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LeCroywaveAce 112 Digital Storage Oscilloscope This two-channel, 100MHz Digital Storage Oscilloscope takes up to 500 million samples per second, has comprehensive USB connectivity and a wide range of features in a stylish, compact package L eCroy are best known for their high-end test equipment. With this series of oscilloscopes they now cater for the entry level Digital Storage Oscilloscope (DSO) market. The size and layout of this unit is similar to other entry-level DSOs. One obvious difference is the styling, which makes a nice change from the 40  Silicon Chip typical beige and grey boxes. The scope comes with two 1-metre 1x/10x 100MHz probes and accessories, a USB cable, a power cable, a software CD and the Getting Started Manual. The probe accessories included are a Review by Nicholas Vinen ground spring (which can replace the alligator clip lead for high frequency applications), extra colour coding rings, a compensation adjustment tool and several additional probe tips including some that suit DIP IC pins. These prevent accidental shorting to adjacent pins when taking measurements. There is also a BNC adaptor siliconchip.com.au The “Alternative” trigger mode is one of the best features of the WaveAce 112. Here we are viewing sine two waves with unrelated frequencies using different time bases and they are separately synchronised. which allows the probes to be plugged directly into BNC sockets. On the rear panel is a pass/fail output, a serial port and a USB socket for connecting the oscilloscope to a computer or printer. On the front panel, in addition to the screen and controls, is a second USB port for flash memory drives, two BNC connectors for the signal inputs, the external trigger BNC input and a calibration output. User interface The display is the now-typical full colour quarter-VGA 5.7” LCD. It is better than average. with excellent contrast and a fast update rate. Most of the screen area is dedicated to waveform display, which is partially occluded by a menu when accessing extended functions. Each menu item corresponds to one of five adjacent “soft” buttons. A single button press dismisses this menu at all times. LeCroy haven’t skimped on the controls either – there are separate vertical adjustment knobs for each channel. Some entry-level DSOs have a common set of knobs with buttons to select which channel is being adjusted. That saves money and reduces clutter but making adjustments becomes significantly more awkward as you can’t always remember which channel is currently selected. Impressively, all of the knobs double as buttons. Pressing a vertical offset knob resets the channel offset to 0V, while pressing the vertical scale button toggles vernier (fine) adjustment for that channel. siliconchip.com.au This demonstrates the tracking cursors mode. The two cursors have been moved to the same point on both traces and the corresponding times, voltages, and deltas can be read off the measurement panel. Pressing the horizontal scale knob toggles the window (zoom) mode and pressing the horizontal offset knob sets the trigger offset to 0s. Similarly, pressing the trigger level knob sets the trigger level to 0V. Input circuitry An important aspect for any DSO is the quality of the analog input circuitry and the analog-to-digital converter (ADC). The WaveAce 112 has an 8-bit, 500MHz ADC (250MHz if both channels are active) with very good noise performance. Captured waveforms are clean, with a minimal amount of vertical “fuzz”. The noise performance is equal to or better than, most entry-level DSOs. Input sensitivity ranges from 2mV/ div to 5V/div with 1x probes. The ability to go down to 2mV/div is very useful for measuring low amplitude signals. Without any probe attenuation bandwidth is limited to 6MHz, so high frequency measurements are made with 10x attenuation, resulting in a sensitivity of 20mV/div to 50V/div. Features There are many buttons on the front panel which provide the extended functions. The table overleaf shows the major functions accessible from each of these buttons. Some features of this unit stand out. The tracking cursors are not really novel but they are particularly well implemented. The “print” button allows screen captures to be saved easily at any time, with or without the menu bar. This is important for showing measurements, since the primary measurement mode shows the values within the menu bar itself. Each channel has a configurable digital filter which can be set to low-pass, high-pass, band-pass or band-reject. In each case the corner frequency is adjustable through a range which depends on the current time base. This is very handy for making certain types of measurements, eg, audio frequency measurements with high frequency noise removed. Unfortunately, as soon as the run control is stopped the filter is automatically disabled, so it can only be used when viewing “live” data. The trigger settings are comprehensive and the Alternate (they call it Alternative) trigger mode is outstanding. In this mode, each channel is not only separately triggered but also displayed separately in a split screen. What’s more, the time base, trigger type (Edge, Pulse, Video or Slope) and other trigger settings can be adjusted independently. It’s like having two complete single channel scopes in one package. When the WaveAce 112 is plugged into a Windows computer via USB, all functions of the oscilloscope can be controlled and data can be captured directly. Support for Windows 7 64-bit edition should be available soon from LeCroy. Automatic adjustments The “auto” adjustment button works June 2010  41 This