The invention relates to systems and methods for obtaining phase information and/or localization of tag devices. In particular, the invention relates to a system for the localization of at least one tag device, the system including: the at least one tag device configured to transmit a tag signal which is a frequency-hopping signal; at least one known position device configured to transmit a reference signal; and a localization device configured to localize the at least one tag device based on the phase difference of arrival, PDoA, of the tag signal and the reference signal.