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Agilent Technologies Agile or Elusive Signals, Information Sheet

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Agilent Technologies Agile or Elusive Signals Information Sheet Download Page 11

©  2013  Agilent Technologies  

11 

©  2013  Agilent Technologies  

If Processing is 

Faster than Sampling

, Perform Additional FFTs With 

Partially-New Time Records as Samples Come In 

 

 

 

 

 

 

 

 

Avoid Loss of Data Due to Windowing 

Accurate Amplitude Measurements of Short Duration Signals 

Overlap Processing 

Overlap 0% 

Overlap 50% 

Processor Idle 

Window  
Function 

Summary of Contents for Agile or Elusive Signals

Page 1: ... 2013 Agilent Technologies Analyze Agile or Elusive Signals Using Real Time Measurement and Triggering Ben Zarlingo Agilent Technologies Inc ...

Page 2: ...roubleshooting Optimizing Two Case Studies Dynamic signal environment ISM band Radar signal Choosing Using Techniques Tools Make the most of what you already know own Swept spectrum analyzers Vector signal analyzers VSA software Oscilloscopes Real time analyzers Using Triggering to Enhance Measurement Effectiveness ...

Page 3: ...y Regulated Signals Not Explicitly Coordinated WLAN typically dominant occupant Bluetooth Cordless Phones And 1 kW microwave ovens And almost anything else Very Dynamic Content not known at any specific point in time May be very low occupancy Lots of Collision Tolerance May Be Needed Potential Cliff Effect at Some Degree of Crowding ...

Page 4: ...160 MHz Dynamics X2 swept RBW changing signals Confuse the View Peak Hold Detects Signals but Frequency Overlap Obscures Signals Typically Short Duty Cycle Total Low Occupancy POI is Approx Low useful concept even if not strictly applicable Single Sweep fast but retrace not as fast Peak Hold short Peak Hold long ...

Page 5: ... Time Analyzer Density or Histogram Display Gap Free Analysis No Signals Missed Density Display Shows Signals Inside Signals Fast Full Display Update Rate Shows Signal Dynamics See Unexpected Behavior Even If Infrequent Individual Display Updates Combine Thousands of Spectra ...

Page 6: ... Latest or Selected Spectrum Same Spectral Data as Density Histogram Individual Spectrogram Line Represents Many Spectra typically thousands View into Dynamics Timing Acquisition Time Setting Affects Way Spectra are Combined to Form Display Update WLAN Signals Active Continuously What are Vertical Bars A Multitone Signal ...

Page 7: ...on Time Determines Amount of Data Processed for Spectrum or Spectrogram Trace Update Each Trace Update Spectrogram Line Represents Fewer Spectra More Trace Updates Second Finer Time Resolution Spectrogram Covers Shorter Interval Determines Time Scale of Spectrogram Use Spectrogram Trace Buffer to Examine Signal Dynamics ...

Page 8: ... High Data Density Easily Understand Signal or Event Frequency Find Very Infrequent Events Find Unexpected Events Behavior Limitations Combining traces combines behavior from different times Limited flexibility RBW span combinations Limited frequency span Power spectrum only Markers only on combined spectrum or density at a point ...

Page 9: ...lly spectrum Real Time Bandwidth RTBW The widest analysis bandwidth where an analyzer can maintain real time operation Duration of maintaining real time operation is not specified it may assumed to be short term or long term or unlimited Current Usage for Signal Analyzers A spectrum or FFT analyzer having a signal processing path where most or all samples even at wide bandwidths are used to create...

Page 10: ...t Technologies Real Time Operation In Real Time Operation the Analyzer s Processing CALC is Fast Enough to Keep Up with All Data Samples CALC Time Includes FFT or Power Spectrum Averaging Display Updates etc However some data may still be lost ...

Page 11: ...ing is Faster than Sampling Perform Additional FFTs With Partially New Time Records as Samples Come In Avoid Loss of Data Due to Windowing Accurate Amplitude Measurements of Short Duration Signals Overlap Processing Overlap 0 Overlap 50 Processor Idle Window Function ...

