Digital Receiver For SALSA
Contents
1. clockwise O A o Se if feedback e1 j l 1 feedback el J J 0 reegbackP Eier cout lt lt endl TFF GOULSsftoedDackP el lt lt endl actual el el g command CB6 resets Rio for elevation g command CB7 resets Rio for elevation cout lt lt endl lt lt the actual elevation is 90 now lt lt endl nme nn u save Flle Tart en nee o t void MainWindow on save 2 clicked 44 opening file dialog to save file QString fileName QFileDialog creating file with the name QFile file fileName file open QTODevice WriteOnly OTextStream out amp file getSaveFileName this tr Save File home salsa banade files tr Text Files txt given by user OIODevice Text Digital Receiver For SALSA Appendix A putting data in file double d1 ui gt azimuth gt value double d2 ui gt elevation gt value OString 1 OString 52 sot SL S S sprintr 3 58 y az out sl endl s2 close file to save Bl Spraznmcr O O file close void MainWindow on load clicked opening file dialog to load file OString fileName fileName QFileDialog getOpenFileName this tr Open File home salsa banade files tr Text Files txt FILE in fopen fileName toAscii rt converting Ostring into c string read the first line from the file char buffer 100 char buffer2 100 fget2. Right movement gq Command SB5 else g command SB4 Left movement g command CBS std string num g command MG IN 8 acquiring feedback pulses from RIO feedback az i 5trtod num c str 0 converting std string into float coute lt teedback azlil if feedback az i 1 1 amp feedback az i 0 detecting feedback pulses feedbackP az counting feedback pulses cout lt lt end1 gt i cout s lt tecabacke az lt lt endl actual az az storing current value of azimuth in actual azimuth g command CB4 resets Rio g command CB5 resets Rio un gt actualaz gt setiext Ostring number actual az E 42 eS SS E elevation Part float totalP el for checking with 3 pulses int teedbackr el U int j 0 double feedback el 999939 feedback pulses for elevation if el gt 90 0 az 90 0 if el 0 0 az 90 0 ltotalP el eleactual el 47 4 feedback pulses in 1 degree totalP el el actual el 3 3 pulses per degree change to any number when known if LotalP el lt 0 r ralp el Orel AL L 41 Digital Receiver For SALSA Appendix A int DOLGLP ell Static Cast sIn total el 0 5 while totalP ell le Teedbackr el if el gt actual el 1 g command SB6 counter clock wise g command SB7 else g command SB6 clockwise g command CB7 3 std
3. float actual az 0 CLOSE SWITCH AZIMUTH float actual el 95 CLOSE SWITCH ELEVATION uSing namespace std MainWindow MainWindow QWidget parent OMainWindow parent ui new Ui MainWindow ui setupUi this MainWindow MainWindow delete ui void MainWindow changeEvent OEvent e OMainWindow changeEvent e switch e gt type case QEvent LanguageChange ui retranslateUi this break default break Galil g 192 168 0 24 check whether works with global dec jenes getting values from Form 01 ny float az Azimuth float el Elevation az ui gt azimuth gt value picking azimuth value from form el ui elevation value picking elevation value from form Perser een Az much Trsckungeeeeeeee i float totalP az for checking with 3 pulses int feedbacke az 0 40 Digital Receiver For SALSA Appendix A int i Q double feedback az 99999 feedback pulses for azimuth if az gt 360 0 az 360 0 if az lt 0 0 az 360 0 totalP az az actual_az 4 4 feedback pulses in 1 degree totalP az az actual az 3 3 feedback pulses in 1 degree change to any number when known nf toralp az lt 0 botalk az LOUdLP az 4 1 7 int totalP azl static cast int totalP az 0 5 converting float to the nearest integer while totalP azal t feedbackP az i Lf az actual az g command SB4
4. string num2 g command MG IN 9 he reecoack ell TESTECOO MIE Str 9075 couts reedback el 4 if feedback el j 1 1 amp feedback el J 0 FecabackP eltt cout lt lt endl cout lt lt tecdbackP 2l lt sendl Jsebs cout lt lt tecdbackP elssendal actual el SL g command CB6 resets Rio for elevation g command CB7 resets Rio for elevation u gt actualel gt Ssetiext Dated number actual el TI cout lt lt end lt lt endl Galil g 192 168 0 24 check whether works with global dec if noise g command SB2 molse diode is on on DO2 if noise g command CB2 noise diode is off on DO2 void MainWindow on track clicked when reset button clicked It resets antenna to 0 degree azimuth North and 90 degree elevation zenith Galil g 192 168 0 24 check whether works with global dec 42 Digital Receiver For SALSA Appendix A double reser az 99399 7 int k Qs int sum 1 making do while in this way g command SB4 right movement g command SB5 right movement while sum 0 amp sum 48 jy if a contineous stream of Us or contineous stream of 1S occurs it comes out of loop std string num3 g command MG IN 8 acquiring azimuth pulses reser az k sstrtod nums e Str 00 z 4 converting StO S5EEIDg IDEO double couts reset az k if k gt 50 counting number of zeros or ones at close sw
5. 3 Flow Graph of Noise Diode 5 2 4 Saving Coordinates in a File The antenna motion controller software enables the user to save the current coordinates azimuth and elevation values to a text file as illustrated in the flow chart below get coordinates from GUI and write Closes file to save into file in string the contents format Click Save to Enter the name of Program creates a open save file the file and click fie with the name dialog OK given by user Figure 5 4 Flow Graph of Saving File 5 2 5 Loading coordinates From File The software also has an option of loading coordinates azimuth and elevation from a saved text file Flow of the procedure is illustrated below Program reads the Click load to file line by line Load variables to Select a file to load R open load file and save the double spin Closes file coordinates dialog coordinates in box in GUI variables Figure 5 5 Flow Graph of Loading File 5 2 6 Graphical User Interface The GUI of the software is developed by using the C Ot library The main window of the software has double spin boxes for getting the azimuth and elevation values Text boxes are used to show the actual values after steering of the antenna Push buttons are used to perform several tasks like saving and loading of file etc A check box is used to activate and deactivate the noise diode 31 Digital Receiver For SALSA Chapter 5 Antenna Motion Controller Soft
