HF and Shortwave bands can be full of strange voices and noises. Some good fun can be had by experimenting with radio and PC , Mac or Android devices to try to decode the data within some of the noises we hear.
One company who has released some interesting apps is Black Cat Systems.
Visit http://blackcatsystems.com/ to view their catalogue.
While our license conditions may restrict our foundation operators from transmitting digital signals, everyone can receive and try to decode the data signals we hear on air.
Have fun… Philip – VK3JNI