Start Freq

Sets the frequency at the left side of the graticule. While adjusting Start Freq, Stop Freq is held constant, which means that both Center Frequency and Span will change.

Start Freq also sets the frequency entry mode to Start or Stop. In Start or Stop mode, the start frequency and stop frequency values are displayed below the graticule, and the default active function in the Frequency menu is Start Freq.

Remote Command

[:SENSe]:FREQuency:STARt <freq>

[:SENSe]:FREQuency:STARt?

Example

:FREQ:STAR 200 MHz

:FREQ:STAR?

Notes

Max value depends on Hardware Options

Dependencies

By direct entry:

  • You cannot set Start Freq > Stop Freq

  • You cannot set Start Freq = Stop Freq

  • You cannot select Zero Span by setting Start Freq = Stop Freq

  • You cannot set Start Freq to a value that would create a span of less than 10 Hz

If you try to do any of the above, Stop Freq changes to maintain a minimum of 10 Hz for the difference between Start Freq and Stop Freq

With the knob or step keys:

  • You cannot increment Start Freq to a value greater than Stop Freq – 10 Hz. If already in Zero Span,  you cannot increment at all, and the first decrement is forced to at least 10 Hz

Start Freq can be limited by Span limits, if Stop Freq is below its preset value

If the electronic/soft attenuator is enabled, any attempt to set Start Freq such that Stop Freq would be >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 Start 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

The four parameters Center Frequency, Start Freq, Stop Freq and Span are interdependent, as changing one necessarily affects one or more of the others. The couplings between Center Frequency and Span are detailed under the control descriptions for those controls. These couplings also affect Start Freq and Stop Freq

Preset

Start Freq does not preset. On Mode Preset, Span & Center Frequency preset, and Start Freq is derived. On Meas Preset, only Span presets, but Center Frequency does not, so Start Freq will vary depending on Center Frequency

When Mode Preset is performed while in External Mixing, the Start frequency of the current Mode is set to the nominal Min Freq of the lowest harmonic range in the Harmonic Table for the current mixer setup

Note that, if the current measurement has a limited Span available to it, and cannot achieve the Span shown in the table (Span = Stop Freq – Start Freq), the instrument uses the maximum Span the measurement allows, and sets Center Frequency to the midpoint of the Start Freq and Stop Freq values in the Harmonic Table. Thus, in this case, Start Freq presets to a frequency below the preset Center Frequency by ½ of the maximum Span

When Restore Input/Output Defaults is performed, the mixer presets to the 11970A, whose Start frequency is 26.5 GHz

Therefore, after Restore Input/Output Defaults, if you switch to External Mixing and do Mode Preset while in Spectrum Analyzer Mode, the resulting Start Freq is 26.5 GHz

State Saved

Saved in instrument state

Min

-80 MHz, unless Source Mode is set to Tracking, in which case it is limited by the minimum frequency of the Source

Instrument Type

Min Value

VXT model M9421A

55 MHz

VXT models M9410A/11A/15A/16A

330 MHz

6.5 kHz with Option LFE

VXT model M941xE (VXT model M941xA associated with M9471A)

RF port on S9110E

330 MHz

750 kHz with Option LFE

RRH Port on S9110E

22.7 GHz

M8920A

80 kHz

If the knob or step keys are being used, depends on the value of the other three interdependent parameters

While in External Mixing, the minimum Start Freq you can set is determined by the external mixing parameters. It will be close to the minimum LO frequency (3.8 GHz if undoubled, 8.6 GHz if doubled) times the harmonic number, for the lowest harmonic range in the Harmonic Table for the current mixer setup. It can be queried with :FREQ:STARt? MIN

Max

Depends on the instrument maximum frequency – 10 Hz. Note that, if Source Mode is set to Tracking, the effective instrument maximum frequency may be limited by the source maximum frequency

If the knob or step keys are being used, it depends on the value of the other three interdependent parameters

While in External Mixing, the maximum Start Freq you can set is determined by the external mixing parameters. It will be close to the maximum LO frequency (7 GHz if undoubled, 14 GHz if doubled) times the harmonic number, for the highest harmonic range in the Harmonic Table for the current mixer setup. It can be queried with :FREQ:STARt? MAX

Annotation

Start <value> appears in the lower left corner of the display. This replaces Center <value>

Status Bits/OPC dependencies

Non-overlapped