Page 12: ...t and time to discovery Signals found can be measured as necessary Knowledge of signals may be perfect or simply adequate A More Rigorous Treatment in MicroApp From Richard Overdorf Understanding Probability of Intercept for Intermittent Signals IMS 2013 MicroApp presentation Agilent Aerospace Defense Symposium presentation 2013 Evaluate These Techniques Against Your Requirements ...

Page 13: ...igger FMT Trigger Based on In Band Power scalar Spectrum Spectral Mask Eval High Low Limits Logic Trigger Generated from High Speed FFT Engine Trigger Not Time Aligned Trigger Timing Resolution May Be 1 FFT Period Trigger a Single Spectrum Measurement or Time Capture VSA etc ...

Page 14: ...alysis The Logical Extension and Complement to a Real Time Analyzer Superheterodyne Downconversion to All Digital IF Adaptable to swept spectrum analysis and real time analyzer Full vector data preserved Capture Memory Measurements Short Long Data Block Vector Demodulation ...

Page 15: ... 2013 Agilent Technologies 15 2013 Agilent Technologies VSA Spectrum of ISM Band Signals 1 kpoint vs 100 kpoints Much More Informative Higher POI ...

Page 16: ...aster than FFT speed goes down Narrow Frequency Span to the Minimum Needed Time record is longer in time for given number of points Use IF Magnitude Trigger Pre Post Delays Holdoff Avoid measuring when no signal present in span Use Persistence or Density History Displays Typically persistence to make peaks last long enough to be noticed Peak Hold Result POI Dramatically Improved Though may not be ...

Page 17: ...itude Frequency Mask Triggers Triggered Individual Measurements or Signal Captures Sqrt I2 Q2 of each sample is easier faster VSAs FFT power Spectrum is slower but more selective RTSAs VSA architecture can do both Capture Memory Measurements Short Long Data Block Vector Demodulation IF Mag or Freq Mask Trig ...

Page 18: ...Agilent Technologies Flexible Triggering to Initiate Capture IF Magnitude Trigger Frequency Mask Trigger Pre Post Trigger Delay Adjustable Power Level Delay Holdoff time type Other Types Channel External TTL Periodic Magnitude Freq Mask ...

Page 19: ...lysis Including Vector Demodulation Time Capture Playback Connection to Many Signal Analzyer Front Ends Signal analyzers Oscilloscopes Digitizers Multi Channel Analysis Including Channel Time Alignment Including multi channel capture analysis Beam forming MIMO space time coding Multi Band Analysis Multi Measurements Excellent Complement to Single Channel RTSA ...

Page 20: ...Capture Just Press the Red Button Use Existing Center Span Wider is ok Press Record Then Press Play Adjust Capture if Desired Length seconds samples time records or use default Input Range Frequency Center Span Better Faster Insights from Measuring Same Signal with Different Settings ...

Page 21: ...hnologies 21 2013 Agilent Technologies Control Playback Speed with Overlap How Time Records Step Through Capture Memory Higher Overlap Slower Playback Overlap Adjustable 0 to 99 99 full speed to 1 10 000 speed 50 90 98 ...

Page 22: ...ies 22 2013 Agilent Technologies Gap Free Overlapped Spectrogram Analysis of Amplitude Frequency Time See Everything At Once See Entire Event at a Glance Find Unexpected Behavior Select Any Trace From Deep Buffer and Measure ...

Page 23: ... 2013 Agilent Technologies 23 2013 Agilent Technologies Example ISM Band Capture WLAN Bluetooth Microwave Ovens 16 7 ms ...

Page 24: ... 2013 Agilent Technologies Focus on a Time and Frequency Region Play back until signal appears Click drag analysis region position Marker CF reduce span ...

Page 25: ... 2013 Agilent Technologies Span Center Freq Change to Analyze Demodulate 2 5 MHz span Bluetooth demod preset short result length ...

Page 26: ...Use Start Stop Times to Train Adaptive EQ Simple Gated Spectrum Measurement or Train Equalizer on Selected Time Segment Read Equalizer Coefficients to Understand Channel Frequency Response Time impulse response Using Gated Spectrum Using Demodulation Result ...