6. 3 5 Software Receiver Snapshot 3 4 LAB VERIFICATION Before testing the receiver in real environment a setup was made to test the software receiver for eventually Valve Open 1 FFT Filter Decimation 1 Taps gr firdes complex ba Complex Conjugate Keep 1 in N N 5 k Vector to Stream Num Items 1 024k FFT Sink Title SIG REF REF Sample Rate 2M Baseband Freq 1 42046 Y per Div 10 dB Y Divs 10 Ref Level dB 100 FFT Size 512 Refresh Rate 30 Grid Position 0 0 2 4 Notebook note 0 1 debugging the software checking each of the receiver blocks and investigating the sensitivity issues since it would be a cumbersome job to setup the PC with all the wiring connections in real outdoor environment directly The purpose of this setup was to test the USRP2 for its sensitivity to weak signals and to check whether a weak signal hidden in the noise is detectable by the software receiver or not The USRP2 was seen to have a sensitivity of around 60 dBm which means it cannot detect signals below this level For detecting lower level signals that would be the case for astronomical objects we need pre amplifiers and set some gain of USRP2 device as well to amplify the incoming signal as much as it can be seen by the receiver to have the signal greater than 60 dBm 17 Digital Receiver For SALSA Chapter 3 Design For The Software Receiver Using GnuRadio Umair Naeem Test Signal 1420 4 MHz No
7. Antenna Figure 5 3 Flow Graph of Noise Diode Figure 5 4 Flow Graph of Saving File Figure 5 5 Flow Graph of Loading File Figure 5 6 The Main GUI of Antenna Motion Controller Software Figure 5 7 GUI When Saving Coordinates to a txt File Figure 5 8 GUI When Loading Coordinates From a txt File Figure 5 9 Figure Elaborating Detection of Feedback Pulses Figure 5 10 Antenna Motion Controller software testing in real environment C 00 NUN O Ur INN U U Ww C0 WwW U C0 W W NH NH NH NH NB NB NHB NHB NB NB NH E RR kl Fk E kl lk RP BS AR AR WN hN lE Fl Fl OO N DDH HN A N Nn kk kl WO WON DUH KR RB vii vili CHAPTER 1 INTRODUCTION TO RADIO ASTRONOMY RECEIVERS 1 1 TRANSMISSION AND RECEPTION In typical scenario Radio Frequency or RF signals are used to communicate information Audio Voice Video Data etc from one place to another The Information signal is modulated on a RF carrier wave and transmitted using antennas wireless case which convert electrical signals into electromagnetic waves that can travel though a wireless medium On the receiver side the same frequency signal is received using the antenna and fed to the receiver consisting of filters amplifiers down converters and demodulated to retrieve the transmitted information In radio astronomy since there are no man made transmissions it is usually required only to amplify very weak signals from sky and introduce some techniques to remove noise to get some sor
8. Average Avg Alpha 0 0010 12 Axis Options 129 126 e 1dB div 125 O 2 dB div 12 O 5 dB div 123 gt 10 dB div 125 20 dB div 2i Brevet Amplitude dB 12 in Autoscale 1 4194 1 4196 1 4198 1 42 1 4202 1 4204 1 4206 1 4208 1 421 1 4212 1 421 Frequency GHz stop Figure 3 13 Spectra When Antenna is aligned from the Hydrogen Source 22 CHAPTER 4 ANTENNA MOTION CONTROLLER HARDWARE CONFIGURATION 4 1 REVIEW OF THE AVAILABLE HARDWARE In our application there were many options for choosing hardware for controlling the motors and reading the feedback encoders Different vendors provide such hardware with different features This section describes some of the available hardware and motivates our choice of Galil RIO 47200 because of its advantages over other available hardware 4 1 1 Rabbit op 7210 eDisplay Rabbit provides op 7210 eDisplay Ethernet intelligent operator interface It provides 16 digital inputs and 8 digital outputs Digital outputs are individually configurable in software for different current and voltage outputs Current and voltage can be set up to 350mA and 36VDC respectively It provides Ethernet as well as two RS 232 or one RS 232 with CTS RTS interfaces Programs are developed for the op 7210 using Rabbit s industry proven Dynamic C software development system This development system offers almost all the capabilities like pop up me
9. Chapter 6 Conclusion And Future Work 38 OO OCC APPENDIX A ANTENNA MOTION CONTROLLER C CODE A 1 mainwindow h ifndef MAINWINDOW H define MAINWINDOW H include lt QMainWindow gt namespace Ui class MainWindow class MainWindow public QMainWindow Q OBJECT publrto MainWindow QWidget parent 0 MainWindow protected void changeEvent QEvent e private Ui MainWindow ui private slots vola on load clicked0 void on azimuth valueChanged double vola on save 2 clickedi void onm track clicked VOLO On noise clioked bool checked void on OK clicked be tendif MAINWINDOW H A 2 main cpp include lt QtGui QApplication gt include mainwindow h include Gall ar int main int argc char argv OApplication a argc argv MainWindow w w show return a exec A 3 mainwindow cpp include mainwindow h include ui mainwindow h include lt stdio h gt finclude lt stdlib h gt include lt math h gt include lt ctype h gt include lt unistd h gt include lt string h gt include lt fentl h gt include lt iostream gt include lt sstream gt 39 Digital Receiver For SALSA Appendix A include lt cstring gt include lt cstdlib gt include lt fstream gt include lt qfile h gt include lt gtextstream h gt include lt gdir h gt include lt qapplication h gt include lt QFileDialog gt include lt fstream gt include Galil h
10. Frequency GHz Stop Options REFERENCE O Peak Hold Avg Alpha 0 2000 m gt Axis Options 1 dB div 2 dB div 5 dB div a 10 dB div 20 dB div Ref Level De Amplitude dB 100 Autoscale 1 413 1 414 1 415 1 416 1 417 1 418 1 419 1 42 1 421 1 422 Frequency GHz Stop Figure 3 8 SIGNAL and REFERENCE Spectra Observed in Testing Top Block Options SIG REF REF C Peak Hold Average Avg Alpha 0 0667 Axis Options gt 1 dB div O 2 dB div 5 dB div 10 dB div 20 dB div Ref Level Amplitude dB Autoscale 1 413 1 414 1 415 1 416 1 417 1 418 1 419 1 42 1 421 1 422 Frequency GHz Stop Average Alpha 100m Graphs ii M Figure 3 9 Observation of Signal within Noise using SIG REF REF Technique tt Digital Receiver For SALSA Chapter 3 Design For The Software Receiver Using GnuRadio Umair Naeem 3 5 TESTING IN REAL ENVIRONMENT The whole setup was assembled outdoor in order to test the system for Hydrogen line detection This testing in real environment would be validating that all the components are placed in the right order antenna LNA power supply etc First the antenna was pointed in a random direction and the power level of the signal was noted Then the antenna was pointed towards the sun and power spectrum lifted a little showing that
