LeCroy Digital Oscilloscopes Manual 

Chestnut Ridge, NY 10977–6499 Tel: (914) 578 6020, Fax: (914) 578 5985 LeCroy SA 2, rue du Pré-de-la-Fontaine 1217 Meyrin 1/Geneva, Switzerland Tel: (41) 22 719 21 11, Fax: (41) 22 782 39 15 Internet: www.lecroy.com Copyright © April 1998, LeCroy. All rights reserved. Information in this publication supersedes all earlier versions. Specifications subject to change. 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. I 2C is a trademark of Philips. MathCad is a registered trademark of MATHSOFT Inc. MATLAB is a registered trademark of The MathWorks, Inc. Microsoft, MS and Microsoft Access are registered trademarks, and Windows and NT trademarks, of Microsoft Corporation. PowerPC is a registered trademark of IBM Microelectronics. DeskJet, ThinkJet, QuietJet, LaserJet, PaintJet, HP 7470 and HP 7550 are registered trademarks of Hewlett-Packard Company.. Manufactured under an ISO 9000 Registered Quality Management System Visit www.lecroy.com 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 equipment in standard waste receptacles. For more information about proper disposal and recycling of your LeCroy product, please visit www.lecroy.com/recycle. LCXXX-HG-E Rev C 0498

on LeCroy Color DSOs. 3ULPDU\6SHFLILFDWLRQV Basic Elements...................................................................1–2 Bandwidth............................................................................1–3 Sample Rate .......................................................................1–4 Memory Length...................................................................1–4 6LJQDO&DSWXUH Acquisition Technique ........................................................1–5 Analog–Digital Conversion.................................................1–6 Number of Channels ..........................................................1–6 Triggering............................................................................1–6 6LJQDO9LHZLQJ............................................................................1–7 0HDVXULQJ Pulse Parameters...............................................................1–8 Waveform Math..................................................................1–8 6LJQDO$QDO\VLV Time Domain ......................................................................1–9 Frequency Domain .............................................................1–9 Statistical Domain...............................................................1–9 'RFXPHQWDWLRQ Removable Hard Disk Drive (HDD).................................1–10 Interfaces...........................................................................1–11

through its basic functions. )URQW3DQHO&RQWUROV................................................................2–2 ,QVWDOODWLRQ&KHFN.....................................................................2–4 ,QLWLDOL]DWLRQ.................................................................................2–4 :DYHIRUP$FTXLVLWLRQ.............................................................2–7 TRACE ON/OFF.................................................................2–8 TIMEBASE Controls...........................................................2–9 Vertical Controls................................................................2–10 TRIGGER Controls...........................................................2–11 ZOOM................................................................................2–12 CURSORS/MEASURE....................................................2–14 Waveform Parameters.....................................................2–16 Summed Averaging..........................................................2–17 Fast Fourier Transform (FFT)..........................................2–20 Waveform Storage ...........................................................2–21 Save and Recall Setup.....................................................2–23

scope, in a series of easy-to-follow, step-by-step tutorials. )LUVW6WHSVLQ0HDVXULQJ........................................................3–2 The basic steps for setting up practically any measurement. 'LJLWL]LQJZLWK$OO(LJKW%LWV................................................3–6 How to set up the scope for digitizing on all eight bits. &KDUDFWHUL]LQJD3XOVH............................................................3–9 Parameter measurement and statistical values made easy. $FFXUDWH0HDVXULQJZLWK&XUVRUV...................................3–16 Ensure accurate measurements. 8VLQJ$YHUDJHWR5HPRYH1RLVH .....................................3–26 Reduce non-systematic noise and improve the signal-to-noise ratio. '9LHZLQJZLWK$QDORJ3HUVLVWHQFH ...........................3–31 Explore the new dimensions Analog Persistence reveals. &RORUVWKDW/LQNDQG'LVWLQJXLVK......................................3–39 Color Association makes signal viewing clearer and easier. &XWWLQJ'HDGWLPH%HWZHHQ(YHQWV.................................3–53 For a choice of single-shot waveform segments without deadtime. 7KH6FRSHDV6SHFWUXP$QDO\]HU ...................................3–63 Perform signal power distribution as a function of frequency. 3UHFLVLRQ$QDO\VLVZLWK+LVWRJUDPV ..............................3–70 Use the WPO3 option to display and calculate signal jitter. ,QWHUSRODWLRQ 0RUH,QIRUPDWLRQ.....................................3–87

7HVWLQJ$JDLQVWD7HOHFRP0DVN....................................3–96 Telecom-measure pulse-shaped signals to industry standards. 6WRULQJWR5HPRYDEOH+DUG'LVN....................................3–109 The portable PC Card hard disk drive (HDD) simplifies storage. &DOFXODWLQJRQ/RQJ:DYHIRUPV.....................................3–114 Handle longer FFTs and multiple long-waveform zoom, math and storage. 60$57*OLWFK&DSWXULQJ....................................................3–127 Find and capture glitches with the SMART Trigger. &DSWXULQJ5DUH3KHQRPHQD..............................................3–135 Use the SMART Trigger to increase knowledge of rare waveforms. 7ULJJHULQJRQ/RVW6LJQDOV................................................3–144 Ideal for detecting interruptions in data streams. 7UDQVIHUULQJ'DWDWR3& .....................................................3–150 By GPIB, floppy or RS232 communication port. 7UDQVIHUULQJ,PDJHVWR3&...............................................3–158 Copy screen TIFFs and BMPs to computer.

