TriggerScan uses high-speed hardware triggering capability to capture only the signals of interest and provide answers up to 100X faster than other methods. Traditional fast display update modes work best on frequent events occurring on slow edge rates while TriggerScan excels in finding infrequent events on fast edge rates.
Since hardware triggering is used to capture only the elusive events, TriggerScan is more effective at finding anomalies quickly compared to simple display technologies.
A built-in automated Trigger Trainer analyzes the waveforms, identifies normal behavior, and then sets up a large set of rare event smart trigger setups that target abnormal behavior. The trainer ‘learns’ trigger setups to identify faulty operation based on slew rates, periods, amplitudes outside of a range and then applies them sequentially. It then rapidly sequences through each individual trigger with a user-defined dwell time, and captures and displays any anomalous signals that meet the trigger conditions.
A LeCroy Xi or Zi series oscilloscope.
1 passive Probe
WaveSource 100 demonstration signal source
The WS 100 Demonstration Signal Source
The WS 100 signal source is a USB powered circuit board which has 6 sets of output waveforms. There are two sets of duplicate output connections on the WS 100 which are marked Ch1, Ch2, and Trig. Table 1 summarizes all the available outputs. In this tutorial we will use selection S6 (SIG) and the Ch2 output.
Displays shown in the tutorial are based on the following initial setup on a WaveRunner 6 Zi scope:
- Recall the default setup: File pull down > Recall Setup> Recall Default.
- Turn off channel 2 by pressing the 2 button in the Vertical control group on the front panel twice.
- Verify that the input coupling on channel 1 is DC 1 MΩ: Touch or click the channel 1 annotation box>touch or click on the coupling field >select DC 1MΩ.
- Using the C1 dialog box of the front panel vertical scale control, set the channel 1 vertical scale to 500 mV/division and the vertical offset to -1.5V.
- Touch or click the Trigger annotation box on the display of the oscilloscope. Set up the trigger as follows: Edge-Trigger, Source :C1, Coupling : DC, Slope: Positive, Trigger Level: 1.5 V
- Press the Normal button in the Trigger area on the oscilloscope’s front panel.
- Connect the WS 100 to a front panel USB connector. If the Found New Hardware Wizard appears press the cancel button. Select S6 (SIG) of the WaveSource100 using the small pushbutton switch on the circuit board.
- Connect one passive probe to Channel 1 of the scope and the probe tip to Ch2 of the WS 100. Ch2 is the SIG2 signal which contains a glitch and a non-monotonic edge anomaly. Connect the probes ground clip to the ground pad shown in Figure 1.
- Touch or click the Timebase annotation box on the display of the oscilloscope. Set Time/Division: 500 μs, Select Set Maximum Memory and set Maximum Sample Points to 2.5MS.
- This completes the initial setup. The scope display should be similar to Figure 2.
Touch or click the trigger annotation box or press the Setup button in the front panel Trigger area. This will cause the Trigger dialog box to be displayed. Select the TriggerScan tab. On the TriggerScan tab press the Delete All button. The display should look like Figure 3.
TriggerScan finds anomalous trigger events by statistically measuring the key parameters of the signal being analyzed including period (interval), width, and amplitude. It then automatically sets up a number of exclusion triggers which will trigger on events which are not ‘nominal’ for the signal in question. Press the Trainer button on the TriggerScan tab. This will bring up the TriggerScan Trainer setup shown in Figure 4.
The Trainer setup allows the user to select the trigger source as well as the criteria used for creating the exclusion triggers. The default setup is to use all criteria including Edges, Widths, Runts, Interval (Period), and Glitches.
Press the Start Training button. The scope will make several quick acquisitions and then populate the Trigger List with the suggested trigger setups. An example is shown in Figure 5. Users can edit this list by manually setting up the desired trigger and then pressing the Add New button. Alternatively, they can select any entry and delete it by pressing the Delete Selected button. Provision is also made for deleting all the entries on the list using the Delete All button. The Load Selected button transfers the selected entry into the oscilloscope’s trigger setup; while Update Selected will copy the current trigger setup into the selected entry.
The TriggerScan Setups area on the right hand side of the TriggerScan tab is used to save the TriggerScan setup. The user can select a folder and filename into which the TriggerScan setup will be stored. Pressing the Load button will recall the setup from the selected file.
The Control section of the dialog box is used to initiate the actual scan. This is done by pressing the Start Scan button. Note that the user can select a dwell time from 100 ms to 100s. This allows each TriggerScan entry to acquire data for that length of time. Checking the Stop On Trigger checkbox stops TriggerScan when it successfully triggers the scope on one of the entries. This allows the user to evaluate the effectiveness of that setting and edit it if so desired. The Stop Scan button can be used to manually stop the scan process.
Press the Start Scan button. The scope will begin stepping through the TriggerScan entries in the Trigger List. After about 10 seconds you should see one of the pulse anomalies. After about 30 seconds you should have seen both.
Check the Stop on Trigger checkbox. The scope will stop on after the next successful acquisition.
Turn on zoom by pressing the Zoom button on the front panel of the scope. You should see the runt or the nonmonotonic edge as shown in Figures 6 or 7.
Open the Trigger tab on the Trigger dialog box. The trigger is currently setup using the highlighted selection from the trigger list. In my example it is for the Glitch Trigger highlighted in Figure 7.
The trigger tab is shown in Figure 8. The trigger type is glitch with a trigger threshold of 1.535V, positive polarity with a width less than 245 μs. As can be seen in Figure 8 by looking at the trigger location, the scope triggered on the half amplitude step whose width is less than 245 μs. If desired, you could edit this setup and import it back into the TriggerList on the TraggerScan tab by pressing the Update Selected button.
This completes this tutorial.