11. R to run the project e Now you are ready with Antenna Motion Controller Software 49
12. antenna and process it in software domain This includes tuning the receiver controlling the attenuator and gain as well as reading the signal strength To complete a third party software defined receiver based on hardware platform all that is needed is DSP software running on the PC to filter and demodulate the low IF 12 kHz signal made available by the receiver This 12 kHz IF signal is available at the output of the Digital Receiver For SALSA Chapter 2 Overview Of Existing System And Some of the SDR Architectures Umair Naeem receiver and is usually externally connected to the line input of the sound card For standard USB connected G303e receivers the IF signal is available via the USB interface 2 3 3 Vanu 8 Vanu is a software radio that is primarily used for mobile communication It utilizes a software radio base station to form software RAN Radio Access Network solutions Vanu also developed MultiRAN to support multiple virtual base stations vBTS running on a single BTS hardware platform Different resources like antennas BTS electronics and backhaul can all be shared MultiRAN allows multiple operators to virtually share a single physical network This allows operators to experience the cost benefit of shared infrastructure without the cost complexity and risk associated with traditional network sharing arrangements 2 3 4 Pentek Model 7142 428 9 Digital transceiver with digital down converter and interpolation filt
13. named USRP2 from Ettus Research and implement a new software for data analysis based on GNU radio The hardware specifications of the existing system available for the project are summarize in the table below Table 2 1 Specification of the existing system for use in the project Components Specification 2 3m Antenna F D 0 4 LNA Gain 28 dB NF 0 34 dB 1420 MHz Amplifier Filter Range 1000 2000 MHz Gain 24 dB Feed Horn Inner Dia 15 5 cm 0 733 1420 MHz 2 1 1 Feed horn Figure 2 3 Feed horn used mounted over the antenna The feed horn is a corrugated aperture controlled horn in which the phase variation over the aperture is small By referring the design graph in 4 page 339 the directivity was calculated to be about 6 dB Digital Receiver For SALSA Chapter 2 Overview Of Existing System And Some of the SDR Architectures Umair Naeem 36 8 cm 22 1 cm 11 2 cm Figure 2 4 Top and Side View of the Feed Horn 2 1 2 Parabolic Reflector Antenna Figure 2 5 Parabolic Reflector Antenna The Antenna is a parabolic mesh surface reflector having the diameter of 2 3 meters Following is the parabola arc of the reflector From this graph the F D ratio was calculated to be about 0 4 0 I 100 2 200 Bw m 300 li E 400 1500 1000 500 0 500 1000 1500 Figure 2 6 Parabola Arc of the Reflector Antenna Digital Receiver For SALSA Chapter 2
14. pass cut off of the receive converter 6 The TV RX converts the incoming signal into a 5 75MHz IF The desired frequency and bandwidth are settable using the GnuRadio toolkit and GUI 6 The USRP was developed by Matt Ettus 1 Later on the USRP2 was built on the success of the original USRP and added new features 10 like Gigabit Ethernet 25 MHz bandwidth etc Digital Receiver For SALSA Chapter 2 Overview Of Existing System And Some of the SDR Architectures Umair Naeem GnuRadio is an open source SDR toolkit which contains a library of signal processing blocks like in Simulink Matlab which are interconnected like a flow graph Each signal processing block is written in C The processing blocks in GnuRadio are arranged or organised with a Python based applications framework The Python code manages interconnection of processing blocks and also provides user interface functions Table 2 2 shows the comparison between different SDR platforms NI PXle 5641R 2 IF inputs and 2 IF outputs 20 MHz real time IF bandwidth Xilinx Virtex 5 SX95T FPGA optimized for DSP 100 MS s 14 bit ADC 200 MS s 14 bit DAC Built in digital upconverters and downconverter S gt 76 dB input SNR 250 kHz to 80 MHz IF center frequency 143 dBm Hz input noise density Table 2 2 Comparison between different SDR platforms WinRadio IF of 12 kHz USB interface Extraordinary sensitivity Real time spectrum analyzer Spo
15. to sample the incoming pulses as fast so that not a single pulse would be missed 33 Digital Receiver For SALSA Chapter 5 Antenna Motion Controller Software Nabeel Ahmed Durrani 111111111111 111111111111 Figure 5 9 Figure Elaborating Detection of Feedback Pulses In the program the incoming pulses are sampled so fast that there would be a stream of around 70 ones or zeroes under normal conditions Then the program looks for the consecutive 1 and O or in order words going down pulses as marked by a bold square in figure 5 9 The sampling is so fast that we are confident that not even a single feedback pulse is missed therefore the program and pointing are so accurate 5 4 Outdoor Testing The software was tested thoroughly in lab with real antenna mount but without the antenna load on it After completing all the coding and testing all the software parts in lab an outdoor testing was conducted An antenna mount with a parabolic antenna shown in Figure 2 7 was placed in a windy environment and hardware is setup as shown in Figure 5 10 to test the Antenna Motion Controller Software in real environment PC with Antenna Motion Controller Software Figure 5 10 Antenna Motion Controller software testing in real environment The antenna is mounted in such a way that the horizontal close switch is in north direction and vertical close switch is in zenith direction The main problem in the outdoor testing is the windy environme
