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Subject to change O.Gerlach 07.2009 - 1MA29_7e

Products: R&SAFQ100A, R&S

AFQ100B, R&S

SMF100A, R&S

SMR, R&S

SMJ100A, R&S

SMV,

R&SSMU, R&S

SFU, R&S

FSL, R&S

FSP, R&S

FSQ, R&S

FSU, R&S

FSV, R&S

NPR - Noise Power Ratio

Signal Generation and

Measurement

Noise Power Ratio (NPR) is an add-on tool for WinIQSIM / WinIQSIM2 to generate noise power ratiostimulus signals and measure the resulting noise power ratio of a device under test (DUT) using Rohde &

Schwarz instruments via IEEE or LAN interface.

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FreRes Frequency Response Measurement

1MA29 2 Rohde & Schwarz

Contents

1 Overview ................................................................................................. 22 Software Features................................................................................... 33 Hardware and Software Requirements................................................... 4

Hardware Requirements.................................................................... 4

Software Requirements ..................................................................... 44 Connecting the Computer and Instrument .............................................. 55 Installing NPR.......................................................................................... 56 Starting the Software / Measurement...................................................... 6

Parameters ...................................................................................... 14Sampling Parameters ................................................................. 14Notch Related Parameters.......................................................... 16Phase / Magnitude Distribution................................................... 17Notch List .................................................................................... 17Calculate FFT ............................................................................. 18Connected................................................................................... 19

Menu ................................................................................................ 19Load / Save Configuration File.................................................... 19

Devices ....................................................................................... 21Optimize Crest Factor................................................................. 23Performing NPR Measurements................................................. 24Using NPR with Microwaves....................................................... 25

7 Additional Information ........................................................................... 288 Ordering information ............................................................................. 28

The following abbreviations are used in this Application Note for Rohde &Schwarz test equipment:

The IQ Modulation Generators R&SAFQ100A and R&S

AFQ100B are

referred to as AFQ.

The IQ Modulation Generator R&SAMIQ is referred to as AMIQ.

The Vector Signal Generator R&SSMU200A is referred to as SMU.

The Vector Signal Generator R&SSMBV100A is referred to as SMBV.

The Vector Signal Generator R&SSMJ100A is referred to as SMJ.

The Vector Signal Generator R&SSMV03 is referred to as SMV.

The Vector Signal Generator R&SSMIQ is referred to as SMIQ.

The Broadcast Test System R&SSFU is referred to as SFU.

The Spectrum Analyzer R&SFSL is referred to as FSL.

The Spectrum Analyzer R&SFSP is referred to as FSP.

The Spectrum Analyzer R&SFSQ is referred to as FSQ.

The Spectrum Analyzer R&SFSU is referred to as FSU. The Spectrum Analyzer R&S

FSV is referred to as FSV.

The Spectrum Analyzer R&SFSIQ is referred to as FSIQ.

The Spectrum Analyzers R&SFSEA and R&S

FSEB are referred to as

FSE.

The Microwave Generator R&SSMF100A is referred to as SMF.

The Microwave Generator R&SSMR is referred to as SMR.

The R&S logo, Rohde & Schwarz, and R&S are registered trademarks ofRohde & Schwarz GmbH & Co. KG and its subsidiaries.

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1 Overview

Noise Power Ratio (NPR) is an add-on tool for WinIQSIM / WinIQSIM2 togenerate noise power ratio stimulus signals and measure the resultingnoise power ratio of a device under test (DUT) using Rohde & Schwarz in-struments via IEEE or LAN interface. The Noise Power Ratio measurement

technique can characterize the linearity of a wide band amplifier over a cus-tom frequency range. Since NPR drastically reduces measurement timecompared to classic gain wobbling, it is particulary interesting for productionspecific applications.

2 Software Features

The software offers:

custom notch definition

generator and analyzer control load / save device configuration

automatic measurement of specified notch with adjacent channelpower (ACP) option

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3 Hardware and Software Requirements

Hardware Requirements

The software runs on a PC with:

CPU: 1 GHz or faster

RAM: 512 MBytes or more

Monitor: VGA color monitor

GPIB bus: National Instruments or Agilent GPIB controller board

and / or

LAN Standard on-board 10/100 MBit/s (FSV up to 1 GBit/s)controller or switch / hub.

It supports following instruments:

AFQ100,AMIQ: I/Q modulation generator

SMBV, SMIQ, SMJ, SMV03, SMU, SFU, SMIQ: Signal generator with I/Qinputs

FSL, FSP, FSQ, FSU, FSV, FSE, FSIQ spectrum analyzer with ACP ca-pability.

SMF, SMRmicrowave generator supported, but not mandatory.

