Mavic Pro Controller antennas and function

[iowahill]

You've always got to remember that running a transmitter into ' No ' Aerial ( or faulty aerial ) could destroy the output stage of the transmitter or some of the associated components.
The longer you run it, the greater the risk.

I learned THAT sad lesson a few years ago when doing FPV on my P2's!

 

[iowahill]

I thought this discussion had reached the end of life stage... UNTIL beanbubba just responded to my questions posed to him via messaging:

"

He is close, but no cigar

The M1 RC left port is a dual function RX/TX port. The right port is an RX-only port and serves in a MIMO role (not diversity).

The M2 is identical with one exception on the RC, the left and right antenna ports are reversed. I have many posts and threads covering this.

Both the M1 and M2 only need 1 amp on the RC and the second amp is just for show if you choose to have 2 amps.

Many thanks for the reply! Not sure what "MIMO" is, MinMout? Is that similar in function to diversity?

So now we await an explanation of "MIMO" which evades me for the moment. But we're getting closer to understanding the functions of the antennas. My thanks to beanbubba for his contribution.

 

[iowahill]

Beanbubba look to him for your answers, he does alot of testing.

He is close, but no cigar

Beanbubba replied to my message to him as follows:

The M1 RC left port is a dual function RX/TX port. The right port is an RX-only port and serves in a MIMO role (not diversity).

The M2 is identical with one exception on the RC, the left and right antenna ports are reversed. I have many posts and threads covering this.

Both the M1 and M2 only need 1 amp on the RC and the second amp is just for show if you choose to have 2 amps.

Many thanks for the reply! Not sure what "MIMO" is, MinMout? Is that similar in function to diversity?

So we're getting more granular in our understanding of the MP1 antenna questions! Thanks 'beanbubba!

 

[iowahill]

I'm going deeper into trying to understand the M1P controller, particularly the antennas. I haven't found a link or forum yet that discusses the function of each of the two antennas but that doesn't prevent me from hazarding an intuitive guess:

The video, telemetry, and control are all in the 2.4GB range (for the M1P's) and one of the antennas is transmit bird control and the other is combined video and telemetry receive.

If I am incorrect please point me to a valid source that covers these functions in more depth.

So later today I'm going to try binding the bird to my controller and iPad, launch the Go4 ap, ensure that I have video and telemetry feed and ability to launch, then try disconnecting each antenna to see what does or doesn't happen. My guess is that there might be enough RF when close but not as I move away from the home point.

I should point out that I have moded my controller with the Itelite Nanosync kit so that I have SMA connectors externally mounted on the controller, so disconnecting one antenna at a time is easy.

If there is a link on our forums, or some other source of informative content please let me know. Meanwhile I'll follow up with what I discover.

 

[iowahill]

Unless we can drag one of DJI's design engineers into this discussion, our two leading contributors to understanding the MP and M2 antennas are beanbubba and James Crutchfield at TitanDrones. To add to their earlier input James just replied to me about beanbubba's post:

"----- Original Message -----From: James CrutchfieldTo: [email protected]Sent: Thursday, December 13, 2018 7:31 AMSubject: Titan Drones, Inc. sent you a new message

You've got a new message.
​

from Titan Drones, Inc.
Multiple input multiple output. I think at this point we are probably splitting hairs as I wouldn’t classify the antenna that way since there are no outputs but hey perhaps he knows more than I do. Regardless the same still holds true that on the Mavic one you only need one amplifier go to the left port. At this point I’m going to disagree with them on the Mavic 2 but I will get back around to testing and see what I come up with. I would love nothing more than to make a one amplifier solution as a lower-cost offering. So I do hope he is correct so far a couple hours of real world testing has proved otherwise for me anyway.
Titan Drones Inc Customer Service P: 1-866-202-5624 E: [email protected]

To respond to this message, reply to this email.​

As always, many thanks for your reply. I'm reposting yours, his, and any others in hopes that we can all come to a better understanding of how this "magic" happens!"

So now we get yet a step closer... UNLESS a DJI expert steps in!

​

​

 

[sea157]

As far as I know, at this time Titan is putting (2) 4w amps in their Switch amped system.

 

[iowahill]

As far as I know, at this time Titan is putting (2) 4w amps in their Switch amped system.

