Mavic Radio Mods Primer

[beanbubba]

I forgot which thread it was posted in but I think it was lolo who mounted the birdside 4w amp inside the Mavic between the boards. I wanted to follow up for anyone who tries this mod. I put it in the same place he did but at a different angle and ended up burning out the ESC board. Just a heads up for anyone considering this location.

I was looking at the 8w amp you have there thinking it might be nice birdside. Wonder how big the board is. Has anyone tried daisy chaining the 4w amps?

Page 16 and 18 of the thread below have the 3 variants of this bird side amp detailed:

Aircraft Antenna Mod

 

[beanbubba]

I forgot which thread it was posted in but I think it was lolo who mounted the birdside 4w amp inside the Mavic between the boards. I wanted to follow up for anyone who tries this mod. I put it in the same place he did but at a different angle and ended up burning out the ESC board. Just a heads up for anyone considering this location.

I was looking at the 8w amp you have there thinking it might be nice birdside. Wonder how big the board is. Has anyone tried daisy chaining the 4w amps?

Regarding daisy chaining amps... here are some hard facts about the "Dragon" amp (the one with the heavy black case).

Dragon Amp Test Results:

0 dBm input = 10 dBm output
10 dBm input = 20 dBm output
20 dBm input = 28 dBm output
25 dBm input = 33 dBm output**

**Input >25 dBm results in no increased output.
**Input >20 dBm results in quick over heating and thermal effects rapidly reduce the output power, there is no benefit to input much over 20 dBm except in short bursts which is not possible in this application.

The "Dragon" amp has the most grossly over stated specs maybe ever. But it is still a great amp, just not close to a 4W amp.

 

[MavicPilot_swe]

I will try with the standard controller by covering one with foil on the ears then the other and see if the same result is found

I have done some testing myself with this and whatever i do i dont get any results with the right antenna, I can be 4 km away at 100m with only the left antenna without any problem, A little more out and i start getting glitches in video feed, but i cant really figure out what the right antenna is doing. I cant remove the left one at all, unlees im within 50 m or so... Have you figured it out yet?

 

[mnoutdoors]

I’m coming to the conclusion the right antenna is a redundant antenna but have not proved this out entirely yet

 

[beanbubba]

I have done some testing myself with this and whatever i do i dont get any results with the right antenna, I can be 4 km away at 100m with only the left antenna without any problem, A little more out and i start getting glitches in video feed, but i cant really figure out what the right antenna is doing. I cant remove the left one at all, unlees im within 50 m or so... Have you figured it out yet?

I have some pretty conclusive evidence from personal experience and commercial radio applications that the only possible gain you will get from the right RC port is if you equally amplify it to the left, then rotate your vertically polarized antenna 45 degrees opposed to the left antenna. This will NOT improve your signal strength, but it has the "potential" to increase data throughput a little bit. For long rang flight applications, all this means is that the live video stream might be a little bit clearer and/or less pixelated. This will NOT extend your distance or signal strength.

And all this is predicated if the mavic radio systems use multiple spatial streams (I have never seen evidence of this). And the relatively low bit rates displayed for the downlink connections suggest otherwise. Again this is all speculation and educated guess work.

 

[mnoutdoors]

Interesting 45 degree theory, I have thought about that before, I was going to rotate one 45 degree and see if anything changed. But have not yet because I did not have the need the signal has been so strong without.
Like mentioned before the signal errors have been almost non existent. But I think the 42 dbm has been compensating for things that with less would have needed improvement. So do you fix something if it’s working.
I guess I just like to experiment. As long as I don’t blow or burn to many things up in the process.

 

[mnoutdoors]

This is the posted specifications on my amps

Description:
Low-noise receive gain.
Signal activity LED indicates
High Gain, High Value, High Performance.
Maximum output power of 8000mW by the Booster.
Plug-and-play, Easy installation, no driver needed.
Ideal for increase the 2400-2500Mhz frequency devices.
Increase the effective range and coverage area of your Wi-Fi network.
Simply attach the booster in between the standard antenna on a wireless router or wireless access point and watch your range grow.
The amplified wireless signal may even penetrate complex environments with many walls and obstacles.
Ideal for use with 2.4GHz Wireless LANs, Support 802.11b, 802.11g, 802.11n (2.4Ghz mode only).
NOTE: The item need to connect to a Access Point or Router which is NOT included.

Specifications:
Operation Range: 2400-2500 MHz.
Operation Mode: Bi-directional, half-duplex, Auto-Switching via carrier sensing.
Frequency Response: ± 1dB over operation range.
Input Power: 3dBm (Min.)-20dBm (Max.).
Input Power 5 ~ 20 dBm.
Optimal Input Power: 9 ~ 13 dBm.
Output Power: 8000mW/39dBm nominal for 802.11b/11Mbps.
Connector: SMA Receptacle, 50 ohm.
Transmit Gain: 17dBm nominal.
Receiver Gain: 11dBm.
Receive Noise Figure: 3.0dBm nominal.
Operating Temperature: -40 to 70 degree.
Operating Humidity: Up to 95% relative humidity.
Material: Cast Aluminium.
Size:10.3cm x 7.7cm x 2.1cm

 

[beanbubba]

This is the posted specifications on my amps

Description:
Low-noise receive gain.
Signal activity LED indicates
High Gain, High Value, High Performance.
Maximum output power of 8000mW by the Booster.
Plug-and-play, Easy installation, no driver needed.
Ideal for increase the 2400-2500Mhz frequency devices.
Increase the effective range and coverage area of your Wi-Fi network.
Simply attach the booster in between the standard antenna on a wireless router or wireless access point and watch your range grow.
The amplified wireless signal may even penetrate complex environments with many walls and obstacles.
Ideal for use with 2.4GHz Wireless LANs, Support 802.11b, 802.11g, 802.11n (2.4Ghz mode only).
NOTE: The item need to connect to a Access Point or Router which is NOT included.

