MDO3000 Programmer Manual.pdf - 第615页
Commands Listed in Alphabetical Order RF:SPECTRogr am:SLICETIMe? (Query Only) Returns the time stamp of the selected spectrogram slice (specified using :RF:SPECTRogr am:SLICESELect). The value represents the number of sec…
Commands Listed in Alphabetical Order
running, are ig
nored. The query form returns the currently selected spectrogram
slice.
To use this com
mand, first turn on the spectrogram (RF:SPECTRogram:STATE).
Then query the number of slices (RF:SPECTRogram:NUMSLICEs?). Stop the
acquisition when you’ve reached the number of desired slices. Then select the
slice to display (RF:SPECTRogram:SLICESELect).
Each slice of the spectrogram corresponds to a single RF acquisition. The FFT
samples the entire spectrum for the incoming signal (at the rate with which new
spectrums are acquired). The newest spectrum is on the bottom edge of the
spectrogram, and the oldest is on the top edge. When the oscilloscope is stopped,
you can sc
roll “back in time” through the spectrogram using the spectrum slice
control. When you select a spectrogram slice, it is displayed in the bottom
window as the RF Normal trace.
NOTE. When acquisitions are stopped and the spectrogram is displayed, the
spectrogram slice trace is displayed as the RF Normal frequency domain trace.
Condi
tions
MDO3000, MDO4000/B, or MDO4000C models with option SA3 or SA6 only.
Group
RF
Syntax
RF:SPECTRogram:SLICESELect <NR1>
RF:SPECTRogram:SLICESELect?
Related Commands
RF:SPECTRogram:STATE, RF:SPECTRogram:NUMSLICEs?,
Arguments
<NR1> is an integer that specifies the spectrogram slice number that is to be
displayed.
For the MDO4000/B/C models, allowable slice numbers range from 0 to –327 in
full-screen mode, and 0 to –147 in split-screen mode. For MDO300
0models,
there is no split-screen mode – the slice numbers always range from 0 to –197.
(The range is negative because the numbering starts with the latest slice (0) and
proceeds backwards in time.)
Examples
RF:SPECTRogram:SLICESELect –5 would select the slice that is five
acquisitions before the most recent one.
RF:SPECTRogram:SLICESELect? might return 0, indicating that the latest
spectrogram slice is being displayed.
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Commands Listed in Alphabetical Order
RF:SPECTRogr
am:SLICETIMe? (Query Only)
Returns the time stamp of the selected spectrogram slice (specified using
:RF:SPECTRogram:SLICESELect).
The value represents the number of seconds since spectrogram acquisitionswere
started after the instrument was powered up, or since the spectrogram was cleared
(see RF:SPE
CTRogram).
Group
RF
Syntax
RF:SPECTRogram:SLICETIMe?
Examples
RF:SPECTR:SLICETIME? returns 0.0E+0.
RF:SPECTRogram:STATE
This command switches the frequency domainspectrogramdisplayonoroff.
The spectrogram illustrates how frequency and amplitude change over time.
It is useful for monitoring slowly-changing RF events, and for identifying
low amplitude signals too subtle for the eye to catch in a regular frequency
domain display. The x-axis shows frequency, and the y-axis shows time.
Amplitude is represented by the color of the trace. Cold colors (blue, green)
indicate low amplitude, and hot colors (red, yellow) indicate high amplitude.
When acquisitions are stopped, you can navigate back through each spectrum
slice in the spectrogram by using the RF:SPECTRogram:NUMSLICEs? and
RF:SPECTRogram:SLICESELect commands.
Conditions
MDO3000, MDO4000/B, or MDO4000C models with option SA3 or SA6 only.
Group
RF
Syntax
RF:SPECTRogram:STATE {OFF|ON|0|1}
RF:SPECTRogram:STATE?
Related Commands
RF:SPECTRogram:NUMSLICEs?, RF:SPECTRogram:SLICESELect
Examples
RF:SPECTRogram:STATE ON or 1 turns the frequency domain spectrogram
display on.
MDO4000/B/C, MSO/DPO4000B and MDO3000 Series Oscilloscopes Programmer Manual 2-585
Commands Listed in Alphabetical Order
RF:SPECTRogra
m:STATE?
might return 0, indicating that the spectrogram
function is off.
RF:SPECTRogram:TIMe? (Query Only)
Queries the number of seconds in the spectrogram since continuous acquisition
started. The value returned is always <= 0.
Group
RF
Syntax
RF:SPECTRogram:TIMe?
Examples
RF:SPECTR:TIME? might return -66.8174, indicating that there were
66.8174 seconds in the spectrogram since continuous acquisition started.
RF:SPECTRUMMode
When only the frequency domain waveforms are displayed (no time domain
waveforms), you can choose whether the MDO4000/B/C should use Triggered
mode or Free Run mode. (MDO3000 series models only use Free Run mode.)
When Triggered mode is selected, you can control all trigger settings, including
Normal and Auto triggering. When Free Run mode is selected, the oscilloscope
generates RF acquisitions as fast as possible. The default is
FREErun. (On an
MDO4000/B/C series model, in order to display only the frequency domain
waveforms, you need turn off all time domain waveforms, including channels1-
4, digital channels 0 - 15, buses, time domain math waveforms, time domain
reference waveforms, and any RF vs. Time traces.)
When the MDO4000/B/C oscilloscope displays both
time and frequency domain
waveforms, then the instrument’s trigger system is in control of the Triggered
mode and the RF acquisitions.
NOTE. Note: the Free Run spectrum mod
e is only possible when all analog and
digital channels are turned off.
Conditions
MDO4000/B/C models only.
Group
RF
Syntax
RF:SPECTRUMMode {TRIGgered|FREErun}
RF:SPECTRUMMode?
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