shows you what the scope can do as you operate it. The guide offers a helping hand to both the beginner and the experienced operator of digital storage oscilloscopes (DSOs). It can be opened at almost any page and used to enable you to get the most out of the instrument. $OO$ERXWWKH'62 ³an overview of the principles of DSO operation, including data sampling, triggering, recording, how sampling rate affects usable bandwidth and how long memory improves sampling rate. *HWWLQJ6WDUWHG ³shows you around the scope and step-by-step how to capture waveforms and perform basic measurements. 0HDVXULQJ6NLOOV ³ a set of tutorials describing — again, step-by-step — how to make the most useful measurements using the scope's advanced functions. “HANDS ON” FOR THE COMPLETE PICTURE IN SIGNAL CAPTURE, VIEW AND ANALYSIS. C A P T U R E V I E W A N A L Y Z E

(DSO) so useful? What are the many ways in which it can be put to work for you? Part 1 maps the digital landscape and shows you where to find and mine its riches. Basic concepts are explained and the main digital concepts and techniques outlined. The advantages of your LeCroy scope are also covered. Having completed Part 1, you’ll then be ready to zoom in on your scope in Part 2. C A P T U R E V I E W A N A L Y Z E

used to capture, view and analyze waveforms, measure signal characteristics and document the output. There are three main DS0 categories. Top-end models with a bandwidth of around 400 MHz or more are the most suitable for R&D-type work. The 100–200 MHz models are good for professional and general purposes. And the sub-100 MHz, low-cost scopes, are useful for work on low-frequency signals. %DVLF(OHPHQWV The way in which each element of the DSO works separately and in conjunction with the other elements: Ø Amplifier — amplifies the input signal so that it can be measured Ø Analog-to-Digital Converter (ADC) — converts the analog signal into digital form by translating it into a series of sample points that are then measured and transformed into digital codes representing the signal samples Ø Acquisition Memory System — stores resulting digital data Û System Memory of up to 64 MB

special monitoring and measurement functions Ø Display System — translates stored data into a graphic display of the signal. %DQGZLGWK 5HFRUG /HQJWK 'LVSOD\ 3ULQWHU $'& $PSOLILHU $FTXLVLWLRQ 0HPRU\ 6\VWHP 0HPRU\ 8SWR0E 3URFHVVRU ,QSXW 6LJQDO 6DPSOH5DWH The character of your signals will determine the primary specifications of the DSO you will want to use. While your DSO’s secondary specifications will be determined by the demands of your applications. In assessing the overall signal representation quality of a digital oscilloscope, particular consideration needs to be given to the cardinal parameters of bandwidth, sample rate, and acquisition memory length. %DQGZLGWK The bandwidth specification of a DSO indicates the ability of its front- end amplifier to faithfully track an incoming signal. The DSO’s bandwidth is defined as the frequency at which a sinusoidal input signal has been attenuated to about 70 % of its real amplitude. This point, at which the vertical amplitude error is about 30 %, is called the –3 dB point. It is generally advisable to use an instrument whose

component of the signal to be studied. 6DPSOH5DWH The higher the sample rate the better the signal resolution. This is particularly important for single-shot waveform capture and measurement. The danger with low sample rates is that important information may be lost between samples. Accurate waveform capture requires a sample rate of at least five times the highest frequency component to be captured. For repetitive signals the sample rate is a less critical factor, as the signal can be captured over many cycles. 0HPRU\/HQJWK Acquisition memory length determines the number of input signal samples that can be stored. The greater the capacity for stored samples, the faster the possible sample rate for a given waveform duration. The signal captured with a long-memory DSO has a greater resolution, while for short-memory DSOs, the high sample rates quoted are only available at a few fast time-base settings. Long-memory DSOs allow operation at the highest possible sample rate, and over a far greater number of timebase settings. +RZ$UH'62V8VHIXO" &DSWXUH &DSWXUHDQG'LVSOD\ 9LHZDQG5HFRUG $QDO\VLV 'RFXPHQWDWLRQDQG'DWD 7UDQVIHU The DSO can perform the same operations as an analog oscilloscope and much more: Capture of one-off (single-shot) events, stored in memory Data stays on screen while the scope waits for the next trigger View of the waveform before the instant of triggering, recording an event’s cause and effect. Analysis of signals, providing precise measurement results Documentation of signals, and the transfer of data via storage media to PC, or direct to print using an internal or external printer, or to a plotter.

by these three parameters (by others, too). The bandwidth must be sufficient to allow all the signal components to pass through the signal-conditioning system. And the sample rate has to be high enough to provide a good definition of the signal. Long memory maintains the sample rate for large time windows. 6LJQDO&DSWXUH In addition to the primary specifications described above, capture techniques, trigger system, number of channels, availability and type of probes, and ADC specification all impact the usability and performance of the DSO. $FTXLVLWLRQ7HFKQLTXH Single-shot acquisition is the DSO’s basic acquisition technique, which makes the instrument very suitable for the study of signal phenomena that have a low-repetition rate or are not repeated — hence single-shot. The timebase sweeps and stops at a time after receiving the trigger signal defined by the user. The captured input data signal is transferred to memory for viewing, measurement and analysis. The DSO may also employ a technique called Random Interleaved Sampling (RIS) to increase its effective sampling rate in viewing repetitive signals. LeCroy’s high-performance model has a maximum rate of 10 giga-samples per second. For slower timebases, there exists Roll Mode, where the signal being acquired can be displayed in real time while being captured in memory, scrolling as on a strip-chart recorder. Because digital scopes acquire input signals by sampling, they can miss glitches at the lower sample rates. But LeCroy’s Peak Detect System captures glitches occurring between these samples. When the system is activated, the scope samples at a very fast rate, continuously checking for glitches using a built-in algorithm. Meanwhile, it displays information in accordance with the sweep rate actually set. When a glitch is detected, the scope will display it as a thin spike on the displayed waveform. Another of the LeCroy scope’s methods for acquiring signals is Sequence Mode, which captures individually multiple trigger events

