Chapter 4 — Spectrum Analyzer 4-31 Sweep
MS20xxA VNA Master UG 10580-00166 Rev. C 4-55
Reset Sweep
This soft key stops the current sweep, clears trace averaging results, clears the
maximum hold results, if selected, and restarts the sweep at the left side of the screen.
Detection
Several detection methods tailor the performance of the instrument to meet specific
measurement requirements. In general, there are more measurement points across the
screen than display points. The various detection methods are different ways of dealing
with selecting which measurement point will be shown at each display point.
Peak
This method causes the largest measurement point to be shown for each display
point, and assures that a narrow peak is not missed.
RMS
This method performs a root-mean-square calculation of all the measurement
points in each display point, and is particularly useful in displaying the average
value of noise.
Negative
This method causes the smallest measurement point to be shown for each display
point. Typically this mode is used to help detect small discrete signals in the
presence of nearly equal values of noise. The display points that contain only
noise will tend to show lower amplitudes than those that contain discrete signals.
Sample
This is the fastest detection method since for each display point only one
frequency point is measured. Use this method when speed is of paramount
importance and the possibility of missing a narrow peak is not important.
Quasi-peak
Selects the quasi-peak detector. When the quasi-peak detector is selected, the
allowed resolution bandwidths are 200 Hz, 9 kHz, and 120 kHz. Also, the
RBW/VBW ratio is set to 1 so that the video bandwidth is the same as the
resolution bandwidth.
Back
Returns to the previous menu.
Min Sweep Time
This function allows a minimum sweep time to be specified. Use the keypad, the
directional arrow keys or the rotary knob to set the minimum sweep time from
10 microseconds to 600 seconds. When using the keypad, the available time units are
minutes, seconds, milliseconds, and microseconds.
If the required sweep time for accurate measurement is longer than the specified
minimum, then the time required for accurate measurements will prevail.
Trigger Type
Sets the type of trigger to be used.
Free Run
In this mode, a new sweep is started immediately upon completion of an old
sweep. No trigger event is required to initiate a sweep.
10580-00166C.book Page 55 Thursday, February 21, 2008 12:52 PM
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