A: InstaCal is an electronic calibration module built into the S331L. It can be used instead of the external OSL components to perform user calibrations. To perform a calibration with the InstaCal module, a user simply needs to connect the test port cable from the RF Out/Reflection In connector port to the InstaCal/Power Meter connector port. Select InstaCal in the calibration menu, press Measure, and the Site Master will automatically calibrate.