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1、 Hands-On Guide Hands-On Guide to LeCroy Color Digital Oscilloscopes to LeCroy Color Digital Oscilloscopes Revision C April 1998 Revision C April 1998 RadioFans.CN 收音机爱 好者资料库 LeCroy Corporation LeCroy Corporation 700 Chestnut Ridge Road Chestnut Ridge, NY 109776499 Tel: (914) 578 6020, Fax: (914) 57
2、8 5985 LeCroy SALeCroy SA 2, rue du Pr-de-la-Fontaine 1217 Meyrin 1/Geneva, Switzerland Tel: (41) 22 719 21 11, Fax: (41) 22 782 39 15 Internet:Internet: Copyright April 1998, LeCroy. All rights reserved. Information in this publication supersedes all earlier versions. Specifications subject to chan
3、ge. LeCroy, ProBus and SMART Trigger are registered trademarks of LeCroy Corporation. Centronics is a registered trademark of Data Computer Corp. Epson is a registered trademark of Epson America Inc. I2C is a trademark of Philips. MathCad is a registered trademark of MATHSOFT Inc. MATLAB is a regist
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5、trademarks of Hewlett-Packard Company. Manufactured under an ISO 9000 Registered Quality Management System Visit to view the certificate. This electronic product is subject to disposal and recycling regulations that vary by country and region. Many countries prohibit the disposal of waste electronic
6、 equipment in standard waste receptacles. For more information about proper disposal and recycling of your LeCroy product, please visit LCXXX-HG-E Rev C 0498 RadioFans.CN 收音机爱 好者资料库 LLL lowest value; highest value; and sigma, the standard deviation of the data values from the mean value. In order be
7、 sure of the statistics obtained, you will need to perform a number of acquisitions. ? 3XOVH? Trace A, B, C, or D, or Memory 1, 2,3 or 4. Press the corresponding menu to select “$YHUDJH” from the “Math Type” menu. Now, press to turn on Trace A. The screen will display: And (SYSTEM SETUP) to restart
8、Averaging. ? 0HDVXULQJ?6NLOOV The last screen shows the final result of the averaging of 1000 acquisitions. Non-systematic noise has been greatly reduced, as can be seen from a comparison of a single CH 2 acquisition with the 1000-acquisition averaged result on Trace A. Note: With Trace A on, the sw
9、eep counter in the Trace A label at mid-left of screen will mount until the number of sweeps reaches that selected. In the meantime, the intermediate result of the average is displayed (“216 swps”, as shown on the previous page). Once the selected sweeps number is reached, calculation stops and the
10、final result of the average is displayed, as here. ? $QDORJ?3HUVLVWHQFH ?9LHZLQJ?ZLWK?$QDORJ?3HUVLVWHQFH Using persistence to accumulate on-screen points from numerous acquisitions makes it easier to view signal changes over time. But Analog Persistence, with intensity grading, makes this even easie
11、r by signifying the most frequent signal path three-dimensionally. Heres how to use this unique feature to reveal the AM modulation of a sinewave. $SSOLFDWLRQ?6HWXSConnect signal to be measured an AM modulation of a 2 MHz sinewave with 100 kHz squarewave to CH 2. 67(3? 67(3? 67(3? Reset: press , the
12、 top and simultaneously. Then press to turn off Trace 1. Press , then the corresponding to select from the “Coupling” menu the coupling matching the sources impedance 50 . Press again. ? 0HDVXULQJ?6NLOOV Note: The AM modulation signal has a stable trigger. However, in the final periods the signal sh
13、ows a number of jumps. Without LeCroys unique Analog Persistence feature, its not easy to characterize these modulation variations in the normal display mode. 67(3? The screen will display: Now press ? $QDORJ?3HUVLVWHQFH The screen will then display: 67(3? Press ? 0HDVXULQJ?6NLOOV The screen will di
14、splay: Note: Modulation time variations appear clearly in Persistence Mode. Because its source is a squarewave signal, the modulation shown here has different states. The number of acquisitions included in the display (up to one million) is shown beneath the trace label. In this example, 1939 sweeps
15、 have been captured in a short delay to obtain the result displayed. The most recent sweep is shown as a bright vector trace. The Analog Persistence feature is also available in XY and Sequence Modes. 67(3?Press the for “Persistence Setup”. ? $QDORJ?3HUVLVWHQFH Note: The “Persist” menu offers the me
16、ans to apply persistence to all displayed traces, or merely the top two, when more than one trace is displayed. Information on each trace will be shown in its respective trace label at left of screen. When “Top 2” is highlighted in the menu, this relates to the first- and second-from-top labels that
17、 will appear with each additional trace very useful when four traces or functions are shown on-screen and persistence will not be applied to all. The “Persist for” menu offers a choice of persistence duration in seconds. If the duration is set for example at one second, each acquired trace will be d
18、isplayed for a second and then deleted. The default value for this menu is “,QILQLWH”. The screen will then display: 7LSV: Persistence Mode can be cleared and reset manually by pressing the CLEAR SWEEPS button, or by changing any acquisition or waveform processing condition. ? 0HDVXULQJ?6NLOOV 67(3?
