Baseline length is a significant factor in direction finding.The longer the baseline is

the higher the accuracy is.When baseline length is more than half-wavelength

phase difference between two arrays will be ambiguity.Most existing unwrapping phase ambiguity algorithms limit baseline length.Combined with time of arrival (TOA) estimation

a kind of long baseline unwrapping phase ambiguity algorithm is presented to realize direction finding of narrowband signal

which reduces the restrictive conditions of baseline length.The simulation results show that the probability of unwrapping phase ambiguity is insensitive to baseline length and incident angle.High accuracy can be achieved in direction finding by setting baseline length under the appropriate signal to noise ratio (SNR).