pattern arises when sine waves with related frequencies are input on both channels and they are plotted in XY mode. In this mode the display shows dots only but in XT mode, dots or vectors (ie, lines) may be used. very well. It adjusts the vertical, horizontal and trigger system to suit the detected signals and at the same time automatically displays several perti- After pressing the “auto” button with an S/PDIF signal connected to channel one we selected the rising edge mode. The waveform rising edge detail is shown along with the rise time and peak-to-peak voltage. nent measurements at the bottom of the screen – the peak-to-peak voltage, average voltage, period and frequency. You can then switch to one of three additional views which show more measurements via an additional button press. If you want to check the rise or fall time of a digital signal, pressing Button name Major function description CH1, CH2 Input coupling (AC/DC), bandwidth limit, invert signal, digital filtering CURSORS Manual: provides fixed cursors that can be moved across the display Auto: cursors show the measurements currently being read out Track: cursors can be moved horizontally and voltages read off each waveform ACQUIRE Sampling: one reading displayed for each time base increment Peak detect: minimum and maximum values are shown for each time base increment Average: 4/8/16/32/64/128/256 waveforms are time averaged for noise reduction SAVE/RECALL Configurations, screen captures and waveform data (as binary or CSV – comma separated values) can be loaded or saved from/to internal or external (USB flash drive) memory. PRINT Can be configured to immediately save a screen capture to memory or to print the screen to a USB printer plugged in to the rear panel port MEASURE Up to five measurements can be made at one time and are displayed within the menu sidebar. 32 different measurements are available. Alternatively, all measurements from one or more category (voltage, time, period) can be displayed at the bottom of the screen. DISPLAY XT mode: normal display mode with time on the X axis and voltage on the Y axis XY mode: channel 1 voltage on the X axis, channel 2 voltage on the Y axis Display persistence: off, 1 second, 2 seconds, 5 seconds or infinite Graticule: full grid, axes only or off Trace intensity and brightness: 0-100% UTILITY Allows adjustment of button press beeps, on-screen frequency display, system language, calibration, firmware updates, pass/fail testing, waveform recording, screen blanking, serial port baud rate, etc. MATH Operators: add, subtract, multiply, divide, FFT (Fast Fourier Transform) FFT options: window type, zoom, scale, full/split screen The result is displayed as a third, green trace REF Allows one or two reference waveforms to be captured from an input and displayed on screen (in red and mauve) for comparison to measured waveforms. TRIG Mode: Edge, Pulse, Video, Slope, Alternative Common settings: Source (CH1/CH2), Mode (Auto, Normal or Single), coupling (AC/DC), holdoff time Edge settings: Slope (positive, negative, both) Pulse settings: When (positive/negative, less than/greater than/equal to), width Video settings: Polarity, Sync (All lines, line num, odd field, even field), NTSC/PAL Slope settings: When (positive/negative, less than/greater than/equal to), time, polarity Alternative settings: see text 42  Silicon Chip siliconchip.com.au Fast rise and fall times are not a problem for this oscilloscope. Here we have fed in a 3.072MHz S/PDIF stream and the edges are not rounded. The overlaid traces are dued to the biphase encoding. the corresponding button zooms in to the leading or trailing edge of the waveform and the rise/fall time and peak-to-peak voltage are shown. The third additional button zooms in to examine one wave cycle with readings for the minimum, average and maximum voltage as well as the pulse width. Conclusion These are all great features and overall, the WaveAce 112 gives an impression of a very well though-out user interface. This makes the few awkward aspects all the more baffling. The unit can clearly display readings at the bottom of the screen (see top right of previous page). So why can indi- siliconchip.com.au This image shows how up to five individual measurements are displayed in the menu bar at the right edge of the display. The frequency can also optionally be displayed below the traces. vidual user-selected measurements only be shown in the menu (see top right above). This issue could be fixed with a future firmware patch. So could the unnecessarily large number of button presses required each time a screen capture is saved (with the addition of an automatic sequential file naming feature). And while it is a minor quibble, it would be nice to have a split-screen zoom display in the window mode, which some competing models provide. If LeCroy could update the firmware to sort out those three issues, the WaveAce 112 would be just about the perfect entry-level DSO. The combination of features and performance means it is good value, even though it costs a little more than some competing models. For those with smaller budgets, the 60MHz and 40MHz models provide the same features for much less money. Pricing & availability Currently, the WaveAce 112 (100MHz) is available from Vicom (www.vicom. com.au) for $1850+GST, with a 3-year warranty. The WaveAce 102 (60MHz) is $1470+GST and the WaveAce 101 (40MHz) is $1040+GST. Vicom hope soon to offer online sales for these units at lower prices (to be determined). For further details, contact Vicom (mzahra<at>vicom.com.au) or call (03) 9563 7844. Quote SCM1006 for a SILISC CON CHIP reader discount. June 2010  43