When triggering in this mode, the scope grabs a pre-programmed number of samples, resets its trigger, and awaits another event. The resulting waveform is a splicing together of all the waveforms acquired. This eliminates the information-poor deadtime that would appear between triggers if the scope triggered on the first event and then continued to run. Sequence Mode allows acquisition of closely- spaced trigger events. $QDORJ²'LJLWDO&RQYHUVLRQ High-speed DSO performance is made possible by the use of advanced ADCs whose vertical resolution will guarantee a clear representation of the signal. These ADCs measure the voltage level at evenly spaced intervals and store the digitized value in high-speed dedicated memory. The shorter the intervals, the faster the digitizing rate — and the finer the time structure able to be seen. The higher the resolution of the ADC, the better is its sensitivity to small voltage changes. And the greater its memory capacity, the longer the recording time that will be available. 1XPEHURI&KDQQHOV Your LeCroy DSO has four channels, as well as an external trigger channel and a CAL BNC output connector. The CAL BNC can be used as the source of a calibration signal, an output pulse on the occurrence of each trigger, or an output pulse signaling a Pass/Fail condition. 7ULJJHULQJ The power of a DSO in any given application depends on a combination of several features, and particularly on whether it is able to trigger on the event of interest. A trigger system far more sophisticated than that found in conventional oscilloscopes is needed for capturing rare phenomena such as glitches or spikes, logic states, missing bits, timing jitter, microprocessor crashes, network hang-ups or bus contention problems. Your LeCroy scope incorporates this more sophisticated system. Unlike manufacturers who put their ‘best’ trigger design into their more expensive scopes and a less adequate one into the lower- bandwidth, economy models, LeCroy offers all its DSO users, at every bandwidth, both a standard edge trigger and a powerful SMART Trigger for capturing elusive events.

other. Moreover, the LeCroy DSO has a variety of advanced trigger modes. The functioning of these modes is based on two important features. The first is the ability to preset the logic state of the trigger sources: channels CH 1, CH 2, CH 3, CH 4, and EXT and EXT/10. The second is a counter that can be preset and used to count a number of events between 1 and 109, or to measure time intervals from 2.5 ns–20 s in steps of 1 % of the time scale. In combination, these twin capabilities open the door to a wide variety of trigger conditions. But great care has been taken to maintain the SMART Trigger’s ‘user-friendliness’, without losing this versatility. Icons illustrate the trigger conditions on-screen for every mode. 6LJQDO9LHZLQJ  The DSO’s display system translates stored data into a graphic representation of the signal and shows it on the screen. Also displayed are internal status and measurement results, as well as operational, measurement and waveform-analysis menus. The LeCroy DSO’s large screen and a waveform grid that fills the viewing area accelerate visual processing and facilitate more effective communication of on-screen information. Other advanced display techniques give major performance improvements over conventional analog or digital scopes. A hardcopy of the screen contents can be produced at the press of a front-panel screen-dump button. Multiple waveforms can be viewed on separate grids, ensuring the best utilization of the ADCs’ dynamic range. XY and variable persistence displays are also provided, as is Enhanced Resolution Mode. A wide range of processing functions can be performed. Four traces — A, B, C and D — are available for zooming exclusively or together with waveform mathematics. The horizontal expansion can be huge, greatly improving the time resolution on the viewed trace. Several traces can be zoomed onto the same waveform for precise timing measurements.

Most DSOs can measure parameters, but analyzing their statistics can be a time-consuming chore. LeCroy’s parameter measurements and statistics allow worst-case analysis of circuit performance and make the process much faster. 3XOVH3DUDPHWHUV Cursor readouts allow use of full ADC resolution to measure a waveform’s absolute or relative times and amplitudes. However, most users measure the same waveform parameters, such as risetime, falltime, pulse width, overshoot, undershoot, peak voltage, peak-to-peak voltage, maximum, minimum, standard deviation, rms value, frequency, and period. These and many other parameters are available using your LeCroy oscilloscope. :DYHIRUP0DWK Waveform math allows the display of final answers, rather than raw data. For example, inputs from voltage and current transformers can be multiplied together to display power. An important LeCroy DSO feature is the ability to ‘daisy-chain’ math functions: a power trace can be integrated to display energy, for instance.

Once the analog signal has been converted into digital data, the data can be analyzed either by the DSO’s internal digitizer processor or by an external computer. Most current digitizers have a wide analysis spectrum built-in. Depending on the model and its options, LeCroy DSOs offer a selection of the following analytical features. 7LPH'RPDLQ The optional time domain waveform analysis package — includes zooming, summed averaging of up to one million sweeps, derivatives, logarithm, square root, absolute value, ratio, six digital filters and standard arithmetic operations. The zoom feature on high- performance models expands the waveform so that the individual data are very clearly separated. )UHTXHQF\'RPDLQ Spectrum analysis greatly extends the DSO’s processing power and offers two clear advantages over FFT (Fast Fourier Transform) analyzers: higher frequency components, and the ability to monitor both time and frequency information. Fourier transform converts sampled waveform information into a unique set of sine wave components. The data is usually plotted as amplitude vs frequency, exposing information not easily visible in the time domain (amplitude vs time). Ideally, it can be used for such analyses as measuring frequency components of communication signals and monitoring drift in an oscillator. The frequency resolution of an FFT is directly proportional to the number of time-domain points the FFT algorithm can handle. 6WDWLVWLFDO'RPDLQ The existence of measured waveforms in digital representations permits convenient use of the data inherent in those measurements. As well as analysis of signals in the frequency domain and the ability to perform mathematical operations and signal averaging on data, trends can be determined and histograms of the data analyzed. The histogram is a graph of the distribution of values of a measured parameter. For example, when measuring the risetime of a repetitive signal for which all the measurements are equal, the histogram will be a straight vertical line without breadth. However, variations in risetimes create a plot with some horizontal structure, implying variations in the measurements. Your LeCroy DSO is able not only to

