If you tune around certain parts of each band you are likely to hear several digital modes. Refer to the ARRL Band Plan to determine where you should operate digital modes for every band. I recorded the following examples in a few minutes on 20 meters this afternoon just to show how easy it is to find operators using these modes. Many of these modes are available through free or inexpensive software and you probably have the equipment to hand that you will need. I use the sound card in my PC to produce the transmitted audio but I have used USB devices made specifically for using digital modes.
This is Continuous Wave (CW) which is the mode we use to transmit Morse code. I included it because it is the most basic digital mode – just on and off.
The following mode is PSK-31. PSK stands for Phase-Shift Keying and 31 represents 31 Baud.
This next mode is Radio Teletype (RTTY).
The following sample is packet and I do not know anything about it other than this is what it sounds like.
Below is an example of Weak Signal Propagation Reporter (WSPR). This mode is not meant for conversations but for determining propagation with very low output power. The WSPRnet web site has more information. Transmission/reception windows open and close at exactly the same time worldwide so your computer needs to be synchronized with a time server.
This mode is JT-65 and has really taken off over the last few years. It is extremely robust against noise and poor propagation but can only transmit short bits of information. I have only used it a few times. As with WSPR, transmission/reception times are globally synchronized.
Here is an example of Slow Scan TV (SSTV). I listed it last because it is used in the phone portion of twenty meters unlike all the previous modes which are used in the CW-Data portion of twenty meters. Specifically you will find SSTV around 14.230.