Mavic Radio Mods Primer

[SkyNinja]

Most amp's introduce very little additional noise and it would be negligible. BUT all amp's not only amply the desired signal, they amplify the entire noise floor (garbage in, garbage out).

Your statement: "better to have a weaker clean signal than a strong noisy signal" is neutral in effect. It's best to have signal at the level required that is above the noise floor. There is always a noise floor, but it's higher in NYC than in the Arizona desert.

In laymen terms using audio as an example, a busy airport terminal would have a high noise floor. A library study room would have a low noise floor. In the library you can whisper to the person next to you and fully communicate effectively. In the airport you would have increase your voice signal to exceed the noise floor so that the person next to you can understand what you are saying. Neither example is better than the other as long as the other person could decode your voice payload and effectively communicate with you. To take a step further, in that busy airport if the person you were talking to stepped away say 30 feet, you might have to cup your hands around your mouth to focus the sound towards the other person. Well, these high gain panel antennas are doing the exact same function and focusing the signal where directed.

Not sure if I answered all your questions.

Yes thank you, that answers my question.

So when I was looking at specs of different USA made amplifiers it seems like wattage plays a factor in transmission power but doesn’t have any bearing on receiving gain. Is there something similar to watts that determine receiving gain?

L-com Item # HA2401DX-XL3000 3 Watt 2.4 GHz 802.11b Indoor Amplifier
Transmit Power 3 Watt (35 dBm)
Receive Gain 15 dB

L-com Item # HA2401GI-1000 1 Watt 2.4 GHz 802.11b Indoor WiFi Amplifier(
Transmit Power 1 Watt (30 dBm)
Receive Gain 15 dB

RF LINX 2400SAXU 1W
Transmit: Automatically adjusts to specified Power Output
Receive: 20 dB

L-com HyperLink Wireless brand 2.4 GHz 802.11b Indoor WiFi Amplifier – 6 Watt Model: HA2406TI-NF
Transmit Power 6 Watt (38 dBm)
Receive Gain* 17 dB Nominal

YDI AMP2440 2.4 GHZ (?W)
* 14dB transmitter power gain (standard)
* 16dB receive gain

 

[beanbubba]

Yes thank you, that answers my question.

So when I was looking at specs of different USA made amplifiers it seems like wattage plays a factor in transmission power but doesn’t have any bearing on receiving gain. Is there something similar to watts that determine receiving gain?

L-com Item # HA2401DX-XL3000 3 Watt 2.4 GHz 802.11b Indoor Amplifier
Transmit Power 3 Watt (35 dBm)
Receive Gain 15 dB

L-com Item # HA2401GI-1000 1 Watt 2.4 GHz 802.11b Indoor WiFi Amplifier(
Transmit Power 1 Watt (30 dBm)
Receive Gain 15 dB

RF LINX 2400SAXU 1W
Transmit: Automatically adjusts to specified Power Output
Receive: 20 dB

L-com HyperLink Wireless brand 2.4 GHz 802.11b Indoor WiFi Amplifier – 6 Watt Model: HA2406TI-NF
Transmit Power 6 Watt (38 dBm)
Receive Gain* 17 dB Nominal

YDI AMP2440 2.4 GHZ (?W)
* 14dB transmitter power gain (standard)
* 16dB receive gain

That sir is a long drawn out answer because everyone uses slightly different terminology and I completely understand anyone's confusion on this topic. I will see what I can write up a little later.

 

[SkyNinja]

That sir is a long drawn out answer because everyone uses slightly different terminology and I completely understand anyone's confusion on this topic. I will see what I can write up a little later.

No worries, it’s not a big deal I was just curious. I was searching the web for specs on HyperLink 2.4 GHz 1000 mW HA2401-AGC1000 (1W) amps and found a lot of FCC testing but it all seems to be focused on transmitting power not receiving.

FCC ID MYF-WL-2401 Hyperlink Extended Range Wireless LAN by L-Com, Inc.

Some of the testing methods and manuel seem like they could be pretty interested, if I knew what the hell I was looking at[emoji20]

 

[beanbubba]

No worries, it’s not a big deal I was just curious. I was searching the web for specs on HyperLink 2.4 GHz 1000 mW HA2401-AGC1000 (1W) amps and found a lot of FCC testing but it all seems to be focused on transmitting power not receiving.

FCC ID MYF-WL-2401 Hyperlink Extended Range Wireless LAN by L-Com, Inc.

Some of the testing methods and manuel seem like they could be pretty interested, if I knew what the **** I was looking at[emoji20]

FCC only cares about what you transmit into the air. They don't care about what you transmit back into your gear, hence the reason you only see descriptors of TX related content.

 

[mb300sd]

Just to confirm I'm reading everything right, is this the optimal setup? I'd like to avoid modding the mavic itself if possible.

2x HG2409MGU-RSP
8W on RC right antenna
4W on RC left antenna
amps attached directly to antennas, with 50ft LMR-400 between amps and RC
1.5W .DJI.configs to boost output on AC side.

Already have the antennas and coax, ordering amps tomorrow if noone points out a mistake..

 

[beanbubba]

I'm about to give up on the AC side amp mods. I've used the 4w AC side to descent effect. The 8w didn't work out. Not sure why but it's too big to mount anywhere anyway. @beanbubba quick question. While messing with the AC amp mod, I unplugged both antennas from the board and was still getting signal between the AC and RC. Can you explain that?

