FFT Operation | Agilent Technologies 54621A, 54621D, 24A, 42A, 22A, 41A

Making Measurements

FFT Measurement

FFT Operation

1Press the Math key, press the FFT softkey, then press the Settings softkey to display the FFT menu.

Source	Frequency	Center	Preset Span	Vertical and	Return to
select	Span	frequency	and Center	Window FFT	previous menu
			frequencies	controls

Source selects the source for the FFT. The source can be any analog channel, or math functions 1 + 2, 1 – 2, and 1 * 2.

Span sets the overall width of the FFT spectrum that you see on the display (left graticule to right graticule). Divide span by 10 to calculate the number of Hertz per division. It is possible to set Span above the maximum available frequency, in which case the displayed spectrum will not take up the whole screen. Press the Span softkey, then turn the Entry knob to set the desired frequency span of the display.

Center sets the FFT spectrum frequency represented at the center graticule on the display. It is possible to set the Center to values below half the span or above the maximum available frequency, in which case the displayed spectrum will not take up the whole screen. Press the Center softkey, then turn the Entry knob to set the desired center frequency of the display.

Preset sets the frequency Span and Center to values that will cause the entire available spectrum to be displayed. The maximum available frequency is half the effective FFT sample rate, which is a function of the time per division setting. The current FFT sample rate is displayed above the softkeys.

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Agilent Technologies 54621A, 54621D, 24A, 42A, 22A, 41A manual FFT Operation

