Spectrum Analysis Back to Basics – Definitions and Measurements

Spectrum Analysis Back to Basics – Definitions and Measurements
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Spectrum Analysis Back to Basics – Definitions and Measurements

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    Agilent TechnologiesSpectrum AnalysisBack to BasicsBack to Basics Training1

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    AgendaIntroductionOverview:• What is Spectrum and Signal Analysis?• What Measurements are available?Theory of OperationSpecificationsModern Signal Analyzer Designs & Capabilities• Wide Bandwidth Vector MeasurementsWrap-upBack to Basics Training2

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    Analyzer DefinitionsSpectrum Analyzer– “A spectrum analyzer measures the magnitude of an input signal versus frequency within the full frequency range of the instrument. The primary use is to measure the power of the spectrum of known and unknown signals.”Vector Signal Analyzer– “A vect...

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    OverviewFrequency versus Time DomainTime domainMeasurements(Oscilloscope)Frequency DomainMeasurements(Spectrum Analyzer)Amplitude(power)Back to Basics Training4

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    OverviewDifferent Types of AnalyzersParallel filters measured simultaneouslyLCD shows full spectral displayAff1f2FFT AnalyzerBack to Basics Training5

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    OverviewDifferent Types of AnalyzersAff1f2Filter 'sweeps' over range of interestLCD shows full spectral displaySwept AnalyzerBack to Basics Training6

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    OverviewTypes of Measurements AvailableFrequency, power, modulation, distortion & noise– Spectrum monitoring– Spurious emissions– Scalar network analysis– Noise figure & phase noise– Harmonic & intermodulation distortion– Analog, digital, burst & pulsed RF Mod...

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    AgendaIntroductionOverviewTheory of Operation:• Swept Spectrum Analyzer HardwareSpecificationsModern spectrum analyzer designs & capabilities– Wide Bandwidth Vector MeasurementsWrap-upBack to Basics Training8

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    Theory of OperationTraditional Swept Spectrum Analyzer Block DiagramPre-SelectorOr Low PassInput FilterCrystalReference OscillatorLogAmpRF inputattenuatormixerIF filter (RBW)envelope detectorvideofilterlocaloscillatorsweepgeneratorIF gainInputsignalADC, Display & Video ProcessingBack to Basic...

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    Theory of OperationDisplay terminologyFreq. SpanStop Freq.Center Freq.Reference LevelAmplitudeBack to Basics Training10Start Freq.

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    Theory of OperationMixerf sigLOff sigLOfLOff sig-LOff sig+RFLOIFMIXER1.5 GHz3.6 GHz6.5 GHzBack to Basics Training11

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    Theory of OperationIF Filter (Resolution Bandwidth – RBW)DisplayInputSpectrumIF Bandwidth(RBW)IF FilterABCBack to Basics Training12

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    Theory of OperationEnvelope DetectorEnvelope DetectorBefore detectorAfter detectorBack to Basics Training13

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    Theory of OperationEnvelope Detector and Detection TypesNegative detection: smallest valuein bin displayedPositive detection: largest valuein bin displayedSample detection: middle value in bin displayedbins/buckets*Other Detectors: Normal (Rosenfell), Average (RMS Power)Digitally Implemented Dete...

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    Theory of OperationAverage Detector TypeTimeVoltsbinPower Average Detection (rms) = Square root of the sum of the squares of ALL of the voltage data values in the bin /50ΩxNeg Peak detectionxxPos Peak detectionEnvelope DetectorADC, Display & Video ProcessingBack to Basics Training15

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    Theory of OperationVideo Filter (Video Bandwidth – VBW)Video FilterBack to Basics Training16

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    Theory of OperationVideo Filter vs. Trace/Video averaging• Video Filter operates as the sweep progresses, sweep time may be required to slow down by the transient response of the VBW filter.• Trace/Video Average takes multiple sweeps, sweep time for each sweep is not affected• Many signals ...

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    AgendaOverviewTheory of OperationSpecifications:• Which are important and why?Modern spectrum analyzer designs & capabilities– Wide Bandwidth Vector Measurements Wrap-upBack to Basics Training18

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    Specifications? Agilent TerminologySpecifications describe the performance of parameters covered by the product warranty (temperature = 0 to 55°C, unless otherwise noted).Typical values describe additional product performance information that is not covered by the product warranty. It is perform...

