This may in part have been due to the jamming against the German radio-beam navigations systems ( X-Verfahren and Knickebein , camouflage and decoy techniques ( ` Starfish sites ' ) were built , mainly south of the town , e.g. out in fields near Foremark ( ref .
This may in part have been due to the jamming of the German radio-beam navigations systems ( X-Verfahren and Knickebein ) , camouflage and decoy techniques ( ` Starfish sites ' ) were built , mainly south of the town , e.g. out in fields near Foremark .