By Robert E. Straub - KC2AIO <kc2aio@juno.com>

Submarine Radio Communications - Fox Schedules

     The frequencies used to receive the Fox schedules were the 4k series, 8k series and the 12k series and the 16kc. series. The fundamental frequency, for example, would be 4145kc. and the harmonics of 8290kc., 12,435kc., 16,580kc. All frequencies would be transmitted simultaneously from the base station. Each base station would use a slightly different fundamental frequency and harmonics for transmitting the Fox schedule. All these possible frequencies were calibrated for the RAL Receiver and the calibration readings, determined by using the LM Frequency Meter, were attached to the receiver. This made changing frequencies relatively easy in a minimum amount of time.

     When attempting to transmit a message from the submarine a ship to shore frequency would be selected. The frequency would fall into the same category as the received signals - 4k, 8k, 12k, and 16k series - but a different fundamental frequency would be used or one of its harmonics, just as in the receiving bands.

     When the radio operator would receive the encoded message for transmission to a shore station, he would make a call to "all stations," indicating there was traffic to send.

     Upon receipt from the shore station the encoded message would be sent to the shore station and at the end of the message the submarine operator would insert a signal called an "authenticator." These signals were selected at random from a predetermined list. The shore station operator also worked from this list and it was his responsibility to give a proper response to the authentication. This verified that the message was received by an authorized shore station.