Incoming!

[Puster Bill]

Originally Posted by GoldenRivet

u-boats were equipped with such a device as well.

it was called "TAG".

It was installed in the control room of the XXI and was set to listen for pre-determined high pitched prop sounds, if one of these pre-programmed sounds was heard, a warning would sound in the u-boat would alert the crew.

I would imagine the allied system was very similar.

That device is what I consider to be "proof" that the germans knew about the FIDO.

I find it hard to believe that a device that had a 25% success rate wasn't noticed by hydrophone operators, and then reported to BdU, by the boats that survived.