Specifications:
Operation Range: 2400-2500 MHz.
Operation Mode: Bi-directional, half-duplex, Auto-Switching via carrier sensing.
Frequency Response: ± 1dB over operation range.
Input Power: 3dBm (Min.)-20dBm (Max.).
Input Power 5 ~ 20 dBm.
Optimal Input Power: 9 ~ 13 dBm.
Output Power: 8000mW/39dBm nominal for 802.11b/11Mbps.
Connector: SMA Receptacle, 50 ohm.
Transmit Gain: 17dBm nominal.
Receiver Gain: 11dBm.
Receive Noise Figure: 3.0dBm nominal.
Operating Temperature: -40 to 70 degree.
Operating Humidity: Up to 95% relative humidity.
Material: Cast Aluminium.
Size:10.3cm x 7.7cm x 2.1cm

Thanks, do you have a link where I can order one of these?

The 3 dBm input trigger is high and a little concerning, but probably not a show stopper.

 

[mnoutdoors]

WiFi Wireless Repeater 2.4GHz 8W 802.11 Signal Extender Range Booster Amplifier | eBay

 

[beanbubba]

Yeah. Get one of these and test it for bird side. Would it not be cool to run a bird side amp and not need anything RC side?

If you want the max possible range, you would want to boost both sides of the RF link. Only boosting one side only takes you so far. And if you are going to only boost one side, the remote is far better because you can use directional antenna and manually point it too the bird in flight. The bird can't use directional antennas because it is flying in all directions. IMHO, a bird side only amp'd solution would be sub par compared to an RC only amp'd solution.

 

[mnoutdoors]

Show a picture of the inside of your amp's if you don't mind. The curiosity has grabbed me

Here you are BB

 

[mnoutdoors]

If you want the max possible range, you would want to boost both sides of the RF link. Only boosting one side only takes you so far. And if you are going to only boost one side, the remote is far better because you can use directional antenna and manually point it too the bird in flight. The bird can't use directional antennas because it is flying in all directions. IMHO, a bird side only amp'd solution would be sub par compared to an RC only amp'd solution.

Ok, here is a brain fart, if we are really looking at 1T2R system why not turn the second amp around on the right side antenna and boost the signal coming back. There is a little higher gain that way I believe on most of these amps maybe 6 dbi higher but that’s huge really.

 

[beanbubba]

Ok, here is a brain fart, if we are really looking at 1T2R system why not turn the second amp around on the right side antenna and boost the signal coming back. There is a little higher gain that way I believe on most of these amps maybe 6 dbi higher but that’s huge really.

I already tried that. All these "Wi-Fi" amps have an input trigger between -10 to 0 dBm. The signal you get from the bird will be between -90 to -50 dBm.

 

[mnoutdoors]

Ever tried parabolic on the right one?

 

[beanbubba]

Ok, here is a brain fart, if we are really looking at 1T2R system why not turn the second amp around on the right side antenna and boost the signal coming back. There is a little higher gain that way I believe on most of these amps maybe 6 dbi higher but that’s huge really.

Your amp looks very similar construction as the "Dragon" amp and a lot of the same circuits. And the rear label is almost identical.

Here is roughly how it operates. The trigger switch is waiting for signal on the input side to reach its threshold. And BTW - the TX/RX chips get literally smoking hot and must have heat dissipation methods.

 

[beanbubba]

I stumbled upon this video from an RF engineer and he actually tested the "Dragon" amp. I was preparing to basically do the same video, but no need now.

The analysis is from 41-64 minutes into the video:

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[mnoutdoors]

Interesting stuff, Thanks for the link

 

[beanbubba]

I have been delayed publishing a new Mavic radio observation video because my spectrum analyzer traffic generator has a peak output of 0 dBm and all the amplifiers we have under test have a minimum input trigger of 3-5 dBm. So I ordered a 20 dBm continuous carrier amp from china that took a month to arrive.

Anyway, the new video version 3.0 is now published and gives great insight that we have not seen before and only previously speculated on the facts. Nothing surprising except for the "8W" amp recently introduced to the forum. It greatly underperformed in TX gain, but was extraordinary with RX gain. This was not expected at all. I triple ran the tests to make sure and this really puts a new wrinkle on overall radio system performance.

I have a couple more significant items to test and will post upcoming videos soon. But the amp comparison video was a long awaited item and I hope you find it insightful and beneficial to your mod's.

@beanbubba


Mavic Radio System Observations 3.0

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[mnoutdoors]

Thanks for your tests, do you have more than one of all the amps? To see if testing was repeatable?

 

[beanbubba]

Thanks for your tests, do you have more than one of all the amps? To see if testing was repeatable?

EDIT:

I have multiples and tested of all the amp's except for the "8W" version. I will order a couple more now. I agree, those results for the "8W" amp are remarkable and not usual for this style amplifier.