A method of measuring seismic signals generated by marine acoustic sources includes deploying at least one seismic sensor unit to a location on a floor of a body of water within a survey area, and recording seismic signals that include a real measured far field signature generated by a seismic source during a marine seismic survey. The method further includes automatically actuating a retrieval device to cause the at least one seismic sensor unit to rise to the surface, in response to expiration of the selected time period or an actuation signal from the surface, retrieving the at least one seismic sensor unit from the surface, and processing seismic data collected from the return signal. Processing including identifying a far field signature of the seismic source based on the signals detected by the seismic sensor, and designaturing the seismic data based on the far field signature.