FLUKE pm33xx_mathplusumeng0200 电路图.pdf

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1、I $XWRUDQJLQJ the other functions require only one source trace. Acquired traces or stored traces can be used as source for mathematical operations and can be selected by using the control in the MATH MATH 1 or MATH MATH 2 submenu. For best results, the source traces must be within the dynamic range

2、 of the scope. Inactive traces or empty memory locations cannot be used and the screen will display the message INVALID SELECTION. The result of MATH 1 is always stored in memory location m1. The result of MATH 2 is always stored in memory location m2. When used for mathematical functions, existing

3、memory locations are overwritten. (Use the Copy function to save important traces in another memory location, before using the mathematical functions.) Independent operation enables separate processes to be performed at the same time. When the result of a mathematical function is placed in a registe

4、r memory, functions can be chained together. An example is Ch1*Ch2, with the result being 2 - 2MATHEMATICS integrated to measure power. In this example, MATH 1 is the multiply function with the product placed in m1 and MATH 2 is the integration process, integrating the contents of m1, and placing th

5、e result in m2. The mathematical functions are performed on traces with differing units. Channel 1 shows volts over time, channel 2 shows current over time expressed in Ampres. The resulting trace of the multiplication fuction is expressed in Watts and gives the power over time. The units for the in

6、tegrated trace are Joules. Notes:-The mathematical functions give useful results only if there is no conflict between the units. For example, you cannot add ampres to volts. -The trigger delay and the timebase setting of the two traces must be equal. This is always guaranteed if the traces were acqu

7、ired at the same time (i.e., they are elements of the same register). Note:Appendix A gives the complete menu structure of the MATH menu. Remote commands: CPL: QW (Command to query a waveform). Refer to the Operating Guide for full details Trace on Ch1 Trace on Ch2 MULTIPLY Result in Register m1.1 F

8、ILTER Result in Register m2.1 math2math1 ST6948 Figure 2.1Example of chained mathematical functions MATHEMATICS2 - 3 2.2DEFINITIONS An example that can be used with the formulas given below, the Probe Adjust signal was sampled and the trace data was sent to a personal computer using the RS-232-C ser

9、ial interface and the Query Waveform command of CPL. The settings used and the most important elements of the response received were as follows: SettingsAttenuator200 mV/div CouplingDC Offset-1.5 div = -300 mV offset. Timebase200 s/div Delay-2.50 div = 500 s pretrigger view DataSYMBOLPARAMETERVALUET

10、YPE YuY-unitsVstring XuX-unitssstring YzY-zero0.3number XzX-zero-0.0005number YrY-resolution3.125e-005number XrX-resolution4e-006number YrngY-range65535number dT-corrdT-correction4688E-04number Nsample count512number Y1sample 19603binary Y2sample 29612binary . . . . . . . . . . . . . . . YNsample N-

11、9599binary The following paragraphs give some definitions and formulas that enable you to interpret the preceding data. The same definitions, symbols, and formulas will be used to describe the discrete mathematical functions of the Mathplus processing functions. DefinitionsYou can describe a wavefor

12、m using two one- dimensional arrays that contain wave sample information: S1.N and T1.N. In both arrays the index n (range : 1.N) corresponds to the sample number. Data in the S array represents the amplitude of the waveform in volts of each sample, Data in the T array represents the sample time in

13、seconds of each sample. A waveform is sometimes expressed in other units. For example, an FFT waveform gives a range of frequencies (T1.TN; expressed in Hz) for the signal amplitude of these frequency components (S1.SN, expressed in dB). 2 - 4MATHEMATICS Formulas: SnSn is the value of sample n, expr

14、essed in Y- units. Y-units are usually volts. SensitivityUsually the sensitivity is expressed in volt/div. In the oscilloscope, the range of the Yn values (Yrng) always equals 216 = 65535, which corresponds with 10.24 divisions on the screen. This gives a maximum vertical resolution of 6400 levels p

15、er division. Sensitivity is expressed in Y-units/division. OffsetOffset is the vertical screen position of the signal ground level, indicated by 1- (excluding Y-pos shift). The offset can be adjusted with the front panel Y POS controls. For calculated traces, the offset can be adjusted with the delt

16、a controls in the MATHematics menu. Offset is expressed in Y-units (volts). NOTE:Traces can also be positioned with the Y-pos control in the RECALL menu, but this does not affect the offset. The reason is that Y-pos is a pure display function, which does not affect the signal sampling nor the calcul

17、ation of a trace using a mathematics function. TnTn is the sample moment, expressed in X-units. X-units are usually seconds. TimebaseIn case of a sampled signal the horizontal scale is called the timebase. The timebase setting is usually expressed in seconds/ division. Without magnification or compr

