My understanding echoes yours.... but am always open to discussion and improved information!
It's my understanding that DJI Lightbridge uses 10Mhz wide OFDM ( click here if you're interested in what OFDM is) channels from 2401MH to 2481MHz (8 channels, DJI 13 -> 20).
When you perform the 32 channel hack, you are adding manual selection capabilities for channels 1 (2281 MHz) through 12 (2401MHz) and channels 21 (2481MHz) through 32 (2601MHz). These lower channels 1-12 were found to belong to HAM radio and Sat/Space Communication, while the upper channels 23-32 belong to Sprint LTE for cellular usage.
Channels 21 and 22 appear to be open ISM channels.
It's my understanding that the DJI control channels for analog sticks, buttons, wheels, etc. are 1-2MHz wide and use FHSS frequency hopping between 2400MHz and 2490MHz only ( click here if you're interested in what FHSS is).
It seems logical that control would require less bandwidth but require more robust and stable communication. Video is secondary to control, requires more bandwidth, and lends itself to user configuration.
The goal of the GO App configuration is to try to eliminate ISM frequency, Wifi interference. 802.11b Wifi uses channels 1, 6, 11, & 14.
For the US, channel 20 is often the best choice since wifi channels 12,13, & 14 aren't used in the US. This would extend to hacked channels 21 & 22 as well. If you are interested in the Wifi spectrum then click on this link to learn more:
DJI Channel | Low Freq | Ctr Freq | Upper Freq | Wifi Channel | 13 | 2401 | 2406 | 2411 | 1 | 14 | 2411 | 2416 | 2421 | 1,2,3 | 15 | 2421 | 2426 | 2431 | 2,3,4,5 | 16 | 2431 | 2436 | 2441 | 4,5,6,7 | 17 | 2441 | 2446 | 2451 | 6,7,8,9 | 18 | 2451 | 2456 | 2461 | 8,9,10,11 | 19 | 2461 | 2466 | 2471 | 10,11,12,13 | 20 | 2471 | 2476 | 2481 | 12,13,14 | 21 | 2481 | 2486 | 2491 | 14 | 22 | 2491 | 2496 | 2501 | - |
This information could always be inaccurate, so please share your sources and correct my inaccuracies! |