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Bendix Format Files

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This file format is frequently used in field tests with the Pacific Data Model 9820 recorder.

Bendix format files consist of a header block followed by binary data. The header structure used in these files is defined below:

typedef struct tagHEADER {

short   Model;

short   Chan;

short   Module;

short   Config;

short   NumPost;

short   Profile[15];

char    Eventname[40];

double  Trigger;

short   CounterLoop;

long    StartTime;

char    Status[8];

short   Memory;

char    Engineering[14];

float   Baseline;

float   Calibration;

char    AutoX[8];

float   LowerLimit;

float   UpperLimit;

char    AutoY[8];

float   PlotStart;

float   FinishPlot;

short   PostSegs;

short   SEGM[16];

char    TriggerStatus[8];

char    ProtectSwitch[8];

char    ProtectFlag[8];

char    ErrStatus[8];

char    FilterValue[8];

char    Measurement[14];

char    StampTime[8];

char    StampDate[10];

char    Bunker[14];

char    AmpGain[8];

long    DECTrigger;

long    DECDummy;

float   VoltsLSB1;

float   VoltsLSB2;

char    AmpNumber[14];

char    CableNumber[14];

char    JBoxNumber[14];

char    GageNumber[14];

char    GageType[14];

char    CableType[14];

char    TermResistor[14];

char    OperName[14];

short   NumberChannels;

float   VoltsLSB3;

float   VoltsLSB4;

short   SampleClockCode;

short   CoarseOffset;

short   FineOffset;

short   Dummy[296];

char    DataBaseVersion[2];


The Bendix format is used for a variety of Pacific Data recorder models. However, DPlot only supports files produced with the model 9820 recorder (Model=9820 in the Header block).

Calibration data (if present) consists of 1024 2-byte values located between offsets 1024-3071 in the file. The raw data for Model 9820 files starts at offset 3072 in the file. Raw data is organized into 15 segments of either 4096 or 8192 2-byte integers each. Each segment can have a unique time step. The time step (in microseconds) for a given segment is determined from:

dT = 1.0 << (16-(Profile[segment] & 15);

The raw data and calibration data are translated to engineering units by:

Y = float(Volts-2047)*VoltsLSB1;

where Volts represents the raw data, and VoltsLSB1 is from the file header.

If calibration data is present (indicated by a non-zero Calibration in the header), the output amplitudes are adjusted by:

Y = (Y - CalBase)*Calibration /(CalCal-CalBase);

where CalBase is the average of the 1st and 3rd blocks of 256 calibration values, and CalCal is the average of the 2nd and 4th blocks of 256 calibration values.



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