915
Common Measurement Functions
FREQ Channel
Dependencies: By direct entry:
You cannot set the Stop frequency < Start frequency. You cannot set Start
frequency = Stop frequency. You cannot select zero span by setting Start =
Stop. You cannot set Stop Frequency to a value that would create a span of
less than 10 Hz. If you try to do any of these, Start Frequency will change to
maintain a minimum value of 10 Hz for the difference between Start and Stop.
With the knob or step keys:
Cannot decrement Stop Freq to a value less than Start Freq + 10 Hz. If already
in zero span, cannot decrement at all, and the first increment will be forced to
at least 10 Hz.
The Stop Frequency can be limited by Span limits, if the Start Frequency is
above its preset value.
If the electronic/soft attenuator is enabled, any attempt to set the Stop
Frequency >3.6 GHz fails and results in an advisory message. If the
equivalent SCPI command is sent, this same message is generated as part of a
“–221, Settings conflict” warning.
If Source Mode is set to Tracking, and the Max or Min Stop Freq is therefore
limited by the limits of the source, a warning message is generated, “Data out
of range;clipped to source max/min” if these limits are exceeded. Note that
for an external source, these limits can be affected by the settings of Source
Numerator, Source Denominator and Power Sweep.
Couplings: In the Spectrum Analyzer, the four parameters Center Freq, Start Freq, Stop
Freq and Span are interdependent, as changing one necessarily affects one or
more of the others. The couplings between Center Freq and Span are detailed
under the key descriptions for those keys. These couplings also affect Start
Freq and Stop Freq.
You cannot set Start frequency = Stop frequency. You cannot select zero span
by setting Start = Stop. The instrument will alter the value of the last setting to
maintain a minimum value of 10 Hz for the difference between Start and Stop.