The Aanderaa recorder uses a Digiquartz type 2-300a quartz crystal pressure transducer. The pressure sensor consists of a convoluted bellows linked to a 40kHz quartz crystal resonator coupled by piezoelectric action to an electronic resonator. Data are recorded on to 0.25 inch magnetic tape on an Aanderaa data logger in the same case. A quartz crystal clock is used for controlling the sampling interval.
The data are recorded as 10 bit binary words in serial form with the frequency count from the sensor stored as the most and least significant counts. The pressure recorder is a deep water instrument and is usually deployed on a pop up mooring.
Data Processing Notes
Instrument samples every hour, 28 seconds before the hour, for 56 seconds. Clock lost 4 seconds over 123 days 12 hours 0 minutes 4 seconds; no correction made.
(BODC Series Ref. 36795)
Nominal sampling interval
IOS Data Processing of Off-Shore Pressure Recorder Data
Data processing consists of two stages:-
Pressures have been sample rate reduced from the basic time step of the recorder to produce the hourly values and have been interpolated by a cubic spline to generate the value on cardinal hours.
Instrumental drift has been removed and the drift free series is produced with an artificial mean value, usually of 100mbar.