Agilent Technologies E1439, User Manual

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185
Agilent E1439 Programmer's Reference
Functions listed alphabetically
AGE1439_GENERATE_OFF disables triggering. This is useful in multi-module systems with the
same trigger type where you want only certain module(s) to generate a trigger.
genTrigPtr points to the current value of the genTrig parameter.
magDwell represents the number of samples that the signal magnitude must dwell low before begin
recognized as a low for the purpose of generating a magnitude trigger.
AGE1439_MAGDWELL_DEF
AGE1439_MAGDWELL_MAX
AGE1439_MAGDWELL_MIN
magDwellPtr points to the current value of the magDwell parameter
magLevel is used to set the triggering to detect when the envelope of a signal crosses the threshold while
using the magnitude trigger type.
AGE1439_MAG_LEVEL_MAX sets the maximum allowable level and AGE1439_MAG_
LEVEL_MIN sets the minimum allowable level.
AGE1439_MAG_LEVEL_FS sets the full scale magnitude trigger threshold.
AGE1439_MAG_LEVEL_DEF sets the default magnitude trigger threshold.
The threshold is set to ( AGE1439_MAG_LEVEL_SCALE
×
magLevel ) dB relative to full scale
signal, where
−
337
≤
magLevel
≤
40.
Comment
Magnitude triggering is performed on the log magnitude of the signal. Magnitude triggering
occurs when the log magnitude of the signal crosses the specified magnitude trigger threshold.
Because of these facts magnitude trigger operation will not always be intuitive, and there is a case
that can be misinterpreted as improper operation:
Magnitude triggering may not occur when the magnitude trigger threshold level is set below the
known maximum amplitude of the input signal. The problem in such a case is that the trigger
threshold level is actually set too low, so that few, if any, signal samples fall below that level. A
transition from below the magnitude trigger threshold to above may never be detected if a sample
is not taken while the signal is below the trigger threshold. The solution is to INCREASE the
magnitude trigger level to the level at which there are frequent filter samples occurring both
above and below the magnitude trigger threshold
magLevelPtr points to the current value of the magLevel parameter.
slope selects the edge of the trigger source on which a trigger occurs for ADC and external triggers.
AGE1439_POSITIVE sets triggering on the positive slope and AGE1439_NEGATIVE on the
negative slope.
slopePtr points to the current value of the of the trigger slope parameter.
trigType determines the trigger source.
AGE1439_ADC generates a trigger based on the raw data samples from the ADC.
AGE1439_MAG generates a trigger based on the log magnitude of the signal after it has been
filtered to a selectable bandwidth around the center frequency established by the age1439_
frequency_setup function.