16. which Linux any version is already installed e Copy and paste antenna motion controller software along with all of its files in to home folder copy folder banade e To download Qt SDK go to http qt nokia com downloads Choose LGPL open source license Click the version which suits your machine type 32 or 64 bit and start download e After downloading install QT SDK on your machine Installation instructions are given on download page e This will install Ot library 4 6 and also an editor Qt creator 1 3 1 on your computer This Qt creator have already added all the paths and libraries you don t have to worry about it anymore e Now install Galil Tools Go to http www galilmc com support software downloads php and click on link install files under Linux tab It will lead you to the registration page Register yourself its free e After registration download and install the latest version of GalilTools Installation instructions are available on the same page e After installation search for Galil so copy it and paste it in to usr lib This is the easiest way to locate Galil communication library otherwise you have to give complete path of Galil so in banade pro e Now Antenna Motion controller software is ready to run on this computer You can directly run executable file banade in the folder banade which you have pasted in home folder in step 2 OR you can load file banade pro in Qt creator and then press Ctrl
17. DIGITAL RECEIVER FOR SALSA Umair Naeem Nabeel Ahmed Durrani Group of Advanced Receiver Development GARD Radio and Space Science with Onsala Space Observatory CHALMERS UNIVERSITY OF TECHNOLOGY Goteborg Sweden 2010 ABSTRACT The SALSA receiver uses a 2 3m parabolic antenna steerable in azimuth and elevation by motor driven mount A horn with a probe integrated with a Low Noise Amplifier LNA is mounted in the focus of the parabola The horn and the antenna are optimized for 1420 MHz which is the frequency at which atomic hydrogen in the Milky Way is emitting This Master thesis entitled Digital Receiver for SALSA describes the upgrade of the existing receiver and antenna control We designed the new digital receiver system that use a reconfigurable I O RIO FPGA in conjunction with antenna control software and a software receiver Software Defined Radio or SDR The purpose of upgrading the system was to include some enhancements in the antenna controller as well as in the receiver In the previous system a C program just worked as a GUI for the user taking data and sending it to a microcontroller based hardware system which decodes this data signal and sends appropriate signal to the antenna mount and then reads feedback encoder In this project a flexible and scalable software is realized to replace this complicated hardware In the upgraded receiver a Antenna Motion Controller software completely controls antenna The software i
18. EE NA LANARNCR Nm 9 Ka MN e M 9 ZO WAIVING Tr E 10 234 Penlek Model 7142 429 9 iusiii descen bie ai duoc ou E E 10 235 AJSRP and Ouais ee II 10 2 4 CHOICE OF SDR PLATFORM sss s sssssss 11 CHAPTER 3 13 DESIGN FOR THE SOFTWARE RECEIVER USING GNURADIO 13 3 1 INTRODUCTION IA 13 3 2 DESIGN ANALYSIS AAA 13 3 3 IMPLEMENTATION IN GNURADIO AND USRP2Z ssssssssssuue 13 o PP E E N E E 15 5 9 FERO ee ee ee 15 3 3 3 Power Spectrum and AVAE ii 15 3 3 4 Signal Reference Reference uuesssssssssssssssssnnnnneeeeeennnnnnnnnnnnnnnnnnnnnnnnnnssnnnnnnnnnnnnnnnnnnnnnnnnnsssnnnnnnnnnnnnnnnsnnnnnnnnn 15 3 3 5 Conversion to Time Domain and FFT Scope wwa 16 330 FUSION iii aa 16 3 4 LAB VERIFICATION naci 17 3 5 TESTING IN REALENVIRONMENT inesset uti ege secante cores ras ios seis 20 CHAPTER 4 23 ANTENNA MOTION CONTROLLER HARDWARE CONFIGURATION 23 4 1 REVIEW OF THE AVAILABLE HARDWARE 23 ATL RaBbIE0B7210 CD IS Olay cc 23 4 1 2 TRIO MO CAN e ee 23 4 13 UNLeompacthiO SENES rd 23 44 Gall DIME TM eur ren 23 4 2 Choice of hardware for Antenna Motion Controller o oooooocococoncncocococococononcncorocococononos 24 4 3 SY
19. For higher frequencies and for more sensitive receivers with ultimate performance the first stage of LNA is not present 2 As shown on figure 1 1 a correlator calculates the power spectrum based on Wiener Khinchin Theorem which states that the power spectrum of a signal is the Fourier transform of its autocorrelation function ACF The correlator might be analog or digital For a digital correlator the signal is first digitized using analog digital converter ADC Figure 1 2 shows a digital receiver which incorporates an A D down conversion This type of receiver is built using modern high speed ADCs and powerful FPGAs This works on the principle that the magnitude square of the Fourier transform is the power spectrum Digital Receiver For SALSA Chapter 1 Introduction to Radio Astronomy Receivers Umair Naeem Correlation and Founer Transform 4naloaz or Dig tal Figure 1 1 A typical block diagram of a hardware based Radio Astronomy Receiver with analog or digital Correlator s aftware Coantralled Digital amp cquisition Board Baseband Processing Fourier Transform Integration Logging etc Figure 1 2 A typical block diagram of a hardware based Radio Astronomy Receiver with digital processing to calculate Power Spectrum The existing SALSA receiver is based on what is shown in figure 1 1 Figure 1 2 shows the system that is implemented in software and will be discussed in detail After being received from antenna typical
20. Overview Of Existing System And Some of the SDR Architectures Umair Naeem 2 2 SOFTWARE DEFINED RADIO SDR A software defined radio SDR system is a hardware cum software based radio communication system which can tune to any frequency band and decode different modulations encoding schemes across a large frequency spectrum by means of a programmable hardware which is controlled by software An SDR performs significant amounts of digital signal processing in a general purpose computer PC or a reconfigurable piece of digital electronics 5 SDR has evolved with advancement in computing machines and high speed analog digital A D and digital analog D A converters Thus SDR allows a single device to support a wide range of capabilities previously available only through multiple products Usually it is required that signals received by an antenna should be digitized so that SDR may use these digitized samples at RF frequencies around GHz frequencies to perform further signal processing steps IF conversion filtering baseband conversion etc But due to certain limitations like unavailability of A D converters at very high frequencies starting from a few GHz and very high speed general purpose computers digitization takes place after the IF or baseband demodulator stage That typically means that hardware is still required to convert the signals of interest into and out of the baseband frequencies in the digital domain but all of the com
