PWM and ELRS how it works

What is ExpressLRS technology: 

ELRS Receivers – Notes

Some ELRS receivers are extremely small, with only one antenna. This compact design can be a limitation for long-range flights or when flying in areas with poor signal due to polarization issues. In such cases, signal quality can drop as low as 2%, especially when the receiver struggles to maintain proper communication.

Modern receivers typically connect via UART, which allows direct communication with flight controllers like INAV. However, a common issue is the voltage requirement: while many receivers work on 5V or 8V, some models only provide outputs like 8.4V or higher, which may not be compatible. This is a frequent challenge with ultra-compact receivers.

Models like the ER6 or ER8 support dual antennas and operate between 5V and 8V. These are generally more reliable than PWM-based systems and are better suited for telemetry and stable communication. Their dual-antenna setup also helps maintain better signal integrity.

For users needing a mid-sized option, the RP4TD is a solid choice. It supports 4V to 12V input, features dual antennas, two internal oscillators, and offers real-time signal synchronization. Using a cross-polarized antenna setup improves signal consistency during flight.

One of the most advanced solutions is the Gemini system. Designed for use across multiple frequency bands (e.g., 40MHz), it supports advanced signal stability and cross-polarization. However, it requires a dedicated Gemini-compatible radio, which is a significant investment. The benefit is that you can operate reliably on a single frequency with high precision.