Abstract: Apparatus for registering a chance event, particularly the passage of a ball over a closed boundary line in a game, is described wherein the ball contains an oscillatory circuit. Two parallel conductors, fed by an a.c. generator in phase opposition extend along the boundary line so that a receiving conductor extending between the transmitting conductors is subject to a resultant zero voltage until the ball approaches and passes the boundary line so disturbing the electromagnetic fields radiated by the transmitting conductors. The receiving conductor current then passes through an amplifier, phase comparison means, a pulse generator and display device. The phase comparison means is connected to distinguish the direction in which the ball crosses the line and also enables a zero setting device to accommodate prolonged extraneous signals. A compensating antenna and circuit eliminate stray field effects. The transmitting and receiving conductors can encircle a goal structure.

Abstract: Interruptions in the playing time of a game having a set playing time are recorded by the transmission of signals by the referee at the beginning and end of each interruption. The referee's signals are transmitted by wireless to a reception conductor located in or on the playing area and conducted therefrom to recording and display devices. To prevent interference by signals other than those from the referee, interference receiving conductors are located outside the playing area and/or around the spectator areas and signals received by these loops are suppressed by comparison with the signals emitted within the playing area. Interference may be further prevented by providing for the referee to transmit two separate signals the characteristics of which are compared with those of predetermined signals and elapsed time only recorded when the signal characteristics coincide.