Spectrum Analyser

7/31/2019 Spectrum Analyser

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SpectrumSpectrum AnalyserAnalyser

A HandA Hand--ShakeShake


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OverOver--ViewView

This lecture is basically to familiarize withThis lecture is basically to familiarize with

SA functions & taking C/N Ratio Meas.SA functions & taking C/N Ratio Meas. Newer Anritsu Model MS 2661B/C isNewer Anritsu Model MS 2661B/C is

chosen as standardchosen as standard

It has some new modern features toIt has some new modern features tofacilitate measurementsfacilitate measurements

A little peep into more difficult area is alsoA little peep into more difficult area is alsogiven here & there, so that the peoplegiven here & there, so that the peopleinterested can get into the nittyinterested can get into the nitty--gritty'sgritty's


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SpectrumSpectrumAnalyserAnalyser

Measures Amplitude (power) of differentMeasures Amplitude (power) of different

Frequency Components in the signalFrequency Components in the signal MaxMax RfRfInput is 30Input is 30 dBmdBm, 50, 50 , in some, in some

new models 75new models 75

is also selectable.is also selectable. DC is strict noDC is strict no--no.no.

In some new models dcIn some new models dc uptoupto 50 V is50 V isacceptableacceptable


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Main Parameters/Functions of SAMain Parameters/Functions of SA

FrequencyFrequency

AmplitudeAmplitude

MarkerMarker

DisplayDisplay

StorageStorage

DetectionDetection

Coupled (Input Processing) FunctionCoupled (Input Processing) Function

CalibrationCalibration

MeasurementMeasurement

Save FeatureSave Feature

Print OutPrint Out


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FrequencyFrequencyHow to set the FrequencyHow to set the Frequency

CentreCentre--Span ModeSpan Mode StartStart--Stop ModeStop Mode

Keys/Terms To RememberKeys/Terms To Remember FrequencyFrequency

Center FrequencyCenter Frequency

SpanSpan

StartStart--Stop FrequencyStop Frequency


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AmplitudeAmplitudeHow to set the AmplitudeHow to set the Amplitude

Choose Reference LevelChoose Reference Level Choose Log ScaleChoose Log Scale

Choose Input ImpedanceChoose Input Impedance

Keys/Terms To RememberKeys/Terms To Remember

AmplitudeAmplitude

Reference LevelReference Level Log ScaleLog Scale

Input ImpedanceInput Impedance


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MarkersMarkersHow to set MarkerHow to set Marker

Go to Marker Menu & selectGo to Marker Menu & selectKeys/Terms To RememberKeys/Terms To Remember

Normal MarkerNormal Marker Delta MarkerDelta Marker

Zone MarkerZone Marker

Zone WidthZone Width

Peak MarkerPeak Marker


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DisplayDisplayHow to select Display ModeHow to select Display Mode

Go to A,B (Display) Menu & selectGo to A,B (Display) Menu & selectKeys/Terms To RememberKeys/Terms To Remember

Trace A & BTrace A & B Trace A on BTrace A on B

Over Write Display etc.Over Write Display etc.


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StorageStorageHow to select Storage ModeHow to select Storage Mode

Go to A,B (Display) Menu, then Storage &Go to A,B (Display) Menu, then Storage &selectselect


NormalNormal

AveragingAveraging

Max HoldMax Hold

Min HoldMin Hold


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DetectionDetectionHow to select Detection ModeHow to select Detection Mode

Go to A,B (Display) Menu, then DetectionGo to A,B (Display) Menu, then Detection& select& select


NormalNormal

SampleSample

Pos PeakPos Peak

NegNeg PeakPeak


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Coupled (input processing) FunctionCoupled (input processing) FunctionHow to select Coupled FunctionHow to select Coupled Function

Select Coupled Function KeysSelect Coupled Function Keys


RBWRBW

VBWVBW

Sweep TimeSweep Time AttenuatorAttenuator


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CalibrationCalibrationHow to select CalibrationHow to select Calibration

Select Calibration (shift 0) KeysSelect Calibration (shift 0) KeysKeys/Terms To RememberKeys/Terms To Remember

All CalAll Cal Level CalLevel Cal

Frequency CalFrequency Cal

FM CalFM Cal

Factory CalibrationFactory Calibration


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MeasurementMeasurementHow to select MeasurementHow to select Measurement

Go to Measure Menu & SelectGo to Measure Menu & Select


C/N Ratio MeasurementC/N Ratio MeasurementNoise Power MeasurementNoise Power Measurement

Frequency CountFrequency Count Channel Power Measurement etc.Channel Power Measurement etc.