21. STEM BLOCK DIAGRAM u 24 A ES O AA NEPOTES 24 rs a lO BOK a eRe ea ME IM Ra M Wa 25 ss Antenne MIOUOL Somme Icio To otio bdo aoa tut dfe teorie dew ust e indo cS todas 26 4 4 CONFIGURATION OF RIO ii asias 27 CHAPTER 5 29 ANTENNA MOTION CONTROLLER SOFTWARE 29 5 1 OVER VIEW e 29 5 2 PROGRAM FLOW c 29 SAL Steerin OTAN E EDD US 29 S222 nitialization oft Antenna POSO Neta rai 30 523 NOUS DGC Sie x 30 5 2 4 Saving Coordinates IN a FIle ii ad Nbre pa us Ua uta etev NEA Evol dtd eU eu eU a o AE e WM e ba TUUS 31 5 25 Foadihg coordibiates FEODN Files 31 5 2 5 Graphical Hser Inter faeB studiert osea Dre ta iod oo bet nfi ento tu da 31 5 3 PROGRAM S MAINDA Ui E 33 53 1 dagtertacihe WIRIO cata tor ee een 33 5 32 iDetecting Tee back PUSES en ee een eisen 33 5 4 Outdoor Testing EE TOT ICI CEU 34 CHAPTER 6 35 CONCLUSION AND FUTURE WORK 35 REFERENCES 37 APPENDIX A 39 ANTENNA MOTION CONTROLLER C CODE 39 APPENDIX B 47 ELECTRICAL DIAGRAM OF AMPLIFIER BOX 47 APPENDIX C 49 INSTALLATION OF SOFTWARES 49 LIST OF FIGURES AND TABLES Figure 1 1 A typical block diagram of a hardware based Radio Astronomy Receiver with Analog or Digital Correlator __ 2 Figure 1 2 A typical block diagram of a hardware based Radio Astronomy Receiver with digital processing to calculate Power Spectrum Figure 2 1 Block Diagram of t
22. Supply for DO O 7 Output Power GROUND for DO 0 7 Direction signal for azimuth Motion signal for azimuth Direction signal for elevation otion signal for elevation o enable IN jumpers Elevation feedback nput common DI 8 15 Azimuth feedback Noise diode control Rio has two power options external power supply and PoE Power over Ethernet When external power supply is used then four jumpers are placed at pins labelled as AUX on Rio default setting and when power over Ethernet is required then instead of placing 4 jumpers on AUX 4 jumpers are placed at pins labelled as PoE on Rio The INC jumpers can be used when an external power supply is not desired for digital inputs 0 15 These inputs can use the internal 5V from the RIO instead To do this place a jumper on the pins labelled INC 16 Digital Receiver For SALSA Chapter 4 Antenna Motion Controller Hardware Configuration Nabeel Ahmed Durrani 28 gt CHAPTER 5 ANTENNA MOTION CONTROLLER SOFTWARE 5 1 OVERVIEW Antenna motion controller software is developed using C language and used for steering of the antenna in azimuth and elevation directions resetting the antenna to the north and zenith positions enabling and disabling noise diode saving azimuth and elevation coordinates in a txt file The User can also load the coordinates from a saved file The GUI Graphical User Interface is built mainly by means of the C Ot library which is specially de
23. Window window hamming N Shift No Add Const FFT Sink Title SIGNAL Sample Rate 10M Baseband Freq 1 4179G Y per Div 10 dB Y Divs 10 Ref Level dB 0 FFT Size 1 024k Refresh Rate 10 Grid Position 0 0 4 10 Notebook note 0 0 FFT Sink Title REFERENCE Sample Rate 10M Baseband Freq 1 4179G Y per Div 10 dB Y Divs 10 Ref Level dB 0 FFT Size 1 024k Refresh Rate 10 Grid Position 4 0 4 10 Notebook note 0 0 FFT FFT Size 1 024k Grid Position 0 0 1 1 Constant 1 N Vec Length 1 024k ID high cutoff Value 375m Vec Length 1 024k Forward Reverse Forward Window window hamming N Variable ID fft size Variable Check Box ID gui onoff Label Check to Parameters Default Value False True True False False Variable Chooser ID onoff Label Graphs Default Value 1 Choices 1 0 Labels Save Saved Type Button Grid Position 3 3 1 1 Notebook note 0 1 Variable ID Sig freq Value 1 024k Value 1 4204G Variable Slider ID BW Label Bandwidth Default Value 2 5M Minimum 500k Maximum 2 5M Converter Float Grid Position 0 4 1 1 Variable Config ID Ref freq save Default Value 1 4174G Type Float Config File er var config Section main Option key WriteBack 1 4179G File Sink File RA Receiveer Output Frequency Xlating FIR Filter Decimation 1 Taps gr firdes complex ba Center Frequency 2 5M Sample Rate 10M Figure
24. all the connections were fine and that the pre amplifier and software receiver is working properly in accordance with the lab test results Then the antenna was pointed towards the hydrogen line source Figures 3 10 3 12 3 13 show the setup and the difference in the spectrum of sig ref ref without and with the antenna pointed towards the Hydrogen line source respectively It can be seen from the figures 3 12 and 3 13 that the receiver worked properly as the signal is differentiable from noise Comparing the spectrum taken with the old configuration of SALSA 11 figure 3 11 pointed toward the same direction of the galactic plane Galactic longitude 2120 degrees Galactic latitude b 0 and the spectrum figure 3 13 obtained with the upgraded digital software receiver pointing in the same direction clearly shows the functionality of the upgraded digital receiver The difference is spectrum can be explained by the approximate pointing during our experiment but it certainly looks like a detection It would also have been useful to observe in a slightly larger or shifted towards right band 11 The observed spectrum range seems far wider than the actual spectrum band needed to observe within red circle in figure 3 13 This is due to the FFT Scope block of the GnuRadio where no zooming on a particular section of the spectrum is possible hence we have to see the whole band which is being translated from analog to digital domain through samplin
25. available GnuRadio with USRP2 was chosen in this thesis to develop SDR for the astronomical spectrometer for the detection of Hydrogen line at 1420 MHz For this purpose DBS_RX daughterboard is used to get RF and convert it to IF and baseband for further processing USRP2 and Gnuradio were chosen for the following reasons e Input signal frequency from 800 MHz to 2 4 GHz e Largest Single Sided bandwidth of 25 MHz e Open Source Cost effective and expandable solution 11 Digital Receiver For SALSA Chapter 2 Overview Of Existing System And Some of the SDR Architectures Umair Naeem 12 I CHAPTER 3 DESIGN FOR THE SOFTWARE RECEIVER USING GNURADIO 3 1 INTRODUCTION Keeping in mind the main goals of the project the whole existing correlator receiver was converted into software receiver using the GnuRadio software platform The USRP2 serves as an RF front end to get the digital signals for GnuRadio 3 2 DESIGN ANALYSIS The signal flow in the existing receiving system was as follows e The RF signal coming from the antenna amplified through the LNA and pre amplified as necessary is fed into an IF stage which converts RF into IF e This IF is used to calculate the frequency content of the signal hence the power spectrum is calculated in the correlator and fed into an accumulator to integrate several spectra for averaging purpose This averaging ensures the removal of as much random noise as possible e The observations were do