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    Key Specifications• Frequency Range• Accuracy: Frequency & Amplitude• Resolution• Sensitivity• Distortion• Dynamic RangeBack to Basics Training20

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    SpecificationsFrequency RangeDescriptionSpecificationsInternal MixingBands03 Hz to 3.6 GHz1 3.5 to 8.4 GHz2 8.3 to 13.6 GHz3 13.5 to 17.1 GHz4 17 to 26.5 GHz5 26.4 to 34.5 GHz6 34.4 to 50 GHzBack to Basics Training21

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    SpecificationsFrequency Readout Accuracy• From the PXA Data Sheet:RBW ErrorIF filter center frequency errorSpan AccuracyResidual ErrorDetermined by Reference Accuracy± (marker frequency x freq reference accuracy +0.1%*span + 5% of RBW + 2Hz + 0.5 x Horiz. Res.*)*Horizontal resolution is span/...

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    SpecificationsFrequency Readout Accuracy ExampleFrequency: 1 GHzSpan: 400 kHzRBW: 3 kHzSweep points: 1000Calculation: (1x109Hz) x (±1.55x10–7/Year ref. Error)= 155Hz400kHz Span x 0.1%= 400Hz3kHz RBW x 5%= 150Hz2Hz + 0.5 x 400kHz/(1000-1) = 202HzTotal uncertainty = ±907Hz*Utili...

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    SpecificationsAmplitude accuracyComponents which contribute to amplitude uncertainty are:• Input mismatch (VSWR)• RF Input attenuator (Atten. switching uncertainty)• Mixer and input filter (frequency response)• IF gain/attenuation (reference level accuracy)• RBW filters (RBW switching u...

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    SpecificationsAmplitude Accuracy: Reference Level SwitchingUncertainty applies when changing the Ref. LevelAlso called IF Gain UncertaintyDecision: Do I change the reference level or live with the display fidelity uncertainty in my measurements?However with today’s X-series analyzers, provided ...

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    SpecificationsAccuracy: Display FidelityDisplay Fidelity includes:• Log Amp Fidelity• Envelope Detector Linearity• Digitizing Circuit LinearityDisplay fidelity error applies when signals are not at the same reference level amplitude when measuredIn the past, technique for best accuracy was ...

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    SpecificationsResolution: Resolution BW3 dB10 kHz10 kHz RBWDetermines resolvability of equal amplitude signalsBack to Basics Training27

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    SpecificationsResolution BW Selectivity or Shape Factor3 dB60 dB60 dBBW60 dB BW3 dB BW3 dB BWSelectivity =Determines resolvability of unequal amplitude signalsBack to Basics Training28

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    10 kHzRBW = 10 kHzRBW = 1 kHzSelectivity 15:110 kHzdistortion products60 dB BW = 15 kHz7.5 kHz3 dB60 dBSpecificationsResolution BW Selectivity or Shape FactorBack to Basics Training29

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    SpecificationsResolution: RBW Type and SelectivityDIGITAL FILTERANALOG FILTERSPAN 3 kHzRES BW 100 HzTypical SelectivityAnalog 15:1Digital ≤5:1Back to Basics Training30* The X-series RBW shape factor is 4.1:1

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    SpecificationsResolution: Noise SidebandsNoise Sidebands can prevent resolution of unequal signalsPhase NoiseBack to Basics Training31

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    SpecificationsResolution: RBW Determines Sweep TimePenalty For Sweeping Too FastIs An Uncalibrated DisplaySwept too fastMeas UncalBack to Basics Training32

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    SpecificationsResolution: RBW Type Determines Sweep Time280 sec134 sec10.7 sec8563E Analog RBWPXA Swept RBWPXA FFT RBWBack to Basics Training33

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    SpecificationsSensitivity/DANLSweepLOMixerRFInputRes BWFilterDetectorA Spectrum Analyzer Generates and Amplifies Noise Just Like Any Active CircuitBack to Basics Training34

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    SpecificationsSensitivity/DANLSignalEqualsNoiseSensitivity is the Smallest Signal That Can Be Measured2.2 dBBack to Basics Training35

