 Each pair of antennas was connected to a motorized switch that rapidly switched between the pairs , a technique known as lobe switching . Both signals were then sent to a cathode ray tube ( CRT ) for display , with one of them passing through a voltage inverter . If the target was to the left , the display would show a longer blip on the left than the right . When the target was dead ahead , the blips would be equal length . There was an inherently limited accuracy to such a solution , about five degrees but it was a practical solution in terms of limiting the antenna sizes . 