26. e Bystrom in OSO and Per Bjorklund in OSO for providing help regarding antenna pointing towards source regarding existing receiver providing feedback on final results and regarding amplifier design Thanks to all of the OSO people for their moral support and for providing a good working environment TABLE OF CONTENTS CHAPTER 1 1 INTRODUCTION TO RADIO ASTRONOMY RECEIVERS 1 1 1 TRANSMISSION AND RECEPTION cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccceccccccccesccceccccescce 1 1 2 RADIO ASTRONOMY RECEIVERS nun see on 1 1 3 OBSERVING TECHNIQUES 3 1 4 THESIS MOTIVATION ee 3 1 5 THESIS ORGANISATION us nee 3 CHAPTER 2 5 OVERVIEW OF EXISTING SYSTEM AND SOME OF THE SOFTWARE DEFINED RADIO SDR ARCHITECTURES 5 2 1 OVERVIEW OF THE EXISTING SYSTEM s 5 21 1 a e o LM MM DM 7 2 1 2 Parabolic Reflector Antenna 0 ccccccecceccseccecceccecceccecceecceccecceccuscuececceecesccseceecaeceeceeececeseceececeeceeceseeeeeeeeeeeeeeaeeans 8 2 2 SOFTWARE DEFINED RADIO SDR scsccscsscsceccscsccccsccccsceccscescscsccecsceccscescscsscccsseccscescscesscssecees 9 2 3 REVIEW OF AVAILABLE SDR PLATFORM ccccccccccccccccccccccccccccccccccccccccccccccceccccecccceccsoecccoecs 9 Ew M
27. e a feedback mechanism which is fairly simple A 12 leg wheel as shown in figure 4 5 is mounted on a shaft in one of the gearboxes of antenna motor so whenever the antenna moves it also rotates this wheel There is an opto couple behind this wheel so that TTL pulses are created when light from the opto couple falls on it These are TTL pulses and have frequency ranges from 8 to 12Hz One degree rotation in azimuth or elevation generates 4 feedback pulses which gives an angular accuracy of 0 25 degree the full moon has an angular diameter of about half a degree 18 The angular resolution of the 2 3m SALSA antenna is about 7 at the frequency of the HI line 1420 MHz 18 These pulses directly go to the digital input of the Rio which is then read by the antenna motion controller software Antenna Motor Y Y ital circuitary Creates lt a d 5 Figure 4 5 Opto couplers and the Wheel Providing Feedback of Antenna Position 26 Digital Receiver For SALSA Chapter 4 Antenna Motion Controller Hardware Configuration Nabeel Ahmed Durrani 4 4 CONFIGURATION OF RIO The following table contains physical interfaces which are connected to Rio A small description of every interface is also given in the table below Table 4 1 Physical Interfaces Connected to RIO Wire colour number Connected to Yellow Gray Wire 1 Noise diode Description 18 36V Power Supply Ground for Power Supply 12 24V Output Power
28. ecimation 10 Variable Frequency Hz 1 4179G ID N Gain dB 27 Value 1 024k Value 10 ID note 0 Variable Notebook Tab Orientation Left ID samp rate Labels Signals Output Value 10M Variable Slider ID Ref freq Label Reference Frequency Default Value 1 4179G Minimum 1 4174G Maximum 1 4184G Converter Float Grid Position 0 1 1 3 Variable ID Sig minus Ref Value 2 5M Grid Position 1 0 1 5 Variable Slider ID avg alpha Label Average Alpha Default Value 100m Minimum 1m Maximum 250m Converter Float Grid Position 3 0 1 3 Notebook note 0 1 Variable Slider ID gain Label Filter Gain Variable ID low cutoff Value 125m Default Value 1 Minimum 1 Maximum 32 Converter Float Variable FFT Filter Decimation 1 Taps gr firdes complex ba FFT Filter Decimation 1 Taps gr firdes complex ba Stream to Vector Num Items 1 024k FFT FFT Size 1 024k Forward Reverse Forward Window window hamming N Shift No Complex to Mag 2 Vec Length 1 024k Single Pole IIR Filter Alpha 100m Vec Length 1 024k Open 1 Stream to Vector Num Items 1 024k Complex to Mag 2 Vec Length 1 024k Single Pole IIR Filter Alpha 100m Vec Length 1 024k Divide Digital Receiver For SALSA File Sink File RA_Receiveer Signal Valve Open 1 File Sink File Receiveer Reference FFT FFT Size 1 024k Forward Reverse Forward
29. ed Instead the whole band consisting of the signal as well as the reference was obtained for processing In our case this was as follows Signal at 1420 4 MHz with 2 5 MHz bandwidth 1419 15 1421 65 MHz 13 14 Digital Receiver For SALSA Chapter 3 Design For The Software Receiver Using GnuRadio Umair Naeem Reference at 1417 9 MHz with 2 5 MHz bandwidth 1416 65 1419 15 MHz Total bandwidth comprising of Signal and Reference thus became 5 MHz e The signal and reference signals are then filtered through separate filters their FFT is calculated averaged and finally the above mathematical equation is applied to detect the required signal Figure 3 1 Functional block diagram of the developed software receiver FFT Scope Signal Filter USRP Source 1 0MIsps gt Reference Filter T FFT Scope Power Power Spectrum and j Spectrum and Averaging Averaging Signal Signal Reference l Reference umm mm m L i mmm E Conversion to I Time Domain FFT Scope Figure 3 1 Functional Block Diagram of Software Receiver Digital Receiver For SALSA Chapter 3 Design For The Software Receiver Using GnuRadio Umair Naeem 3 3 1 USRP2 Source This source block defines the parameters to get signals from USRP2 Source refers to the signal flow starting from USRP2 as seen from the GnuRadio point of view Parameters are defined be
