well since satellite technology wasn't around much before the '70's how can they make comparisons to how it was in the 1920's? Military sites? Where? on the tarmac of an AFB where a B52 is warming up? What's a ground station? Some major city or a field out in the middle of nowhere? In the tropics or in the poles? And how accurate were the instruments 100 yrs ago as compared to today?
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