GoldExI : FAQ : Measure V(I

Question

How V(I_wfm) works? How to measure the response of the system to the digital input sequence(s)?

Answer

Imagine you have a system (black box) with N inputs and M outputs. Using GoldExI you can measure the system response on various input sequences. In GoldExI you can program and use simultaneously up to 16 sequences (waveforms). Read here how to program waveforms. After programming waveforms, you have to associate the virtual currents with them. Do this in Options | Virtual currents or directly from measurement window. For example, if you have put the desired sequence into waveform 7, you may then set the type of current 1 equal to "waveform 7", etc... Your may associate more than one current with various waveforms. When you go to Measurements | V(I_wfm) and push "DoIt", GoldExI finds all currents associated with waveforms and sets them so that they follow the programmed waveform vs. time. While the currents are set so that they follow corresponding waveforms, GoldExI measures all voltages defined as "positive" or "negative" and plots them vs. time.

You can control different aspects of the measurement via Options | Measurements | V(I_wfm) or directly pushing "Options" button in V(I_wfm) measurement window. The following options are available:

Number of samples per LU -- how many samples per logical unit (LU) GoldExI will set and measure. One LU corresponds to one character in the waveform sequence (for not stretched waveform), e.g. waveform defined as "0010" consists of 4 LUs.
Interval between samples -- The time interval between the samples, more precisely between consecutive settings of the currents. In milliseconds.
The group x-axis gives the possibility to choose what exactly to show along x-axis. The choices are:
- time -- show real (physical) time in seconds
- ticks -- show the tick (i.e. sample) number
- LUs -- shows in terms of LUs
Shift consequent voltages by -- When you have more than one active voltage the resulting curves may overlap and obscure the view. You can automatically shift them by a given amount (of volts). The shift is calculated as CurveNumber*GivenAmount.

The total number of samples (ticks) measured is equal to the Number of samples per LU * Number of LUs in the longest waveform.

When using stretched waveforms the number of LUs is not equal to the number of characters in the waveform description e.g. the waveform "0010" with stretching factor 2 is 8 LUs long. The stretching factor can be set in the same window where you program the waveform i.e. in Tools | Program waveforms | ....

When using several waveforms in the same time it may happen that their lengths do not coincide. GoldExI will always use the longest waveform to calculate the number of LUs to measure. The shorter waveforms will be either prolonged using the value of logical "0" or repeated periodically. The prolongation method can be specified in the same window where you program the waveform.