This paper focuses on the stochastic Cramer-Rao bound (CRB) for the direction of arrival (DOA) for binary phase-shift keying (BPSK) and quaternary phase-shift keying (QPSK) modulated signals observed on the background of nonuniform white noise with an arbitrary diagonal covariance matrix. Explicit expressions of the CRB for the DOA parameter alone in the case of a single signal waveform is given thanks to the decoupling of the power and phase parameters in the Fisher information matrices (FIM) and compared with CRBs obtained with different a priori knowledge. Then, these results and comparisons are extended to the case of two independent sources where an explicit expression of the CRB of the DOA parameters alone is given for large SNR.