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    SpecificationsSensitivity/DANL10 dBAttenuation = 10 dBAttenuation = 20 dB signal levelEffective Level of Displayed Noise is a Function of RF Input AttenuationSignal To Noise Ratio Decreases as RF Input Attenuation is IncreasedBack to Basics Training36

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    SpecificationsSensitivity/DANL: IF Filter(RBW)Decreased BW = Decreased Noise100 kHz RBW10 kHz RBW1 kHz RBW10 dB10 dBDisplayed Noise is a Function of IF Filter BandwidthBack to Basics Training37

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    SpecificationsSensitivity/DANL: Video BW filter (or Trace Averaging)Video BW or Trace Averaging Smoothes Noise for Easier Identification of Low Level SignalsBack to Basics Training38

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    SpecificationsSensitivity/DANL: POWER AT MIXER =INPUT - ATTENUATOR SETTING dBmSIGNAL-TO-NOISE RATIO, dBc0-20-40-60-80-100-60-300+30.Displayed Noise in a 1 kHz RBWDisplayed Noise in a 100 Hz RBWSignal-to-Noise Ratio Can Be GraphedBack to Basics Training39

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    SpecificationsSensitivity/DANL: SummaryNarrowest Resolution BWMinimum RF Input AttenuationSufficient Averaging (video or trace)Using the Preamp also improves sensitivityLow Noise Path (PXA only)Noise Floor Extension (PXA only)For Best Sensitivity Use:Back to Basics Training40

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    SpecificationsDistortionFrequency TranslatedSignalsSignal ToBe MeasuredResultantMixer GeneratedDistortionMixers Generate DistortionBack to Basics Training41

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    SpecificationsDistortionTwo-Tone IntermodHarmonic DistortionMost Influential Distortion is the Second and Third Order< -50 dBc< -50 dBc< -40 dBcBack to Basics Training42

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    SpecificationsDistortionDistortion Products Increase as a Function of Fundamental's Power3f2f3fPowerin dB2ff2f - f1212Powerin dB33212f - fTwo-Tone IntermodHarmonic DistortionThird-order distortionSecond-order distortionSecond Order: △2 dB/dB of FundamentalThird Order: △3 dB/dB of Fundamenta...

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    SpecificationsDistortionDistortion is a Function of Mixer LevelPOWER AT MIXER =INPUT - ATTENUATOR SETTING dBmDISTORTION, dBc0-20-40-60-80-100-60-300+30TOISecondOrderThirdOrderSHIBack to Basics Training44

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    Attenuator Test: Change power to the mixerNo change in amplitude: distortion is part of input signal (external)Change input attenuatorby 10 dB1Watch distortion amplitude on screen2Change in amplitude:at least some of the distortion is being generated inside the analyzer (internal)Specification...

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    SpecificationsSpectrum Analyzer Dynamic RangeDynamicRangeThe ratio, expressed in dB, of the largest to the smallest signals simultaneously present at the input of the spectrum analyzer that allows measurement of the smaller signal to a given degree of uncertainty.Back to Basics Training46

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    SpecificationsDynamic RangeDynamic Range Can Be Presented GraphicallyPOWER AT MIXER =INPUT - ATTENUATOR SETTING dBmSIGNAL-TO-NOISE RATIO, dBc -20-40-60-80-100-60-300+30..TOIOptimum Mixer LevelsMaximum 2nd Order Dynamic RangeMaximum 3rd Order Dynamic RangeSOIBack to Basics Training47

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    SpecificationsDynamic RangeNoise SidebandsDynamic Range Limited By Noise SidebandsdBc/HzDisplayed AverageNoise LevelDynamic RangeCompression/NoiseLimited By100 kHzto1 MHzDynamic Range for Spur Search Depends on Closeness to CarrierBack to Basics Training48

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    SpecificationsSummary: Optimizing Dynamic Range•What settings provide the best sensitivity?•Narrowest resolution bandwidth•Minimal input attenuation•Sufficient averaging•How do you test for analyzer distortion?•Increase the input attenuation and look for signal amplitude changes•The...