characteristics. This is extremely useful when analyzing pulse amplitudes, widths or timing jitter. Other LeCroy analysis techniques include Pass/Fail testing, Mask Comparison testing, EYE-diagram analysis for telecom applications, and the specialized testing for magnetic media applications, DDM (Disk Drive Measurements) and PRML (Partial Response Maximum Likelihood). 'RFXPHQWDWLRQ Storage and recording functions are key requirements in many test applications. The LeCroy digital scopes produce excellent output, in the form of either digital data or hard-copy records. 5HPRYDEOH+'' Files saved in the TIFF format can be imported into PCs and other computers. The portable PC Card HDD (Hard Disk Drive) is a PCMCIA Type III device much faster than a floppy disk and with far greater capacity that can be popped in and out of your LeCroy DSO or computer. There is an HDD adapter on the rear panel of your scope. Note that test data can be processed far more quickly inside a DSO, and saved on the scope’s internal HDD, than by transfer via GPIB link to computer. The PC Card Memory Card drive and built-in floppy disk drive — located on the front panel of your LeCroy DSO — can also be used to store waveforms and screen shots. The built-in thermal printer is quick and convenient for producing a screen-output plot. The scope can output to a printer through its parallel port.

or RS-232 ports. As well as storage, printing and transfer to memory devices, the scope offers push-button transfer of waveforms and settings to the LW series of arbitrary waveform generators. This enables, for example, a reference waveform to be captured from a known good device and used as a test stimulus applied to other devices.

runs through them with you. You’ll get a basic idea of what the instrument can do and start working with it quickly and effectively. Following this, you’ll be ready to go on to Part 3, and to connect your own signals to the scope. For complete details on all features of your LeCroy color digital oscilloscope, see the accompanying 2SHUDWRU·V0DQXDO. C A P T U R E V I E W A N A L Y Z E

$8726(783 —acquires and displays repetitive signals in less than two seconds. $1$/2*3(56,67 — for the unique Analog Persistence feature: each persistence data map is displayed in various intensities of the trace color. )8//6&5((1 — expands the waveform and grid to fill the entire screen. 7,0(%$6(75,**(5 — includes trigger-mode, -level and -position selection, as well as TIME/DIV control. &+$11(/6 — turns the input channels on and off, and controls the OFFSET and the vertical sensitivity for input channels. The VAR button, also in this group of controls, gives variable, fully calibrated sensitivity throughout the scope’s range. 6<67(06(783 — the dark-gray menu-entry buttons that dominate this group access the main on-screen menus and the acquisition, processing, and display modes. The two knobs adjust menu values and command cursors. 0HQX%XWWRQV .QREV — seven buttons and two knobs that control on-screen menu selection. Each controls the menu to its immediate left on the screen. =2200$7+ — allows the selected trace to be moved and expanded or have a mathematical operation applied to any of the scope’s channels or other Zoom/Math functions.

source corresponds to the scope’s range — any AC power source of 90–250V, 50 or 60 Hz. (See the 2SHUDWRU·V0DQXDO for Safety details.) Use the cable provided to connect to the power source. Then turn on the scope by pushing the POWER button at the bottom left-hand corner of the front of the scope. Before a display appears, the instrument will perform hardware and software self-tests, followed by a full system calibration. The front- panel ‘standby’ LED light, located below the right-hand corner of the screen, will be illuminated during this sequence. The full testing procedure will take approximately ten seconds, after which the display will appear. before powering up.) ,QLWLDOL]DWLRQ To initialize the scope to its default settings and make your screen displays similar to those shown on the following pages: First, press on the control panel, illustrated on the facing page.

of-screen. Either “Recall” or “Save” will be highlighted. Press the top menu button to select “5HFDOO”. Now press the “FROM DEFAULT SETUP” menu button. Note: When a word or number is highlighted on- screen, front-panel controls will apply to the function, action or trace represented. Each menu button in the column of buttons running down beside the screen corresponds to the menu immediately next to it. The individual buttons illustrated three- dimensionally in this drawing are those used for the actions described here. Throughout the guide, 3-D buttons and knobs that punctuate the text represent particular controls to be used, while the group illustrations show where they are found on the front panel.

some of its basic functions. %XWILUVW:HQHHGD6LJQDO Connect a BNC cable from the CAL output at right to the Channel 1 (CH 1) BNC input at left. We can now go on to acquire and display waveforms.

button. This will automatically set the trigger-level, timebase and vertical settings needed for displaying the input signal. The screen will show a 1 kHz square wave. Both Channel 1 (the square wave) and Channel 2 (the horizontal line) are displayed. Channels’ time and volts per division are shown in the trace labels at top-left of screen. Note: Auto Setup is a particularly useful feature that facilitates the display of a wide range of repetitive signals, including those with duty cycles as small as 0.1 %.

Press the corresponding TRACE ON/OFF button, located on the CHANNELS control panel. This action removes both the trace and its label from the screen.

the timebase. The selected time/division setting is shown on the lower left-hand side of the screen. Now, to capture the signal for a shorter period, change the setting to 0.2 ms/div. But make sure to reset it to 0.5 ms/div for the remainder of these exercises.

