A test laboratory view of EMC measurement uncertainties

The calculation and presentation of measurement uncertainties are a mandatory requirement for all UKAS accredited test laboratories. However, if a meaningful measurement is to be made then the uncertainty of the measurement process with a specified confidence level must be provided. There are a number of good sources of help available to a test laboratory to assist in the production of uncertainty budgets. However there is still a significant investment required in both manpower and time to ensure meaningful uncertainties are produced and maintained. The advent of prEN50222 has ensured that, whilst the requirement for the test laboratory to produce uncertainty budget is still essential, the measurement uncertainties inherent in an EMC test no longer place an undue design burden on the customer. The calculation of uncertainties clearly has advantages for both the customer and the test laboratory. Measurement uncertainty calculations provide valuable training for test engineers and allow a laboratory to demonstrate its commitment to quality and excellence. The customer has the assurance of measurement uncertainties in a test report with which an informed technical decision can be made, but does not have to over engineer his product to ensure it passes despite the laboratory´s measurement uncertainties