Technical data

85108L System Manual
Operation
Pulsed-RF Measurements Overview
3-15
Pulse Profile Domain
A repetitive sampling technique is used to make measurements in the pulse profile domain.
Measurements are taken at a single frequency as determined by the start frequency setting. Data is
reconstructed from samples taken from a series of pulses. This allows display of the S-parameters
versus time during the pulse. For each pulse, a single point in the pulse is measured. A profile of the
pulse is made by measuring the first pulse at the user-specified Start time, then increasing the
measurement trigger delay by a certain time increment for each pulse until the specified number of
points is measured. Refer to Figure 3-12 for an example of this process.
Figure 3-12 Pulsed-RF S-Parameters versus Time (Pulse Profile Domain)
Measurement Internal Pulse Output and Internal Measurement
Trigger
Time zero is the leading edge of the internally-generated pulse output waveform, or the falling edge
of the externally-generated measurement trigger waveform. The network analyzer automatically
controls the time increment between samples, called the measurement resolution period, using an
algorithm that depends on the greater of the user-specified pulse width or stop time. This automatic
selection of the measurement resolution period can be seen by changing the number of points and
the time span. For narrow pulses and small time spans, the measurement resolution period can be
as small as 100 nanoseconds; for wide pulses and large time spans, it can increase to multiples of 10
microseconds. With the internal measurement trigger, the first sample can be taken up to 6
resolution periods prior to time zero. When using external triggering, the external trigger sets time
zero and the first sample can be taken three resolution periods after time zero.
A method for making pulse profile measurements at multiple frequencies is described in the next
section, “Making Pulsed-RF Measurements.”