The idea is a frequency sounds like you are jamming when you are sending intelligence on that frequency.
Two transmitters and two receivers are used. Top transmitter sends jamming at first of pulse cycle then second transmitter sends intelligence portion at back half of cycle.
First receiver is to turn on and off second receiver to collect the secret intelligence.
What type of Multiplexer and Demultiplexer circuits used is not known. I have no circuit on how this WWII communication was done.
The method was patiented in 1953.
A puzzle for someone to try.
