The term "checksum" was created to describe early error detection techniques
which used summing formulas and appended the result to the data. Checksum now has
a more-general meaning, encompassing sophisticated algorithms such as the CRC
(Cyclic Redundancy Code). The CRC algorithm treats the message as an enormous
binary number, divides it by another fixed binary number, and makes the remainde
the "checksum". The receiver can perform the same division and compare that remainder
to see if the message was correctly received.
correlation
height
The strength of the signal. Limits, depending on type of float, are specified in
the rfb header.
cycle
a) used by ARTOA-II to mean a float mission; this allows ARTOA-II
to work on multiply-submerging floats (such as Marvor and ALFOS)
b) a complete set of listening operations (usually listening and stopping three times).
Usually the same as line or record. See also phase.
drift
The amount by which a clock can be deduced to change over some time
interval. Source clock drifts are quoted in seconds per interval
between pongs. Float clock drifts are quoted in seconds per day
(negative = fast).
edit
a) to select the TOAs you want from all those available for a
given float
b) to correct your initial selections (of TOAs, temperature or
pressure values)
mission
The amount of time a float was meant to stay submerged.
offset
a) an amount by which a TOA for a given source or float is always
off from the correct time
b) a momentary difference between an instrument clock and the
correct time.
An "initial offset" (a) would always be applied. A "final offset"
(b) would be combined with an initial offset and divided by the
duration of the deployment to calculate the drift.
phase
Used by ARTOA-II in headers. Phase is used to mean a complete
schedule of listening intervals. For example, "phases per cycle"
means the number of listening intervals in the mission of a float.
[This is to replace "cycle", now used to mean a descent and ascent.]
schedule
Hours between first pongs - which has also been called "cycle" (q.v.)
window
a) a figure on the screen, as in "an editing window"
b) a single interval, usually around 30 minutes, during which a float
is listening for pongs.
