Is it possible the surface ship would have noticed the implosion sound or shock-wave either physically or on sensors?
Yes. But I am still uncertain about the communications system; from what I have read, there were 2 different periods of PING types.
1. A PING was sent from the submersible every 30 seconds, and that informed the submersible of its position relative to the surface mothership. That was the method for navigation of the submersible in the descent “water column.” This PING method could include a short string of text characters.
2. A PING would be sent from the submersible every 15 ssconds, if there was an emergency/serious problem.
At approx. 105 minutes into the 150 minutes (estimated) descent, the expected 30 second PING was not sent, and no 30 second PING’s followed.
Apparently, at least 2 of the 15 second type PING’s occured.
105 [minutes] / 150 [minutes] = 0.7
0.7 x 12,500 ft [depth of Titanic] = 8,750 ft
Somewhere around that depth, may be when the submersible had dropped some weight . . . that was discovered by the ROV that found the weight framework and submersible’s tailcone on the seabed approx. 1,600 ft away from the Titanic’s bow.