PNI CompassPoint Prime - Manual (Page 20)

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Prime User Manual – July 2011 Page 14
new data as soon as the previous request has been fulfilled. Note that the inverse of
the Poll Delay is somewhat greater than the sample rate, since the Poll Delay does not
include actual acquisition time.
Interval Delay
The Interval Delay is relevant when Push Mode is selected, and is the time delay, in
seconds, between completion of the Prime module sending one set of sampled data
and the start of sending the next sample set. If the time is set to 0 then the Prime will
begin sending new data as soon as the previous data set has been sent. Note that the
inverse of the Interval Delay is somewhat greater than the sample rate, since the
Interval Delay does not include actual acquisition time.
Acquire Delay
The Acquire Delay sets the time between samples taken by the module, in seconds.
This is an internal setting that is NOT tied to the time with which the module
transmits data to StudioPrime or the host system. Generally speaking, the Acquire
Delay is either set to 0, in which case the Prime is constantly sampling or set to equal
either the Poll Delay or Interval Delay values. The advantage of running with an
Acquire Delay of 0 is that the FIR filter can run with a relatively high Tap value to
provide stable and timely data. The advantage of using a greater Acquire Delay is
that power consumption can be reduced, assuming the Interval or Poll Delay are no
less than the Acquire Delay.
Flush Filters
Selecting this box results in the FIR filters being flushed (voided out) after each
measurement reading. This can be useful if a single, accurate reading is desired and
there is sufficient time to re-populate the filters The default is not to flush the filters.
Note: I f “Flush Filters” is selected the rate at which the output is updated will be inversely
proportional to the number of taps. For example, if 8 taps and flush filters are selected, the
output will be updated at ~3.5 Hz, while it will be updated at ~1 Hz if 32 taps is selected.
5.3.6 Calibration Settings
The Prime supports both magnetic sensor and accelerometer calibration. These
calibrations can be performed independently or simultaneously. The relevant
StudioPrime inputs for these calibrations are discussed below. See Section 6.2 for
information on how to perform a calibration.
Stability Checking
By default when calibrating the module, a measurement must be stable for 3
consecutive readings prior to saving the sample for use in the calibration. This is why
the module must be held steady between points during the field calibration. This
stability helps to ensure a proper heading and allow for higher accuracy, but it also