Is there a gadget that can identify the different RF signals in a noisy environment?
Not in general. One radio's signal is another radio's noise, especially in the case of high-bandwidth digital signals. The problem is essentially the same as wanting one radio to receive every type of signal in the environment. Which is theoretically possible (as long as each modulation is already known to the radio), but as far as I know not something that's been done.
You can get a spectrum analyzer, or a SDR receiver, which will give you a plot of power vs. frequency vs. time (waterfall plot). (The difference between the two for this purpose is that a spectrum analyzer is calibrated, giving measurements in absolute units, and much more expensive.) This will show you the strength of the signals, but it won't let you tell the difference between different protocols or devices (unless you know when particular devices are transmitting and can match up the timing).
If you just want to figure out which channels are least-occupied, or find the signal-to-noise ratio for a particular configuration (have your device transmit, see how far it sticks up above the background), then this is sufficient.