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As I've stated in previous posts, when I first started flying the Spark, I was lucky to get much over 200 yards in distance. At that distance, I would receive warnings about weak/failing video, and weak signal in general. It was at that point that I began trying to eliminate anything that would interfere with the software/hardware/network operations of the phone and controller, and try to make things as efficient as possible. First, here is my setup:
DJI Spark and remote controller running DJI Go 4 with all software and firmware up to date Motorola Z2 Play phone with 32 GB memory running Android 7.1.1 I am NOT using an OTG cable!
Although I can't put my finger on any one thing that is a clear winner, here's everything I did to consistently fly over one mile under good conditions with signal to spare:
Mods for the phone: Put the phone in “Airplane Mode” while flying. This will also turn off WiFi, but you can switch WiFi back on by itself before starting and during Go 4. Completely eliminate the phone dealing with incoming calls by call-forwarding any incoming calls to another number.
If your Android phone supports precision GPS locating, go into that phone setting and turn off location services that use cellular and WiFi for location. Choose the option to use GPS only for location.
Shut down/disable/uninstall any other software on the phone that may be constantly trying to access network services. Needless to say, Facebook no longer resides on this phone .
In general, try not to run any software on the phone that isn’t absolutely necessary while flying. The idea here is to free up processor time.
If your phone is using an SD memory expansion card, make sure it is a "fast" memory card. It appears that when I bought my phone, the sales people fudged on my SD expansion card and put in a slower card than the phone specs called for. That problem has been fixed.
Mods for DJI Go 4: Increase the camera buffer from the default 2G if your phone has the memory. I’ve run mine as big as 8G. And, clear the buffer before every flight.
Put the camera/video in Manual mode, and run the ISO speed and Frames-Per-Second as slow as you can get away with. I try to run mine at 100 ISO and 60 Frames-Per-Second. I'm not worried about the video quality coming back to the controller. All I want is a good enough video to fly with. I don’t need HD video streaming back to the controller eating up bandwidth since any pics or video I take will be stored on the SD card in the drone in HD mode anyway. And, make sure you have a “fast” SD card in the Spark.
People have suggested that you have a formatted SD card in the drone to remedy range and video drop out problems. However, this didn't seem to help me.
When running in the default 5.8ghz mode, you really need to be line-of-sight with the drone since the shorter wavelength of 5.8 doesn't penetrate obstacles as well as 2.4ghz. I use a program for Android called “WiFi Analyzer” to see how much WiFi network traffic is in my area before I fly. This, along with the built-in WiFi detector in Go 4 let’s me find the least congested WiFi channels, and I manually select which channel I want to use in Go 4. On 01/12/2018, I consistently flew over one mile line-of-sight in clear weather using 2.4 Ghz channel 1 with flawless video stream and no signal drop outs. And, the key here is “line-of-sight” and a clean WiFi channel. The more obstacles you have between you and the drone, the shorter your range will be. And, (if it’s not congested) the 2.4 Ghz band will penetrate trees and foliage better than 5.8 Ghz. And, don't forget that atmospheric conditions affect WiFi range. Clear conditions and low humidity work better than high humidity and fog.
Your own flying situation may take some special tweaks, but hopefully these suggestions will give you a good start.
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lvl.2
Second Officer
Captain
lvl.4