Quote:
Originally Posted by gimpy117
Q: I was told by my grandfather US subs had an early IFF system...is this true??
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Yes, it is true, but only to a certain extent.
For those that do not know, IFF stands for Identification Friend or Foe. It is a radar/transponder based system designed to determine if a particular unit (ship or plane) is friendly. A radar type pulse of a specified frequency is sent out from your unit to the approaching unit. The pulse activates a transponder and it pulses back at a different frequency. This pulse is received at the sending unit and identifies it as friendly. While better than nothing, the system is not perfect as it will
not positively identify a unit as unfriendly. If no pulse is received from the transponder, the contact is considered unfriendly. However, a friendly unit's transponder may be out of commission or damaged in battle and thus unable to respond.
The Naval Research Laboratory developed the first IFF system, the XAE, as early as 1937. Radar in general was in its infancy at the time and radar systems were poorly understood and mistrusted by the USN in general until about late 1942. The exception was the Submarine Service. It was seen as a valuable tool and was quickly embraced as soon as the technology became available. IFF systems were slower to be introduced, with the first system installed on the USS Angler (SS-240) in late 1943. Many boats still did not have IFF installed at the end of the war.