SeaTag-MOD

Engineering Status Reporting

 SeaTag-MOD will transmit an engineering packet every tenth transmission. In a decoded ARGOS log recovered via SeaWatch or the ARGOS web site and decoding with SeaDock, these packets are identified by the name SDPT_MODENG.

The SDPT_MODENG always indicates the tag status at the time of the transmission of this packet. So, SDPT_MODENG packets are never archived and never stored in memory.

These packets provide current tag status, can be used to diagnose errors and are useful for ground-truthing magnetic/light based position estimates by comparing these current estimates to the ARGOS position reported for the tag. Use the header in the decoded log to identify the data fields. Use the key below to interpret the data.

Checksum OK

A TRUE value indicates there is no corrupted data in this packet. It’s best to use only TRUE packets so that you can trust the data.

Status

Indicates the current tag status. The code is a so-called bitmap. Convert the value to a binary number using for example the Windows calculator. The least significant bit is called B0 (which is the furthest to the right when looking at the converted binary number, ie: 0 when looking at the example below), and the most significant bit is B7 (which is the furthest to the left when looking at the converted binary number, ie: 1 in the example below). A condition is present when the corresponding bit is ‘1’.

B0: No noon time detected. The tag has not identified a valid local noon time in about the last 30 hours.

B1: Clock loss occurred. The time is no longer valid. This may happen due to a processor crash or a power loss. This condition also triggers a mission abort.

B2: Tag encountered the crush depth and has released.

B3: A release trigger has occurred. This is set independent of the release being normal or due to an exceptional condition, i.e. processor crash, clock loss, constant depth release or crush depth release. If you see this bit set, the tag is transmitting archived data.

B4: Constant depth release occurred.

B5: Not currently used, always ‘0’

B6: Not currently used, always ‘0’

B7: A mission abort has occurred and the tag is transmitting archived data. See the other bits to find the cause of the mission abort.


Example:

The status is 138. Converted to binary, this is 10001010. Bits B7, B3 and B1 are set. This means that a mission abort has occurred (B7), and the tag has released (B3). The cause is a clock loss (B1), which may be the result of the tags recovery from either a power loss or a processor crash.


Tag Serial Number

The physical serial number of the tag.

Argos Transmission Number

This counter starts at zero when you configure a tag, then counts up with each ARGOS transmission. By comparing the transmit count to the packet receive count, you can determine how successful the transmissions are. In the open ocean, a transmit to receive ratio of around 17% - 23% is normal under good conditions. This reflects the approximate percentage of time that an ARGOS satellite is in sight. If a tag is dragged down a lot, or is transmitting from a rarely surfacing animal, or conditions are otherwise adverse, you will see a lower percentage.

Note that this count also resets to zero if a tag has crashed and then recovered.

Date/Time

The current time per the tag’s clock. By comparing it to the satellite reporting time, you can check for clock drift. If the tag crashes, or looses power, it will start at January 1, 1970. So, a time warp back into the 70’s means something went wrong. Even then, correct time such as for geo-positioning can be re-constructed by calculating the offset between the satellite time and the tag reporting time, and time adjusting the tag reports accordingly using the Time Offset field in SeaTrack.

Noon time

Time and date of last detected local noon. Along with ‘Magnetic Field Amplitude Avg’, this can be used for light/magnetic position ground-truthing, by comparing the current light/magnetic position estimate to the ARGOS reported position of the tag.

Day Length

Detected ‘length of day’ in seconds. Useable as a reliability check for the reported noon time. If the reported length of day is not reasonable (hours too short or long), then the noon time probably can’t be trusted.

Solar Panel Avg

Average solar panel voltage for the last day. Can be used to estimate tag fouling (declining values over time), or general light exposure.

Capacitor Avg

Average capacitor voltage for the last day. Using established voltage threshold values, can be used to determine if the tag is generally running at a energy surplus or deficit.

Temp Avg

Average temperature for the last day. Can be used for sensor temperature compensation purposes.

Magnetic Field Amplitude Avg

Average magnetic field strength for the last day. Useable in conjunction with Noon Time to establish the tags current light/magnetic position for ground-truthing by comparing it to the reported Argos position of the tag.

Magnetic Field Amplitude

The current (momentary) magnetic field strength reading. For sensor performance verification.

Depth Avg

Average depth for the last day.

Depth

Current depth. For sensor performance verification.