The Acquisition folder allows parameters of the transient acquisition process to be defined. The left-hand side labels (“Time of”) show: the time taken to sample one point of the transient (reciprocal to the Sampling Rate), the duration of the whole transient (“1 scan”), i.e. (1 sample) x (No of samples), in seconds, and the duration of the whole measurement (“all scans”), i.e. (1 sample) x (No of samples) x (No of scans). The highest Sampling Rate depends on the hardware (Acquisition board) and is defined in the Lap_sys.ini file. If a file (data or configuration) is read which attempts to set the sampling rate higher than the allowable sampling rate specified for the hardware configuration the three labels associated with sampling durations are shown in red. It is possible to manipulate the transients, however, measurements are disabled. In such a case it is necessary to reduce the sampling rate before measurements can be done.
The time of “all scans” is doubled when the pulse 2 is used and the time needed for the hardware reprogramming (depending on the interlacing of pulses) is in this value included. It means that more the pulses are interlaced a true measurement time becomes longer.
The gain (not variable in some configurations) defines a span of voltages to be measured by the acquisition card. Any change in the gain is reflected on the Vertical bar of the Main Graph. The range of capacitances shown on this bar is calculated by the software using the sensitivity of the signal source meter (capacitance meter for DLTS), and the full-scale output voltage, the acquisition full-scale input voltage and gain. When the UMIST card is used the gain is permanently set to 1. All parameters of the Acquisition are stored in the configuration file.