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Question about how transmitter works.
3952 20 2016-10-19
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lilsou
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We already know there are a ton of modifications for the remote, to help improve transmission signal to the drone. What I don't understand is, are we not limited by what the drone transmits back to the remote? Why are there no drone modifications to improve the signal the drone sends back to the remote?
I'm just trying to understand how this all works. From my understanding, the remote sends control signal to the drone from one antenna, and the other antenna is to receive signal from the drone?

If we modify the remote to send a stronger signal, that can reach greater distances/penetrate through more objects but do not modify the drone's signal coming back, aren't we still limited by the signal from the drone being weaker than the modified remote's signal?

Someone, please englighten me
2016-10-19
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Aardvark
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Usually the receiver Antenna on the RC is modified as well, either to amplify the weaker incoming signal, or to add a reflector to concentrate signal received over a larger area onto the receive antenna, or both.

For most the stock antenna should give more than sufficient range.
2016-10-19
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Cetaman
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Aloha lilsou,

     The recent spate of updates I am aware of included P3A, P3P and P4.  P3P and P3A had updates for the DJI GO app and Remote controller.  The P4 had a complete series of updates, DJI GO app, Remote Controller and a refresh of the Aircraft firmware.  So, yes, the problems with the P4 pixelation and green screens was addressed with the required refresh (using DJI Assistant 2) of the aircraft.  The P3A and P3P updates appear to have made the transmission system more robust without having to update the firmware of the aircraft.

     The recent updates did do some rework of the two directions of communication between the RC and the AC as you were interested in in this thread.

     Hope this helps!

Aloha and Drone On!
2016-10-19
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nigelbrinkmann
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Hi, you have two antennas on your remote one is for transmitting to the aircraft and the other is for receiving from your aircraft, don't quote me but I think the left channel antenna is for transmitting to your aircraft, stick inputs etc, and the right channel antenna is for receiving from your aircraft, all feed back and video from your drone etc
So basically one antenna talks and the other antenna listens.
So as for your question on only modifying the transmitter and not the drone, you really don't need to modify the drone, if your left and right antennas are strong at transmitting and receiving.
2016-10-19
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lilsou
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nigelbrinkmann Posted at 2016-10-19 18:20
Hi, you have two antennas on your remote one is for transmitting to the aircraft and the other is fo ...

I understand that much, but what I'm trying to get at is this:

Let's say the stock drone can only transmit video signal 3 miles range.
You modify your remote to transmit signal up to 5 miles.
However, since the drone can only transmit video signal 3 miles, the controller modification is not useful for longer than 3 miles, because the drone can not even send a signal back to the remote.
Does that make sense?
Maybe I'm not understanding the receiving end and how it works? I don't know.
2016-10-19
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Cetaman
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nigelbrinkmann Posted at 2016-10-19 15:20
Hi, you have two antennas on your remote one is for transmitting to the aircraft and the other is fo ...

Aloha nigel,

     Actually, inside each flat antennae are two elements doing what you say.  You have the right idea but they are in each antennae.  I tested it with a range booster in a curtain of jungle foliage.  Both sides gave equal results.  There are also threads of broken antennae on the Forum that show the two elements inside the flat antennae.  I thought the same thing you said, so I had to find out and test it.

     The result is the same as you say in your post.  But the P4 was having difficulties and the AC FW had to get refreshed to match the new FW for the RC.  The P3A and P3P did not have the same problem as the P4 so the AC FW stands.

     Hope this helps!

Aloha and Drone On!
2016-10-20
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Cetaman
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lilsou Posted at 2016-10-19 20:34
I understand that much, but what I'm trying to get at is this:

Let's say the stock drone can only ...

Aloha lilsou,

     Yes, you understand the basic principle and that is what was done with the recent DJI updates and upgrades.

Aloha and Drone On!
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nigelbrinkmann
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lilsou Posted at 2016-10-20 14:34
I understand that much, but what I'm trying to get at is this:

Let's say the stock drone can only ...

Right I see what you are saying, but I can't 100% answer that, maybe its FW for the drone to improve this returning signal.....? unsure, some one technical from dji may be able to help you out.
2016-10-20
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nigelbrinkmann
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Cetaman Posted at 2016-10-20 16:27
Aloha nigel,

     Actually, inside each flat antennae are two elements doing what you say.  You h ...

Hi Cetaman,
Thanks for the extra info!!
2016-10-20
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Aardvark
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lilsou Posted at 2016-10-20 07:34
I understand that much, but what I'm trying to get at is this:

Let's say the stock drone can only ...

"However, since the drone can only transmit video signal 3 miles, the controller modification is not useful for longer than 3 miles, because the drone can not even send a signal back to the remote."

There is no limitation as to how far the signal will travel, it will just get weaker the further it has to go. In post #2 I said that this weaker signal can be amplified or concentrated by modifying the RC receive antenna. This then boosts the weaker signal to a level where it becomes usable again. That's the beauty of digital signalling, being a square wave it can easily and accurately be regenerated.
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rodger
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Keep this in mind. Your Drone is in free space, in that it is high in the air with nothing around it. Height is everything with a radio signal. The signal strength will decrease when you encounter an obstruction such as a building. An example is the signal from a GPS Satellite which is in milliwatts.
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jwt873
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It would seem logical that DJI would want to have the craft putting out it's maximum legal power in order to get the greatest range.

