I understand that you have to sync the D9 with the transmitter before each dive. I realize that I will have to sync it to read the pressure when I set up my gear, but what happens if I forget to sync it again when I start my dive up to an hour later? Can I sync underwater by just reaching back and putting the D9 near the transmitter while I am underwater, say 30ft for example, or is does that have to be done on the surface? I searched and couldn't find an answer. Thanks.