19、 Note: The image displayed shows the changes in the sample event over time. Statistical integrity is preserved because the decay is proportional to the persistence population for each amplitude or time combination in the data. The brightness level of a single color is used to denote signal intensity
20、. Particular populations are given distinguishing shades of color. These are dynamically updated as data from new acquisitions are accumulated. Population distributions in rare events can be highlighted by additional saturation, as illustrated in the screen at right. Then turn the lower menu to adju
21、st the value of the saturation to 10 %. The screen will display: ? $QDORJ?3HUVLVWHQFH 67(3? Note: By default, the most recent sweep is shown as a bright vector trace on top of the persistence display. This menu allows to show or not the last trace on top of the persistence. Press the corresponding m
22、enu to select “2II” from the “Last Trace (show)” menu. The screen will display: ? 0HDVXULQJ?6NLOOV 67(3? Note: Instead of the brightness of a single color as used by the Analog Persistence feature, Color Graded Persistence uses a color spectrum from red through violet to map signal intensity, as sho
23、wn in this example*. Press the corresponding to select “ Number of samples acquired 10 000; Sampling rate 500 MS/s; Time between samples 2 ns/point; Total time acquisition 20 ms. 67(3? Again turn to adjust the timebase, this time until two pulse trains are acquired. ? f the distance in hertz between
24、 the center frequencies of two neighboring FFT bins, where f = 1 Time/ Div 10 ; 500 pts the total number of FFT points. Then press the to select “FFT” from the “Math Type” menu. Now press to turn on TRACE A. The screen will now display: 7LSV: To enable any Math function to use more of the acquired d
25、ata, press MATH SETUP and set “for Math use Math points” to the maximum value 10 million. The scope will use all of the acquired data. Calculations will be slower but more accurate. In this example, the FFT is performed on all 500 points of acquired data. ? 6SHFWUXP?$QDOVLV 67(3? Turn to move the tr
26、ace to the right of the screen and zoom the lower frequencies. The screen will then display: 67(3? Turn to obtain details of the lower frequencies. ? 0HDVXULQJ?6NLOOV Note: The scale in the “Trace A” trace label at left-of-screen changes when zooming. Here, the dual frequencies are 1 kHz and 3 kHz.
27、The screen will then display: 7LSV: The frequency span can be made greater by increasing the number of points acquired. There are several ways of doing this, but basicly acquired points are multiplied by increasing the value in the TIMEBASE “Record up to” menu, or by selecting a slower timebase whil
28、e keeping the same sampling rate. ? 6SHFWUXP?$QDOVLV Note: Rather than zoom the FFT directly, it is possible to zoom on a copy of the FFT on Trace B (as is shown here), C or D. (From top) Squarewave signal, FFT and FFT zoom on Trace C. ? 0HDVXULQJ?6NLOOV 3UHFLVLRQ?$QDOVLV?ZLWK?+LVWRJUDPV The WP03 Wa
29、veform Processing package a powerful tool for the statistical analysis of waveform parameters allows histograms to be made for any supported parameter, for quick and precise acquisition information. Heres how to use this parameter-distribution-analysis firmware with histogram to display and calculat
30、e signal jitter distributed across acquisitions. 6RIWZDUH?5HTXLUHGWP03 parameter-distribution-analysis firmware with histogram for LeCroy oscilloscopes. $SSOLFDWLRQ?6HWXSConnect the signal to be measured which should show edge jitter to CH 2. 67(3?Reset: press , the top and simultaneously. Then pres
31、s to turn off Trace 1. ? $QDOVLV?ZLWK?+LVWRJUDPV 67(3? 67(3? 67(3? Press , then the corresponding to select from the “Coupling” menu the coupling matching the sources impedance 50 . Press again. Turn to select a single period of the signal. The screen will display: ? 0HDVXULQJ?6NLOOV 7LSV: Persisten
32、ce Mode can be used to show the width variation, or jitter, of the acquired signal. By pressing DISPLAY and then the menu button to select “2Q” from the “Persistence” menu, the signal can be displayed with edge jitter in persistence mode, as shown here. Persistence should then be turned off. 67(3? P
33、ress to access the “ZOOM + MATH menus. And then press the corresponding s for “REDEFINE $”, and then to select “HV” from the “use Math?” menu. ? $QDOVLV?ZLWK?+LVWRJUDPV The screen will now display: Note: The Average function in the “Math Type” menu is selected by default. All functions that can be s
34、et up with standard and optional software where installed are shown in this menu. 67(3? Press the corresponding to select “+LVWRJUDP” from the “Math Type” menu. ? 0HDVXULQJ?6NLOOV The screen will display: Note: The Histogram function records the selected parameter values and presents data in a stati
