Mach
I don't know that any useful signal will be transmitted by a 406 GPS plb on the way down.
The GPS in the plb has never been turned on before. It has no idea of date, time or which hemisphere it is in. So it will be a totally cold search for satellites (ie if it only knew date and time and hemisphere, it knows which satellites should be visible and thus looks for those first).
It is akin to the well known problem of Garmin x96's that have lost charge in small internal battery, a cold start takes many minutes to achieve sufficient satellites to get a GPS position.
I hope I am wrong in this, and stand to be corrected.
John
Last edited by rjtjrt; 31st Dec 2012 at 00:23.