Prediction Program, and were used to calculate optimum transmission times for our 

 Western North Atlantic study area. The programmed transmission period was twenty 

 minutes, or almost twice the time it normally takes a satellite to pass from horizon to 

 horizon, and thus allowed for animal movements of 3,000 km in any direction away from 

 the initial tagging area. This synchronization of the transmission cycle with the satellite's 

 movement had never been attempted by any Argos PTT manufacturer, and saved an 

 estimated 60% of the transmitter's battery power. The resulting PTT had an operational 

 life of approximately six months. 



A 64 bit message was transmitted at each surfacing during the programmed twenty 

 minute "transmit" cycle and included the following information: 



Discrete Data (from the dive just completed): 

 The duration of the dive (± 2 s) 

 The maximum depth of the dive (± 17 m) 

 The number of surfacings since the previous 



transmission (ITD) 

 The water temperature (± 0.5°C) at maximum depth 



Summary Data (during a 4-hour summary period): 



The number of dives 



The average duration of those dives 



The maximum depth achieved during the 4-hour 

 period 

 Other : 



Error detection (CRC) code for the discrete data 



Dives were defined as a submergence of at least 6 s to avoid counting swells and 

 splashes as dives. 



The error detection (CRC) code was included because our 1987 pilot whale data 

 (Mate, et al.,in prep.) confirmed the experience of other Argos users that 8% - 15% of 

 all messages contained transmission errors. Most buoy and balloon users of the Argos 

 system repeat their messages because the information does not change quickly. This 

 repetition allows them to easily detect transmission errors. Since we transmit unique 

 messages (discrete information) regarding each dive, we needed an independent means 

 of detecting errors. 



Attachment 



During the cetacean radio tagging workshop and subsequent discussions, Joseph 

 Geraci made three specific recommendations: 1) increase the depth of the attachment; 2) 

 immobilize the implant as much as possible; and 3) increase the surface area of the 

 attachments as much as possible while minimizing the amount of damage to the skin 

 surface area. 



