Scale and offset considerations | Agilent Technologies 22A, 54621D

Making Measurements

FFT Measurement

2 Press the More FFT softkey to display additional FFT settings.

FFT Scale	FFT Offset	Window	Return to
			previous menu

Scale allows you to set your own vertical scale factors for FFT expressed in dB/div (decibels/division). Press the Scale softkey, then turn the Entry knob to rescale your math function.

Offset allows you to set your own offset for the FFT. The offset value is in dB and is represented by the center graticule of the display. Press the Offset softkey, then turn the Entry knob to change the offset of your math function.

Scale and offset considerations

If you do not manually change the FFT scale or offset settings, when you turn the horizontal sweep speed knob, the span and center frequency settings will automatically change to allow optimum viewing of the full spectrum. If you do manually set scale or offset, turning the sweep speed knob will not change the span or center frequency settings, allowing you see better detail around a specific frequency. Pressing the FFT Preset softkey will automatically rescale the waveform and span and center will again automatically track the horizontal sweep speed setting.

Window selects a window to apply to your FFT input signal:

Hanning - window for making accurate frequency measurements or for resolving two frequencies that are close together.

Flat Top - window for making accurate amplitude measurements of frequency peaks.

Rectangular - good frequency resolution and amplitude accuracy, but use only where there will be no leakage effects. Use on self-windowing waveforms such as pseudo-random noise, impulses, sine bursts, and decaying sinusoids.

3To make cursors measurements, press the Cursors key and set the Source softkey to Math.

Use the X1 and X2 cursors to measure frequency values and difference between two frequency values (∆ X). Use the Y1 and Y2 cursors to measure amplitude in dB and difference in amplitude (∆ Y).

5-28

Image 196

Agilent Technologies 22A, 54621D, 24A, 42A, 54621A, 41A manual Scale and offset considerations

