File:Chain Home screen shot -NEDAD.2013.047.058A.jpg

English: A screen-shot of a late model Chain Home radar display (likely from a video). The image shows the actual radar return as the bumpy trace just below the MILES scale at the top. The large spike just visible on the extreme left is the return caused by leftover signal from the transmitter. Returns from targets closer than this distance, about 5 miles, were invisible. Three "blips" are visible to the right of this, one large one at about 18 miles, another at about 25 miles, and a third at about 30 miles. The pointer on the miles scale was moved by the operator to overlay a selected blip, in this case the most distance one. By pressing a button, the current setting of that marker and the goniometer that measured the angle of the return were both sent electrically to the "fruit machine", an analog computer. The fruit machine then applied corrections to the angle for known oddities of the receiver, then used the corrected angle and reported range the produce X and Y locations. These were plotted on paper maps, and then forwarded up the chain of command. Image is RAF Air Defence Radar Museum's catalog number NEDAD.2013.047.058A.