All radios will radiate a good signal straight from the connector port on the board. Your milage may vary, but you usually can depend on 10-50 feet of quality range even if nothing has an antenna.

 

[beanbubba]

Just to confirm I'm reading everything right, is this the optimal setup? I'd like to avoid modding the mavic itself if possible.

2x HG2409MGU-RSP
8W on RC right antenna
4W on RC left antenna
amps attached directly to antennas, with 50ft LMR-400 between amps and RC
1.5W .DJI.configs to boost output on AC side.

Already have the antennas and coax, ordering amps tomorrow if noone points out a mistake..

Depends on what you are trying to accomplish. High gain omni's aren't very good if you like to fly high altitudes. And there are better prices out there for antennas if you are on a budget.

 

[Rnl]

Can you amp. just one side, I was thinking amp transmit side on bird and same on remote would that work. Seems like receiving signal doesn't boost much with amps.

 

[mb300sd]

Depends on what you are trying to accomplish. High gain omni's aren't very good if you like to fly high altitudes. And there are better prices out there for antennas if you are on a budget.

I already had those antennas from a different project, so figured they were a good starting point, might build an antenna tracker if anyone ever figures out how to feed the Mavic's position to a 3rd party app. Not trying to go too high, just maximum distance without worrying about aiming antennas. Mostly flying out of my lake house, so I want to be able to punch through a line of trees and maybe a house or 2, and then it's completely clear for miles.

 

[beanbubba]

I already had those antennas from a different project, so figured they were a good starting point, might build an antenna tracker if anyone ever figures out how to feed the Mavic's position to a 3rd party app. Not trying to go too high, just maximum distance without worrying about aiming antennas. Mostly flying out of my lake house, so I want to be able to punch through a line of trees and maybe a house or 2, and then it's completely clear for miles.

It wasn't clear to me exactly what you are trying to do. Is the 50' coax so you can fly from inside your house and mount the antennas outside?

 

[mb300sd]

It wasn't clear to me exactly what you are trying to do. Is the 50' coax so you can fly from inside your house and mount the antennas outside?

Either inside or on the back deck, depending on weather, with the antennas on the roof.

 

[Rnl]

I'm trying same thing.

 

[Rnl]

This will be on roof

 

[beanbubba]

Either inside or on the back deck, depending on weather, with the antennas on the roof.

This setup allows you to align the antenna heading from inside with a remote. It's certainly not a tracking antenna system, but if you know for example you will be flying in a general direction you can pair with sector antennas and point them in the general direction for a particular flight. This would at least double or triple the range of your flight over the omni's you listed in the prior post (I would recommend 90-120 degree beam width panels depending how much you want to adjust the mast rotor during flight) . This setup also does not penalize for high altitude flights.

Channel Master 9521A Antenna Rotator
https://www.amazon.com/gp/product/B01EIDKT0K/

Easy Up 36' 6" Telescoping Mast
https://www.amazon.com/gp/product/B010GAQ3K4/

Steel Antenna Mast 5ft
https://www.amazon.com/gp/product/B000SONAJ6/

CM-9025 3-Inch Heavy-Duty Wall Mount
https://www.amazon.com/gp/product/B001RCMEEA/

Heavy Duty Ground Mount for Telescopic Mast
https://www.amazon.com/Heavy-Ground-Mount-Telescopic-Masts/dp/B010E2GXCM/

Alternatively, put one omni and one sector panel on your antenna mast. Then just swap the RC left coax connector depending on your mood (TX/RX-Combo port).

 

[beanbubba]

View attachment 34339 This will be on roof

You read my mind I was typing the same when you posted!

 

[Rnl]

I like that, is that your setup?

 

[mnoutdoors]

B.B., what’s at the top camera ? And what’s by the window ?

 

[Rnl]

Yes, when I fly at home I go 2 directions, so I figured I could get it programmed in pretty close. Thanks for the tips.

 

[beanbubba]

I like that, is that your setup?

Yep, that's my home base shop. But those are 30x30 degree beam width panels specifically for flying in straight lines out for distance competition. Just adjust your antenna type to meet your local flying needs. I can recommend models if you need help.

Here is a google earth video I did to help visualize different antenna types against the Grand Canyon as a backdrop. This was a simulation to help train laymen on antenna characteristics:

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[beanbubba]

@beanbubba
Can this thing be run just like the WiFi amps we have been using for the AC mods? Here's a step down converter to power it with.

Thanks for the step down converter link, I need some of those for testing. That amp is a continuous carrier amp and is incompatible with the pulsed carrier amps that we all use on the TX/RX-Combo ports (on both bird and RC). This is due to the half duplex characteristics of Wi-Fi and the closely related proprietary Mavic radio systems.

BUT, I have yet to test and is a top priority to test this amp on the RX-Only ports on both the bird and RC. The 8W amp we have been discussing outperforms this guy by 5dB for RX, but for bird side I have high hopes that it will be a significant improvement for the RX-Only port on the bird.

My current estimate/theory is that the optimal bird side radio mod will have the dragon amp on the TX/RX-Combo port and the aforementioned continuous carrier amp on the RX-Only port. I look forward to test this when my day job gives the opportunity

EDIT: I also have some of these units on order from china to see how they perform compared to the other unit being discussed.

0.01-4GHZ Wideband Amplification LNA Ultra-low noise NF =21dB Amplifier | eBay