30. eeping smooth running of the program when saving data The software could also be upgraded for supporting different file formats save the spectrum that is currently shown etc by the use of Python or C programming The current receiver is designed for the detection of the Hydrogen line and may be slightly modified to detect some other lines A new receiver can be built to detect Pulsars based on either filter bank or employing a reverse channel filter A filter bank consists of a number of narrow band filters or channels the output of each of which is delayed separately by different amount and then are added This is to remove dispersion effects that are caused to pulsar signals during their journey through dispersive medium The other way to remove dispersion is to employ and anti dispersive or reverse channel filter that has the characteristics just opposite of the dispersive medium or channel and will reshape the Pulsar signals Finally since Pulsar signals arrive in the form of pulses with highly accurate timing one has to take each pulse and add them together to have enough energy to be detectable 35 Digital Receiver For SALSA Chapter 6 Conclusion And Future Work The following consideration could be taken into account for the extension of the antenna motion controller software First in the current software files can be saved in standard fits format but because of the time limitation of the project reading the antenna positions fro
31. er is a complete software radio system in a PMC XMC module with a decimation range from 2 to 65 536 and interpolation range from 2 to 32 768 It includes four A D and one D A converters with bandwidths up to 40 MHz and above for connection to HF or IF ports of a communications or radar system 2 3 5 USRP and GnuRadio GnuRadio http www gnu org software gnuradio provides a comprehensive toolkit for the experimentalist in SDR to produce applications in a variety of disciplines The work originated at MIT with Eric Blossom shepherding its emergence as a GPL licensed toolkit that is seeing significant usage by RF experimenters and engineering students worldwide 6 The GnuRadio project resulted in the Universal Software Radio Peripheral USRP which is a digital acquisition DAQ system containing four 64 MS s 12 bit A D converters ADCs four 128 MS s 14 bit D A converters DACs and supports USB 2 0 interface The USRP is capable of processing signals with 16 MHz of bandwidth The USRP takes daughter cards to map the frequency ranges of interest into the baseband that is visible by the A D hardware Several different daughter cards are available but the cards of most interest to amateur radio astronomy enthusiasts would be 6 e DBS RX RXonly covers 850 2250 MHz e TV RX RXonly covers 50 800Mhz The DBS RX converts the incoming RF into complex signals in a direct conversion approach with the signals extending from DC up to the low
32. ere are feedback pulses for azimuth and elevation from the motors which rotate the antenna These feedback pulses wires are connected to the digital input of the Rio as these are TTL pulses of 8 12Hz frequency Digital Receiver For SALSA Chapter 4 Antenna Motion Controller Hardware Configuration Nabeel Ahmed Durrani UA AUA RN RRE es BEERERBEEREFFERE RRHOASRRERALVOIS Figure 4 2 Rio 47200 4 3 2 Amplifier Box The output from the Rio are TTL levels but the motors which rotate the antenna requires at least 18V with a continuous current of 2 5A and a 4A peak current so there is an considerable need of amplifier between Rio and antenna motor Azimuth amp elevation Figure 4 3 Amplifier Box inside view Furthermore the direction of steering is changed by changing the polarity of the power supply and this is accomplished by creating a control signal with the power supply which when enabled delivers power with positive polarity and when disabled delivers power with negative polarity The amplifier front panel contains discrete input connection from Rio to the amplifier and amplified output azimuth and elevation control signals marked by solid black boxes in figure 4 4 to the antenna motors 25 Digital Receiver For SALSA Chapter 4 Antenna Motion Controller Hardware Configuration Nabeel Ahmed Durrani Figure 4 4 Amplifier box front view 4 3 3 Antenna Motor The antenna motors which rotate the antenna hav
33. g To observe only a small part of spectrum one could decimate the SIGNAL REFERENCE REFERENCE signal to a point where the bandwidth is half the decimated sampling rate Nyquist Theorem Actually a small decimation is performed here if we compare figures 3 13 and 3 9 to see the difference Digital Receiver For SALSA Chapter 3 Design For The Software Receiver Using GnuRadio Umair Naeem USRP NA el iine Si Fro Ante Ethernet Interface EIncoming Signal From Antenna B W jene amp PC N 3 u Pa un E 40 D A4 E 1419 0 1419 5 1420 0 1420 5 1421 0 1421 5 frequency MHz Figure 3 11 Spectra of Hydrogen Line Taken From Existing System in Units of Temperature 21 Digital Receiver For SALSA Chapter 3 Design For The Software Receiver Using GnuRadio Umair Naeem Top Block Options SIG REF REF Peak Hold Average Avg Alpha 0 0043 Axis Options e 1 dB div 2 dB div 5 dB div 10 dB div 20 dB div Ref Level 120 Autoscale 1 4194 1 4196 1 4198 1 42 1 420 1 4204 1 4206 1 4208 1 421 1 4212 1 421 Frequency GHz stop O a a 9 E O E a E d O O Il Figure 3 12 Spectra When Antenna is Misaligned towards Hydrogen Source La Lr Top Block Filter Gain Reference Frequency 1 4179G Bandwidth Signals cic y Options SIG REF REF Peak Hold Output
34. he Existing System Figure 2 2 Existing SALSA Receiver Q Radio Block Diagram Table 2 1 Specification of the Existing System For Use in the Poject Figure 2 3 Feed Horn Used Mounted Over the Antenna Figure 2 4 Top and Side View of the Feed Horn Figure 2 5 Parabolic Reflector Antenna Figure 2 6 Parabola Arc of the Reflector Antenna Table 2 2 Comparison Between Different SDR Platforms Figure 3 1 Functional Block Diagram of Software Receiver Figure 3 2 Power Spectrum And Averaging Block Figure 3 3 Observation Block Figure 3 4 Conversion to Time Domain Block Figure 3 5 Software Receiver Snapshot Figure 3 6 Block Diagram of Simulation Figure 3 7 Test Setup Figure 3 8 SIGNAL and REFERENCE Spectra Observed in Testing Figure 3 9 Observation of Signal within Noise using SIG REF REF Technique Figure 3 10 Testing in Outdoor Environment Figure 3 11 Spectra of Hydrogen Line Taken From Existing System in Units of Temperature Figure 3 12 Spectra When Antenna is Misaligned FromThe Hydrogen Source Figure 3 13 Spectra When Antenna is Aligned Towards Hydrogen Source Figure 4 1 Block diagram for antenna motion controller Figure 4 2 Rio 47200 Figure 4 3 Amplifier Box inside view Figure 4 4 Amplifier box front view Figure 4 5 Opto couplers and the Wheel Providing Feedback of Antenna Position Table 4 1 Physical Interfaces Connected to RIO Figure 5 1 Flow Graph of Antenna Steering Figure 5 2 Flow Graph of Resetting
