Summarized dive data and detailed time-stamped data can be compressed and transmitted through the Argos satellite system. These data can be combined with locations from Argos, Fastloc® GPS or light-based geolocation, providing a precise picture of horizontal and vertical behavior.
Diving behavior studies are reliant on accurate depth and temporal archival data. TDR10 tags require tag retrieval for full archival data recovery, whereas SPLASH, MiniPAT and sPAT tags transmit summarized depth data via Argos satellites. Summary options include Time-At-Depth Histograms, Time-Series Depth, Dive-Duration Histograms, Dive-Maximum-Depth Histograms, and Behavior Collection Dive-Profile Logs.
Time-At-Depth (TAD) histograms report the percentage of a specified time period (histogram summary periods of 1 to 24 hours) spent within a depth range (bin range.) Both the histogram summary periods and bin ranges are user-definable. Each bin value reflects the percentage of the histogram duration that the depth readings were within the bin range.
Wildlife Computers developed efficient compression algorithms to provide low-frequency reporting of readings from more frequently sampled data stored in the archive. This compression allows messages containing a time series of depth to be transmitted through the Argos system. This type of message is useful when the behavior of the study animal is unknown.
Time-Series messages can be generated using one of five sample intervals (75, 150, 300, 450, 600 seconds.) The sample interval determines the number of messages generated per day. Faster sampling gives more resolution but will result in more messages generated. Selecting a longer sample interval produces fewer messages but decreases the chance that there will be gaps in the time covered by the Time-Series messages. The number of messages received through the Argos system is governed by animal behavior and battery capacity. You will need to balance your animal’s behavior and your study objectives to determine the sampling interval that provides the best balance between coverage and temporal resolution.
Each Time-series message provides
- The time series data sampled at the specified interval for that message period
- The minimum and maximum values encountered during the period of time covered by the Time-Series message period as measured at the faster archive sampling rate. This gives you insight to the amount of aliasing that has occurred when generating the Time-Series message.
Dive-Duration histograms report the number of qualifying dives measured during a specified time period (histogram summary periods of 1 to 24 hours) whose durations fell within a dive duration bin range. Both the histogram summary periods and bin ranges are user-definable.
Dive-Max Depth histograms report the number of qualifying dives measured during a specified time period (histogram summary periods of 1 to 24 hours) whose maximum depth fell within a depth bin range. Both the histogram summary periods and bin ranges are user-definable.
The Dive-Profile log is an efficient way to get higher-resolution dive data through the Argos system. The animal’s behavior is divided into “dives” and “surface events”. These events can be reconstructed to provide a profile of the animal’s diving behavior. Each dive and each surface event are described in a message with the details below.
- Dive duration
- Maximum dive depth
- The shape of the dive (Square, V, U, or unclassified)
- Time spent at the surface
- Fraction of that time spent below the user-defined depth reading that determines the start and end of dive
In the graph below, green is the archived sampled depth readings and blue is the dive-profile log data.