Idiot. I never said that so called greenhouse gasses don't absorb radiation...typical of warmers, you make up some ridiculous argument to rail against rather than what I actually said.
You don't know what you say from post to post. That's one reason why everyone laughs at you so hard.
So, why does the IR spectrometer measure an IR spectrum that shows the peaks and troughs that correspond with greenhouse gas emissions?
Remember, your explanation for why an uncooled camera shows colder clouds so accurately is that the camera sensors know to radiate more towards colder parts of the sky. You flat out rejected the idea that backradiation was being detected by the camera.
So, we have the IR spectrometer. It would work uncooled as well, though with less accuracy, and show those peaks and troughs across the spectrum corresponding with GHG emission bands.
According to your theory, that has to somehow be caused by the receptors in the camera. So how do they do it? How do they know to restrict single frequencies from emitting?