Decca Locking constant
Locking constant (in Decca)
The overall phase shift resulting from two causes, the close proximity of the receiver to the master transmitter and, at the slave station, a possible fixed displacement from the nominal zero phase difference condition that is assumed to exist between the received master signal and the out-going slave transmission.
The value of the locking constant for each pattern is found at the start of a survey by observations at exact known distances from the slaves and is thereafter subtracted from all observed Decometer readings.
Please note that this is the term as it stands in the original IALA Dictionary edition (1970-1989)
International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM