Agilent Technologies 34420A, User Manual

Page: 59 / 294

Digital Filter
•
The digital filter is a moving average (boxcar) filter. Equal weighting
is applied to all readings to calculate the displayed reading.
•
Three digital filters are available:
SLOW (average last 100 readings),
MEDIUM (average last 50 readings), or
FAST (average last 10 readings)
•
When the digital filter is enabled, the ‘Filt’ annunciator flashes until
the required number of readings are obtained. The measurement
displayed before the ‘Filt’ annunciator is steady is the average of the
number of readings taken so far. For example, with the filter set to
MEDIUM (average of 50 readings), the measurement displayed after
20 readings will be the average those 20 readings. The ‘Filt’
annunciator will flash until 50 readings have been taken.
•
The filter count resets (and the ‘Filt’ annunciator will flash) if the
function, range, integration time, or channel is changed.
•
The filter count resets if a reading is outside a set range of the
average. The amount of input reading change required to reset the
filter count is:
1mV Range All Other Ranges
FAST ±
400 ppm of range
±
100 ppm of range
MEDIUM ±
700 ppm of range
±
300 ppm of range
SLOW ±
2000 ppm of range
±
1000 ppm of range
Analog Filter
The analog filter is an 11 Hz, two-pole low pass filter. Use this filter to remove
line frequency noise from the input measurement.
•
The filter requires approximately 300 milliseconds after the input is
present to settle. Using the filter, therefore, slows the measurement
rate significantly.
•
Use the analog filter only when line power noise (50/60 Hz) is causing
an overload (OVLD) condition. See page 65.
•
The analog filter is available for voltage and thermocouple
temperature measurements. The analog filter is not available for
resistance measurements.
•
The analog filter is available for the 1 mV, 10 mV, and 100 mV ranges.
3
Chapter 3 Features and Functions
General Measurement Configuration
57