I see that the Titan Switch system can be custom configured and priced accordingly, and James stated that only one amp is needed for left antenna for the Mavic Pro 1. The dis -assembly of the controller is moderately the hardest part, but not that hard if you've previously ventured into replacing parts of the bird itself. No soldering is required.

The online howto's for various manufacturers and suppliers of controller mods all show installation of external SMA connectors that are essentially all the same except for the mechanical mounting of antenna support brackets and/or hardware. One conversion should be all that is needed.

I'm going to take my MP1 bird up today for a range test using the Itelite (passive antennas) NanoSync kit which I installed yesterday. After that I'll look at amplification to extend video reception range.

 

[iowahill]

As far as I know, at this time Titan is putting (2) 4w amps in their Switch amped system.

Don't know if you saw my earlier post of James' reply to me this morning regarding the antennas, so here it is again:

Multiple input multiple output. I think at this point we are probably splitting hairs as I wouldn’t classify the antenna that way since there are no outputs but hey perhaps he knows more than I do. Regardless the same still holds true that on the Mavic one you only need one amplifier go to the left port. At this point I’m going to disagree with them on the Mavic 2 but I will get back around to testing and see what I come up with. I would love nothing more than to make a one amplifier solution as a lower-cost offering. So I do hope he is correct so far a couple hours of real world testing has proved otherwise for me anyway.​

 

[sea157]

Don't know if you saw my earlier post of James' reply to me this morning regarding the antennas, so here it is again:

​

Multiple input multiple output. I think at this point we are probably splitting hairs as I wouldn’t classify the antenna that way since there are no outputs but hey perhaps he knows more than I do. Regardless the same still holds true that on the Mavic one you only need one amplifier go to the left port. At this point I’m going to disagree with them on the Mavic 2 but I will get back around to testing and see what I come up with. I would love nothing more than to make a one amplifier solution as a lower-cost offering. So I do hope he is correct so far a couple hours of real world testing has proved otherwise for me anyway.

Yes I did see your earlier post but what I am saying is as far as I know, at this time Titan is putting (2) 4w amps in their Switch amped system. They may change this in the future if they find out the one antenna may not need an amp on it.

 

[Capcadet05]

Renewing this line of discussion : I understand right antenna is MiMo only. I guess my question is would it harm the system if I only used one amp the ? Why would companies sell a second amp unless they were just interested in $$ mark up on hardware .... seems a little skeptical ?. I’m going to field test this since I am flying tomorrow and have two amps. I guess my question would be hooking up a second amp on MiMo right antenna; does that Help with rx sensitivity at all?

 

[Rnl]

No it doesn't help much

Renewing this line of discussion : I understand right antenna is MiMo only. I guess my question is would it harm the system if I only used one amp the ? Why would companies sell a second amp unless they were just interested in $$ mark up on hardware .... seems a little skeptical [emoji2955]. I’m going to field test this since I am flying tomorrow and have two amps. I guess my question would be hooking up a second amp on MiMo right antenna; does that Help with rx sensitivity at all?

 

[FoxhallGH]

I'm very sceptical of this mention of MIMO ... MIMO tech' is designed to support Multiple transmission paths and is designed to combine the multiple signals received when you have WiFi transmissions bouncing around inside a building for example. By its nature, DJI's controller and drone should have clear line of sight and therefore the need to accommodate multiple transmission paths at either end of the controller/drone link doesn't exist. I'm open to being proved wrong on this though - if anyone can point to a reference that DJI uses MIMO tech' - I'd be very interested to see it.

 

[AZDave]

I'm very sceptical of this mention of MIMO ... MIMO tech' is designed to support Multiple transmission paths and is designed to combine the multiple signals received when you have WiFi transmissions bouncing around inside a building for example. By its nature, DJI's controller and drone should have clear line of sight and therefore the need to accommodate multiple transmission paths at either end of the controller/drone link doesn't exist. I'm open to being proved wrong on this though - if anyone can point to a reference that DJI uses MIMO tech' - I'd be very interested to see it.

Sorry for the reply to an old post, but line of sight does not assure that you aren't receiving mutliple transmission paths. Signals can bounce off the side of adjacent objects (buildings, water towers, etc) and cause addition/subtraction to the direct line of sight signal. Dependining upon the material of adjacent object and angle of incidence of the signal, the undesired signal strength can be almost as strong as the direct path. Drop a bowling ball into one end of a swimming pool ... you won't end up with a planar wave at the other end of the pool because of bounces off the sides.