MOGlabs QRF041 User manual

Quad RF Synthesizer
QRF041/QRF241
Version0.2.0,Rev2hardware

Limitation of Liability
MOGLaboratoriesPtyLtd(MOGLabs)doesnotassumeanyliabi-
lity arising out of the use of the information contained within this
manual. This document may contain or reference information and
products protected by copyrights or patents and does not convey
any license under the patent rights of MOGLabs, nor the rights of
others. MOGLabs will not be liable for any defect in hardware or
softwareorlossorinadequacyofdataofanykind,orforanydirect,
indirect, incidental, or consequential damages in connections with
orarisingoutoftheperformanceoruseofanyofitsproducts. The
foregoing limitation of liability shall be equally applicable to any
serviceprovidedbyMOGLabs.
Copyright
Copyright c MOGLaboratoriesPty Ltd(MOGLabs) 2015– 2020.
Nopartofthispublicationmaybereproduced,storedinaretrieval
system, or transmitted, in any form or by any means, electronic,
mechanical, photocopying or otherwise, without the prior written
permissionofMOGLabs.
Contact
Forfurtherinformation,pleasecontact:
MOGLaboratoriesP/L
49UniversitySt
CarltonVIC3053
AUSTRALIA
[phone]
[email protected]
MOGLabsUSALLC
41914thSt
HuntingdonPA16652
USA
[phone]
www.moglabs.com

Preface
Acousto-optic modulators (AOMs) are an integral part of many mo-
dern laser-based experiments. They are used for frequency shif-
ting, amplitude modulation, and laser frequency stabilisation. The
MOGLabsQRF quad RF synthesizer provides a user-friendly device
thatcansimultaneouslycontrolfourAOMsatonce,withdirectoutput
ofupto2Wperchannel.
Thewidefrequencyrange(10to200MHz)iscompatiblewithmost
commonAOMs,anditprovideshigh-resolutionfrequency,amplitude
andphase control. TheQRF provides analoguemodulation of each
channelwith70kHzbandwidth,ergonomicfront-panelcontrols,and
ethernet/USB interface. Theincludedtablemodeallowsgeneration
ofpredefinedtime-dependentwaveforms. TheQRFisissinglesmall
(half-rackwidth)boxwhichconnectsdirectlytoACmainspower.
Asyoudelveintothismanualyouwilluncovermoreandmorecapa-
bility,butthemicrocontrollerattheheartoftheQRFallowssoftware
improvements to add new features, so please check the MOGLabs
websiteforupdates,examplecode,andassistance.
We hope that you enjoy using the QRF, and please let us know if
you have any suggestions for improvement in the QRF or in this
document,sothatwecanmakelifeinthelabbetterforall.
MOGLabs,Melbourne,Australia
www.moglabs.com
i

ii

Safety Precautions
Safeandeffectiveuseofthisproductisveryimportant. Pleaseread
thefollowingsafetyinformation beforeattemptingtooperate. Also
please note several specific and unusual cautionary notes before
usingtheMOGLabsQRF,inadditiontothe safetyprecautionsthat
arestandardforanyelectronicequipment.
CAUTION Toensurecorrectcoolingairflow,theunitshouldnotbeope-
ratedwithcoverremoved.
WARNING Highvoltagesareexposedinternally,particularlyaroundthe
mains power inlet and internal power supply unit. The unit
shouldnotbeoperatedwithcoverremoved.
NOTE The MOGLabs QRF is designed for use in scientific research
laboratories. It should not be used for consumer or medical
applications.
iii

Protection Features
TheMOGLabsQRF includesanumberoffeaturestoprotectyouand
yourdevice.
Open/short circuit Each RF output should be connected to a 50Ωload where
possible. The high-power output can tolerate open-circuit,
butshouldnotbeshort-circuited.
Mains filter Protectionagainstmainstransients.
Temperature Severaltemperaturesensorscontrolthefanandwilltriggera
shutdownifthetemperatureexceedsasafelimit.
iv

RoHS Certification of
Conformance
MOGLaboratoriesPtyLtdcertifiesthattheMOGLabsDiodeLaser
Controller(Revision3)isRoHS-5compliant. MOGLaboratoriesno-
tes,however,thattheproductdoesnotfallunderthescopedefined
in RoHS Directive 2002/95/EC, and is not subject to compliance,
inaccordancewithDIRECTIVE 2002/95/EC Out of Scope; Electro-
nics related; Intended application is for Monitoring and Control or
Medical Instrumentation.
MOG Laboratories Pty Ltd makes no claims or inferences of the
compliancestatusofitsproductsifusedotherthanfortheirintended
purpose.
v

