Protocol for comparative sensitivity measurements between English mine detectors No. 3 and No. 4 and the Swedish magnetic mine detector

This document, dated August 13, 1946, and issued by the Swedish National Defence Research Institute (Försvarets Forskningsanstalt), details the results of comparative sensitivity tests conducted on English mine detectors (designated No. 3 and No. 4) and a Swedish magnetic mine detector. The objective of the study was to determine the distance at which a clear signal could be detected in the headphones of these devices when exposed to six specific test objects. The test objects included various sizes of iron, brass, and aluminum plates, as well as a German mine mechanism identified as T. Mi. Z. 35. The results are presented in a table, showing the detection distance in millimeters for each device against each object. The report concludes that the No. 3 detector is the most sensitive, that the No. 3 and No. 4 detectors perform at a similar level, and that the Swedish magnetic mine detector is significantly less effective than the English models tested. The document is signed by A. Hejdenberg and certified as a true copy by B. Sjöstedt.