Owner: Ishman Mann
ToDo:
Come up w/key features and Modify the schematic by Nolan Haines for groundside TX applications
Create a corresponding layout
Table of Contents
Background
This board will take the best parts of ELRS Gemini TX and ELRS Redundant Diversity RX, and combine them into a groundside TX. Likely this board won’t use Diversity TX (which doesn’t really exist), but Xrossband.
Ideas
something like Xrossband would be pretty cool. It's the next step after Gemini in terms of TX. Basically have two Geminis on the board, with one at 900-910 MHZ and the other at 2.4-2.44GHz. https://fpvguru.in/blogs/expresslrs-gemini-xrossband-the-future-of-dual-band-fpv-control/ . Hardware wise it could use the same LR221s, main differences would be in firmware
Key references:
Needs Assessment
Top goals
Have 2 Geminis (4 LR221s) on the board for Xrossband. Make it compatible with the RX board.
Improve upon the ELRS Gemini TX.
Port over existing features and add new ones
Design to solve/avoid the issue it was having!
Easily programmable
Configurable over UART, WIFI, etc…
Constraints
Size and weight are not limiting factors
Architecture
consider dual passband filter of somekind
Test/Validation Plan
Layout Considerations
https://www.youtube.com/watch?v=SwNb0ndIT5k&ab_channel=Rogers%27AdvancedElectronicsSolutions
ENIG has more losses than bare copper for coplanar waveguides
https://resources.altium.com/p/microstrip-ground-clearance-how-close-too-close
Note: the main point of a ground pour is manufacturability and shielding, but it may not be desirable everywhere if we want a microstrip configuration instead of waveguide