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Save Recall FeatureSave Recall FeatureHow to select Save Recall FeatureHow to select Save Recall Feature

Select Recall/shift Recall (Save) KeySelect Recall/shift Recall (Save) Key


Parameter DataParameter Data Waveform DataWaveform Data


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Print OutPrint OutHow to select Print OutHow to select Print Out

Select shift Copy Key & SelectSelect shift Copy Key & Select


Serial PortSerial Port GPIB PortGPIB Port

CentronicsCentronics CableCable Parallel PortParallel Port


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Setting Observation FrequencySetting Observation Frequency

11


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Center Span ModeCenter Span Mode


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Start Stop ModeStart Stop Mode


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Setting Level RangeSetting Level Range

Setting Log-Scale


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Setting Reference levelSetting Reference level


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Setting Input ImpedanceSetting Input Impedance

Impedance Transformer


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Marker FunctionsMarker Functions

Marker Mode

Normal Marker

Delta Marker

Zone Marker

Marker off

Switching Marker

Search Mode

Marker Search

Peak Search

Next Peak Search

Next Right Peak

Search

Next Left Peak Search

Dip Search

Setting Parameters Using

Marker Values

Mkr CF / Mkr RLV

Delta Mkr Span

Zone Span


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Marker ModeMarker Mode

Normal & Delta MarkerNormal & Delta Marker

11

2211

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Marker Normal Marker Delta MarkerMarker


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Marker ModeMarker Mode

Zone MarkerZone Marker

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Changing Zone Position

Changing Zone Width Switching Marker Search Mode

Marker Search Peak DipMarker

Searching the max & min value in the zone

marker is selected by this Key


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Marker SearchMarker Search

Next Peak SearchPeak Search


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Marker SearchMarker Search

Next Right/Left Peak Search


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Setting Parameters Using Marker ValuesSetting Parameters Using Marker Values

CF & RLV KeysCF & RLV Keys



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MkrMkr CF /CF / MkrMkr RLVRLV

Marker Mkr CF

Mkr RLV

Marker

S i P U i M k V lS tti P t U i M k V l


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PeakPeak CF / Peak RLVCF / Peak RLVPeak CF

CF Sets the max peak point & zone marker to the center frequency

Peak RLV

RLV Sets the max peak level to the reference level

S tti P t U i M k V lS tti P t U i M k V l


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DeltaDelta MkrMkr SpanSpanMarker Delta Mkr SpanMarker

S tti P t U i M k V lS tti P t U i M k V l


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Zone SpanZone Span

Zone SpanMarkerMarker


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Display MethodDisplay Method

Display ModeDisplay Mode

Trace A, Trace B etc.Trace A, Trace B etc. Trace A & B Overwrite Display etc.Trace A & B Overwrite Display etc.

Storage ModeStorage Mode

Averaging FunctionAveraging Function

Max, Min HoldMax, Min Hold FuntionFuntion

Detection ModeDetection Mode Selecting Measured level by Detection ModeSelecting Measured level by Detection Mode

Di l M th dDi l M th d


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Display MethodDisplay Method

Display KeysDisplay Keys

Display ModeDisplay Mode


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p yp yTrace A & B Overwrite DisplayTrace A & B Overwrite Display

Trace A on BA,B

Trace B (max hold)

Trace A (normal)

St M dStorage Mode


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Storage ModeStorage Mode

Selection of Averaging, Min & Max Hold FunctionSelection of Averaging, Min & Max Hold Function

Selection Averaging Function

A,B

Time Storage

Normal

Max Hold

Averaging by Video Filter Increases Sweep

Time

As sweep time increases it takes a long time

to verify the whole spectrum

On the other hand digital video averaging

smoothes the trace w/o narrowing the video

b/w.

Also S/N improvement is obtained with

averaging

Min Hold

Average

View

Return

Detection ModeDetection Mode


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Detection ModeDetection Mode

Selection of Normal, Pos,Selection of Normal, Pos,NegNeg PeakPeak

Selection Detection Modes

A,B

Time Detection

Normal

Positive Peak

SampleNegative Peak

Return

Normal Traces the max & minvalue between sample points

Pos Peak Traces the max valuebetween sample points

Sample Traces the instantaneous

value between sample pointsNeg Peak Traces the min value

between sample points

Coupled FunctionCoupled Function


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Auto to Manual OperationAuto to Manual Operation

ManualRBW

ManualVBW

ManualSweep Time

ManualAtten



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UncalUncal WaveformWaveform

Optimum Sweep Time gives a

waveform like 1. However if thesweep time is too fast decreases

the waveform amplitude as

shown in 2 & 3. When waveform

1 cannot be maintainedUNCAL is displayed.



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Input AttenuatorInput AttenuatorAtten Manual

Auto

Pre Ampl

On Off

All Auto

For Manual Setting

Optimally keep the atten. in auto

& measure the signal level near

Reference level. But when youwant to measure a low level

signal by raising the sensitivity

then choose atten. Settings

according to the adjacent table.

lib i


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lib iC lib i


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S /R ll F iS /R ll F i


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Save/Recall FunctionSave/Recall Function

Saving Parameter

& Waveform DataRecalling Parameter

& Waveform Data

Selecting Recall

Item

C i P iC ti t P i t


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Connecting to PrinterConnecting to Printer

RS-232C Cable

Printer

GPIB Cable (or

Centronics Cable)Printer Selection

M tM t


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MeasurementMeasurementMain Measurements

Noise Power Measurement

C/N Ratio Measurement

E l f C/N R ti M tE l f C/N R ti M t


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Example of C/N Ratio MeasurementExample of C/N Ratio Measurement

Always Set Detection Mode

to Sample Mode

Center Freq. : 1.9 GHz

Offset Freq. : 100 KHz



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Example of C/N Ratio MeasurementExample of C/N Ratio MeasurementSet span to 3-4 times the offset freq.

