Span
Changes the displayed frequency range symmetrically about the center frequency. While adjusting Span, Center Frequency is held constant, which means that both Start Freq and Stop Freq will change.
Pressing Span also sets the frequency entry mode to Center/Span. In Center/Span mode, the Center Frequency and Span values are displayed below the graticule, and the default active function in the Frequency menu is Center Frequency.
Span also includes a toggle switch to go back and forth between Swept Span and Zero Span. Zero Span is a special sweep type in which the instrument stops sweeping over a range of frequencies, and stays at the Center Frequency. In Zero Span, the instrument sweeps in the time domain, showing you the instantaneous amplitude versus time at the Center Frequency. For more details, see Zero Span. Selecting Swept Span places the instrument in Center/Span frequency entry mode.
When in Zero Span, you can return to your last Swept Span by pressing the Swept Span/Zero Span toggle on Span. (This replaces the Last Span function found on older HP/Agilent/Keysight Analyzers.)
NOTE
We use the term Swept Span to mean spans other than Zero Span, even though sometimes when we are in what we call a Swept Span we might be performing an FFT-style sweep, which is not a true Swept Span.
If Span is set to a value greater than the maximum allowable span of the instrument, an error message is generated indicating the data is out of range and was clipped to upper limit.
|
Remote Command |
[:SENSe]:FREQuency:SPAN <freq> [:SENSe]:FREQuency:SPAN? |
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Example |
Set the span to 2 GHz: :FREQ:SPAN 2GHz |
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Dependencies |
If the electrical attenuator is enabled, any attempt to set Span such that the Stop Freq would be >3.6 GHz results in an error If Source Mode is set to Tracking, and Span 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 In instruments with an RF Preselector, such as MXE, you cannot sweep across the band break at 3.6 GHz while the RF Preselector is on in Continuous sweep, because there is a mechanical switch that bypasses the RF Preselector above 3.6 GHz. For details, see Stop Freq |
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Couplings |
Span affects Res BW, Sweep Time, FFT & Sweep choice (including FFT Width, Phase Noise Optimization and ADC Dither auto couplings) When operating in Swept Span:
Span cannot be set to zero by setting Start Freq = Stop Freq. The value of the last setting changes to maintain a minimum difference of 10 Hz between Start Freq and Stop Freq |
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Preset |
Depends on instrument maximum frequency, mode, measurement, and selected input See Span Presets |
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State Saved |
Saved in instrument state |
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Min |
10 Hz, unless entered directly, then 0 Hz is allowed, but no value between 0 and 10 is ever allowed If the Zoomed Trace window is visible, Zero Span is not allowed, so Span may not go below 10 Hz If the Zone Spectrum window is visible, Zero Span is not allowed in the Spectrum window, so Span may not go below 10 Hz in the Spectrum window |
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Max |
Depends on instrument maximum frequency, mode, measurement, and selected input. See Span Presets If the knob or step keys are being used, depends on the value of the other three interdependent parameters: Center Frequency, Start Freq, Stop Freq Note that, if the Source Mode is set to Tracking, the effective instrument maximum Span may be limited by the source maximum frequency |
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Annotation |
Span <value> appears on the first line of the annotation in the lower right corner of display |
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Status Bits/OPC dependencies |
Overlapped if Signal Track is on (OPC does not return or clear until the zooming has completed for the new span) |
Span Presets
The following table provides the Max Span, for the various frequency options:
|
Freq Option |
Max Span (can't set higher than this) |
|---|---|
|
503 (all but CXA) |
3.7 GHz |
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503, F03 (CXA, CXA-m) |
3.08 GHz |
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507 (all but CXA) |
7.1 GHz |
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507 (CXA, CXA-m) |
7.575 GHz |
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508 (all but MXE) |
8.5 GHz |
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508 (MXE) |
8.5 GHz |
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513, F13 |
13.8 GHz |
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526 (all but CXA and MXE) |
27.0 GHz |
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526 (MXE) |
27.0 GHz |
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526, F26 (CXA, CXA-m) |
26.55 GHz |
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544 |
45.08 GHz |
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550 |
52 GHz |
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F06 & EP6 (VXT models M9410A/11A) |
6.27 GHz |
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F06 & LFE & EP6 (VXT models M9411A) |
6.5999935 GHz |
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M9415A-F06 |
6.27 GHz |
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M9415A-F08 |
8.27 GHz |
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M9415A-F12 |
12.57 GHz |
Input 2:
|
Model |
Max Span (can't set higher than this) |
|---|---|
|
CXA opt C75 |
1.58 GHz |
|
MXE |
1.000025 GHz |
Note that if you are in External Mixing, the maximum Span will be equal to the Maximum Stop Frequency – Minimum Start Frequency for the currently selected mixer.
