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DIGIBAR-PRO Profiling Sound Velocimeter

Mã sản phẩm : 1490505117

The velocity of sound and depth values displayed on the DIBIGAR-PRO front panel are measured, stored in memory, and displayed by the system's internal microprocessor and its associated circuitry.

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  • Odom Hydrographic Systems, Inc.

    The velocity of sound and depth values displayed on the DIBIGAR-PRO front panel are measured, stored in memory, and displayed by the system's internal microprocessor and its associated circuitry. The processor applies Del Grosso's formula to the sing-around frequency calibration constants, yielding accurate and traceable velocity results. The addition of a pressure sensor to the velocimeter probe lends new versatility to the instrument. Calibration of single beam echo sounders using the earlier model DIGIBAR was always easier to accomplish than the traditional "bar check" method of velocity determination and that utility has been maintained in the new DIGIBAR-PRO. The addition of precise profiling capabilities to the new model means that multi-beam echo sounders are now able to utilize the output of the DIGIBAR-PRO directly in their critical ray-bending calculations.
    Theory of Operation
    Mounted near the end of the sampling probe is the high frequency "sing-around" transducer and its associated reflector. This precisely spaced pair is used to measure the velocity of sound in water by transmitting and receiving a signal across their known separation distance. After the first transmission, the received echo is gated and introduced into the feedback loop of an oscillator that re-triggers the transmitter and begins the cycle again. The frequency resulting from this regenerative feed-back loop is determined by the distance the signal travels (transducer to reflector and back) and is directly proportional to the velocity of propagation of the sound pulse through the measured medium (in this case water). This method of direct sampling means that all factors that influence the speed of sound, including salinity, pressure, and temperature, are taken into account. An embedded RISC processor in the probe digitizes the sing-around frequency and depth information, sending that data along with temperature and calibration constants in ASCII format via a 2 wire current loop up the cable to the hand-held control unit at a 10 Hz rate.
    In the control unit, another microprocessor accepts data from the probe, converting the frequency information to sound velocity, and the pressure data into depths, storing them in internal memory. In addition to converting both values to usable units, the control unit provides an easy to use operator interface. The multi-line display and system of menus guide the operator through the steps required to complete a successful velocity cast. Other features of the control unit include, data storage space, interfacing circuitry for transmission of collected data to a PC, and a power source (three Alkaline C-cells) for driving both the probe and its own internal circuitry. The velocity and depth information collected from up to 10 casts can be stored in DIGIBARPRO's internal memory. The average velocity value of each cast can be calculated, or the entire velocity profile of the cast can be up-loaded to a PC, in spreadsheet format, for subsequent use in ray-bending calculations.

    GENERAL SPECIFICATIONS
    Velocity / Depth Probe
    Sing-Around Frequency:                                                          11 kHz
    Communications:                                                                    RS485, 19.2 k Baud
    Temperature Range:                                                                4° to 30° C Typical
    Sample Rate:                                                                         10 Hz
    Depth Sensor Accuracy:                                                          > 1.0 ft (31.0 cm)
    Dimensions:                                                                           14.7l x 2.0d inches (37.3l x 5.0d cm)
    Weight:                                                                                  4.0 lb. (1.8kg)
    Depth Rating                                                                          NTE 100m

    Hand-held Control Unit
    Velocity Range:                                                                      4595 – 5250 ft/sec (1400 – 1600 m/sec)
    Resolution:                                                                             0.1 ft/sec (0.1 m/sec)
    Accuracy:                                                                               ± 1.0 ft/sec (±0.3 m/sec)
    Power Requirement:                                                                 Three "C" cell Alkaline Batteries
    Communications:                                                                     RS232, Selectable Baud Rate
    Dimensions:                                                                            11.4l x 5.5w x 3.7d inches (29.0l x 14.0w x 9.4d cm)
    Weight:                                                                                   2.6 lb. (1.2 kg)

    Cable
    Construction:                                                                           4 Conductor, Kevlar reinforced, and Polyethylene jacket
    Diameter:                                                                                0.27 in. (6.9mm)
    Breaking Strength:                                                                   400 lb. (182 kg)
     

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