This takes me back to when I was still in the (Dutch) navy, there was a project to replace the submarines and as part of the upgrade they were planning to repla

This takes me back to when I was still in the (Dutch) navy, there was a project to replace the submarines and as part of the upgrade they were planning to replace the old periscope mast with an upgraded optronic system. This was basically a webcam on a pedestal that would quickly go above water, take a 360 degree photograph and then dip below the waves again. This would take mere seconds, minimizing the time that the submarine would be visible. The data could then be analyzed at length while safely underwater. However, the newer system was so much faster that the GPS antenna mounted on the periscope mast could not get a fix in time. If they wanted a position fix as well as a look around, they would need to leave the mast up much longer. (Submarine navigation is much more difficult than navigation for surface vessels, basically all INS. Getting a GPS fix every now and then is really helpful) By the time I left, it was still an open research question on how they would go about it. IIRC, one of the ideas was to simply collect a wide spectrum recording of whatever could be received and do all the analysis later. This would result in a position fix somewhere in the past, which would then be combined with the data from inertial navigation sensors to get an approximate current location. No idea if that system is what they eventually went with though.