The transmitted signal from the drone has to conform with rules set out by whatever local agency regulates the radio spectrum. (For example, the FCC in the US)...  I the drone is is already putting out all the power that it's allowed to, there would be no legal way of increasing it.

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Aardvark
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jwt873@gmail.co Posted at 2016-10-20 13:58
It would seem logical that DJI would want to have the craft putting out it's maximum legal power in  ...

I thought the legal limit was to be able to see the aircraft at all times, so the 3 or 5 mile range is almost academical
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lilsou
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Aardvark Posted at 2016-10-20 02:55
"However, since the drone can only transmit video signal 3 miles, the controller modification is n ...

I understand that, but there has to be a point in which the signal is completely gone. It surely cannot go on indefinitely...there has to be a point where the signal is so weak or gone that there is no way to amplify it?

But the other posts kind of answers my question. I guess the drone is limited by the FCC regulations or whatever and therefore can only put out so much. So, technically, if anyone modified the drone transmitter then it'll be violating those laws I guess.
2016-10-20
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Insomniak2
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I wanted to know how the antenna system works on the RC... is one for receiving and the other transmitting or vice versa? Or are they identical.

The reason I ask is this, Ive noticed if i unhook my right antenna (if your looking down at the remote) and only use the left antenna, the phantom still flies fine and I can get out to about 2800+ feet easily.

If I do the opposite and unhook the left antenna and only use the right antenna, the phantom loses signal completely in about 20 Feet from me, like it's not flyable.

Can someone enlighten me and tell me if I have a bad RC? or just a bad antenna? Or is this how it's supposed to work?

Thanks!
Daniel

(before you ask) I didn't do any mods to the RC. I just opened it up and unhooked the little gray factory wires and tested each one individually.
2017-1-19
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Phantomski
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i do not see how modifying the radio is not violating the fcc regs as well.. after all the whole point of an amplifier is to increase the signal sent by the radio, right? I wonder if those extended antenna amps have FCC stickers, and if so, how the heck did they do that?  And yes, I can see the point of the original OP - u amp the signal on the radio, but at some point the link failure will probably not be the tx signal being readable by the drone, but the drone's reply not reaching the TX.. so people going 5mi +, that  shows that the signal coming back from the drone, is actually stronger than the stock signal sent to the drone, if there was no amplifier on the transmitter...  Interesting.
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Cabansail
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There will be limits to the power that can be transmitted legally.  The other thing to consider is that the power increase to get more range is not linear. Each 3db gain will require a doubling of power. It soon gets to the point where the extra power required will not give a lot of added performance.

The other thing to consider is how the power is sent and received. The Transceiver in the drone would need to be omnidirectional. That is send and receive in all directions. It probably has a radiation pattern like a donut so sends and receives in a big circle with less above and below. That is sort of fixed as if you modify the field you will get dead spots. On the controller the situation is similar but you can fit modifiers to the antennas. This concentrates the signals in a smaller area. It makes the transmitter range longer and the ability to receive more sensitive. This will increase range but come at a cost. You must make sure the the beam is directed at the drone at all times as if it drifts out of it then it will lose the signal.
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Kneepuck
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Insomniak2 Posted at 2017-1-19 14:05
I wanted to know how the antenna system works on the RC... is one for receiving and the other transmitting or vice versa? Or are they identical.

The reason I ask is this, Ive noticed if i unhook my right antenna (if your looking down at the remote) and only use the left antenna, the phantom still flies fine and I can get out to about 2800+ feet easily.

You want to be careful doing that.  Using the transmitter with no load ( antenna ) on it can quickly destroy the final amplifier transistor.
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KM5RG-Robert
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Increasing the gain of an antenna system improves both transmit and receive signal levels. That is why antenna mods at the RC will also improve the range from the drone to the RC.
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Stinky711
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Insomniak2 Posted at 2017-1-19 14:05
I wanted to know how the antenna system works on the RC... is one for receiving and the other transmitting or vice versa? Or are they identical.

The reason I ask is this, Ive noticed if i unhook my right antenna (if your looking down at the remote) and only use the left antenna, the phantom still flies fine and I can get out to about 2800+ feet easily.

You may have already damaged your remote, always have antenna connected when operating.
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Stinky711
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Aardvark Posted at 2016-10-20 01:55
"However, since the drone can only transmit video signal 3 miles, the controller modification is not useful for longer than 3 miles, because the drone can not even send a signal back to the remote."

There is no limitation as to how far the signal will travel, it will just get weaker the further it has to go. In post #2 I said that this weaker signal can be amplified or concentrated by modifying the RC receive antenna. This then boosts the weaker signal to a level where it becomes usable again. That's the beauty of digital signalling, being a square wave it can easily and accurately be regenerated.

This kit is designed to amplify the video signal coming from your Phantom.
It's not for me but it's out there.

http://fpvcustoms.com/products/air-side-booster-mod-kit
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