For our Case Choose RBW 10 KHz

Set Ref. Level near to Carrier Peak using CF &

RLV Keys

Set Delta marker with say 50 KHz offset for

beacon

Take C/N measurement

Change offset freq. by pressing marker & knobor keys entry

Change RBW value & select the best C/N

Also make the atten value minimumTo Note: Even when the marker freq. is moved

to carrier level the measurement result does not

become 0 dB, ref. marker is considered as

noise & SA adds correction value to the carrier

E l f C/N R ti M tE l f C/N R ti M t


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Measurement AccuracyMeasurement Accuracy


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Measurement AccuracyMeasurement Accuracy For Maximum Sensitivity both Input Attenuator & RBWFor Maximum Sensitivity both Input Attenuator & RBW

setting must be minimized.setting must be minimized.

If possible keepIf possible keep attenatten. setting below 10 dB. setting below 10 dB

Also VBW can be used to view signal near noise floor.Also VBW can be used to view signal near noise floor. Sample detection mode is good for noise measurements.Sample detection mode is good for noise measurements.

Use ALL Cal for taking Accurate measurementsUse ALL Cal for taking Accurate measurements

Log scale linearity factor can be overcome by setting theLog scale linearity factor can be overcome by setting thepeak of the signal under test at RLVpeak of the signal under test at RLV

The measured C/N is overThe measured C/N is over--approximated by about 1.7 dBapproximated by about 1.7 dBin manual mode due to correction factor RBW & Videoin manual mode due to correction factor RBW & Video

filtering. RBW reads 1.2 (.8 dB) more noise, butfiltering. RBW reads 1.2 (.8 dB) more noise, butaveraging by video filter & the nonaveraging by video filter & the non--linear processes bylinear processes bylog amplifier & detector cause the noise level to belog amplifier & detector cause the noise level to bedisplayed 2.5 dB below the actual value.displayed 2.5 dB below the actual value.


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Log CalculationsLog Calculations

dB TipsdB Tips



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dB TipsdB Tips 3 dB3 dB multiplying/dividing power by 2multiplying/dividing power by 2

66 dBdB multiplying/dividing power by 2multiplying/dividing power by 22 = 42 = 4

i.e., every increase of 3 dB multiply by 2i.e., every increase of 3 dB multiply by 2

10 dB10 dB multiplying/dividing by 10multiplying/dividing by 10

220 dB0 dB multiplying/dividing by 10multiplying/dividing by 1010 = 110 = 10000i.e., every increase of 10 dB multiply by 10i.e., every increase of 10 dB multiply by 10

00 dBmdBm means 1means 1 millimilli--wattwatt

00 dBWdBW means 1 Wattmeans 1 Watt

dBWdBW = 30= 30 dBmdBm (as 1 Watt = 10(as 1 Watt = 10101010 1mW)10 1mW)



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Log Calculationsg C

dB tipsdB tips 1 dB1 dB multiply/divide bymultiply/divide by ~1.26~1.26

2 dB2 dB multiply/divide bymultiply/divide by ~1.58~1.58 3 dB3 dB multiply/divide bymultiply/divide by ~2~2

4 dB4 dB multiply/divide bymultiply/divide by ~2.51~2.51


7 dB7 dB multiply/divide bymultiply/divide by ~5~5


10 dB10 dB multiply/divide bymultiply/divide by 1010

Power LevelsPower Levels


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dB tipsdB tipsmultiply/divide by 2multiply/divide by 2 3 dB3 dB

multiply/divide by 3multiply/divide by 3 4.77 dB4.77 dB

mulmul/div by 4 (2/div by 4 (22)2) (3+3 = 6) dB(3+3 = 6) dB

multiply/divide by 5multiply/divide by 5 7dB7dB

mulmul/div by 6 (2/div by 6 (2

3)3)

(3+4.77 = 7.77) dB(3+4.77 = 7.77) dBmultiply/divide by 7multiply/divide by 7 8.45dB8.45dB

mulmul/div by 8 (2/div by 8 (2222)2) (3+3+3=9) dB(3+3+3=9) dB

mulmul/div by 9 (3/div by 9 (33)3) (4.77+4.77 = 9.54) dB(4.77+4.77 = 9.54) dBmulmul/div by 10 (2/div by 10 (25)5) (3+7 = 10) dB(3+7 = 10) dB



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ExamplesExamples

43 dB43 dB= 10 +10= 10 +10 +10+10 + 10 + 3 =+ 10 + 3 = 101044 22

27 dB27 dB

== 10 +10 + 7 =10 +10 + 7 = 101022 5=5005=500

oror

== 10+10+3+3+1 =10+10+3+3+1 = 101022 22 22 1.26 ~ 5001.26 ~ 500

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Spectrum Analyser