Fluke 1595A - Manual (Page 50)

1594A/1595A Super-Thermometer
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41) if the digital filter is ON. If the digital filter is OFF, measurement samples are passed directly to
Conversion.
4. Conversion - after filtering, the fundamental ratio measurement can be converted to the selected unit
of measure such as Temperature (Section 5.7.2.3, EDIT PROBE (F3), on page 36). If RATIO is the
selected unit of conversion, the measurement is passed directly to Display.
5. Display - after conversion, the measurement is sent to the display, remote interface, statistics
calculations, and memory at a rate of once per Display Interval. The statistical mean that is displayed in
the Measurement screen is based on n number of displayed measurements, not number of samples.
The Timing Settings screen contains the following measurement timing fields.
SAMPLE PERIOD - sets the length of time required to obtain a fundamental ratio measurement sample. The
options are 1, 2, 5, and 10 seconds. The default option is 2 seconds.
Note: When the sample period is changed, measurement will stop. It must be restarted by the user.
The 1 second option is useful for applications that require measurements at the highest possible speed, such
as thermal response tests. However, it can be expected to observe greater measurement noise will be greater
when using a 1 second sample period. The 2 seconds option provides good stable measurements for most types
of thermometer probes. The 10 seconds option may yield better results for very high resistances or with probes
that have unusually large settling effects which may be caused by electrical leakage or dielectric absorption.
A probe may be tested for electrical settling by comparing measurements made with the 2 seconds and 10
seconds sample periods.
With the 1 second and 2 seconds options the sensing current is reversed at a basic interval of 0.2 second. With
the 5 seconds and 10 seconds options the current is reversed at a basic interval of 1.2 seconds.
Sample Period cannot be larger than the Display Interval setting.
DISPLAY INTERVAL - determines how often measurements are passed to the display, statistics fields,
memory, and remote interface ports. Possible options are 1, 2, 10, 30, and 60 seconds. The default option is 2
seconds. Changing the Display Interval setting may affect the Sample Period setting, as Sample Period cannot
be greater than Display Interval.
AVERAGE ENABLE - determines whether fundamental measurement samples are averaged before being
passed to the digital filter step. If Average Enable is ON, all fundamental measurements acquired during the
Display Interval are combined by averaging. If Average Enable is OFF, or if Sample Period is the same as
Display Interval, only a single sample, the most recent, is passed to the next step in the measurement process.
The default option is ON.
STOP TIMER ENABLE - enables or disables the stop timer, which stops measurement after a specified
length of time. If Stop Timer Enable is ON, the stop timer begins counting down when measurement is started
using the START MEASUREMENT (F1) function key in the Measurement screen, and stops measurement au-
tomatically when the timer elapses. If STOP TIMER ENABLE is OFF (default setting is OFF), measurement
continues indefinitely until the user stops measurement.
When the stop timer is enabled and measurement is enabled, an hourglass symbol and the time remaining, in
hours, minutes, and seconds appears at the bottom of the Measurement screen.
TIMER DURATION - sets the stop timer duration. The value is a number of hours, minutes, and seconds,
ranging from 00:00:01 to 23:59:59. The default value is 01:00:00. This setting is only relevant when Stop
Timer Enable is ON.
AUDIO INDICATION - enables or disables the audio alert that tells the user when the stop timer elapses and
measurement stops. The default option is ON.
The Sample Period, Display Interval and Average Enable settings in the Timing Settings menu can be auto-
matically configured by selecting one of the following preset function keys (a full description of each field can
be found later in this section):
PRESET NORMAL (F1) - is used for most applications. This setting provides a balance between speed and
precision. Sample Period and Display Interval are both set to 2 seconds and Average Enable is set to ON.