What is the purpose of the transistor behind the transmitter? Is it some sort of pulldown? I was trying a similar project and couldn't get the pins 'quiet'. Would be interested to know the connections of that resistor.

You say you transmit radio waves signals, yet in the code you mentioned the LDR in the RX side? So are you transmitting the Morse over visible light or radio waves?

radio, 433MHZ in this, but it could any method of transmitting data since what it is looking for is HIGH and LOW state combinations of specific time periods.

radio

This would be cool... imagine a bunch of people using the same device once completed, create a  channelized system with every user having their call sign hard coded in the firmware for every transmission, one could create their own chat room with ham radio, independent of any grid based system. Even create an email system that could be accessed on command, specific to a particular call sign as an identifier.... i should learn more about ham radio, maybe someone already created it?

that is correct, unmodulated,  the duration of the transmitted signal form defines the data, if you were to listen to it on an SDR, it sounds like nothing.

From your code, it looks like you're doing true CW - just transmitting unmodulated 433 MHz carrier. Correct? And how convenient that those NRF modules fall in the middle of the 70-cm ham band - at least in the US.