Contents
Preface i
Safety Precautions iii
Protection Features iv
RoHS Certification of Conformance v
Getting started ix
1 Introduction 1
1.1 Operatingmodes..................... 2
1.2 Featurecompatibility . . . . . . . . . . . . . . . . . . 3
2 Connections and controls 5
2.1 Frontpanelcontrols . . . . . . . . . . . . . . . . . . . 5
2.2 Menusystem....................... 6
2.3 Rearpanelcontrolsandconnections. . . . . . . . . . 8
2.4 InternalDIPswitches . . . . . . . . . . . . . . . . . . 9
3 MOGRF host software 11
3.1 Devicediscovery . . . . . . . . . . . . . . . . . . . . . 11
3.2 Devicecommander . . . . . . . . . . . . . . . . . . . . 12
3.3 MOGRFmainwindow . . . . . . . . . . . . . . . . . . 13
4 External modulation 17
4.1 Operationalprinciple. . . . . . . . . . . . . . . . . . . 17
4.2 Modulationgain . . . . . . . . . . . . . . . . . . . . . 18
4.3 Dualmodulation . . . . . . . . . . . . . . . . . . . . . 18
4.4 PIDstabilisation . . . . . . . . . . . . . . . . . . . . . 21
4.5 TTLswitching....................... 23
vi

Contents vii
5 Table mode 25
5.1 Operationalprinciple. . . . . . . . . . . . . . . . . . . 25
5.2 Externaltrigger . . . . . . . . . . . . . . . . . . . . . . 27
5.3 Re-armandrestart . . . . . . . . . . . . . . . . . . . . 27
A Specifications 29
B Firmware upgrades 31
B.1 Upgradeviamogrf .................... 31
B.2 Factoryreset....................... 32
C Command language 35
C.1 Arguments......................... 35
C.2 Generalfunctions . . . . . . . . . . . . . . . . . . . . . 36
C.3 Basiccontrol ....................... 36
C.4 PrimaryRF control.................... 37
C.5 Modulation ........................ 38
C.6 Clockreference...................... 39
C.7 Tablemode ........................ 40
C.8 PIDfeedback....................... 42
C.9 Ethernetsettings . . . . . . . . . . . . . . . . . . . . . 43
D Communications 45
D.1Protocol.......................... 45
D.2TCP/IP........................... 45
D.3USB............................ 46
E Code examples 49
E.1 python ........................... 49
E.2 matlab ........................... 50
E.3 LabVIEW .......................... 51

viii Contents

Getting started
1. Connect to mains power usingthesuppliedIEC cord.
2. Power on the device usingtherockerswitchontherear.
3. Waitforthedevicetobootandthemenusystem(§2.2)tobe
displayed.
4. Set power limits for each channel using the Options menu.
Devicesareshippedwitha30dBmlimitthatshouldbeadjus-
tedasrequired. Thepowerlimitsshouldbechosentoensure
attacheddevicesarenotdamagedbyaccidentallyoutputting
toomuchpower.
5. Attach devices totheRFSMAconnectors,whicharenominally
50Ωloads. Under nocircumstancesshouldthe RF output be
shortcircuited.
6. Switch on outputusingtheLHSfront-panelpush-buttons. Chan-
nelswithoutattachedloadsshouldnotbeenabled.
7. Modulation inputs canbeusedtocontroltheRFwithanana-
log signal (chapter 4). Each channel has an associated SMA
inputthataccepts±1V.
8. External control ofthesignalisachievedwithTTLSMAinputs,
whichcanbeusedtogeneratesharppulses(§4.5).
Host connection
Therecommended modeof operationis usingthe WindowsTM host
application (chapter 3) which provides a simple interface for con-
trollingdevicefunctionality. Instructionsforconnectingviaethernet
andUSB areprovidedinAppendixD.
ix

