Patent Application
20110208461
This application claims the priority benefit of Taiwan application serial no. 99105321, filed on Feb. 24, 2010. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of specification.
1. Field of the Invention
The invention relates to a measurement correcting system and a method thereof. More particularly, the invention relates to a measurement correcting system capable of improving measurement accuracy by reducing an interference noise, and a method thereof.
2. Description of Related Art
It is important to correctly measure a near-field intensity during product development and scientific research. However, during the measurement, an environmental noise is generally infiltrated into a signal wire connected to a measuring probe through coupling, and is superposed to a measuring signal of the probe which results in errors that cannot be ignored. To obtain an accurate measurement value, the influence of the coupled noise has to be eliminated.
According to a conventional method, a plurality of ferrite cores is added to a transmission line to filter a common mode noise. Moreover, Taiwan Patent No. 1224420 also discloses a method for suppressing the noise interference, by which a transmission line is connected to a common mode noise filtering circuit in series to reduce the influence of the environmental noise. However, the filtering effects of the above two methods are limited within certain bands, so that only a part of the correction effect can be achieved.
The invention is directed to a measurement correcting system and a method thereof, which are used for reducing an influence of environmental interference noise generated during a measurement process.
The invention provides a measurement correcting system including a field measuring unit and a processing unit. The field measuring unit simultaneously senses a first signal to be measured and a second signal to be measured, and correspondingly generates a first output signal and a second output signal, wherein the first signal to be measured and the second signal to be measured have opposite polarities and substantially the same magnitude. The processing unit determines the first signal to be measured according to the first output signal and the second output signal.
In an embodiment of the invention, the field measuring unit includes a first field measuring probe and a second field measuring probe. The first field measuring probe senses the first signal to be measured, and the second field measuring probe senses the second signal to be measured.
In an embodiment of the invention, the field measuring unit further includes a first transmission line and a second transmission line. The first transmission line is electrically connected between the first field measuring probe and the processing unit. The second transmission line is electrically connected between the second field measuring probe and the processing unit. Moreover, the first transmission line and the second transmission line have the same size and length, and are arranged in parallel, so that the first signal to be measured and the second signal to be measured that are measured by the field measuring unit have substantially the same magnitude.
In an embodiment of the invention, the first field measuring probe and the second field measuring probe are arranged in minor symmetric, so that the first signal to be measured and the second signal to be measured that are measured by the field measuring unit have opposite polarities.
In an embodiment of the invention, the processing unit calculates a difference between the first output signal and the second output signal, and divides the difference by two, so as to obtain the first signal to be measured.
In an embodiment of the invention, the processing unit calculates an arithmetic average of the first output signal and the second output signal to obtain an interference noise.
In an embodiment of the invention, the interference noise includes a common mode signal and a differential mode signal.
The invention also provides a measurement correcting method. The measurement correcting method can be described as follows. A first signal to be measured and a second signal to be measured are simultaneously sensed and a first output signal and a second output signal are correspondingly generated, wherein the first signal to be measured and the second signal to be measured have opposite polarities and substantially the same magnitude. Then, the first signal to be measured is determined according to the first output signal and the second output signal.
In an embodiment of the invention, a method for simultaneously sensing the first signal to be measured and the second signal to be measured includes arranging a first field measuring probe and a second field measuring probe of a field measuring unit in minor symmetric, so as to measure the first signal to be measured and the second signal to be measured that have opposite polarities.
In an embodiment of the invention, a method for simultaneously sensing the first signal to be measured and the second signal to be measured includes arranging a first transmission line and a second transmission line of the field measuring unit in parallel, so as to measure the first signal to be measured and the second signal to be measured that have substantially the same magnitude, wherein the first transmission line and the second transmission line are respectively electrically connected to the first field measuring probe and the second field measuring probe, and the sizes and lengths of the first transmission line and the second transmission line are substantially the same.
In an embodiment of the invention, the step of determining the first signal to be measured according to the first output signal and the second output signal includes calculating a difference between the first output signal and the second output signal, and divides the difference by two, so as to obtain the first signal to be measured.
In an embodiment of the invention, the measurement correcting method further includes calculating an arithmetic average of the first output signal and the second output signal to obtain an interference noise.
In an embodiment of the invention, the interference noise includes a common mode signal and a differential mode signal.
According to the above descriptions, since the first output signal and the second output signal are respectively generated according to the first signal to be measured and the second signal to be measured that have opposite polarities and substantially the same magnitude, the noise interference can be removed and the first signal to be measured can be obtained by processing the first output signal and the second output signal.
