A system and method is designed to measure its own environmentally caused inaccuracies and, based upon these measurements, adjust itself to compensate for the inaccuracies. In one embodiment, a test system first measures the signal loss through a model “long” path constructed in the same substrate as is the main test circuit. Since the test path is constructed on the same substrate it then represents the actual environmental impact on the test circuit. The test signal is then sent through a “short” test path and the ratio difference from a reference measurement condition between the two paths yields the necessary compensation which is then used to calibrate the test circuit. In another embodiment, a test signal is applied across a capacitance made up of copper on different layers of substrate material. The actual environmental conditions on the substrate layers modify the measured capacitance value, which is then provided along with temperature as input to a model which determines compensation for the test circuit. Both embodiments can be applied to individual circuits or to systems that are subject to environmentally induced changes to their transmission line loss characteristics.