Telemetry system for the wireless measurement of a quantity, comprising at least a passive transducer (1; 9, 10) sensitive to a variation of said quantity and a reading unit (5; 17) coupled to said passive transducer and suitable to detect, condition and process information of a measurement coming from the passive transducer, wherein: - each passive transducer comprises a resistive transduction sensitive element (2; 11, 12), a calibration capacitor (3; 13, 14), suitable to define a working frequency of the system, and a first coupling inductor (4; 15, 16), wherein the resistive transduction sensitive element (2; 11, 12), the calibration capacitor and the first coupling inductor (4; 15, 16) are connected as an oscillating RLC circuit; - the reading unit comprises a second coupling inductor (6; 18) suitable to realise an inductive coupling with said first coupling inductor, and detection means configured to detect a variation of amplitude of the real part of the impedance of the assembly constituted by the passive transducer and the second coupling inductor, at the working frequency and at a fixed distance (d) between the first inductor and the second coupling inductor, said amplitude of the real part of the impedance depending on the resistance value of the sensitive element, wherein the value of the calibration capacitor (3; 13, 14) is set to adjust the working frequency (f L) of the system, whereby the value of the calibration capacitor (3; 13, 14) is set such that the working frequency (f L) of the system comes to be identified as the value at which a curve ( ┌ 1) of the real part of the impedance of the assembly formed by the oscillating RLC circuit of the passive transducer and the second coupling inductor (6; 18) of the reading unit reaches the first relative maximum, characterized in that the reading unit further comprises processing means configured to obtain the resistance value (Rx) of the sensitive element from the amplitude of the real part of the impedance at the working frequency (Re(f L)) according to the relation Rx = α Re ƒ L β d − γ Re ƒ L where α, β and γ coefficients are dependent on the characteristics of the passive transducer and the reading unit, and d is the distance between the passive transducer and the reading unit and is kept constant during the measurement. - each passive transducer comprises a resistive transduction sensitive element (2; 11, 12), a calibration capacitor (3; 13, 14), suitable to define a working frequency of the system, and a first coupling inductor (4; 15, 16), wherein the resistive transduction sensitive element (2; 11, 12), the calibration capacitor and the first coupling inductor (4; 15, 16) are connected as an oscillating RLC circuit; - the reading unit comprises a second coupling inductor (6; 18) suitable to realise an inductive coupling with said first coupling inductor, and detection means configured to detect a variation of amplitude of the real part of the impedance of the assembly constituted by the passive transducer and the second coupling inductor, at the working frequency and at a fixed distance (d) between the first inductor and the second coupling inductor, said amplitude of the real part of the impedance depending on the resistance value of the sensitive element, wherein the value of the calibration capacitor (3; 13, 14) is set to adjust the working frequency (f L) of the system, whereby the value of the calibration capacitor (3; 13, 14) is set such that the working frequency (f L) of the system comes to be identified as the value at which a curve ( ┌ 1) of the real part of the impedance of the assembly formed by the oscillating RLC circuit of the passive transducer and the second coupling inductor (6; 18) of the reading unit reaches the first relative maximum, characterized in that the reading unit further comprises processing means configured to obtain the resistance value (Rx) of the sensitive element from the amplitude of the real part of the impedance at the working frequency (Re(f L)) according to the relation Rx = α Re ƒ L β d − γ Re ƒ L where α, β and γ coefficients are dependent on the characteristics of the passive transducer and the reading unit, and d is the distance between the passive transducer and the reading unit and is kept constant during the measurement.