The invention relates to continuously or near continuously acquiring seismic data where at least one pulse-type source is fired in a distinctive sequence to create a series of pulses and to create a continuous or near continuous rumble. In a preferred embodiment, a number of pulse-type seismic sources are arranged in an array and are fired in a distinctive loop of composite pulses where the returning wavefield is source separable based on the distinctive composite pulses. Firing the pulse-type sources creates an identifiable loop of identifiable composite pulses so that two or more marine seismic acquisition systems with pulse-type seismic sources can acquire seismic data concurrently, continuously or near continuously and the peak energy delivered into the water will be less, which will reduce the irritation of seismic data acquisition to marine life.