I'm currently developing a device (which I will propose later here) and I use several sensors connected by remote RF to the main equipment.
I put a trace on this equipment to look all the trames received but it was not convenient.
So, I decided to make a very simple tool, connect to a notebook, and listening over the air, all exchanges between the sensors and the device.
I used a USB-UART integrated module, with 3.3v output. This is enough to power the PIC (18F2420) and one RFM12 module.
All the time something is sent, the PIC send the full trame to the PC. Very simple and convenient. It is small and working well.
Something to highlight is the poor stability of the 3.3V provided by the USB-Uart interface. I had to put capacitors on the supply because lot of wrong receiving information.
I'm thinking to add a display, to avoid the PC but so far, with a simple notebook, it is enough. Before this, will provide simple PCBA.