Threshold is the amount of measurement change required before a measuring instrument reacts with a change in measurement output or produces a specified result.
Resolution
Bit to Measurement Resolution Converter
This bit to resolution converter will calculate the reading resolution of a DAC or ADC and answer in steps, %FS, ppm and decimal ratio.
Vacuum gauge for minus 150 mbar range with a 0.1 mbar display resolution
We are looking to measure have to measure vacuum from zero to -150mbar to a resolution of 0.1 milibar
Pressure Calibration
This guide will answer many of your questions about using & selecting pressure calibration equipment.