These parts were radio silence, radio deception, and radio monitoring.
A subtle and extensive radio deception plan was put into motion that allowed for a seamless shift to false radio traffic when the carriers went silent, followed by seemingly real transmissions until the Kido Butai reached Hawaii.
47) The stations involved in the radio deception were to use the old drill calls of the carriers, principally Akagi, and other ships of the Kido Butai for the next three weeks.
While the radio silence hid the Kido Butai's location, then, radio deception strove to convince American communications intelligence that the strike element of the Combined Fleet, its carriers, was still in home waters.
For the next three days the ships stayed at Saeki, and the Pacific Fleet COMINT summaries reported that "the carriers are mostly in the Kure and Sasebo and with the exception of a few in the Kyushu area" (56) While this statement could be interpreted as covering all the possibilities, the specific locations mentioned were centers for radio deception, and this suggests that false radio traffic may have supported Hawaii's conclusion.
Japanese radio deception may have begun to bear fruit by this time.