Campbell OBS-3A Especificaciones descargar pdf (Pagina 8)

Section 1. Introduction

Depending on the number of sensors and the statistics selected, the OBS-3A

can log as many as 200,000 lines of data (one per hour for 23 years) including:

time, date, depth, NTUs,

C, and salinity. When sampling with a full suite of

sensors, the unit will run about 300 hours. When using the instrument for

surveys, the data are captured by a PC running the OBS-3A Utility in the log

file created at initialization.

1.1 OBS Sensor

The OBS sensor consists of an infrared-emitting diode (IRED) with a peak

wavelength of 875 nm, four photodiodes, and a linear temperature transducer.

The IRED produces a conical beam with half-power points at 50

(FIGURE

1.1-1). The IR scattered between 140

and 160

is detected after passing

through a daylight-rejection filter and is proportional to turbidity and sediment

concentration. See Section 10—Specifications.

FIGURE 1.1-1. Anatomy of an OBS Sensor

1.2 Temperature and Optional Sensors

Temperature is measured with a fast-response, stainless steel-clad thermistor.

Pressure is measured with a semiconductor piezoresistive strain gage.

Conductivity is measured with a four-electrode conduction-type cell. Working

depths for available pressure sensors are listed in TABLE 2.1-1.

1-2

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Campbell OBS-3A Especificaciones Pagina 8