xGetting started

1. Introduction
The MOGLabs QRF consists of an AD9959, which provides four in-
dependentdirectdigitalsynthesizer(DDS)sources,anda2Wam-
plifier for each channel. The frequency, amplitude and phase of
each output is software-controlled via a microcontroller, which can
beadjustedinreal-timeusingthefront-panelcontrolknobs,orvia
a scripting language over ethernet or USB. The RF parameters can
bedefinedinalookuptable(loadedviaethernetorUSB)toenable
complexsequenceswithfasttransitions.
The block diagram below shows the key components. A microcon-
trollerprogramstheDDS,whichgeneratesRFoutputthatislow-pass
filtered,pre-amplified,andthenfurtheramplifiedwithacustomGaN
hybridhigh-poweroutputstage(QRF241 only).
The microcontroller provides a front-panel display with rotary en-
coders(knobs)andpush-buttons,aswellasexternalinterfacesover
TCP/IP andUSB communications.
Front Panel Display
Micro
controller
ADC + lter
(1 per channel)
Ethernet
10/100
USB
RF OUT
4x MOD IN
RF on/o
RAM table
memory
DDS
RF amplier
Local
Clock
External
Reference
RF switchFilter
Figure 1.1: BlockdiagramofmajorcomponentsintheQRF.
1

2Chapter 1. Introduction
Thedeviceallowsanaloguemodulationthroughanalogue-to-digital
converters(ADCs)withanti-aliasingfilters. Whenmodulationisena-
bled, the microcontroller reads the value of the modulation signal
andusesthatvaluetoadjusttheDDSfrequency,powerand/orphase.
TheQRF includes memory forstoringcomplexwaveformsequences,
whereeachstepinthesequencedefinesthefrequency,power,phase
anddurationofthatstep. Thiscapabilitycanbeaccessedviaeither
TCPIP or USB communications. See Chapter D for information on
communicationsoptionsandsetup.
Once communications are established, the QRF is controlled with
simple text commands. The commands can be very basic, for ex-
ampletodefinethefrequencyorpower,ortheycandefinecomplex
dynamicsequences. AppendixCprovidesasummaryoftheavailable
commands.
1.1 Operating modes
TheQRFcanbeusedatvaryinglevelsofcomplexity,aseitherafree-
runningRFsourceortofollowpre-determinedinstructionsdefinedin
atable. Themodesofoperationareoutlinedbelow,andthecurrent
operationalmodeofeachchannelcanbeindividuallysetusingthe
MODE command.
NSB: Basic mode
Default state on power-up. In this mode, each channel acts as a
simplesingle-toneRFsource. Thefrequencyandpowerofthesignal
canbecontrolledviathefrontpanel,usingsimpleinstructionsover
the computer interface (e.g. FREQ or POW), or using the modulation
inputs. BasicmodeisconvenientfordrivingAOMsandothersingle-
frequencydevices,withtheflexibilityofmodulation.

1.2 Feature compatibility 3
NSA: Advanced mode
Advanced mode provides direct user-control of the DDS and its in-
ternal registers via the DDS command. Direct programming of each
DDS iscomplexandnotnecessaryformostapplications;itrequires
carefulreferencetotheAD9959 datasheetandmanualcalculationof
thehardwareregisters.
TSB: Simple table mode
In table mode, the RF parameters are automatically sequenced by
themicrocontrollerusingatablestoredinSDRAM.Thetableentries
aredefinedbysimpletextcommandsfromthehostcomputerwhich
definetheRF frequency,amplitude,phaseasdetailedinchapter5.
The minimum duration of a TSB entry is 5µsand each table can
compriseupto8191instructions.
1.2 Feature compatibility
TheQRF providesawiderangeoffunctionality,butnotallfeatures
are compatible with each other. The following table summarises
whichfeaturescanbeusedinwhichmodes.
NSB NSA TSB
Front-panelcontrols 3 7 7
Externalmodulation(AM/FM/PM)3 7 7
PID control 3 7 7
DirectTTL on/offcontrol 3 3 7
DirectDDS control 7 3 7
Autonomousexecution 7 7 3
ExternalTTL trigger 7 7 3
Table 1.1: Summaryoffeaturecompatibility

4Chapter 1. Introduction

2. Connections and controls
2.1 Front panel controls
4 Ch. RF Sythesizer
Ch. 1 Ch. 2 Ch. 3 Ch. 4
Figure 2.1: Front-panellayoutofQRFdevices.
Thefront-panelincludesaninteractivemenusystemfordisplaying
the device state and controlling its settings. Each channel has an
individual on/off button on the left-hand side, and an associated
multicolourstatusLED thatindicatesthecurrentoutputstateofthe
channelasshowninthefollowingtable.
Colour DDS active Amplifiers
Off 7 7
Green 3 3
Yellow 3 7
Blue 7 3
Purple Debugmode
Red Errorstate
5

