uniform shape. It can have a severe notch at certain angles, particularly in the vertical plane. Notches of 40 dB are not at all unusual even for 2-element antenna arrays such as is the case for our drones, and a negative 40 db would turn a 1 watt equivalent signal into 0.0001 watt (1 ten-thousandth of a watt).

I'm a ham radio operator with antenna modeling software. I just modeled two vertical antennas spaced one half wavelength apart and fed in phase ... at a much lower frequency than used by our drones but the principle is equivalent. The side notch is just over 40 db down from the main lobe, and the overhead notch (although very sharp) is down more than 100 dB!!
This is to any Admin or Moderator: Is it possible to delete this whole post? If so please do.
 

lissforester

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re: The title of this thread.... at this point I feel I better keep my thoughts to myself.

re: Your problem in post #1, hopefully you'll get some thoughtful, concise replies to help you figure it out.
Ty Umanbean,
Love the name by the way LOL.
Yeah I had a couple of responses that were helpful thanks.
But not sure I will bother asking anything again, most (Not all) seem to be expert and seem to think I am a pr ck because I am a Newbie and not an expert.
Well we all know the definition of an EXPERT, an Ex is a Has been and a Spurt is a Drip under pressure (Doesn't really work in text)

I will continue to peruse these pages, and gain what help I can, but as a silent member.
Lissforester has gone 10-10 but on the side.
 
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