18、ession, the oscilloscope always displays 50 samples per horizontal division. NOTE:The horizontal scale can differ, like the FFT scale. In this case it is expressed in X-units per division. S n YzY n Yr()+()Yu= Sensitivity6400Yr Yu div - -= OffsetYzYu= T n Xzn1()Xr+()dTcorrXr()Xu+= Timebase50Xr Xu di

19、v - -= MATHEMATICS2 - 5 DelayThe time delay between the trigger and the moment that the first sample is taken. If the delay is negative, the first sample is taken before the trigger. This is called pretrigger view. In pretrigger view, the trigger point (horizontal position of which Tn=0) is indicate

20、d on the screen. The delay or the position of the trigger point can be adjusted with the TRIGGER POSITION control. Delay is usually expressed in X-units (seconds). These values can also be expressed in divisions: NOTE:The X-POS control in the RECALL menu can also be used to position traces horizonta

21、lly, but this does not affect the delay or signal sampling because X-POS is purely a display function. DelayXzdTcorrXr()+()Xu= TriggerpositionXzdTcorrXr()+()Xu= Delay XzdTcorrXr()+() Xr - - 1 50 - -div= Triggerposition XzdTcorrXr()+() Xr - - 1 50 - -div= 2 - 6MATHEMATICS 2.3ADD Description: The ADD

22、function performs a point-to-point addition of two traces, related to the two ground levels (indicated as -). The result of the ADD function is a new trace in a different register. The resulting trace can be scaled, and offset can be added for positioning. NOTE:The front panel keys CH1+CH2 (or CH3+C

23、H4) can also be used to display additional active traces of the sums of these channels. But you can use the mathematical ADD function even after a single shot or on stored traces. Scaling is used to fit the resultant trace onto the screen. The TRACK control adjusts scaling. Vertical positioning is c

24、alled offset. It offsets each sample in the resultant trace with a value so that the trace can be moved vertically. The control adjusts the vertical positioning. The scale factor and the offset factor are displayed in the MATH SCALE menu. Pressing the autoscale softkey automatically selects the sett

25、ings so the trace continues to fit onto the screen even if the input signals use the full dynamic range of the oscilloscope. The amplitude settings are also used by the mathematical functions to obtain correct results if the settings of the two sources are different. Either newly acquired traces or

26、previously stored traces can be used as the sources for this process. The cursor controls are used to select sources. The resulting trace is automatically written into a register memory (m1 for math1 or m2 for math2). To see the result more clearly, press the DISPLAY SOURCE on/off softkey to turn of

27、f the two source traces. ST6953 ch1: m1.1: CH1 CH2 100mV 100mVMTB500sch1 ch2: 1 2 Figure 2.2Trace m1.1 is the result of the ADD function MATHEMATICS2 - 7 Mathematical description: Discrete mathematical formula: For an explanation of the symbols, refer to Section 2.2. Key sequence: SrS1S2+=where Sr i

28、s the result Sr n S1n S2n += Control to select the ADD function. Control to select the first source trace. Control to select the second source trace. Toggle softkey to switch the ADD function on or off. Control to adjust the scale factor. Control to adjust the offset factor. Toggle softkey to select

29、 autoscaling. Toggle softkey to switch the source traces on and off. MATHMATH1(2) ST6752 9303 DISPLAY SOURCE yes no on off T SCALE TRACK auto scale TRACK ch1 m4.3 2 - 8MATHEMATICS 2.4SUBTRACT Description: The SUBTRACT function performs a point-from-point subtraction of two traces, related to the two

30、 ground levels (indicated as -). The result of the SUBTRACT function is a new trace in a different register. The resulting trace can be scaled and offset can be added for positioning. NOTE:The front panel keys CH1+CH2 (or CH3+CH4) can also be used to display additional active traces of the subtracti

31、on of these channels. But you can use the mathematical SUBTRACT function even after a single shot or on stored traces. Scaling is used to fit the resultant trace onto the screen. The TRACK control adjusts scaling. Vertical positioning is called offset. It offsets each sample in the resultant trace w

32、ith a certain value so that the trace can be moved vertically. The control adjusts the vertical positioning. The scale factor and the offset factor are displayed in the MATH SCALE menu. Pressing the autoscale softkey automatically selects the settings so the trace continues to fit onto the screen ev

33、en if the input signals use the full dynamic range of the oscilloscope. The amplitude settings are also used by the mathematical functions to obtain correct results if the settings of the two sources are different. Either newly acquired traces or previously stored traces can be used as the sources f