Contents

Agilent 54621D/22D/41D/42D Mixed-Signal Oscilloscopes Utilities Display shows current input signalsHorizontal Controls select sweep speed and delay parameters Softkeys extend the functionality of command keys This Book Page Contents Trigger Types Contents Run/Stop/Single/Infinite Persistence Operation Using Labels on the Mixed-Signal Oscilloscope Cursor Measurements Saving and Recalling Traces and SetupsCapturing Data Math Functions Utilities Contents-6 Getting Started Getting Started Getting Started Setting up the Oscilloscope To inspect package contents To inspect package contents Package contents for 54620/40-Series Oscilloscopes To inspect options and accessories To inspect options and accessories Model Description To inspect options and accessories Accessories available Plug Type Cable Part Number To inspect options and accessories Power Cords To clean the oscilloscope Disconnect power from the instrumentTo clean the oscilloscope To adjust the handle To adjust the handle To power-on the oscilloscope Press the power switchTo power-on the oscilloscope To adjust the waveform intensity To adjust the waveform intensity To connect the oscilloscope analog probes To connect the oscilloscope analog probes To compensate your analog probe To compensate your analog probePress Autoscale To use the digital probes mixed-signal oscilloscope only To use the digital probes mixed-signal oscilloscope only Connect the clip to a node in the circuit you want to test Signal Lead Ground Lead Clip Signals Ground To connect a printer To connect an RS-232 cableTo connect a printer To verify basic oscilloscope operation Press the Autoscale key on the front panelTo verify basic oscilloscope operation Getting started using the oscilloscope interface To verify basic oscilloscope operation Using Quick Help Getting Started Loading an updated language file from floppy disk Loading an updated language file from floppy diskPage Front-Panel Overview Front-Panel Overview Important Oscilloscope Considerations Using Single versus Run/StopUsing Auto trigger mode versus Normal trigger mode Viewing signal detail with acquire mode Important Oscilloscope Considerations Using Vectors Display menu Post Acquisition Processing Delayed Sweep 54620/40-series Oscilloscope Front Panels 54620/40-series Oscilloscope Front Panels 54624A 4-Channel Oscilloscope Front Panel Entry knob Autoscale key Softkeys 54621D, 54622D D, and 54642D digital channels Front-Panel Operation Interpreting the display Interpreting the display To use analog channels to view a signal To use analog channels to view a signalExample To use digital channels to view a signal To use digital channels to view a signal Undo Autoscale To display signals automatically using AutoscaleTo display signals automatically using Autoscale How Autoscale Works To apply the default factory configuration To apply the default factory configuration Measurement Hints To adjust analog channel vertical scaling and positionCenter the signal on the display using the position knob To adjust analog channel vertical scaling and position To set the vertical expand reference for the analog signal To set analog channel probe attenuation factorExpand About Center To display and rearrange the digital channels To display and rearrange the digital channels Press the Main/Delayed, then press the Vernier softkey To operate the time base controlsTo operate the time base controls To start and stop an acquisition First set trigger Mode/Coupling Mode softkey to NormalTo start and stop an acquisition To make a single acquisition Press Main/Delayed To use delayed sweepPress the Delayed softkey To use delayed sweep To make cursor measurements To make cursor measurements To make automatic measurements Choose what measurement you want on that source by pressingTo make automatic measurements To modify the display grid To print the displayTo modify the display grid Triggering the Oscilloscope Triggering the Oscilloscope Trigger Out connector Selecting Trigger Modes and Conditions To select the Mode and Coupling menu To select a trigger mode Normal, Auto, Auto Level To select a trigger mode Normal, Auto, Auto LevelAuto Level and Auto modes Normal mode To select trigger Coupling To select Noise Reject and HF RejectTo select trigger Coupling To set holdoff To set holdoff To set holdoff Holdoff Operating Hints External Trigger Probe Settings External Trigger InputExternal Trigger Input Previous menu MegaZoom Technology Simplifies Triggering Trigger Types To use Edge triggering Select 1, 2, Ext, or Line as the trigger sourceTo use Edge triggering To use Edge triggering To use Pulse Width triggering To use Pulse Width triggering Press the qualifier softkey to select the time qualifier Qualifier time set softkey Qualifiers can be set as follows To use Pattern triggering To use Pattern triggering Specifying an Edge in a Pattern To use can triggering To use can triggering Press the Trigger softkey to select the trigger condition Press the Baud softkey to set the can signal baud rate To use Duration triggering To use Duration triggering To use Duration triggering When the duration trigger occurs To use I2C triggering To use I2C triggering Ack Data Stop Start Address R/W Condition Frame Start Addr7 Read Ack Data or Condition 26th clock edge To use I2C triggering To use Sequence triggering To use Sequence triggering Sequence Selected Press the Stage softkey and select Find Press the Find softkey and select the Find stage conditionEdge Pattern 1 and Edge Edge Pattern 2 and Edge Nth Edge Press the Stage softkey and select Trigger on Edge 1 or Pattern 1 and Edge Timeout Press the Stage softkey and select Reset on To use Sequence triggering To use SPI triggering To use SPI triggering Resetting all bits in the serial data string to one value Assign source channels to the clock, data, and frame signals To use SPI triggering To use SPI triggering To use TV triggering To use TV triggering To use TV triggering Provide Correct Matching Press the Mode softkey to select the TV triggering mode TV standard Field Alt Field Alternate Triggering To trigger on a specific line of video Line Number Represents Count Line Numbers per Field for Each TV Standard To trigger on all TV line sync pulses To trigger on a specific field of the video signal To trigger on all fields of the video signal To trigger on odd or even fields Holdoff Settings To use USB triggering To use USB triggering To use USB triggering Trigger Out connector MegaZoom Concepts and Oscilloscope Operation MegaZoom Concepts and Oscilloscope Operation MegaZoom Concepts Deep Memory Deep MemoryMemory depth values Oscilloscope Responsiveness Oscilloscope ResponsivenessMegaZoom Technology Display Update Rate Display Update Rate To setup the Analog channels To setup the Analog channelsTurning channels off To setup the Analog channels Press the Imped impedance softkey Press the BW Limit softkey to turn on bandwidth limitingPress the Invert softkey to inverted the selected channel Press the Probe softkey to display the channel probe menu Main mode To setup the Horizontal time basePress the Main softkey to select Main horizontal mode To setup the Horizontal time base Press the Vernier softkey to turn on the time base vernier To setup the Horizontal time base Delayed mode To setup the Horizontal time base XY mode Roll mode Acquisition Modes Press the Acquire key to display the Acquire menuAcquisition Modes Peak Detect All points displayed after Single or Stop Smoothing # Avgs=1 or High-resolution mode Average Mode Realtime Mode Clear display