Software Requirements

MICROSOFT WINDOWS XP/VISTA operating system.

IEEE bus driver.

TCP/IP network protocol installed.

WINIQSIM V4.4 or WINIQSIM2 V2.X (or higher) installed. This is a soft-ware tool that generates standard and custom I/Q signals e.g. forACPmeasurements. It can upload I/Q data to an AFQ / SMU I/Q modulationgenerator and control one of the SMx signal generators named above.NPR communicates with WinIQSIM / WinIQSIM2 via the TCP/IP net-work protocol. Both programs must run simultaneously to enable data

transfer. Download the latest WINIQSIM version from http://www.rohde-schwarz.com.

VISA driver by National Instruments or Agilent. See manufacturer's websitefor latest revision.
http://www.rohde-schwarz.com/http://www.rohde-schwarz.com/http://www.rohde-schwarz.com/http://www.rohde-schwarz.com/http://www.rohde-schwarz.com/

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4 Connecting the Computer and Instrument

Connect the computer running NPR to the instruments that are involvedwith the measurement, such as an AFQ, AMIQ IQ modulator, an SMx sig-nal generator and an FSx spectrum analyzer. Make sure that all instru-ments have different GPIB bus addresses.

REF In

REF Out

RF Input

RF Output

QI

WinIQSIM

WindowsXP/Vista

NPR

AFQ, AMIQ

SMx

IEEE bus

RS Analyzer(FSx)

DUT

TCP/IP protocol

Fig. 1 Connecting Instruments

5 Installing NPR

Make sure that WINIQSIM orWINIQSIM2 is installed on your hard disc.

Execute NPR_4.X.EXE and follow the installation notes.

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6 Starting the Software / Measurement

Execute NPR.EXE. The example setup below shows three notches generatedwith AUTOCALC NOTCHES. NPR configuration is stored in NPR.CFG at exit.

Fig. 2 Main Menu

Devices can be configured in the device menu. See DEVICES for details. Then

define a custom signal with the sampling and notch specific parameters (SAMPLE

RATE, FFTLENGTH, NOTCH COUNT, etc.). Prepare the IQ data for transmission

to WinIQSIM by pressing CALC FFT. The DATA VALID LED indicates that thedata is ready for transfer. After transferring the data to the AMIQ via WinIQSIM(see following section, step 4) press the PRESETNPRMEAS button to put the

analyzer in ACP measurement mode. Then select a NOTCH NR and press theMEASURE button to receive the signals NPRand calculated SIGNALPOWER.

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Execute WINIQSIM.EXE / WINIQSIM2.EXE and load the configuration fileNPR.IQS. / NPR.SAVRCL This affects following settings:

1. IMPORT settings for TCP/IP link.

Fig. 3 WinIQSIM Import Settings

Fig. 4 WinIQSIM2 Import Settings

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2. FILTER set to ideal low pass.

Fig. 5 WinIQSIM Filter Settings

Fig. 6 WinIQSIM2 Filter Settings

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3. Graphic Display

Fig. 7 WinIQSIM Graphic Setting

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Be sure to run NPR before WINIQSIM / WINIQSIM2 at restart to a avoida TCP/IP warning. After pressing the UPDATE button in the WinIQSimgraphics window the following display appears.

Fig. 8 WinIQSIM Graphic Display

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The WinIQSIM2 graphic display is automatically updated when a pa-rameter is changed in NPR.

Fig. 9 WinIQSIM2 Graphic Setting and Display

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4. To transfer the signal to the AMIQ press the WinIQSim menu itemAMIQ ->TRANSMISSION or the short cut key AMIQ.

Fig. 10 WinIQSIM AMIQ Transmission

Fig. 11 WinIQSIM2 SMU Transmission

5. NPR can set up the analyzer for Noise Power Ratio measurement of aspecified notch automatically (see Performing NPR Measurements). Fol-lowing analyzer parameters are affected.

DetectorRMS

Resolution bandwidth: manual < 30ms depending on sample rate.

Sweep time > 0.5s

Channel bandwidth = notch width * 0.8.

Channel spacing = notch width * 1.1

Center frequency is moved so adjacent channel fits inside notch.

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The analyzer (e.g. FSP) would show following display. The adjacentchannel fits perfectly into the second notch (cu1 - ACP upper). If thenotch's mid frequency is smaller than the generator's center fre-quency then cl1 - ACP lower channel is used.

Fig. 12 FSP ACP Display

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Parameters

Sampling Parameters

Fig. 13 Sampling Parameters

SAMPLE RATE Configures the AMIQ D/A converter sample rate. This value

affects the LINE SPACING display. A noise and notch pattern can beminimized by decreasing and expanded by increasing the sample rate.Range: 10 kHz - 105 MHz.

