In one or more embodiments, a receiver circuit generates impairment correlation estimates for a desired signal that are compensated for the use of different transmission scrambling codes in transmitting the desired signal and an associated pilot signal. In one embodiment, an impairment correlation estimation method comprises determining impairment correlation estimates from a pilot signal in a received CDMA signal, adapting the impairment correlation estimates for scrambling code effects if the desired signal and pilot signal are transmitted under different transmission scrambling codes, and performing one or more signal processing operations with respect to the desired signal based on the impairment correlation estimates. For example, in at least one embodiment, the receiver circuit is configured to compensate elements of an impairment correlation matrix that correspond to signal delays of the desired signal based on transmit power allocation differences between pilot and desired signal scrambling codes.