V/div, operating in a 1–2–5 sequence. To reduce the sensitivity: Turn and set the gain to 500 mV/div. The selected volts/div setting is shown in the Channel 1 trace label. To fine-tune the vertical gain: Press the button. Turn through several complete rotations, so that the entire signal reaches from top to bottom of the grid. The volts/div setting still shows in the trace label Filling the grid in this way ensures that the signal uses the full range of digitizing levels available — 8 bits = 256 levels — for the best vertical resolution. To return the vertical gain to its 1–2–5 sequence: Press again. The knob controls the vertical position of the acquired race. Note the ground marker for Channel 1, , next to the menus. Press to see that its channel, too, has a trace label. Press again to turn off Channel 2.

the selected trace is highlighted on its respective trace label. The vertical controls — including VOLTS/DIV, OFFSET and COUPLING — will operate for this trace only. To choose another trace: Press the desired SELECT CHANNEL button, to which the controls will then apply. 75,**(5&RQWUROV The knob adjusts the trigger’s horizontal position — from 0 % to 100 % pre-trigger, and from left- to right-hand edge of the grid. This knob can also be used for setting the post trigger in seconds up to 10 000 divisions. The trigger position is shown by at the bottom of the grid. The knob adjusts the trigger’s vertical threshold. Arrows on either side of the grid, , indicate the threshold position — arrows that are only visible if the trigger source is one of the traces on the screen, and then only if that trace input is DC-coupled. The smaller knobs on the scope’s front panel are acceleration-sensitive — the faster they are rotated, the greater are the increments that result.

it can bee seen in more detail: Press Then press the corresponding to select “'XDO” from the “Grids” menu. Now two grids are shown on the screen, giving optimum viewing of the expanded trace. Note: The Zoom function is an important benefit of the scope’s acquisition memory. It can also be considered as an additional timebase providing alternative sweep speeds.

Turn to adjust the expansion factor and increase the amount of zoom. Turn to move the expanded part of the upper trace. Turn to expand vertically. Note that the expanded part of the upper trace shows the section of the original waveform being viewed by the zoom. Vertical and Horizontal settings for the zoomed waveform are shown in the “$” trace label.

s to select: “&XUVRUV”, “7LPH” and “$EVROXWH”. Use the upper ‘cursor position’ knob to move the cursor. The Absolute Time cursor appears as a cross-hair on the waveform. As the cursor moves, its time value in relation to the trigger point shows at the base of the lower grid, while indicated in the trace labels is its voltage/amplitude value. Note: Use cursors to make fast, accurate measurements and eliminate guesswork. (See the Operator’s Manual and Accurate Measuring with Cursors in Part 3 of this guide for more about cursors.)

button to change the selection from “Absolute” to “5HODWLYH”. Now two cursor menus are available, operated by the upper and lower knobs, respectively. The Relative Time cursors appear as vertical arrows on the waveform. Shown below the grid is the relative time difference between the cursors, while the trace labels show the voltage/amplitude difference.

button to select “3DUDPHWHUV”. Note: The scope’s capacities go beyond cursor measurements to calculate useful pulse parameters — automatically and with high precision. This saves time, as cursors need not be positioned manually, nor do time and voltage values need to be estimated. Appearing on-screen below the grid is a list of five different voltage parameters. Press the corresponding buttons to select from the “mode” menu “6WG9ROWDJH” and, next, “6WG7LPH”. The list of voltage parameters on-screen will be changed by these selections. The parameters are computed each time the trace is updated. Press the corresponding to select “2Q” from the “statistics” menu. You will now see the average lowest and highest values of each parameter and the standard deviation of the distribution of measurements. To return to normal operation: Press the top to select “2II”. The “statistics” menu is very useful for tracking drift or other changes in signal behavior.

Press to turn on Trace C and ZOOM on it. Now press The menus shown here will appear: Use the Summed Averaging function to improve the vertical resolution of repetitive signals, or to average out unwanted noise on a live signal.

to select “

(FFT) allows acquired waveforms to be converted into frequency-domain traces, revealing valuable spectral information that would otherwise be impossible to detect on a time-domain record. Press the corresponding to select “REDEFINE &”. And then press those s that will make the selections highlighted on the screen below. The lower trace will show the FFT transform of the square wave on Channel 1. Now, you can use the absolute horizontal cursor to make a frequency measurement... But first, press

to select “$EVROXWH” from the “type” menu. Move the cursor to the right of the upper trace until it reaches the FFT trace. Note that the readings are now labeled in Hz (horizontal) and dBm (vertical). The first frequency component at left-of-screen should be the square wave’s fundamental frequency (1 kHz). The following components (3 kHz, 5 kHz, 7 kHz...) are the harmonics that contribute to building the square wave. To return to normal operation: Press the top to select “2II”. Now press to return to normal triggering. :DYHIRUP6WRUDJH The scope has four waveform memories: M1, M2, M3 and M4. In this example, the waveform will be stored in M2. Press to turn off Trace C and FFT. Now press Then press the respective s to select “” from the “store” menu, “0” Note: Waveform memories allow the temporary saving of waveforms for later comparison or analysis — an important benefit of digital oscilloscopes.

Then press to display the stored trace. Then press the s to select “0” from the “from Memory” menu, and “DO RECALL ( – > 0)”. And press to turn off Trace A. Note: As many as four waveforms can be saved and stored until overwritten by other waves or the scope is switched off. Trace A displays the waveform saved in M2, which can then be repositioned and expanded using the ZOOM controls.

Now, as an exercise, randomly change Channel 1’s Change and the Timebase, too. Press the to select “5HFDOO”, for the original settings. Finally, press the for “FROM SETUP 1”. Note: Entire panel setups, such as those of often-performed measurements, can be saved and stored in non-volatile internal memory for later recall. Up to four setups can be stored (thousands with the optional DOS- compatible memory card, floppy or removable hard disk).

perform the most common types of measurements. As in Part 2, the tutorials take a practical, step-by-step approach to famliarizing you with the use of your LeCroy color digital oscilloscope. C A P T U R E V I E W A N A L Y Z E

$SSOLFDWLRQ6HWXS 67(3 Note: At power-up the scope remains set to the last-used setup. After the Reset in Step 1 (not to be confused with use of the RESET button, which is only for ZOOM + MATH), it reverts to its default power-up settings, with both Traces 1 and 2 activated. The traces shown depend on the previous setup and are switched on or off using the corresponding TRACE ON/OFF buttons. When CH 1 is switched off, Channel 2 alone will remain activated — as shown here. Connect the signal to be measured — for example, the calibrator (CAL) — to the Channel 2 BNC input (CH 2). Reset: press , the top and simultaneously. Then press to turn off Trace 1, and display:

well adapted to avoid reflections at input to the oscilloscope. COUPLING, like most of the vertical controls, applies only to the selected channel (highlighted on- screen). Press Then press the corresponding to select from the ‘Coupling’ menu the coupling matching the source’s impedance — 50 Ω in this case. The screen will display:

prelude to performing most of the described measurements that follow...