6Chapter 2. Connections and controls
2.2 Menu system
The main menu (Figure 2.2) shows the current mode and status
of each channel. In basic (NSB) mode, the current frequency and
powerofeachchannelisdisplayed,aswellasanyactivemodulation.
Pressingthe OK buttonwithachannelselectedwillopenthe sub-
menutoadjustsettingsforthatchannel(Figure2.3).
Thebuttonsontheright-handsidenavigatethroughthemenustruc-
tureandtheencoderwheelisusedtoeditvalues. The∧and∨keys
changebetweenmenuitems, exitstothepreviousmenu,andOK
enterstheselectedmenuoractivatestheselectedcommand.
Figure 2.2: Themainmenushowsthecurrentstateofeachchannel. CH1
andCH2areintablemode,withthenumberofentriesinthetableshown.
CH3andCH4 areinbasicmode.
Figure 2.3: Thebasicparametersofeachchannelcanbeediteddirectly.
Turningtheencoderwheelmodifiestheselecteddigitofthecurrentvalue
(left) as indicated by the arrow. Pressing the encoder wheel changes to
digit select mode (right), allowing the selected digit to be changed by
turningtheencoder.

2.2 Menu system 7
Thecolorofeachmenuitemrepresentsitspurpose,aslistedbelow.
White Staticvalue,displayedfordiagnosticpurposes.
Yellow Adjustablevalue,modifiedusingtheencoderwheel.
Orange Currentlyselectedchannel.
Blue Submenu,enteredwiththeOK button.
Green Command,executedbytheOK button.
When an editable (yellow) value is selected, turning the encoder
wheel changes the value of the selected digit as identified by the
arrowandredtext. Tochangethedigitofinterest,eitherusethe<
or>buttonsorpresstheencoderwheeltochangetodigit selection
mode. Inthismode,thecurrentlyselecteddigitisshownonablack
background,andischangedbyturningtheencoderwheel. Pressing
theencoderagainreturnstovalue modification mode.
Theoptionsmenu(Figure2.4)allowsthedeviceconfigurationtobe
adjusted,suchasthepowerlimitofeachchannel(seealsotheLIM
command). Theethernetsettingsofthedevicecanalsobesetusing
thisinterface,includingthestaticIP addressofthedevice. Whenin
use,thenetworkstatusisdisplayedonthedisplayfooter,andonce
connecteddisplaysthecurrentIP address.
Notethatthe“Restartethernet”commandmustbeusedbeforechan-
gesintheethernetmenuwilltakeeffect.
Figure 2.4: The options menu allows configuration of various settings,
suchasthemaximumoutputpower(left)andethernetoptions(right).

8Chapter 2. Connections and controls
The overall brightness of the display can be set with the contrast
valueintheOptionsmenu. Thedisplayalsoincludesasleep timer
thatdimsthedisplayifithasn’treceivedinputinagivenperiodof
time. Thiscanbedisabledbysettingthesleeptimervalueto0.
2.3 Rear panel controls and connections
RF 1 RF 2
MOD 1 MOD 2 MOD 3 MOD 4
ON/OFF 1 ON/OFF 2 ON/OFF 3 ON/OFF 4
RF 3 RF 4
REF CLK
80 264 Vac
47 63 Hz Serial No:
Model:
Made in Australia
Figure 2.5: QRFrearpanellayout.
IEC power in TheQRF iscompatiblewithallstandardAC powersystems,from90
to264Vand47to63Hz.
Fan TheQRF hasfivetemperature-controlledfansdirectingairflowover
the RF power amplifiers, exhausting through the rear vent. Ensure
thattheventdoesnotbecomeblocked.
RF SMAconnectorsfortheprimaryRF outputs. Nominallyconnectedto
a50Ωload,must not be short-circuited.
MOD EachchannelhasanassociatedSMAanaloginput,forAM/FM/PM/PID
applications(seechapter4).
ON/OFF SMA digitalinputsforcontrollingtheRF switch(see§4.5),compati-
blewithboth3.3Vand5Vlogic. Alsousedforexternaltriggering
intablemode.