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Channel Master Operation Manual

page 106 RD Instruments

12 Channel Master PD14 Output Data Format

This section details the specification of an output format for data consisting

of a header (with timestamp), a two dimensional profile of velocity, acous-

tic intensity, and standard error data, tilt sensor data, stage data, and a

checksum. This format is primarily intended for integrating the Channel

Master with other systems or data loggers. Data will be output in this for-

mat when PD14 is selected as the output format.

12.1 Format

Table 29, page 107 below summarizes the PD14 format. The number of

bytes in the ensemble, not including the checksum is reported in the NBytes

field and is equal to 10 * NBins + 23 bytes, where NBins is the number of

range cells in the profile. The NEnsemble field shows the number of en-

sembles since the start of a deployment and provides for tracking sequences

of ensembles and distinguishing one ensemble from another. Tilts are re-

ported as signed quantities in the interval –180.00 to +180.00 degrees.

Stage measurements are reported as unsigned quantities in units of 1/10

mm. Velocities are reported as signed quantities in mm/sec. Acoustic in-

tensities are reported in unsigned units of counts. Standard error will be

reported as unsigned quantities in mm/sec. The checksum will be calcu-

lated as described by the CRC-16 algorithm using the polynomial

+1 with an initial register value of 0xFFFF.

12.2 Invalid Data

Several quantities may on occasion be out of range or may not pass quality

checks. In such cases, an invalid result will be indicated. For tilts, an inva-

lid result will be indicated by a value of –327.68 degrees. Invalid velocities

are indicated by a value of –32768 mm/s. Invalid standard error will be in-

dicated by a value of 65535 (all bits set). Invalid stage measurements are

indicated by a value of 42949.67295 meters (all bits set). No provision will

be made for any other invalid quantities in this format.

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Channel Master CM-6001 Spezifikationen Seite 112