(ADC) offers 256 levels of quantization. Acquisition on all levels gives the best digitizing: the digitized signal covers all eight screen divisions without going off- screen (‘clipping’). Here’s how best to digitize on all eight bits. Connect the signal to be measured — a 1 MHz, 100 mV (peak-to- peak) triangle wave — to CH 2. Reset: press , the top and simultaneously. Then press to turn off Trace 1. Press , then the corresponding to select from the “Coupling” menu the coupling matching the source’s impedance — 50 Ω. Press again.

is acquired on approximately six divisions, corresponding to 5/8 = 192 levels or 7.32 bits of quantification used. 67(3 The screen will display: Use to adjust the channel input sensitivity and have the signal fill all eight divisions of the screen. And to even more finely adjust the sensitivity, press 7LSV: Changing the sensitivity using the VAR button will give a non-rounded gain — for example, 12.8 mV/DIV. Determining the amplitude of the signal by reading visually from the screen can be difficult. To avoid reading errors, use CURSORS (see Accurate Measuring with Cursors, page 3–16).

accurately measure acquired data using standard parameters. Your scope offers a selection of Voltage and Time parameters, as well as parameter customization. This tutorial shows how standard parameters are displayed to characterize pulses vertically and horizontally. Automatic parameter measurement and statistical values thus become easily obtainable. $SSOLFDWLRQ6HWXS Connect the signal to be measured — for example, the CAL signal with the shape selected as “pulse (25 ns)” — to CH 1.

and simultaneously. Then press to turn off Trace 2. Press , then the corresponding to select from the “Coupling” menu the coupling matching the source’s impedance — 50 Ω. Press again. The screen will display:

The screen will display: 67(3 Next, press

displayed beneath the grid (see previous screen): SNSN the difference between maximum and minimum data values PHDQ the average of data values VGHY the standard deviation of the data values from the mean value UPV the square root of the sum of the squares of the data values divided by the number of points DPSO the amplitude with noise and overshoot resistant estimator (amplitude = top base). 67(3 Now, press to select “6WG 7LPH” from the “mode” menu. The five main horizontal parameters of the last pulse, displayed beneath the grid (next screen): SHULRG the duration of a full cycle at 50% crossings ZLGWK of the first <50 pulses (+ or –) in the analyzed region ULVH the transition time on the rising edge for 10–90% amplitude IDOO the transition time for the falling edge from 90%– 10% amplitude GHOD\ the time from the trigger (or t=0) to the first 50% transition.

does not permit measurement of a signal period. Therefore, the period parameter is not calculated and no value is displayed. 7LSV: In order to perform the parameter calculation on a particular section of the signal, adjust the left and right cursors using the upper and lower knobs, respectively, on the SYSTEM SETUP part of the front panel.

measuring the time of the pulse’s falling edge, as indicated by “delay ()”: Note: The number of points used to calculate the parameters is shown in the “to” menu. 67(3 67(3 Use the s to reselect the entire trace as the area of interest, as described in the 7LS on the previous page. Then press the corresponding menu to select “2Q” from the “statistics” menu. Four different values are displayed for each parameter: average value; lowest value; highest value; and sigma, the standard deviation of the data values from the mean value. In order be sure of the statistics obtained, you will need to perform a number of acquisitions.

shown immediately under the grid is the number of acquisitions to which the statistics calculated and displayed apply. To restart the statistics calculation, press the CLEAR SWEEPS button. Only the future acquisitions will be included in the calculation. All these parameters are readable from a PC linked to the scope by GPIB or RS232 remote control using the “PArameter_VAlue?” query.Also possible, using Custom Mode, is the selection of five different parameters (even more with the WP03 package) relating to a variety of traces or memories between the available standard parameters. Finally, press

with your LeCroy color DSO. In Standard Display, Amplitude (Voltage) cursors are lines moved on the grid to measure the amplitude of a signal. And Time (Frequency) cursors are markers moved along the waveform that can be placed at a desired time to read the signal’s amplitude at that time. For details of cursor behavior in the different cursor and display modes, see the 2SHUDWRU·V0DQXDO. $SSOLFDWLRQ6HWXS Connect the signal to be measured — for example, the calibrator (CAL) — to CH 1. 67(3 Reset: press , the top and simultaneously. Then press to turn off Trace 2.

to select from the “Coupling” menu the coupling matching the source’s impedance — 50 Ω. Press again. Turn to adjust the timebase, to fill the screen with the signal. Press to halt the scope and display: Note: Pressing SINGLE is a smooth way of stopping the scope to allow measurement of the waveform captured on- screen.

(“$PSOLWXGH” and “$EVROXWH” will show as the default selections in the “mode” and “type” menus, respectively.) The screen will display: 67(3 Turn corresponding to the “cursor Position” menu, to move the Absolute Amplitude cursor to the top of the signal. Note: In Absolute Amplitude Mode, selected here by default, a single cursor bar in the form of a broken line is displayed (in this example shown placed at the very bottom of the grid). The vertical position of this bar on the grid can be adjusted by turning the corresponding ‘cursor’ knob. The difference in amplitude, between the cursor and the ground level indicated by the “1” at right of the grid, is shown in the trace label at top left of screen.

