Agilent Technologies E1439 GenTrigPtr, MagDwellPtr, MagLevelPtr, SlopePtr, TrigType

Models: E1439

1 246
Download 246 pages 11.5 Kb
Page 195
Image 195

 

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.

185

Page 195
Image 195
Agilent Technologies E1439 GenTrigPtr, MagDwellPtr, MagLevelPtr, SlopePtr, TrigType, Frequencysetup function