The VSM Oscilloscope is supplied as standard with all versions of ProSPICE and models a basic four beam unit and is specified as follows:
- Four-channel or X-Y operation.
- Channel gain from 20V/div to 2mV/div with 2.5x accurate set-up.
- Time base from 200ms/div to 0.5us/div with 2.5x accurate set-up.
- Automatic voltage level triggering locked to either channel.
- AC or DC coupled inputs.
- A+B and C+D channel modes.
- Invert button for each channel.
- Mouse zoom in and out.
- Cursors measurement.
- One-shot mode with zoom in and out the possibility.
- Printing.
- Color change for each channel.
Using the Oscilloscope
To display analog waveforms
- Pick the OSCILLOSCOPE object by selecting the Meter icon in ISIS and then selecting the Oscilloscope from the Object Selector.
- Place one on the schematic and wire its inputs to the signals you want to record.
- Start an interactive simulation by pressing the play button on the Animation Control Panel. The oscilloscope window should appear.
- Set the time base dial-in the Horizontal section to a suitable value for the circuit. You will need to think about the waveform frequencies present in your circuit and convert these to cycle times by taking their reciprocal.
- If displaying signals with a DC offset, select AC mode on either or every input channel as appropriate. You can also turn off unused channels by choosing OFF mode.
- Adjust the voltage and position dials in Channel A...Channel D sections so that the waveforms are of a suitable size and position. If a waveform consists of a small AC signal on top of a large DC voltage you may need to connect a capacitor between the test point and the oscilloscope, as the position controls can compensate for only a certain amount of DC.
- Decide which channel you want to trigger off, using the Source slider from the Trigger section.
- Choose the required part of the waveform by using the slider from the Trigger section It will lock to rising slopes if the slider points up, and falling slopes if it points down.
Modes of Operation
The oscilloscope can operate in the following modes:
- Auto - the Auto button LED is lit in this mode.
- One-Shot - the Auto button LED is off. In this mode, the One-Shot LED will be lit if capturing is in progress and off after the finishing capture.
- X-Y mode - the Source slider from the Horizontal section positioned in the selected X channel.
Triggering
The VSM oscilloscope provides an automatic triggering mechanism that enables it to synchronize the time base to the incoming waveform.
- The Source slider in the Trigger section can select which input channel is used for triggering.
- The AC/DC slider is used for the selection of absolute or channel-linked trigger offset.
- The Level dial is used for trigger offset value setup.
- The Edge selection slider is used for choosing the rising or falling edge of the waveform.
Input Coupling
Each input channel can either be directly coupled (DC coupling) or coupled through a simulated capacitance (AC coupling). The latter mode is useful for displaying signals that carry a small AC signal on top of a much larger DC bias voltage.
The inputs may also be temporarily grounded by selecting the GND slider position that can be useful when aligning them to the graticule prior to taking measurements. Inputs may be switched off by moving the slider into the OFF position. Two inputs can be summed by using A+B or C+D buttons. Using the Invert button each channel may be inverted.
Taking Measurements
Measuring voltage, a difference of voltages, time difference between trigger point and current of between any two points can be performed by using the cursors. To use this feature select the Cursors button. To set the absolute cursor into the screen just move the mouse to the appropriate position and press the left mouse button. To set a different cursor, move the mouse while the left button is depressed. Cursors can be moved by mouse (while the mouse is over any lines of the cursor) as well as deleted using the context menu – items “Delete Cursor” or “Clear All Cursors”.
Deleting a Cursor from the Oscilloscope
Printing
The current waveform displayed on the screen can be printed using the context menu item “Print…”.
Colors
The colors of each channel can be changed in the “Colours Setup” dialog which can be opened by choosing the context menu item “Colours Setup…”.
You can also change the Colours by right-clicking on the Oscilloscope and selecting Setup
