Pni SeaTRAX Manuel d'utilisateur télécharger pdf (Page 54)

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SeaTRAX User Manual Page 49

Initiate a calibration using the kStartCal command. Note that this command

requires indentifying the type of calibration procedure, for example Full-Range

Calibration or 2D Calibration.

Follow the appropriate calibration procedure, as discussed in Section 5. If

kUserCalAutoSampling was set to FALSE, send kTakeUserCalSample when

ready to take a calibration point. If kUserCalAutoSampling was set to TRUE,

then look for kUserCalSampCount to confirm when a calibration point has been

taken. During the calibration process, heading, pitch, and roll information will be

output from the SeaTRAX, and this can be monitored using kGetDataResp.

When the final calibration point is taken, the device will present the calibration

score using kCalScore and save the calibration coefficient set and coefficient

values to volatile memory, assuming the calibration was not aborted.

If the calibration was not good, either perform another calibration procedure,

reboot to restore the prior coefficients, recall another coefficient set

(kMagCoeffSet), or recall the factory coefficients (kFactoryMagCoeff).

If the calibration was good and you want to save the calibration coefficients to

non-volatile memory, send the kSave command.

7.3.11 kStopCal (frame ID 11

)

This command aborts the calibration process. Assuming the minimum number of sample

points for the calibration, as defined in Table 7-5, is not acquired prior to sending

kStopCal, the prior calibration results are retained. If the acquired number of sample

points prior to sending kStopCal is within the allowable range of kUserCalNumPoints,

then new calibration coefficients and a new score will be generated. For instance, if

kUserCalNumPoints is set to 32 for a Full-Range Calibration, and kStopCal is sent after

taking the 12

sample point, then a new set of coefficients will be generated based on the

12 sample points that were taken. They will not be saved, however, unless the kSave

command is sent.

7.3.12 kSetFIRFilters (frame ID 12

)

The SeaTRAX incorporates a finite impulse response (FIR) filter to provide a more stable

heading reading. The number of taps, or samples, represents the amount of filtering to be

performed, and directly affects the time for the initial sample reading, as all the taps must

be populated before data is output.

The SeaTRAX can be configured to clear, or flush, the filters after each measurement.

Flushing the filter clears all tap values, thus purging old data. This can be useful if a

significant change in heading has occurred since the last reading, as the old heading data

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Pni SeaTRAX Manuel d'utilisateur Page 54