It's hard to say. It could be almost anything with a switching power supply and/or microprocessor. You didn't give us enough information to even speculate....So (W)hat could that be?!
yes...437.2203 MHz. Really?
Indoor for aircraft freq.What is the antenna?
i dont know but the dongle via usb yes?!Is anything grounded?
2mhzWhat is the bandwidth of the waterfall display?
i have to checkDoes it go away if you remove the antenna?