Span Presets by Mode
|
Mode |
Preset Value |
|---|---|
|
SA |
8 MHz |
|
WCDMA |
24.6848 MHz |
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WIMAX OFDMA |
50 MHz |
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C2K |
4.5 MHz |
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TD-SCDMA |
8 MHz |
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1xEVDO |
4.05 MHz |
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DVB-T/H |
40 MHz |
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DTMB (CTTB) |
72 MHz |
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ISDB-T |
30 MHz |
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CMMB |
72 MHz |
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LTE, LTETDD, LTEAFDD, LTEATDD, MSR |
25 MHz |
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Digital Cable TV |
40 MHz |
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5G NR |
500 MHz |
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Radio Test |
175 kHz |
N9041B Span Presets
|
Input/Freq Option |
Span after Mode Preset |
Max Span (can't set higher than this) |
|---|---|---|
|
Input 1, all models |
49.99 GHz |
52 GHz |
|
Input 2, opt 585 |
84.99 GHz |
86 GHz |
|
Input 2, opt 590 |
89.99 GHz |
92 GHz |
|
Input 2, opt 5CX |
109.99 GHz |
110 GHz |
Note that if you are in External Mixing, the maximum Span is equal to Maximum Stop Freq – Minimum Start Freq for the currently selected mixer.
Zero Span
While in Swept Span, pressing the Swept Span/Zero Span toggle on Span puts you in Zero Span. You can also switch to Zero Span by setting Span to 0 Hz through SCPI or the front panel numeric keypad. However, you cannot switch to Zero Span by setting Start Freq = Stop Freq using the numeric keypad, nor by using the Step keys and the RPG to “roll” down to zero, because Span can only go as far down as 10 Hz by this means.
|
Example |
Set Span to zero, switch to Zero Span: :FREQ:SPAN 0 Hz Sending :FREQ:SPAN 1 MHz, while in Zero Span, switches to Swept span |
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Dependencies |
If the Zoomed Trace window is visible, Zero Span is not allowed If the Zone Spectrum window is visible, Zero Span is not allowed in the Spectrum window |
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Couplings |
Switching to Zero Span:
|
When you enter Zero Span, the instrument changes the displayed frequency span to 0 Hz. The horizontal axis changes to time rather than frequency. The amplitude displayed is the input signal level at the current center frequency. This is a time-domain mode that changes several measurement functions and couplings. The instrument behavior is similar to an oscilloscope with a frequency selective detector installed in front of the oscilloscope. See Application Note 150 for more information on how to use Zero Span.
While in Zero Span, setting Span to a non-zero value through SCPI or the front Panel returns the instrument to Swept Span. You can also return to your last Swept Span by pressing the Swept Span/Zero Span toggle on the Span control.
The following table summarizes the differences between Zero Span and Swept Span:
|
Zero Span |
Swept Spans |
|---|---|
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X axis is time |
X axis is frequency |
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There is no auto-Res BW selection unless the EMC Standard is CISPR or MIL |
Res BW coupled to Span when Res BW in Auto |
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There is no auto sweep time |
Sweep time coupled to Res BW when sweep time in auto |
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Interval Power calculated in Mkr Function |
Band Power calculated in Mkr Function |
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Can only define time limits when in zero span |
Can only define frequency limits when in Swept SA |
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Marker Count counts at the center frequency |
Marker Count counts at the marker frequency |
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CF Step size set to Res BW value |
CF Step autocouples to 10% of Span |
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Some Marker -> commands not available |
Other Marker -> commands not available |
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Freq entry mode always Center/Span |
Freq entry mode can be Center/Span or Start/Stop |
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N dB points reports a time difference |
N dB points reports a frequency difference |