The ERS is a comb generator that radiates RF continuously every 2MHz over the range 30MHz – 1000MHz. Each 2MHz peak is precisely measured during the calibration process with the ERS orientated both vertically and horizontally. These measurements are correlated against a 3m OATS such that any fully implemented CISPR16 site, measuring at 3m and using height scanning, will read the same. In practice, informal sites and test chambers will produce significant differences due to the presence of reflections and/or lack of height scanning. The ERS allows these differences to be quantified and EUT measurements can then be corrected.
This technique substantially improves the measurement accuracy of radiated emissions on all but the best test sites.
The ERS helps to eliminate the main cause of uncertainty (error) when measuring radiated emissions. These errors are entirely due to the reflections from any nearby metallic objects or surfaces. Also, the ground reflection is a source of error if not using a metallic ground plane and height scanning. Generally, these reflections will account for errors up to 20dB, far too much for compliance measurements.
By replacing the EUT with the ERS, performing a scan and comparing the results with the calibration data, the errors can be quantified and the results from the EUT adjusted accordingly. This technique genarally reduces errors to around 6dB, comparable with test laboratory results.