Patent ID: 6819221
Filing Date: 2004-11-16
Classification: G06K

Abstract:
A method of determining at least one characteristic value (A, B, C; (N-1), P) relating to the communication between a communication device (1) and a transponder (2), which are adapted to communicate with one another in a contactless manner, in which the transponder (2) enters into a communication connection with the communication device (1), which connection starts at a starting instant (TB), and in which the transponder (2) has the communication connection with the communication device (1) for a communication time interval (CP) which starts at the starting instant (TB),wherein at least one time value (A, B, C; (N-1), P) is determined as at least one characteristic value (A, B, C; (N-1), P), which time value represents at least a part (PCP3, PCP2, PCP1; TT, TP) of the communication time interval (CP) which starts at the starting instant (TB); wherein the transponder (2) enters into the communication connection with the communication device (1) and has the communication connection with the communication device (1) for a communication time interval (CP) which starts at the starting instant (TB), and in which the transponder (2) subsequently exits from the communication connection existing with the communication device (1), which connection ends at an ending instant (TE), and no longer has the communication connection with the communication device (1) as from the ending instant (TE); wherein at least one time value (A, B, C; (N-1), P) is determined as at least one characteristic value (A, B, C; (N-1), P), which time value represents at least a part (PCP3, PCP2, PCP1; TT, TP) of the communication time interval (CP) which starts at the starting instant (TB) and which ends at the ending instant (TE); and wherein the transponder (2) moves along a path of movement (x), and a transmission magnetic field is generated with the aid of a transmission coil configuration (27) of the communication device (1), which transmission magnetic field has a field strength variation which, along the path of movement (x) for the transponder 2, first increases to a maximum field strength value and subsequently has a field strength variation which decreases from the maximum field strength value, and in a method step it is detected that the transponder (2) which moves along the path of movement (x) has reached an above-threshold location (a1, a2, a3) where the field strength (H) received by a transmission coil configuration (36) of the transponder (2) has exceeded a given field-strength threshold value (H1, H2, H3), and after the detection that the transponder (2) has reached the above-threshold location (a1, a2, a3), in a further method step, a time-value determining means (14, 15, 16) is activated, and a time value (C, B, A) is determined, which time value is representative of a time interval (PCP1, PCP2, PCP3) which elapses after the activation, and subsequently, in a further method step, it is detected that the transponder (2) which moves along the path of movement (x) has reached a below-threshold location (b1, b2, b3) where the field strength (H) received by a transmission coil configuration (36) of the transponder (2) has decreased below said given field-strength threshold value (H1, H2, H3), and after the detection that the transponder (2) has reached the below-threshold location (b1, b2, b3), in a further method step, the time-value determining means (14, 15, 16) is deactivated, and subsequently, in a further method step, the time value determined by the time-value determining means (14, 15, 16) between the activation and the deactivation of this means (14, 15, 16) is read out, which time value is representative of at least a part (PCP1, PCP2, PCP3) of the communication time interval (CP).