Hey Viraco, good question. I am new to drones and Spark is my first one so I tried to see as much videos and forums as I could, especially about this issue and turned out that I usually found the same info as you. But then I decided to test it and today I had 4 test flights with my spark with amazing results that I would like to share with you guys.
The Flights were in China on a narrow and long park surrounded by hundreds of buildings (15-20 stories) and literally thousands of apartments with WiFis and all kind of possible interference. (Check the picture)
All Flights with iphone 6, BT off, fresh
batteries, same altitude (70mts) and route and reseting all equipment before a new flight test.
1- 2.4GHz, Best channel selected (3), OTG cable disconected
Auto RTH at 220mts distance.
2- 2.4GHz, same best channel (3), OTG cable connected
Auto RTH at 200mts distance
3- 5.8GHz, Best channel selected (149), OTG cable disconected
Auto RTH at 1100mts distance
4- 5.8GHz, same best channel (149), OTG cable connected
Auto RTH at 1150mts distance
Regarding video quality in all cases the quality decreased according to the signal strength even with OTG cable connected, meaning I am screwing up connecting it or it really has no effect on range nor video quality.
My analysis suggests that the environment and surroundings is a key factor when selecting the correct frequency.
I am far away from any opened area to try the same tests on a environment without that much interference so if anybody here could do these tests then we could compare results.
Safe flights for all.