I would like to add a small bit of information to the fine work Prairie Dweller provided about digital modes in Amateur Radio.
One of the things that has kept me from exploring digital modes has been the requirement for a laptop or desktop system, generally running Windows. Firstly, I don’t do Windows. Secondly, two is one, one is none. How will you repair your laptop after TSHTF? How many laptops can you inventory? Do you have large enough Faraday cages?
Given the above, I would like to suggest creating your digital mode hardware setup, using a Raspberry Pi B+ (aka Pi 2). This quad core system is more than capable of running the FLDIGI software, where the original Pi struggled. Add a USB sound card, a 5V power supply, a connector cable for your specific Ham radio, and a few other minor parts… and you should be good to go. Googling search terms “raspberry pi 2 fldigi” will get you going. 73s and Happy DXing – RDG
HJL adds: You might also look at Raspberry Pi’s 7” touch screen and case, which gives a really nice complete solution. I’ve been playing around with this setup, and it has some very interesting possibilities for the experimenter.