Note: Amplitude cursors are moved pixel by pixel up and down the grid. Here the difference in amplitude between the ground and maximum levels of the square wave has been measured and is shown in the trace label. 67(3 Press the corresponding to select “5HODWLYH” from the “type” menu. This will activate the Relative Amplitude Mode and display a pair of cursors.

Note: In Relative Amplitude Mode, two bars, the reference and difference cursors, are controlled to give readings between the two in amplitude. In this example, the reference cursor, moved by turning the upper knob corresponding to the “Reference cursor” menu, has been placed on the base level of the square wave. While the difference cursor, adjusted using the lower knob and “Difference cursor” menu, has been positioned at the top of the square wave — the difference between the two in this case giving the wave’s amplitude, indicated in the trace label. 67(3 7LSV: Press the corresponding menu button to select “Track 2Q” from the “Reference cursor” menu. Now, when the reference cursor bar is moved using the upper knob the difference bar will “track” it and the two lines will move in tandem, remaining the same distance apart. However, turning the lower, “Difference cursor” knob will change the difference cursor position and the distance between the two cursors. Pressing the same menu button as before will turn off tracking. Press the corresponding s to select “7LPH” and “$EVROXWH” from the “mode” and “type” menus, thereby activating Absolute Time Mode.

Note: Time cursors are markers moved to any point along the trace and can be used to measure time and amplitude. The reference point (t=0) is the trigger point indicated by the vertical arrow on the grid base. When the markers are placed on a data point, they change appearance (see the Operator’s Manual for a full description). The Absolute Time cursor is a cross-hair marker. Here, the cursor — highlighted to make it more visible in this example — is shown at the trigger point on the rising edge of the square wave. 67(3 Turn the corresponding to the “cursor Position” menu to change the position of the Absolute Time cursor.

The value measured between the trigger point and the Absolute Time cursor is shown as the “Time” value directly beneath the grid. The (highlighted) cursor in this example has been moved to the falling edge of the square wave. 67(3 Press the to select “5HODWLYH” from the “type” menu and activate Relative Time Mode.

the cursors are a pair of arrows that move along the waveform. In this example, the Reference and Difference cursors — upward- and downward- pointing arrows — are shown highlighted together at the rising edge of the square wave. Using the knob corresponding to its menu, either cursor can be moved independently of the other to any point on the trace. The value representing the time difference between the two will appear below the grid, while the amplitude difference appears in the trace label. The screen will display:

previous screen example, the Relative Time Reference and Difference cursors are used to measure the period and frequency of the oscillations on the square wave, with the result displayed beneath the grid. The Reference cursor has been moved to the falling edge of the square wave, while the Difference cursor has been placed at the maximum level. Displayed in the trace label when “'LII² 5HI” is selected is the gain by division and difference in amplitude between the two cursors. On the next screen the Relative Time cursors have been moved to illustrate how they work: 7LSV: To display in the trace label each cursor’s absolute amplitude relative to ground level: Press the menu button to select “'LII 5HI” from the “show” menu.

displaying the amplitude values for each cursor: Note: The absolute amplitude values of the Reference and Difference cursors are shown in the trace label respectively.

powerful Math functions. Use it to reduce non- systematic noise and improve the signal–to–noise ratio. Here’s how. $SSOLFDWLRQ6HWXS Connect the signal to be measured — a 33 kHz, 1.0 V (peak-to- peak) square wave with noise — to CH 2. 67(3 67(3 67(3 Reset: press , the top and simultaneously. Then press to turn off Trace 1. Press , then the corresponding to select from the “Coupling” menu the coupling matching the source’s impedance — 50 Ω. Press again.

67(3 67(3 Press Press the corresponding menu to select “'XDO” from the “Grids” menu.

67(3 67(3 67(3 Press Press the corresponding menu to select “REDEFINE $”. Press the corresponding menu to select “

acquired signal averaging is available on the “Avg Type” menu. The summed average gives all averaged data the same weight. While the continuous average can be set up to give data different weights —for example, the most recent acquisition could be given greater importance in the average calculation ratio defined by the user. The desired number of sweeps— acquisitions taken into account in the averaging — can also be selected using the corresponding menu button. Here: an average of 1000 acquisitions is selected from the “for” menu. Any trace can be averaged: CH 1, CH 2, CH 3 or CH 4; 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 Averaging.

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 sweep 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 final result of the average is displayed, as here.

easier to view signal changes over time. But Analog Persistence, with intensity grading, makes this even easier by signifying the most frequent signal path ‘three-dimensionally’. Here’s how to use this unique feature to reveal the AM modulation of a sinewave. $SSOLFDWLRQ6HWXS Connect 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 top and simultaneously. Then press to turn off Trace 1. Press , then the corresponding to select from the “Coupling” menu the coupling matching the source’s impedance — 50 Ω. Press again.

signal has a stable trigger. However, in the final periods the signal shows a number of jumps. Without LeCroy’s unique Analog Persistence feature, it’s not easy to characterize these modulation variations in the normal display mode. 67(3 The screen will display: Now press

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 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”.

offers the means 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 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 displayed 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.

