Time; How To Set Sweep Time; Continuous Frequency Sweep - HP 8642A Operating Manual

Operation
Model 8642A/B
RF Frequency Sweep (cont'd)
TIME
How to Set Sweep Time
Sweep time setting limitations are different for Stepped Frequency Sweep and for Phase
Continuous Frequency Sweep.
In all cases, sweep time is set using the following procedure:
TIME ( [ SHIFT 1 [ START FREQ ] ) and the value of the desired sweep time in s or ms
( r W T Z ~ y i or I KHZ MV 1 respectively).
Selecting TIME ( [ SHIFT " I ( START FREQ 1 ) alone displays the current sweep time
setting. If sweep time is not specified, the Signal Generator uses the sweep time value
last entered for either amplitude or frequency sweep.
Note that in Stepped Frequency Sweep, a faster sweep time usually results in fewer steps
with a larger step size.
For Phase Continuous Frequency Sweep, sweep span and sweep time are coupled together;
that is, one may limit the setting of the other. Also, frequency will change in a phase
continuous manner but the X-axis output will change in steps.
The following pages contain detailed information about how to understand the
relationships between sweep span, sweep time, step size, and number of steps for both
Stepped Frequency Sweep and Phase Continuous Frequency Sweep. If you are not
interested in these details, you can just adjust sweep time until the approximate desired
number of steps or step size is obtained. (To skip these sweep time details, turn to page
3-64.)
The remaining portion of "How to Set Sweep Time" is comprised of two parts.
The first part (which starts on page 3-53) develops some calculations for Stepped
Frequency Sweep that will enable you to determine:
1) the number of steps automatically selected,
2) the frequency step size automatically selected,
3) the required sweep time that will select a desired number of frequency steps, and
4) the required sweep time that will select a desired step size.
The second part (which starts on page 3-60) develops some calculations for Phase
Continuous Frequency Sweep that will enable you to choose frequency span and sweep
time so each allows the other's settings. The sweep span limits listed for Phase
Continuous Frequency Sweep in Table 3-12 (page 3-49) will not necessarily be possible
unless sweep time is set within limits that will allow that sweep span. This same
restriction holds true when setting sweep time; that is, the sweep time settings listed in
Table 3-16 will not necessarily be possible unless sweep span is set within limits that will
allow that sweep time.
The calculations for this second part allow you to determine:
1) the minimum sweep span for a desired sweep time and frequency band,
2) the maximum sweep span for a desired sweep time and frequency band,
3) the minimum sweep time for a desired sweep span and frequency band,
4) the maximum sweep time, for a desired sweep span and frequency band,
5) the number of automatically selected X-axis steps based on a sweep time setting, and
6) the required sweep time to select a specific number of X-axis steps.
3-52