I've been playing a lot with my FPGA lately, its such a fun toy! I'm currently trying to participate in the computer vision/computer graphics Project14 with it, but got a bit sidetracked to test something different. As FPGAs can read or generate very fast signals, they are used a lot in higher end SDRs. Usually you would use the FPGA with ADCs, DACs, transceivers, mixers, PLLs, filters, antennas, and what not! But when you are an "el cheapo" you don't need any RF gadgets, just the plain FPGA board to program it and let its tiny pins act as crappy antennas!
So I fed a 440 Hz test tone into an NCO, and let the magic happen:
And it sounds pretty good!
UPDATE:
I made a few modifications and now it can be used to transmit Morse (which I really don't know).
Here is a demo, left button turns the transmitter on/off, right button sends 750 Hz, ~150 kHz bandwidth FM modulated pulses.
