3 IQ Analyzer (Basic) Mode
3.2 IQ Waveform Measurement
LO Dither
When LO Dither is turned on, the local oscillator frequency is rapidly changed by
small, random amounts. This helps spread the power of spurious signals within the
passband, which lowers their level, thus increasing dynamic range. This is only
required in very wide passbands, so this feature only appears with Option H1G.
Remote Command
[:SENSe]:WAVeform:LO:DITHer[:STATe] ON | OFF | 1 | 0
[:SENSe]:WAVeform:LO:DITHer[:STATe]?
Example
:WAV:LO:DITH 1
:WAV:LO:DITH?
Dependencies Only available when the instrument has the Option H1G installed. If you try to turn ON LO Dither in any
other case, an error message is generated, -241,"Hardware missing; Option H1G required"
Only appears in some Modes (for example, VMA and IQ Analyzer)
The LO Dither function is turned OFF and grayed-out when the IF Path is set to a path other than 1
GHz. If you press the grayed-out control, a warning message “LO Dither only available with IF Path 1
GHz” is shown. If you try to set LO Dither to ON remotely while it is grayed-out, a message “-
221,Settings conflict; LO Dither only available with IF Path 1 GHz" is returned
When LO Dither is turned ON, the Phase Noise Optimization control is grayed-out. If you try to change
the PNO value via front panel or SCPI in that case, an error is generated, “LO Dither must be turned off
to change this value"
Couplings As with most parameters with an AUTO state, "Auto Couple" on page 374 sets it to Auto, which then
selects AUTOrange. Setting any specific value (AUTOrange, LOW or HIGH) sets the AUTO state to
false
When LO Dither is turned ON, Phase Noise Optimization is set to “Best Close-In”. If the Phase Noise
Optimization value changes due to turning on LO Dither, a warning message “Phase Noise
Optimization changed due to LO Dither activation” is displayed
Preset
OFF
State Saved Saved in instrument state
IF Gain
Selects the range of IF gain.
When in AUTOrange mode, the IF checks its range once for data acquisition, to
provide the best signal to noise ratio. You can specify the range for the best speed,
and optimize for noise or for large signals.
When IF Gain is set to AUTOrange, the IF Gain is set to HIGH initially for each chunk
of data. The data is then acquired. If the IF overloads, then the IF Gain is set to LOW,
and the data is re-acquired. Because of this operation, the AUTOrange setting
requires more measurement time, as the instrument checks/resets its range. You
can get faster measurement speed by forcing the range to either the HIGH or LOW
IQ Analyzer Mode User's &Programmer's Reference 392
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