34、or this process. The cursor controls are used to select sources. The resulting trace is automatically written into a register memory (m1 for math1 or m2 for math2). To see the result more clearly, press the DISPLAY SOURCE on/off softkey to turn off the two source traces. Figure 2.3Trace m1.1 is the

35、result of the SUBTRACT function ST6954 ch1: m1.1: ch2: CH1 CH2 100mV 100mVMTB20.0s ch1 MATHEMATICS2 - 9 Mathematical description: Discrete mathematical formula: For an explanation of the symbols, refer to Section 2.2. Key sequence: SrS1S2=where Sr is the result Sr n S1n S2n = Control to select the S

36、UBTRACT function. Control to select the first source trace. Control to select the second source trace. Toggle softkey to switch the SUBTRACT function on or off. Control to adjust the scale factor. Control to adjust the offset factor. Toggle softkey to select autoscaling. Toggle softkey to switch the

37、 source traces on and off. MATHMATH1(2) ST6752 9303 DISPLAY SOURCE yes no on off T SCALE TRACK auto scale TRACK ch1 m4.3 2 - 10MATHEMATICS 2.5MULTIPLY Description: The MULTIPLY function performs a point-to-point multiplication of two traces. The value of each data point is related to ground. The res

38、ult of the MULTIPLY function is a new trace in a different register. The resulting trace can be scaled, and offset can be added for positioning. If the source traces are expressed in different units, the result will be automatically expressed in correct units. For example, a volt multiplied by an am

39、pere will result in watts. Scaling is used to fit the resultant trace onto the screen. The TRACK control adjusts scaling. Vertical positioning is called offset. It offsets each sample in the resultant trace offset with a certain value so that the trace can be moved vertically. The control adjusts ve

40、rtical positioning. The scale factor and the offset factor are displayed in the MATH SCALE menu. Pressing the autoscale softkey automatically selects the settings so the trace continues to fit onto the screen even if the input signals use the full dynamic range of the oscilloscope. Either newly acqu

41、ired traces or previously stored traces can be used as the sources for this process. The cursor controls are used to select sources. The resulting trace is automatically written in a register memory (m1 for math1 or m2 for math2). To see the result more clearly, press the DISPLAY SOURCE on/off softk

42、ey to turn off the two source traces. One example of using the MULTIPLY function is the measurement of dissipated power, by taking the voltage across a device and multiplying it by the current through the same device. Refer to section 9.2 for an application example of multiplying a voltage trace and

43、 a current trace using the proper units. Figure 2.4Trace m1.1 is the result of the MULTIPLY function ST6957 ch1: m1.1: CH1 CH2 1 V 1 VMTB50.0sch1 STOP ch2: MATHEMATICS2 - 11 Mathematical description: Discrete mathematical formula: For an explanation of the symbols, refer to paragraph 2.2 Key sequenc

44、e: SrS1S2=where Sr is the result Sr n S1n S2n = Control to select the MULTIPLY function. Control to select the first source trace. Control to select the second source trace. Toggle softkey to switch the MULTIPLY function on or off. Control to adjust the scale factor. Control to adjust the offset fac

45、tor. Toggle softkey to select autoscaling. Toggle softkey to switch the source traces on and off. MATHMATH1(2) ST6752 9303 DISPLAY SOURCE yes no on off T SCALE TRACK auto scale TRACK ch1 m4.3 2 - 12MATHEMATICS 2.6FILTER Description: The FILTER function is a waveform MATH function. It is a post- acqu

46、isition algorithm that can be used for low-pass filtering or as display smoothing. The cut- off frequency of the low-pass filter can be adjusted and the resulting trace can be stored as a new trace in a separate register. This implies that the original waveform or trace is never disturbed by the pro

47、cess, allowing you to experiment with different filter factors. A typical use of this digital low pass filter is to suppress noise even after a (single shot) acquisition. Since the FILTER function is a post acquisition process, it can also be used on single event waveforms. Any newly acquired traces

48、 or previously stored traces can be used as sources for the filter process. The filtering is performed on all traces of a selected source register. The resulting trace(s) are automatically written in memory location m1 for math1 or m2 for math2 and are instantly displayed on the screen. For each sam

49、ple point of the trace, a weighed sum is calculated over a window of K samples (convolution). K is adjusted with the control. The window width K is displayed in the MATH FILTER PARAM menu. The resulting cut-off frequency is the result of the sample rate set by the timebase and the window. While the window is being adjusted, the -3dB point is displayed in the bottom area of the screen. Discrete mathematical formula