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. 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 adjust the value of the saturation to 10 %. The screen will display:

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 menu to select “2II” from the “Last Trace (show)” menu. The screen will display:

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 shown in this example*. Press the corresponding to select “&RORU *UDGHG” from the “Using” menu. The screen now displays: * As this guide is printed in black & white only, references are to monochrome renditions of the colors evident on your screen.

strongly links displayed waveforms and their data. This color association simplifies the viewing of information — especially in analysis of related signals or signal parts. Here’s how color association handles multiple long-waveform zooms (see also Calculating on Long Waveforms). $SSOLFDWLRQ6HWXS Connect the signal to be measured — which can be a waveform of one million points or more — to CH 2.* 67(3 67(3 Reset: press , the top and simultaneously. Then press to turn off Trace 1. Press , then the corresponding to select from the “Coupling” menu the coupling matching the source’s impedance — 50 Ω. * Acquisitions of up to eight million points can be made, depending on the scope model.

to access the “TIMEBASE” menus. Shown at the top of the TIMEBASE menus on the following screen is the number of points acquired — 50 000 samples in this example. At the same time, the “Record up to” menu displays the acquired sample limit set by the user — “50k”.

so that the “Record up to” number of samples is set to at least “1M” points — for this example it is set to “2M”. Turn in order to slow down the timebase, and obtain more time per division, until the number of acquired points displayed is the same as in this example — “2M” points. Press to perform a single two-million-point acquisition and display: Note: With the long acquisition memory, the maximum sampling rate is maintained at many more timebase settings than are possible with short- memory scopes. Particular advantages include: — greater waveform detail — high zoom factor — protection against aliasing — improved time resolution — wider frequency spectrum. (See LeCroy’s Application Note ITI 008 for details).

be selected on any channel or trace. The scope allows display of four different traces in as many grids, while preserving eight-bit resolution. 67(3 The following steps directly illustrate the extreme practicality of the color association system, as different parts of an acquired signal are simultaneously expanded and viewed. Press to make appear the “DISPLAY SETUP” group of menus. Then to select “4XDG” from the “Grids” menu. The screen will display: Now, press

taken, Trace A will be displayed as the zoom (“use Math?” “1R”) of CH 2, as indicated in the “Trace $is ZOOM of” menu (“”). 67(3 Press the corresponding menu for “REDEFINE $”. Next, turn the lower menu to select “”. Then press to turn on Trace A. The screen will display: Use with and with to make the original signal selection, and select the timebase (horizontal zoom) with amplitude (vertical zoom). This allows the selection of a part of the original signal and the part’s vertical or horizontal expansion.

shown on the original trace as reinforced video. The RESET button cancels all the zoom changes and redisplays the original trace. The screen will then display a 10x zoom of CH 2 that indicates a zone of interest: 67(3 Repeat Steps 8 and 9, this time turning on Traces B and C to zoom other parts of CH 2.

67(3 Then and to display the four grids in Full Screen mode without menus.

7LSV: As shown on the next screen, each of the four grids can be shown with its own trace and parameters — up to five at once — simultaneously.

to select “More Display Setup” from “DISPLAY SETUP”. Next, press the to select one of the pre-set numbered color schemes from “Color Scheme”.

67(3 Now, press the to select “8” from “Color Scheme”. This allows the creation of a custom color palette. 7LSV Copy preset schemes to user palettes. These can then act as references and form the bases for choosing object colors in new customized color schemes.

67(3 Now, press the for “CHANGE COLORS”, and then for “COPY SCHEME 1 to U1”. The colors assigned to the objects in “U1” will now be the same as those of the pre-set “1”.

to select an object for color change. Here, Trace B is selected. And then a to select the color of the object selected. “Grass Green” has been selected to replace “Pale Blue” in the following example.

Manual for a description of the displayed objects whose colors can be modified. The screen will display: And in the final screen on the next page, “Text & Menu” has been selected and colored “Yellow”.

complete-waveform segments without unwanted deadtime (see Appendix A in the 2SHUDWRU·V 0DQXDO for the limits). The long intervals of deadtime that often separate consecutive single-shot events are minimized in sequence mode. Complicated event sequences covering large time intervals are captured in fine detail — without the uninteresting periods between. $SSOLFDWLRQ6HWXS Connect the signal — a pulse train (each group of 12 pulses separated by a long signal that need not be acquired) — to CH 2.

and simultaneously. Then press to turn off Trace 1, and display: Press , then the corresponding to select from the “Coupling” menu the coupling matching the source’s impedance — 50 Ω. Press again. Turn to adjust the timebase, and to adjust the gain and fill the screen with the signal. This schema represents how Sequence Mode handles sequence acquisition. The display is activated pressing SHOW STATUS and selecting “Text & Times” from the menu that appears.

one of 12 train pulses. 67(3 67(3 The screen will display: Again turn to adjust the timebase, this time to display all of the train’s pulses. Now press

Note: The “TIMEBASE” information shown at top- right-of-screen, consists of, in this example: Timebase value — 2 ms/div; 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.

Note: As shown at top-right- of-screen, the sampling rate has decreased as the total window time acquisition has increased. Between two trains, a long ground-level signal of no interest has been acquired. Sequence Mode, activated at the next step, is the best way of acquiring the zone of interest only. 67(3 Press Then press the corresponding menu to select “2Q” from the “Sequence” menu. Next, turn the lower ‘menu’ to display “VHJPHQWV” in the “Sequence” menu. Press

Note: The number of trains acquired is now four, with the same sampling rate as for two. The sole difference is that now the duration between two train pulses is half what it was. In the trace label, at left- of-screen, the symbol “2x” indicates two segments acquired in Sequence Mode. The TIMEBASE information shows that two segments of 50 000 points each (“2 F 50 000”) have been acquired. 7LSV: The bottom menu shows the maximum number of points per segment — in this instance, 50 000. The sampling rate or the total number of acquired points can be adjusted. The timebase setting in Sequence Mode is used for determining the acquisition duration of each segment — 10 x TIME/DIV. This setting, as well as the number of segments desired, the maximum segment length, and the total memory available, are used for arriving at the actual number of samples per segment, and the time per point.

selected (corresponding to a single train duration, as already covered at Step 5). The sampling rate is the maximum, and the two trains are captured with a very short delay between triggers. The acquisition is in fact two acquisitions, each a train of pulses. 67(3 Turn the lower ‘menu’ to set the number of segments. On the example screen overleaf, the number of segments is set at eight.