This is a good explanation from TelloFPV programmer:What is the difference of bitrate and iframe?
Please, use "Search" forum fuction located at Magnifier button and you will find lot of post talking about it.Hard to tell but as a rule of thumb: Close range high bitrate for best video, for longer range lower bitrate for better stability and less interference.
Iframe intervals depend if you have long lasting jitter or just for a few milliseconds. If long lasting jitter reduce the iframe period.
vGPS adds mapping capabilities to Tello implementing a virtual GPS by using Tello's Optical Flow Positioning System and Cell Phone hardware.What is the use of vgps really? What differential feature does it add to tello?
Really simple.How can i get the latest manual