Advantages of RBR XR series loggers for CTD and other sensors
Rugged. The conductivity sensor of the RBR XR series is inductive, and can withstand being frozen into ice. Records have been obtained of the salinity of polar lakes during the freeze/thaw cycle.
No pump required. The conductivity cell length and cross section permit adequate flushing in moored applications and excellent flushing in profiling. Records from parallel moorings are available showing the comparison in time response between the RBR cell and contact cells. Short term transients are easily seen on the RBR cell which are not visible on the other system.
No toxic antifouling needed. If biofouling is expected then a non-toxic wax may be applied to the cell without significant detriment to performance.
Calibrated over a wide range of salinity. The inductive sensor is calibrated over salinities from zero to maximum at constant temperature, making the calibration reliable for estuarine work. In contrast, an electrode conductivity system is typically calibrated at a single salinity.
Temperature compensation may be independently determined. The influence of temperature at any salinity may be determined independently of overall calibration.
Adding other sensor channels is very economic. Because of the modular construction of the XR series, up to 6 channels may be incorporated at the time of order with considerable flexibility and with very reasonable incremental cost. Only the channels required by the customer are added.
Specially optimised interfaces. C, T and D have dedicated interfaces, and the interface is used for other sensors are optimised for the sensor. These include a high impedance interface for pH, ORP and galvanic DO, a 5½ decade linear PAR interface, and an autoranging interface for turbidity and fluorometry. A serial interface is available for any sensor that provides a generic serial output (Paroscientific gauge; Optode; etc)
Light weight. The shallow water version of the CTD (up to 740m) has a weight in water of less than 1 Kg including batteries.
Communications options. The basic instrument includes RS-232 and RS-485 as well as modem control for RF and GSM/CDMA modems.
Thresholding software. For the profiling version, the XR-620, battery power and memory are conserved using a software threshold that may be operated on any sensor.
Low power. By careful design and selection of sensors for optimal performance the power use of the instrument in all configurations is very low, and battery life of up to 3 years is feasible in many deployments. Full use of the memory is possible with one set of batteries.
Battery availability. RBR instruments use a type of lithium battery that is widely available in camera stores: size 2/3A. Special batteries are not required, and these cells can be obtained throughout the world without restriction on transport. |