In order to make the aforementioned and other features and advantages of the invention comprehensible, several exemplary embodiments accompanied with figures are described in detail below.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
As shown in
It should be noticed that in the present embodiment, the field measuring probe 112a and the field measuring probe 112b are substantially the same measuring probe, though arrangement methods thereof are different. The different arrangement methods of the measuring probes can result in a fact that the simultaneously sensed signals to be measured DP1 and DP2 may have opposite polarities. For example, in the present embodiment, the field measuring probe 112a and the field measuring probe 112b are arranged in mirror symmetric, so that the signals to be measured DP1 and DP2 simultaneously sensed by the field measuring probe 112a and the field measuring probe 112b have opposite polarities. In detail, assuming that when the field measuring probe 112a having a mark A1 facing to a +y direction senses a field with a positive polarity, the field measuring probe 112b having a mark A2 facing to a −y direction may simultaneously sense a field with a negative polarity. Namely, the field measuring unit 110 can simultaneously sense the signals to be measured DP1 and DP2 that have opposite polarities. On the other hand, a designer can adjust the relative arrangement directions of the field measuring probes according to an actual requirement, so as to ensure that the signals to be measured sensed by the two field measuring probes have opposite polarities. Namely, the arrangement methods of the field measuring probes 112a and 112b are not limited to the example of
Referring to
During the measurement process, the field measuring probes 112a and 112b or the transmission lines 114a and 114b are all interfered by external noises, so that the signal transmitted to the processing unit 120 includes the signal to be measured DP1 and the noise. In detail, the interference noises on the transmission lines 114a and 114b can be categorized into differential mode signals and common mode signals. The signals to be measured DP1 and DP2 that are sensed by the field measuring probes 112a and 112b are respectively transmitted to the transmission lines 114a and 114b in form of the differential mode signals. On the other hand, during the measurement process, environmental noises can also be continually coupled into the transmission lines 114a and 114b. A part of these interference noises is coupled in form of the common mode signals, and another part of the interference noises is coupled in form of the differential mode signals.
In the present embodiment, the output signals V1 and V2 received by the processing unit 120 can be respectively represented by:
V
1
=D
P1
+D
N1
+C
N1 (1)
V
2
=D
P2
+D
N2
+C
N2 (2)
Herein, DN1 and DN2 represent the differential mode signals of the interference noise, and CN1 and CN2 represent the common mode signals of the interference noise. As described above, since the arrangement directions of the field measuring probes 112a and 112b are different, and the transmission lines 114a and 114b have the same size and are arranged closely together in parallel, the relationships of the signals can be represented as follows:
DP1=DP2
DN1=DN2
CN1=CN2
Accordingly, the processing unit 120 can deduce the signal to be measured DP1 according to the output signals V1 and V2. In detail, the signal to be measured DP1 can be obtained by subtracting the output signal V1 in the equation (1) and the output signal V2 in the equation (2), so as to get the difference between the output signals V1 and V2, and then dividing the difference by two, i.e. VA=(V1−V2)/2=DP1=DP2. Here, VA is the signal to be measured DP1, and the common mode signal CN1 and the differential mode signal DN1 are almost removed from output signals. In overall, since the amounts of noise coupled into the transmission lines 114a and 114b are substantially the same, the measurement correcting system 100 can effectively reduce the influence of the interference noise, and can separate the signal to be measured DP1 or DP2 from the output signal V1 or V2. Moreover, since the characteristic of the interference noise has no effect on the calculation of the signal to be measured, the measurement correcting system 100 of the invention is especially suitable for measuring transient signals with relative fast transition.
On the other hand, the processing unit 120 can also calculate an arithmetic average of the output signal V1 in the equation (1) and the output signal V2 in the equation (2) to obtain the interference noise, i.e. VB=½(V1+V2)=DN1+CN1=DN2+CN2. Here, VB represents the environmental noise, which is a superposition the common mode signal DN1 (or DN2) and the differential mode signal CN1 (or CN2). Moreover, in the other embodiments, the measurement correcting system 100 may include a plurality of field measuring units 110 to measure different field signals, wherein an operation method of each of the field measuring units 110 is the same as that described above, and therefore detailed description thereof is not repeated.
According to another aspect, the present embodiment also provides a measurement correcting method, which is suitable for improving measurement accuracy by reducing the influence of the interference noise.
In summary, in the invention, since the two signals to be measured have opposite polarities and substantially the same magnitude, by performing different mathematical operations to the two output signals, the signal to be measured and the noise interference can be separated from the two output signals, so as to obtain an accurate signal to be measured.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 99105321 | Feb 2010 | TW | national |
