Specifics SDR of the device is complete control of the device from a computer, which by default has two input devices - a keyboard and a mouse. The feeling of tuning with these devices cannot be compared to the feeling of tuning with a knob VFO on a regular device. However, it is possible to use special USB buttons designed for multimedia applications, e.g. Griffin PowerMate. Their price is not completely negligible.
Tuning in Power SDR is also possible with the mouse wheel. At the same time, the user can have several mice connected to the computer, which allows one to be used only for this purpose. By disassembling the cheap Genius NetScroll 120 mouse, we find that the wheel sensor is designed as a rotary encoder. Better than trying to mechanically connect this encoder to a large tuning knob is to use a rotary encoder with a knob axis and panel mount. The price of such encoders is approximately two euros. For about six euros, we will significantly increase the comfort of tuning SDR devices.