Stop Frequency (Frequency)

The Stop frequency is the end (highest) frequency of the frequency band to analyze. For information on other ways to set the Start Frequency, see Changing Frequency Settings.

The maximum Stop frequency that the VSA can measure is determined by the measurement hardware.

The following picture shows stop frequency as compared to the other frequency parameters:

$image\freqStop_wmf.jpg$

When the Stop frequency is changed, the VSA changes the Span and Center frequencies, but does not change theStart frequency, except in these two cases:

If a Stop frequency is specified that yields an invalid span, the VSA changes the Start frequency to maintain a valid span.
If a Stop frequency is specified that is less than the Start frequency, the VSA changes the Start frequency to achieve a valid minimum span.

Display Limits for (Trace Blanking)

It is possible to select a Stop frequency that results in a negative Start frequency. It is also possible to specify a Stop frequency that exceeds the VSA's frequency range.

If a Stop frequency that results in a negative start frequency is specifed, there will not be anything displayed to the left of the minimum Start frequency. For example, if the frequency range of the VSA is 0 to 39 MHz Megahertz: A unit of frequency equal to one million hertz or cycles per second. and a Stop frequency that yields a negative Start frequency is specified, there will not be anything displayed to the left of 0 Hz. This is called Trace Blanking.

Likewise, if a Stop frequency above the VSA's frequency range is specified, there will not be anything displayed to the right of the maximum Stop frequency. In the previous example, there will not be anything displayed to the right of 39 MHz.

$image\freqBlankingUpperLim_wmf.jpg$

Start frequency limitations with 2-channel I+jQ(Ch1+j*Ch2) input mode

For information Center and Span when using dual channel I+jQ(Ch1+j*Ch2) input mode, see I+jQ Span and Frequency.

Using "Show All Points"

Use the Show All Points parameter (Utilities > Display Preferences > Trace tab) to view the blanked trace data. The Show All Points parameter displays frequency data even if it extends beyond the VSA’s standard frequency and valid data range. The data may contain alias products, so use caution when selecting this parameter.