I figured as much. The question about why it is needed brought to mind something I was told when I started work there, over three decades ago. It was something along the line that all the signal energy recorded by the observatory’s telescopes integrated over their lifetimes amounted to less energy than is expended by one flea making one jump. I don’t know exactly how accurate that is, but it does rather vividly illustrate the problem.
Well, for fun, that's 2.25 ergs, over 30 years that's an average of -126dBm
That's not that low for signal processing these days, and it'd be much more practically useful to develop the ability to filter out noise to that level than attempting to suppress it over a very broad area. My understanding is that it's the sensitivity of the detectors that's the real issue: they get pushed into clipping since their dynamic range is not that high. A similar thing happens with optical transceivers.
