Kevin Smith
On 9th November you suggested active life of recorders on seabed could be extended by not transmitting active accoustic signals until active searching was observed. The degree of extension depends on ratio of "listening" power drain to "speaking" power drain.I have no idea of this.
An alternative could be to eject recorders(with flotation device) when outside pressure corresponded to few feet of water. Problem would be demonstrating lack of "nuisance" events. You might like to consult with manufacturers of recorder packages.
Keith
As an electrical engineer familiar with transmit vs receive power consumption of various devices I can tell you that transmit power consumption is at least an order of magnitude greater than receive power consumption. That having been said, the low duty cycle of the pingers mean that even when they are active they are only consuming large amounts of power during the "ping" itself. The net effect could be that battery life would not be appreciably extended by putting the device into a listening only mode.