NOISE BW/ SAMP.RATE Configures the noise bandwidth to sample rate ra-tio. This limits the noise bandwidth to prevent upper and lower side bandaliasing effects from influencing the signal. Range: 0.01 to 1.

Noise Bandwidth

Sample Rate / 2

CenterFrequency

NBW / SRate< 1

Notch

Sample Rate / 2

Fig. 14 Noise BW / Sample Rate

NOISE BANDWIDTH (NBW) Displays the valid spectral area for customnotch insertion, which is:

NBW = Sample Rate * NBW / Srate

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FFTLENGTH the number of points in the frequency domain axis that areinversely Fourier transformed into time domain mode for download to

WinIQSIM. This value affects the LINE SPACING display.

Fig. 15 FFT Length

FFT lengths greater than 128kS are marked with an exclamation markto indicate that the Calc FFT function takes unproportionally long in casememory runs out and Windows uses the memory swapping option. Thelatest WinIQSIM revision 3.5 can only display FFT lengths up to 128kScorrectly. An FFT length of 4MS requires an AMIQ 04. Following warning

occurs when decreasing the FFT length:

Fig. 16 FFT Length Warning

No changes take place after pressing NO. After pressingYES all the not-

ches defined previously are deleted. This step is necessary because asmaller FFT length decreases resolution and can leads to an erraticnotch list display.

LINE SPACING Displays the frequency resolution of FFT lines, which is:

LINESPACING = SAMPLERATE/ FFTLENGTH

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Notch Related Parameters

Fig. 17 NPR Notch Related Parameters

NOTCH COUNT Specifies the number of notches within the current noise band-

width. With AUTOCALC NOTCHES the number of notches is restricted to:

NOTCHCOUNTNBW/ NOTCHWIDTH

NOTCH WIDTH The notch width is limited by the current noise bandwidth.

With AUTO CALC NOTCHES all notches have equal widths. If the notchwidth is smaller than the line spacing no notch will be generated. Range:

0.01 MHz - Noise Bandwidth.NOTCH DEPTH With AUTO CALC NOTCHES all notches have equal depths.

Range: 0 - 100 dB.

NOTCH OFFSET Specifies a frequency offset that is added to the notch

center frequencies with AUTO CALC NOTCHES. Avoid effects from insuffi-ciently suppressed carriers by moving the notch out of the danger zo-ne.

foffs

Fig. 18 NPR Notch Offset

AUTO CALC NOTCHES Automatically produces notches with the specifiedparameters to fit perfectly into the noise bandwidth range. The NotchCountis reduced, if necessary.

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Phase / Magnitude Distribution

Fig. 19 Phase / Magnitude Distribution

PHASE DISTRIBUTION

- RANDOM (CONST. SEED) I/Q-phase arrays are filled with random val-

ues between - and +. The random generator always starts withConst.Seed.

- RANDOM (CONTINUE) as above except that the random generator'sseed depends on the last value.

- PARABOLIC I- and Q- phase arrays are filled with an unsymmetrical

chirp signal ranging from - to +. This signal can be used to simulatea wobble generator.

- CONSTANT I/Q phase arrays are filled with constant values. This sig-

nal results in one or more peaks in time domain mode due to identicalphases of numerous frequency lines.

CUSTOM Loads a custom phase / magnitude configuration (*.pmc) file. Af-ter loading the *.pmc file the FFT length input field is dimmed and thenumber of FFT elements in the file is used. The file has the structureshown below.

4096 Element count (usually based on 2n)

0 -3.145e0 0.95

magnitude (range 0 to 1.0)

index nr (range 0 to element count)

phase offset (range )

......

4095 2.4567e0 0.34

Notch List

All active fields (not dimmed) of the notch list can be edited except Notchindex. If there are more than 10 items use the scroll bar to display the de-sired notch configuration line. Since all values are based on a discrete 2

N

array it is likely that a straight value, e.g. 10.00000 is locked to the nearestpoint in the array, e.g. 9.987654. The resolution depends on the FFT length.

Fig. 20 Notch List

Note: All values displayed in one line depend on each other.The last in-put value reconfigures the other ones to make sense.

NOTCH Displays the notch index number.

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CENTER FREQ Edit notch center frequency. Range:

fcarrier NBW / 2 fcenter fcarrier+ NBW / 2

WIDTH Specifies the notch width. Range: 0 - NBW.

START FREQUENCY The start frequency is calculated as:

fstart = fcenter Width / 2

STOP FREQUENCY The stop frequency is calculated as:

fstop = fcenter+ Width / 2

START INDEX Notch's first frequency line number. Range:

FFT Length / 2 - FFT length * (NBW / SRate) / 2 Start Index

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