Abstract: A tire pressure monitoring device for a vehicle having several wheels comprises a central receiving and evaluation device at the vehicle. Each a receiving antenna (A, B, C, . . . N) is arranged stationarily at the vehicle structure adjacent to at least each active wheel and thus attributed to said specific wheel. All said receiving antennas (A, B, C, . . . N) being connected via each a distinctive connecting line (a, b, c, . . . n) with a single receiver means. Said receiver means comprises a multiplexer-circuit connecting per time interval only one single selected receiving antenna or several selected receiving antennas with said receiving means. Further, said receiver means sensing a field strength of each specific radiogram and thus selecting said specific receiving antenna comprising the highest field strength of a received radiogram during said specific time interval.

Abstract: A valve which includes signal generating means generate a signal representing a pressure drop within a vehicle tire. The valve includes an absolute pressure sensor coupled to measure the pressure within the tire. A microprocessor is provided which upon activation following operation of the valve stores a value of the electric pressure signal from the pressure sensor in a memory. During operation of the vehicle, the stored reference electric pressure signal is compared with periodic measurements of pressure within the tire. The transmitter is activated at periodic intervals, whenever a given ratio between the compared values and a threshold value exceeds an upper or lower limit. The system is activated by a acceleration sensor which can detect when the vehicle is moving, thus avoiding power consumption stopped.