In my endeavours to send and receive amateur radio around the world I have purchased a HackRF One, an open source hardware computer controlled SDR transmitter and receiver board designed by SharedBrain Technologies, along with the addon board PortaPack which makes the HackRF One standalone and gives it a touch panel LCD screen and jog wheel control.
Just as the hardware for the boards have been open sourced, so has the software and there is a thriving community focussing on adding extra features to the device constantly.
You can use the HackRF alone connected to the computer and for this purpose it shines. You can send and receive signals at any frequency between 1MHz to 8GHz and above.
The power output is low (in the mW range) but if combined with an RF signal amplifier could be as powerful as your licence or local laws allow.
I got involved with the development side of this board as I want to learn SDR programming and I specifically want to be able to send and receive SSTV (slow scan television) images. While the software has already been developed to send SSTV images directly from the HackRF one and PortaPack board it does not yet have the software to receive them.
While I am learning I have been changing the parts I do comprehend such as the graphical frontend. I have added a custom splash screen and written a simple guide to allow others to do the same, and added clearer, more understandable error messages in the software itself. I also added a full monospaced font to the system and had input on the icon layout, design and colour scheme.