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    AgendaIntroductionOverviewTheory of OperationSpecificationsModern spectrum analyzer designs & capabilities• Wide Analysis Bandwidth MeasurementsWrap-upBack to Basics Training51

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    Modern Signal Analyzer Block DiagramDigital IFYIGADCAnalog IFFilterDigital IF FilterDigital Log AmpDigital DetectorsFFTSwept vs . FFTAttenuationPre-ampReplacedbyBack to Basics Training52

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    Modern Signal Analyzer - SpecificationsDigital IF provides improved accuracyPXA vs. Traditional• Input impedance mismatch ±0.13±0.29 dB• Input attenuator switching uncertainty ±0.14±0.6 dB• Frequency response ±0.35±1.8 dB• Reference level accuracy ±0.0...

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    Format Setups include:Modern Signal Analyzer FeaturesBuilt-in One-Button Power MeasurementsBack to Basics TrainingPower Measurements:Occupied BandwidthChannel Power ACPMulti-carrier ACPCCDFHarmonic DistortionBurst PowerTOI Spurious Emissions Spectral Emissions Mask54

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    Modern Signal Analyzer FeaturesApplication Focused Internal Software (one-button measurements)Phase noiseExt. source controlNoise figureCode compatibility suiteEMI pre-complianceAnalog demodFlexible demodLTE FDD, TDDW-CDMA/HSPA/HSPA+GSM/EDGE/EDGE Evocdma2000 & 1xEV-DOcdmaOneDVB-T/H/C/T2TD-SCD...

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    E N H A N C E DD I S P L AYC A P A B I L I T I E SS P E C T R O G R A M• Allows you to see time history in bottom window• Amplitude displayed using color• Great for finding intermittent signalsPage 56

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    E N H A N C E DD I S P L AYC A P A B I L I T I E ST R A C EZ OOM• Allows you to zoom in on your trace data• Same trace in both screens but bottom screen shows “close up” view with fewer points• Great to look more closely at high-density tracesPage 57

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    16-bit ADC, 100 MS/sAnalog BB inputsSwitched Gain amplifier1 M Ω /50 Ω Z SelectReal-time IQcorrections Re-sampling/Decimation500 MSaCapture MemorySingle ended/Differential SelectProbeInterfaceCalBaseband Calibrator OutBaseband to 40 MHz (for 1ch/2ch) 10, 25 or 40 MHz BW500 MSa memoryPXA/MXA B...

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    Modern designs demand more bandwidth for capturing high data rate signals and analyzing the quality of digitally modulated bandwidthsAerospace and Defense Radar– Chirp errors & modulation quality Satellite– Capture 36/72 MHz BW’s w/high data ratesMilitary communications– Capture hi...

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    PXA Simplified Block Diagram (160 MHz BW)0-3.6 GHz low band3 Hz-50 GHzInputCal input8.3-14 GHz LO10.9M.3M4.8 GHz LORF converter2nd converterFPGA300 MHz LO200 MHz CK100 MHzCKADCADCSwitched filters,F0=22.5 MHz140 MHz3.5-50 GHz high bandFPGA160 MHzFront EndSwept IF, 10 MHz & 25 MHz BW (option ...

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    AgendaIntroductionOverviewTheory of OperationSpecificationsModern spectrum analyzer designs & capabilities• Wide Analysis Bandwidth MeasurementsWrap-upBack to Basics Training61

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    Agilent Technologies’ Signal Analysis PortfolioESAWorld’s most popular 100 Hz to 26 GHz8560ECMid-performanceEXAX-Series Economy-class9 kHz to 26 GHzSep 07PSAMarket leading performance 3 Hz to 50 GHzCXALow-cost 9 kHz to 7.5 GHzOct 09CSALow cost portable100 Hz to 7 GHzMXAX-Series Mid-performanc...

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    Agilent Vector Signal Analysis SoftwareBack to Basics Training89600B VSA Software FFT-based spectrum, time-domain & bit-level modulation analysisSupport for more than 70 signal standards and modulation types20:20 trace/marker capability and arbitrary window arrangementDigital pers...

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    Basic Spectrum Analyzer Application & Product Notes actionURI(http://cp.literature.agilent.com/litweb/pdf/5952-0292.pdf):A.N. 150actionURI(http://cp.literature.agilent.com/litweb/pdf/5952-0292.pdf): actionURI(http://cp.literature.agilent.com/litweb/pdf/5952-0292.pdf):– actionURI(http://cp.l...

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    THANK YOU!Back to Basics Training65