Contents

Agilent 54621D/22D/41D/42D Mixed-Signal Oscilloscopes Display shows current input signals Horizontal Controls select sweep speed and delay parametersSoftkeys extend the functionality of command keys Utilities This Book Page Contents Contents Trigger Types Using Labels on the Mixed-Signal Oscilloscope Run/Stop/Single/Infinite Persistence Operation Saving and Recalling Traces and Setups Capturing DataMath Functions Cursor Measurements 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 To inspect options and accessories Accessories available Model Description To inspect options and accessories Power Cords Plug Type Cable Part Number Disconnect power from the instrument To clean the oscilloscopeTo clean the oscilloscope To adjust the handle To adjust the handle Press the power switch To power-on the oscilloscopeTo 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 an RS-232 cable To connect a printerTo connect a printer Press the Autoscale key on the front panel To verify basic oscilloscope operationTo 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 Using Single versus Run/Stop Using Auto trigger mode versus Normal trigger modeViewing signal detail with acquire mode Important Oscilloscope Considerations Important Oscilloscope Considerations Using Vectors Display menu Delayed Sweep Post Acquisition Processing 54620/40-series Oscilloscope Front Panels 54620/40-series Oscilloscope Front Panels 54624A 4-Channel Oscilloscope Front Panel Entry knob Autoscale key Softkeys Front-Panel Operation 54621D, 54622D D, and 54642D digital channels 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 To display signals automatically using Autoscale To display signals automatically using AutoscaleHow Autoscale Works Undo Autoscale To apply the default factory configuration To apply the default factory configuration To adjust analog channel vertical scaling and position Center the signal on the display using the position knobTo adjust analog channel vertical scaling and position Measurement Hints To set analog channel probe attenuation factor To set the vertical expand reference for the analog signalExpand About Center To display and rearrange the digital channels To display and rearrange the digital channels To operate the time base controls Press the Main/Delayed, then press the Vernier softkeyTo operate the time base controls First set trigger Mode/Coupling Mode softkey to Normal To start and stop an acquisitionTo make a single acquisition To start and stop an acquisition To use delayed sweep Press the Delayed softkeyTo use delayed sweep Press Main/Delayed To make cursor measurements To make cursor measurements Choose what measurement you want on that source by pressing To make automatic measurementsTo make automatic measurements To print the display To modify the display gridTo modify the display grid Triggering the Oscilloscope Trigger Out connector Triggering the Oscilloscope To select the Mode and Coupling menu Selecting Trigger Modes and Conditions 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 Noise Reject and HF Reject To select trigger CouplingTo select trigger Coupling To set holdoff To set holdoff To set holdoff Holdoff Operating Hints External Trigger Input External Trigger Probe SettingsExternal Trigger Input Previous menu Trigger Types MegaZoom Technology Simplifies Triggering Select 1, 2, Ext, or Line as the trigger source To use Edge triggeringTo 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 Qualifiers can be set as follows Qualifier time set softkey To use Pattern triggering To use Pattern triggering Specifying an Edge in a Pattern To use can triggering To use can triggering Press the Baud softkey to set the can signal baud rate Press the Trigger softkey to select the trigger condition 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 Find softkey and select the Find stage condition Press the Stage softkey and select FindEdge Pattern 1 and Edge Press the Stage softkey and select Trigger on Edge Pattern 2 and Edge Nth Edge Press the Stage softkey and select Reset on Edge 1 or Pattern 1 and Edge Timeout 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 Press the Mode softkey to select the TV triggering mode To use TV triggering Provide Correct Matching TV standard Field Alt Field To trigger on a specific line of video Alternate Triggering Line Numbers per Field for Each TV Standard Line Number Represents Count 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 BW Limit softkey to turn on bandwidth limiting Press the Imped impedance softkeyPress the Invert softkey to inverted the selected channel Press the Probe softkey to display the channel probe menu To setup the Horizontal time base Press the Main softkey to select Main horizontal modeTo setup the Horizontal time base Main mode 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 Roll mode XY mode Press the Acquire key to display the Acquire menu Acquisition ModesAcquisition Modes All points displayed after Single or Stop Peak Detect Average Mode Smoothing # Avgs=1 or High-resolution mode Realtime Mode Display modes Press the Display key to view the Display menuInfinite Persistence Clear display 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 Memory Depth/Record Length Memory Depth/Record LengthRun/Stop versus Single Single To run and stop an acquisition To take a single tracePress the Single key To run and stop an acquisition Connect a signal to the oscilloscope Set up the trigger To capture a single eventTo capture a single event Operating Hints To use infinite persistence To use infinite persistenceClearing stored infinite persistence waveforms Press the Display key, then press the Clear Display softkey To clear the waveform displayTo clear the waveform display Configuring the Mixed-Signal Oscilloscope To display digital channels using Autoscale Interpreting the digital waveform display Activity indicatorInterpreting the digital waveform display List of stacked channels To turn individual channels on and off To turn individual channels on and off To force all channels on or all channels off To change the display size of the digital channelsPress the Turn on or Turn off softkey Displayed 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 Press the Label key To assign a predefined label to a channelTo assign a predefined label to a channel To define a new label Label Assignment Auto-Increment FeaturesTo define a new label To define a new label Label List Management To reset the label library to the factory default Press the Default Library softkeyTo reset the label library to the factory default Defaulting labels without erasing the default library Press the Save/Recall key to display the Save/Recall menu Saving and Recalling Traces and SetupsMaking 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 Press the CSV, TIF, or BMP softkey Saving printing screen images to floppy diskSaving printing screen images to floppy disk Recalling the factory default setup Recalling the factory default setup Making Measurements Making Measurements Concepts about the 54620/40-series Oscilloscopes Main and Delayed Sweep Capturing Data Making Measurements To use delayed sweep To reduce the random noise on a signal To reduce the random noise on a signal LF Reject Use averaging to reduce noise on the displayed waveform Press the Acquire key, then press the Averaging softkey Smoothing # Avgs=1 or High-resolution mode Making Measurements Characterize the glitch with delayed sweep Press the Main/Delayed key, then press the Roll softkey To use the Roll horizontal modeTo 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 Functions Math Operating Hints 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 Phase Delay Automatic MeasurementsAverage Amplitude Base Maximum Minimum Peak-to-Peak RMS Top Preshoot Overshoot Making automatic measurements Making automatic measurements Making time measurements automatically Making time measurements automaticallyFFT measurements Digital channel time measurements Counter Duty CycleFrequency Period Making time measurements automatically Fall Time Rise Time+ Width Width Making time measurements automatically At Min Isolating an event for frequency measurement Making Delay and Phase Measurements Making Delay and Phase MeasurementsDelay Digital channel measurements Phase Measurement Making voltage measurements automatically Making voltage measurements automaticallyMath Measurements and Units Measurement definitions Using delayed sweep to isolate a pulse for Top measurement Top 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 Loading an updated language file from floppy disk Language Info softkey 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 CSV length Scale factorsGray scale printing Form feed To use the floppy disk Deleted files cannot be recoveredTo use the floppy disk To set up the I/O port to use a controller To set up the I/O port to use a controllerPress the XON DTR softkey to set the RS-232 handshake Press the Baud softkey to set the RS-232 baud rate Pin Number Signal RS-232 Connections 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 To perform service functions To perform service functionsPress Start User Cal to start the routine User Cal Self test User Cal StatusAbout Oscilloscope Default Library softkey mixed-signal oscilloscopes only To set other optionsTo set other options Expand softkey Performance Characteristics Performance Characteristics Acquisition Analog Channels Agilent 54620-series Performance CharacteristicsAcquisition Digital Channels on 54621D and 54622D only Agilent 54620-series Performance Characteristics Vertical System Analog Channels Vertical System Digital Channels 54621D and 54622D only Accuracy = ±2.0%80 mV + 0.4%80 mV = ±1.92 mV Horizontal Sample rate of 200/400 MSa/s Trigger System Can Digital D15 D0 Channel Triggering 54621D and 5462 2D Analog Channel TriggeringExternal EXT Triggering Measurement Features Display System FFT Storage Power Requirements General CharacteristicsInstallation categories Agilent 54620-series Performance Characteristics Agilent 54640-series Performance Characteristics Acquisition Digital Channels on 54641D and 54642D only 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 Index Numerics Index Missing acknowledge condition, I2C trigger Index-3 Index-4 Declaration of Conformity Product Regulations EMC Declaration of Conformity Product Regulations Safety Document Warranty Agilent Technologies, Inc