A diversity receiver that receives modulated signals may determine signal usability of the received signals in the following manner. A modulated signal that includes a desired component and an undesired component is received in each receiver branch of the diversity receiver, wherein the desired component includes an originally transmitted signal and the undesired component includes noise and interference. Each receiver branch estimates the desired and undesired components and processes the modulated signal with a channel gain/phase estimator, a complex conjugator, and a complex mixer to produce a complex output. The complex output of each receiver branch is derived independently of the undesired component and combined to produce a diversity resultant. The diversity receiver estimates the signal usability of the diversity resultant based on the estimated desired components and the estimated undesired components.