A method in a diversity receiver for calculating an estimate of a differential phase between a first local oscillator of a first antenna and a second local oscillator of a second antenna in the presence of at least one interference signal (26, 28, 30), the method comprising: receiving a primary communication signal, the primary communication signal being down-converted by the first local oscillator, and filtered by a first adaptive filter, resulting in a filtered primary communication signal; receiving a primary reference signal, the primary reference signal being down-converted by the second local oscillator and filtered by a second adaptive filter, resulting in a filtered primary reference signal; receiving an additional reference signal (38A, 40A), the additional reference signal-being down-converted by an additional local oscillator (37, 39) and filtered by an additional adaptive filter (45, 47), resulting in a filtered additional reference signal (38B, 40B); processing the filtered primary communication signal, the filtered primary reference signal and the filtered additional reference signal (38B, 40B), resulting in a first intermediate signal and a second intermediate signal such that a summation of the first intermediate signal and the second intermediate signal will not comprise or will not substantially comprise the at least one interference signal (12a, 14a, 16a, 26, 28, 30) when the first local oscillator and the second local oscillator are phase aligned; estimating, when a predetermined signal is available, the differential phase between the first local oscillator and the second local oscillator by calculating the differential phase so that a summation of the first intermediate signal and the second intermediate signal with a relative phase shift of the differential phase, equals or is approximately equal to the predetermined signal. receiving a primary communication signal, the primary communication signal being down-converted by the first local oscillator, and filtered by a first adaptive filter, resulting in a filtered primary communication signal; receiving a primary reference signal, the primary reference signal being down-converted by the second local oscillator and filtered by a second adaptive filter, resulting in a filtered primary reference signal; receiving an additional reference signal (38A, 40A), the additional reference signal-being down-converted by an additional local oscillator (37, 39) and filtered by an additional adaptive filter (45, 47), resulting in a filtered additional reference signal (38B, 40B); processing the filtered primary communication signal, the filtered primary reference signal and the filtered additional reference signal (38B, 40B), resulting in a first intermediate signal and a second intermediate signal such that a summation of the first intermediate signal and the second intermediate signal will not comprise or will not substantially comprise the at least one interference signal (12a, 14a, 16a, 26, 28, 30) when the first local oscillator and the second local oscillator are phase aligned; estimating, when a predetermined signal is available, the differential phase between the first local oscillator and the second local oscillator by calculating the differential phase so that a summation of the first intermediate signal and the second intermediate signal with a relative phase shift of the differential phase, equals or is approximately equal to the predetermined signal.