Tag used for monitoring the tire pressure
View Patent ↗A measuring method for measuring physical variables comprises—the selection of a working point (AP) lying within a total measurement range (G) of a physical variable (M) to be measured,—the detection of a measured value (M(t 1 )) of the physical variable at a first measuring time (t 1 ),—the determination of a displacement value (V(t 1 )) as the result of a subtraction of the measured value (M(t 1 )) measured at the first measuring time from the working point (AP),—the formation of change values (C(t 2 ), C(t 3 ) . . . C(tx)) of the physical variable (M) by acquiring subsequent measured values (M(t 2 ), M(t 3 ) . . . M(tx)) of the physical variable at subsequent measuring times (t 2 , t 3 . . . tx) and addition of the displacement value (V(t 1 )) to the subsequent measured values.
1. A measuring method for measuring physical variables, comprising:
the selection of a working point lying within a total measurement range of a physical variable to be measured,
the detection of a measured value of the physical variable at a first measuring time,
the determination of a displacement value as the result of a subtraction of the measured value measured at the first measuring time from the working point,
the formation of change values of the physical variable by acquiring subsequent measured values of the physical variable at subsequent measuring times and addition of the displacement value to the subsequent measured values.
2. A measuring method as claimed in claim 1 , wherein, if the change value exceeds the working point by more than a predetermined upper working range width or falls below the working point by more than a predetermined lower working range width, a new displacement value is determined by adding a variation value to the previous displacement value, the variation value preferably being calculated by subtraction of the change value from the working point.
3. A measuring method as claimed in claim 1 , wherein, if the change value exceeds the working point by more than a predetermined upper working range width or falls below the working point by more than a predetermined lower working range width, a new displacement value is determined as the result of a subtraction of the measured value, measured at this measuring time or at a subsequent measuring time from the working point.
4. A measuring method as claimed in claim 1 , wherein for the total measurement range of the physical variable to be measured an overall resolution of an analog-digital converter sampling the measured values is set, by dividing the total measurement range into a total number of quantization ranges, and a working range resolution of the digital-analog converter of a working range containing the working point is set, by subdividing the working range into a number of quantization ranges.
5. A measuring system having a sensor for detecting a physical variable and for emitting measured values of the detected physical variable, having an analog-digital converter for detecting the measured values emitted by the sensor and for converting them into digital measured values, having calculation means for determining a displacement value as the difference of a measured value measured at a first measuring time from a selected working point lying within a total measurement range of the physical variable, and having addition means, which are constructed to add the displacement value to the measured values supplied to the analog-digital converter, so that as output values the analog-digital converter supplies change values of the physical variable, which are formed from the detected measured values plus the displacement value.
6. A measuring system as claimed in claim 5 , wherein the addition means include a digital-analog converter, controlled by the calculation means and of which the output signal represents the displacement value, and a summation circuit, to which the measured values of the sensor and the output signal of the digital-analog converter are suppliable for summation.
7. A measuring system as claimed in claim 5 , wherein the analog-digital converter has an offset voltage input for adjusting a displacement of a zero point of the digitization range of the analog-digital converter and the addition means comprise a controllable voltage source connected to the offset voltage input, which voltage source is adjustable by the calculation means to a voltage representing the displacement value.
8. A measuring system as claimed in claim 5 , wherein the analog-digital converter has a control input for setting the resolution.
9. A measuring system as claimed in claim 5 , wherein the analog-digital converter is in the form of a sigma-delta converter.
10. A measuring system as claimed in claim 5 , wherein the sensor is in the form of a pressure sensor and the measuring system is in the form of a tire pressure-measuring system.
11. A data carrier for measuring physical variables, having a measuring system as claimed in claim 5 , wherein the data carrier comprises transmitting means for wireless transmission of the change values and/or of measured values of the measured physical variable determined by the measuring system.
12. A data carrier as claimed in claim 11 , wherein the transmitting means emit electromagnetic signals in the UHF band.
13. A data carrier as claimed in claim 11 , wherein the data carrier comprises receiving means for receiving an electromagnetic field and for extracting electrical energy from the electromagnetic field for supplying the data carrier with electrical energy.
14. A data carrier as claimed in claim 13 , wherein a chargeable battery in the form of a secondary cell, or a rechargeable energy storage mechanism, is provided, which are chargeable using energy from an electromagnetic field that is receivable by the receiving means.