Display modesPress the Display key to view the Display menu Infinite Persistence Vectors On/Off Pan and Zoom Pan and ZoomZoom To pan and zoom a waveform To pan and zoom a waveform Run/Stop/Single/Infinite Persistence Operation Acquiring Data Acquiring DataSingle versus Run/Stop Single Memory Depth/Record LengthMemory Depth/Record Length Run/Stop versus Single To run and stop an acquisition To run and stop an acquisitionTo take a single trace Press the Single key Operating Hints Connect a signal to the oscilloscope Set up the triggerTo capture a single event To capture a single event To use infinite persistence To use infinite persistenceClearing stored infinite persistence waveforms To clear the waveform display Press the Display key, then press the Clear Display softkeyTo clear the waveform display To display digital channels using Autoscale Configuring the Mixed-Signal Oscilloscope Activity indicator Interpreting the digital waveform displayInterpreting the digital waveform display List of stacked channels To turn individual channels on and off To turn individual channels on and off Displayed To force all channels on or all channels offTo change the display size of the digital channels Press the Turn on or Turn off softkey To change the logic threshold for digital channels To change the logic threshold for digital channels Using Digital Channels to Probe Circuits Using Digital Channels to Probe CircuitsInput Impedance High-Frequency Probe Equivalent Circuit Probe Grounding Best Probing Practices Using Labels on the Mixed-Signal Oscilloscope To turn the label display on or off To turn the label display on or off To assign a predefined label to a channel Press the Label keyTo assign a predefined label to a channel Label Assignment Auto-Increment Features To define a new labelTo define a new label To define a new label Label List Management Defaulting labels without erasing the default library To reset the label library to the factory defaultPress the Default Library softkey To reset the label library to the factory default Saving and Recalling Traces and Setups Press the Save/Recall key to display the Save/Recall menuMaking a hardcopy print To Autosave traces and setups To Autosave traces and setups MegaZoom Concepts and Oscilloscope Operation To save traces and setups to a new file on the floppy disk To save traces and setups to a new file on the floppy diskTo create a new file name, press the New File softkey To recall traces and setups To recall traces and setupsRecalling overwrites current settings Saving printing screen images to floppy disk Press the CSV, TIF, or BMP softkeySaving printing screen images to floppy disk Recalling the factory default setup Recalling the factory default setup Making Measurements Concepts about the 54620/40-series Oscilloscopes Making Measurements Capturing Data Main and Delayed Sweep Making Measurements To use delayed sweep To reduce the random noise on a signal To reduce the random noise on a signal LF Reject Press the Acquire key, then press the Averaging softkey Use averaging to reduce noise on the displayed waveform Smoothing # Avgs=1 or High-resolution mode Making Measurements Characterize the glitch with delayed sweep To use the Roll horizontal mode Press the Main/Delayed key, then press the Roll softkeyTo use the Roll horizontal mode To use the XY horizontal mode To use the XY horizontal mode Signal centered on the display Calculate the phase difference using the formula below Signals are 90 out of phase Signals are in phase Math Operating Hints Math Functions Math Scale and Offset Math Scale and OffsetMath Scale and Offset are Set Automatically Multiply Multiply Subtract Subtract Differentiate Differentiate Figure below shows an example of differentiate Integrate Integrate Integrate and Signal Offset FFT Measurement FFT Measurement Aliasing FFT Operation Scale and offset considerations FFT Measurement Hints FFT Measurement FFT Measurement Hints Cursor Measurements To make cursor measurements Select the X and Y softkeys to make a measurement Cursor Examples Cursors measure frequency of pulse ringing Measuring pulse width with cursors Preshoot Overshoot Phase DelayAutomatic Measurements Average Amplitude Base Maximum Minimum Peak-to-Peak RMS Top Making automatic measurements Making automatic measurements Digital channel time measurements Making time measurements automaticallyMaking time measurements automatically FFT measurements Period CounterDuty Cycle Frequency Width Making time measurements automatically Fall TimeRise Time + Width Isolating an event for frequency measurement Making time measurements automatically At Min Digital channel measurements Making Delay and Phase MeasurementsMaking Delay and Phase Measurements Delay Phase Measurement Making voltage measurements automatically Making voltage measurements automaticallyMath Measurements and Units Measurement definitions Top Using delayed sweep to isolate a pulse for Top measurement Making overshoot and preshoot measurements Making overshoot and preshoot measurementsPreshoot Making overshoot and preshoot measurements Overshoot Page Utilities Utilities To configure Quick Help languages To configure Quick Help languages Language Info softkey Loading an updated language file from floppy disk To update your instrument to the latest application software To configure a printer To configure a printerPress the Format softkey to select the print format Form feed CSV lengthScale factors Gray scale printing Deleted files cannot be recovered To use the floppy diskTo use the floppy disk Press the Baud softkey to set the RS-232 baud rate To set up the I/O port to use a controllerTo set up the I/O port to use a controller Press the XON DTR softkey to set the RS-232 handshake RS-232 Connections Pin Number Signal To set the clock To set the clock To set up the screen saver To set up the screen saverPress the Saver softkey to select the screen saver type To set up the screen saver User Cal To perform service functionsTo perform service functions Press Start User Cal to start the routine User Cal Status Self testAbout Oscilloscope Expand softkey Default Library softkey mixed-signal oscilloscopes onlyTo set other options To set other options Performance Characteristics Performance Characteristics Agilent 54620-series Performance Characteristics Acquisition Analog ChannelsAcquisition Digital Channels on 54621D and 54622D only Vertical System Analog Channels Agilent 54620-series Performance Characteristics Accuracy = ±2.0%80 mV + 0.4%80 mV = ±1.92 mV Vertical System Digital Channels 54621D and 54622D only Sample rate of 200/400 MSa/s Horizontal Can Trigger System Analog Channel Triggering Digital D15 D0 Channel Triggering 54621D and 5462 2DExternal EXT Triggering Display System Measurement Features Storage FFT General Characteristics Power RequirementsInstallation categories Agilent 54620-series Performance Characteristics Acquisition Digital Channels on 54641D and 54642D only Agilent 54640-series Performance Characteristics Agilent 54640-series Performance Characteristics Vertical System Digital Channels 54641D and 54642D only Range Ns/div to 50 s/div Resolution Vernier Minimum pulse width setting 2 ns Digital D15 D0 Channel Triggering 54641D and 54642D Display System Window Rectangular, Flattop, Hanning Noise Floor General Characteristics Page Numerics Index Missing acknowledge condition, I2C trigger Index Index-3 Index-4 Declaration of Conformity EMC Product Regulations Declaration of Conformity Product Regulations Safety Agilent Technologies, Inc Document Warranty