by the use of information " 'sufficiently distinguishable to be purged of... 14. U.S. P &mean, 594 F.2d 1190, 57 A.L.R. Fed. 632, C.A.8 (Minn.), March Dl, 1979(Nos. 78-1 6, 78-1550.78-155078-1526) ...transponder, commonly known as a beeper device, to track an aircraft in public airspace did not cons