35、stical form. It produces a waveform consisting of one point for each histogram bin, where the value of each point is equal to the number of parameter values falling into the corresponding bin. Analysis of histogram distributions is supported by a wide range of automated statistical parameters, and p
36、rovides insight into, and quantitative analysis of, difficult-to- measure phenomena. 67(3?Press the corresponding menu for “MORE HIST SETUP”. ? $QDOVLV?ZLWK?+LVWRJUDPV The screen will now display: 67(3? Press the corresponding menu for “PARAMETER SETUP”. ? 0HDVXULQJ?6NLOOV Note: The software install
37、ed in the oscilloscope determines which sets of parameter categories are available from the “Category” menu. Categorizing the parameters simplifies their selection. For example, those parameters useful for characterizing histograms are grouped under “Statistics” (further down the menu and not visibl
38、e here). And, and as the name suggests, the “All” category covers all parameters. 67(3? The screen will display: Press the corresponding s or turn the upper to select from the “measure” menu the parameter for which the histogram is to be made “ZLGWK” in the example screen that follows. Then press or
39、 turn the lower to select the channel on which the measurement will be performed “?” in this case. ? $QDOVLV?ZLWK?+LVWRJUDPV Note: A short definition of each parameter selected is displayed under the grid.(See the Operators Manual for more details.) 67(3? 7LSV: Press the menu button for “DELETE ALL
40、TESTS” if preliminary parameters have been set up in a previous acquisition, to ensure the newly chosen parameters form the required set. Press to turn off CH 2, then so that only Trace A, the histogram of the width of the trace acquired on CH 2, is displayed. ? 0HDVXULQJ?6NLOOV The screen will disp
41、lay: 67(3? Press to go back to the preceding menu, allowing the histogram to be set up. Then press the for “FIND CENTER AND WIDTH”. As shown on the next screen, the horizontal axis is set to a new scale, accurately showing the distribution. ? $QDOVLV?ZLWK?+LVWRJUDPV Note: The trace label shows the h
42、orizontal scale here, 5 ns/div, which corresponds to the width values. It also displays the vertical scale #10/bin, corresponding to the number of acquisitions for the same width value. As well, it shows the percentage of width values off-screen left and right; in this example, all width values are
43、within screen limits. And, finally, it displays the number of acquired and measured parameter values used to create the histogram. All values displayed in the trace label can be changed as required. Because Trace A is a function, horizontal and vertical scales and positions and thus zoom can be used
44、 for the histogram. Pressing the RESET button cancels all changes and displays the original histogram. ? 0HDVXULQJ?6NLOOV This screen shows a histogram whose horizontal and vertical display parameters have been adjusted. Turning the upper menu knob will change the number of bins that classify the di
45、fferent parameter values. When this number is changed, the new horizontal scale is adjusted and displayed in the trace label, as shown on the facing page. ? $QDOVLV?ZLWK?+LVWRJUDPV This screen shows the histogram after bin-number adjustment: 7LSV: As many as two billion measurements can be included
46、in a parameter histogram display. This limit is set by pressing the RETURN button in order to go back to the “SETUP OF $” menus. The appropriate menu button or knob is then used to set the required limit in the “using up to” menu (see screen following Step 6). ? 0HDVXULQJ?6NLOOV 67(3? The final step
47、s in this tutorial describe how to select parameters that characterize the histogram. Many statistical measurements can be made on the histogram for analysis of the characteristics of selected parameters including the highest value, standard deviation, and the most common value of the histogram. Pre
48、ss Then press the s to select “3DUDPHWHUV” from the top menu, and “” in the “Function” menu, and “?” from the “of” menu. ? 0HDVXULQJ?6NLOOV The screen will now display: Note: With the Sin(x)/x interpolation selected, a label appears under the grid giving information on the function. Here, the interp
49、olation will generate 500 points from the 50 of the original trace. The sampling rate is 500 MS/s and the Nyquist Frequency limit 250 MHz. The 100 MHz sinewave signal contains components whose frequency is lower than the Nyquist. The interpolation Sin(x)/x can be performed without aliasing. 67(3?Press Then press the to select “XDO” from the “Grids” menu (next screen). 7LSV: Two tr
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