Radar developments in the period 1955 – 1965
In the fifties and sixties, various research disciplines worked together on the further development of radar for the Armed Forces. New radar techniques and digital signal processing were combined.
In the 1950s, anti-jamming receivers were developed to deal with radar jamming by an adversary. Around 1960, an automatic channel selector was developed to automatically select the least disturbed radar frequency from a set of five frequencies.
The introduction of height radars made it possible to determine the height of a target in addition to its direction. That function was later added to a search radar.
The Armed Forces continuously asked for extending the detection range of radar and the detection of even smaller targets. Using the Doppler effect, small targets could be detected despite the unwanted clutter by environmental reflections, such as precipitation (rain, hail), buildings, afforestation, and waves. By using the difference in Doppler frequency of flying objects and clutter, signals can be separated. In a radar clutter suppressor, the Doppler effect is used to weaken the clutter and to make the weak echoes visible in the weakened clutter. The use of the Doppler effect is not easy with magnetron-based radars. A magnetron does not have a very stable frequency of its transmission pulses as a result of which the Doppler frequency varies from pulse to pulse. The laboratory, however, developed a smart circuit to overcome this challenge.
In parallel, LEOK worked on the digital processing of radar data. In 1963, the Radar Information Processing Equipment (RIVA) project used a digital computer of one’s own design. This computer processed the radar information obtained by means of a video integrator and generated control data for steering the height radar antenna.
More information on digital processing of radar target information and its presentation on radar screens can be found at Digital Technologies: Radar image processing page.
The ‘follow-up’ to the RIVA project was the 3D-simulator project for the Royal Navy (from 1965 till 1970). The 3D simulator injected simulated targets and clutter into the processing equipment of the 3D radar that was under development.
More on the computers can be found at: Computer history: LEOK period 1961 -1974.
The developed 3D radar was installed at the Tromp class frigates of the Netherlands Royal Navy. The radar system combined the aforementioned radar functions of search, tracking, direction-distance-altitude, anti-jamming and Doppler.