Page 27: ...13 Agilent Technologies Save a Time Frequency Portion of Capture Use Capture Triggering to find What You Want Select the Signal or Time Region Desired Change Center Frequency and or Span Save Segment for Later Analysis Playback Re Use ...

Page 28: ...ologies 28 2013 Agilent Technologies Pass Captured Data to Other Tools Processes Captured Data can be Fully Time and Frequency Corrected Data can be Fully Alias Protected Save as MATLAB CSV Text Send as ARB Register Data ...

Page 29: ...Agilent Technologies 29 2013 Agilent Technologies Case Study 2 S Band Acquisition Radar Raster Scanning Pulse Width 6 μs PRI 600 μs 7 Pulses 10 MHz Spacing Stepping Low High Frequency Pulses 30 MHz to 30 MHz ...

Page 30: ... 2013 Agilent Technologies Fast Clear Signal View Blue Indicates Very Low Duty Cycle Amplitude Varies over Seconds Set Persistence Long Peaks Consistent Case Study 2 S Band Acquisition Radar ...

Page 31: ... 2013 Agilent Technologies 31 2013 Agilent Technologies S Band Acquisition Radar Spectrum Analyzer View Peak Hold Many Measurements Required Signal Still Not Clear Dynamics Not Shown ...

Page 32: ...echnologies S Band Acquisition Radar Real Time Spectrogram View Long Acquisition Time Long Persistence Excellent for Long Term Signal View seconds Spot a Pattern Spot Big Pulse Set Many Spectra default 10 000 Combined Pulses Still Shown Together ...

Page 33: ...3 2013 Agilent Technologies S Band Acquisition Radar Spectrogram with Short Acquisition Time Short Term Signal View ms to 1 seconds per screen A more Rapid Pattern is Revealed Fewer Spectra Combined 33 Pulses May Now be Separated ...

Page 34: ...Technologies Vector Signal Analysis Same Setup Then Capture Post Processing Overlap Frequency Mask Trigger IF Magnitude Trigger Positive Negative Trigger Delay Capture Without Trigger Spectrogram Shows Timing Adjust Overlap and FFT Length points ...

Page 35: ...nt Technologies Vector Signal Analysis Gap Free Post Processing Reveals an Anomaly Defects Hidden in one Mode or View are Obvious in Another Triggering Not Necessary for Repeating Signal Use Magnitude Trigger To Capture Highest Signal Levels ...

Page 36: ...A Post Capture Tune Zoom Digital Resampling Digital Local Oscillator Focus on Signal of Interest Filter Out Other Signals Select Analysis Time Interval Use Gating Windows uniform rect here pulse is self windowing Any Analysis Type Including Vector Demodulation ...

Page 37: ...lity phase noise noise figure ACPR EMI apps etc Real Time Analyzer Find elusive signals some ability to characterize spectrogram PVT Spot unknown signals signal behavior Monitor spectrum trigger on spectral behavior Vector Signal Analyzer VSA software on signal analyzer platform Detailed vector analysis and demodulation Signal capture flexible playback Post processing for signal selection re use S...

Page 38: ...d Signals Avoid Measuring When No Signal Present Monitor Other Frequency Bands Trigger on Other Activities External trigger from your circuit Oscilloscope or logic analyzer Consider all you know about signals systems transitions Take advantage of repeating signals inter signal timing pos neg delays Triggering Can Enhance Measurement Performance Time or synchronous averaging Periodic trigger Trigge...

Page 39: ...evel polarity Selectable holdoff holdoff type Playback IF magnitude trigger Frequency Mask Real time calculation of spectrum test against spectral mask Upper lower limits Build from trace adjust or manual parameter entry Trigger timing ambiguity 1 FFT Logic Enter leave in out enter leave leave enter Negative positive trigger delays Compare Triggers IF Mag Frequency Mask ...

Page 40: ...g Probability of Intercept for Intermittent Signals by Richard Overdorf Agilent application note Measuring Agile Signals and Dynamic Signal Environments April 2013 Agilent PXA Real Time Signal Analyzer Technical Overview literature number 5991 1748EN Vector Signal Analysis Basics Agilent literature number 5989 1121EN ...

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