Models LB480A/LB680A
USB Powe™
Product Manual PPA (Pulse Profiling Application)
Revision: 08/02/11
31
EXAMPLE
: Set
Measurement Threshold
to -20 dBm. Setup a normal marker on top of the pulse. Click
Marker to
next peak right
and notice the active normal marker requires the threshold value to be met before it will search for the
next peak. Since our signal is below -20 dBm it will not move. Set the marker threshold back to the default value (-55
dBm).
Pulse Criteria
Pulse Criteria
is used to define the beginning and the end of a pulse. More precisely, pulse criteria defines the edges
of the positive portion of the entire pulse. The pulse criteria is relative (or added) to the measurement threshold if
threshold is enabled. The pulse criteria is relative to the noise floor if threshold is disabled: For example, if the
threshold is -55dBm (default) and the pulse criteria is 6 dB, then the resultant level is -49 dBm. This means that the
signal level must exceed -49 dBm before the start of a pulse is considered to have occurred. It also means that the
level must subsequently fall below -49 dBm to define the end of a pulse. The area between the rising edge and the
falling edge defines the outer edges of a pulse.
Pulse Criteria
is used to define that portion of the total trace that is to be considered part of a pulse. While this
measurement is useful and necessary it is not sufficient to make pulse measurements. We still have to analyze the
pulse to define the pulse top. For this we must discover the points on the rising and falling edges that are 3 dB down
from the pulse top.
