wspr
WSPR, my first attempt at it. $139 for a 200 milliwatt (.2 watt or 2/10ths of a watt) digital transmitter. You have to be a general licensed ham radio operator for this. This transmitter is powered off any 5V USB source. It transmits and whatever receiving stations around the world that get it post it on a world map you can look at online to see where your signal got to.
This is great for testing antenna setups and locations, and for determining which ham bands are working well at a given time.
200 milliwatts! Digital signal on this Hamstick Octopus antenna. You are supposed to have identical Hamsticks opposite one another to make a dipole, which gives you 4 bands. I screwed in random untuned Hamsticks. It's about 20 feet up in front of our house in the middle of town at the bottom of the Connecticut River valley, surrounded on all but the west side by hills and mountains. The thing isn't even properly grounded. It is running off the USB port in my computer for power.
Digital modes have been revolutionizing ham radio. You can now get a good signal through where the human ear cannot hear voice or other analog communications.
There are various modes on various frequencies used for different purposes.
For instance APRS (Automatic Packet Reporting System) is a digital communication system used in amateur radio to transmit real-time data, primarily location information, but also messages and weather data, using packet radio. It's a way for ham radio operators to share their location, communicate, and track objects using a network of repeaters and internet gateways.
