Description: This item provides measurements of the upstream receive modulation error ratio (RxMER) for each subcarrier. The CMTS measures the RxMER using an upstream probe, which is not subject to symbol errors as data subcarriers would be. The probes used for RxMER measurement are typically distinct from the probes used for pre-equalization adjustment. For the purposes of this measurement, RxMER is defined as the ratio of the average power of the ideal QAM constellation to the average error-vector power. The error vector is the difference between the equalized received probe value and the known correct probe value. If some subcarriers (such as exclusion bands) cannot be measured by the CMTS, the CMTS indicates that condition in the measurement data for those subcarriers.