Advances in Soviet nuclear submarine performance during the 1960s rendered the existing NATO sonar equipment, which were based on analogue technology of World War II origin and had limited range, obsolescent. In 1968 the Admiralty issued a draft Staff Requirement for the Type 2016 hull sonar, which was intended to replace not only the widely used Type 184, but other types of specialist sonars, such as the Types 170, 176 and 177. Type 2016 had an effective range of up to in calm conditions in coastal waters, and up to in deep water, compared to for the Type 177. It used pre-formed digital beams at lower frequencies than previous types, that could track many more targets, whilst using fewer ratings to process the information. The drawback of the use of much lower frequencies however, was the need for a much longer array. The urgency of the need led to the plan to convert "Matapan" being revived, as a test bed for the new equipment.