A temporary dip in the research
Around 1965, the Royal Netherlands Navy, unfortunately, felt that the Netherlands would be too small to develop its own active and passive sonar systems. Instead, a connection would be sought with other (larger) countries. This also included the circumstance that, especially for passive sonars, there was only very little or no sailing time available for testing. After this decision, the emphasis of the Underwater Acoustics group of the TNO laboratory was therefore on the study and research of those parts of the sonar that determine its quality, such as the transducer, the signal design (for active sonars), the signal processing and the belonging presentation. By maintaining the expertise in this way, one was able to provide advice to the Navy on many aspects of sonar. This was especially important when the sonar equipment of the “Van Speijk” class of guided missile frigates was specified and technically tested at a later stage.