PicoScope 6 sampling rate adjustment

When changing the timebase in the PicoScope 6 software, you may wonder why the sampling rate shown in the Properties view also changes. This application note aims to demonstrate why.

A PicoScope 5444D was used to create the screenshots below, with the signal generator output (5 Hz sine wave) connected to Channel A, but this note applies to all oscilloscope and data logger products supported by the software.

Timebase at 200 ms/div

This figure shows a waveform trace captured in slow sampling mode. The timebase is set to 200 ms/div (two seconds collection time across the screen), with 1 MS requested from the device.

Timebase at 100 ms/div

Note the change in sample interval when the timebase is changed to 100 ms/div (the switch out of slow sampling mode capture is due to PicoScope 6 settings). The collection time has changed but the number of samples is fixed.

Timebase at 50 ms/div

When the timebase is changed again to 50 ms/div, we are still requesting 1 MS from the device but the collection time is now 500 ms. The software finds the smallest possible sample interval and collects a number of samples based on that sample interval and the collection time selected.

To summarize, the sample rate is set according to the collection time and the maximum number of samples that the device can collect, based on the number of samples requested.