High Frequency Direction Finder -- Equipment for locating the source of high frequency radio transmissions from German U-boats played a major part in defeating the submarine menace in the Atlantic. The finders were accurate enough to pinpoint the exact positions of any subs using high frequency transmission. Here is the control unit of the finder installed in the USS Philadelphia. January 14, 1946. (Photo by ACME).
High Frequency Direction Finder -- Equipment for locating the source of high frequency radio transmissions from German U-boats played a major part in defeating the submarine menace in the Atlantic. The finders were accurate enough to pinpoint the exact positions of any subs using high frequency transmission. Here is the control unit of the finder installed in the USS Philadelphia. January 14, 1946. (Photo by ACME).