https://yo8rxp.com/home-made-transceiver-rxp2/

This would be my second home made HF transceiver. Contest transceiver 6 bands, cw only, Elecraft K3 codes emulation for PC interfacing.

I/Q quadrature + 9 mhz crystal filter I.F. stage

H-mode RF mixer

Si5351 VFO but heavy filtered for each band, TX and RX (more than 60 dB second harmonic rejection)

Teensy controller for logic

Teensy + audio shield as Hilbert DSP for LSB / USB rejection

// N1MM is expecting a fixed number of characters, if lower or higher, it is stalling.

// so a trailing or leading zeroes is to be implemented to set that fixed lenght

// Serial data is not reliable until a CTS, RTS signaling low level is implemented

// If using just blind RX and TX only it is prone to errors, so a higher baud rate is needed ... To be fixed