35. he controller Q radio The C program which controls Q radio sends commands in string format to the Q radio in which a microcontroller decodes these commands and send appropriate signal to antenna motors Then Q radio reads feedback pulses from the antenna feedback mechanism and sends the number of feedback pulses to the C program again in string format The main idea of this master thesis is to replace this complicated hardware by simplified software and to minimize the hardware needs therefore the system block diagram is very simplified The mount of the antenna is provided by Alfa Radio Ltd It s a heavy duty antenna rotator Each axis uses a double worm gear drive system Two windshield motors are used as drivers Motors operate on 12 24V 2 5A with peak starting current of 4A Motors have two limit switches in each axis One limit switch is at a complete rotation in azimuth 360 degree and the other is on 95 100 degrees in elevation 17 4 3 1 Rio 47200 Rio 47200 has multiple digital inputs and multiple digital outputs As shown in block diagram Rio is connected to the PC via Ethernet 100Base T which takes care of the communication part between the PC and the Rio board Two wires for azimuth control and two wires of elevation control of the motor are connected to the digital outputs of the RIO and these outputs are controlled by the Antenna Motion Controller software defined in next chapter To control the rotation of the antenna th
36. ialized motion controlling boards They have 32 bit processor and provide standard PCI and ISA slots for communication They also provide different modes of motion like point to point positioning jogging etc 15 23 Digital Receiver For SALSA Chapter 4 Antenna Motion Controller Hardware Configuration Nabeel Ahmed Durrani 4 2 Choice of hardware for Antenna Motion Controller The main reason for choosing the RIO family is its simplicity It provides number of digital outputs which are perfectly matching our application in which we have to give commands to the azimuth and elevation motors It also has digital inputs which makes easy to read feedback encoders to get azimuth and elevation pulses from the motor It also provides standard 100Base T Ethernet and RS 232 options to interface with PC Galil provides its own made C communication library which makes it really easy to communicate with RIO and interrogating about its I O status It provides on board programming which can be a very important feature when using RIO as standalone motion controller It provides flexibility to add more RIO units with it via Ethernet or RS232 port 16 4 3 SYSTEM BLOCK DIAGRAM feedback pulses Ethernet Amplifier Box Azimuth Figure 4 1 Block diagram for antenna motion controller One of the main goals of this master thesis is to minimize the hardware used in the previous system Q radio In the previous system a C program just provides GUI to t
37. ise Diode Variable Attenuator LALA 28 dB Coupler 10 000K dB 1 dB zain LISRP2 15 Filter 24 dB 25 dB zain gain 1 to 2 GHz Figure 3 6 Block Diagram of Simulation Figures 3 6 and 3 7 show the block diagram and the photograph respectively of the setup in which a noise diode 10 000 K In addition a test signal at 1420 4 MHz was injected through pre amplifier s to have a total gain of around 70 dB including the USRP2 gain The noise floor showed up above the 60 dBm which means that the incoming signal has been provided sufficient with gain to cross the 60 dBm sensitivity limit and is detectable The weak test signal around 125dBm was not detectable from within the noise diode s noise as it has very low level see figure 3 8 To detect this test signal the sig ref ref method see figure 3 9 was performed and the test signal appeared verifying that the new system is now ready to test for Astronomical sources Figure 3 7 Test Setup 18 Digital Receiver For SALSA Chapter 3 Design For The Software Receiver Using GnuRadio Umair Naeem Top Block Filter Gain p Reference Frequency 1 41799G 1 41796 0 4179G Bandwidth T Signals SIGNAL Options Peak Hold Output Average Avg Alpha 0 2000 i I Axis Options 1 dB div 2 dB div 5 dB div 10 dB div 20 dB div Amplitude dB Ref Level B Autoscale 1413 1 414 1 415 1 416 1 417 1 418 1 419 1 42 1 421 1 422
38. itch sum 0 for ant Je 2 d Sum t reset az k L cout lt lt sum lt lt oe g command WT5 k g command CB4 resets Rio for elevation q oommand CEBO cout lt lt azimuth is reset to 0 degree lt lt endl double reset 0119999817 ine m e 0 int sum2 1 g command SB6 right movement right movement q command 5B7 sum2 48 while sum2 0 std string num4 g command MG IN 9 reset sstetod numt e str 0 eout lt lt reset el mi if m gt gt 0 sume 0 for int 2550 mie m suma e reset ellwm nl cout lt lt sum lt lt 43 Digital Receiver For SALSA Appendix A g command WT5 mt g command CB6 gq command CB resets Rio for elevation cout lt lt endl lt lt elvation is reset to 100 degree lt lt endl float Totale els int fesdbacke eL 9r Tnt q 0 double Ieedback el 92999 float el 90 float ctual el 95 total el el actual e totalP el total el totale OL al 7 int totalp ell whlle tortalP ell q command SB6 5 q command CB7 4 std string num2 reedback el cout lt lt feedback el a el derual el graci cast rm P TeedbackP el1 1 g command MG IN 9 PS SLELOG UNG 0 SEU can be array of bool 3 3 feedback pulses in 1 degree change to any number when known 4 4 feedback pulses in 1 degree COtalLP ek 0 5
39. low Frequency This is the frequency which will be down converted to O Hz baseband It was set to the center of Reference frequency band i e 1417 9 MHz Decimation This parameter sets the decimation that USRP2 should perform Normally since the USRP2 provides a bandwidth of 50 MHz it means that the sample rate of the output signal from USRP2 is at 100 Msamples sec twice of bandwidth according to Nyquist Theorem We require 5 MHz of bandwidth so we need 10 Msamples sec of sample rate Therefore decimation should be 100 10 10 3 3 2 FFT Filters There are two FFT filters to filter out Reference and Signal The FT filter performs filtering in frequency domain which is faster than time domain filtering 3 3 3 Power Spectrum and Averaging Figure 3 2 Power Spectrum and Averaging Block These blocks calculate the Fast Fourier Transforms FFT of both Reference and Signal and then take the square of the magnitude to get the power spectrum Averaging filters perform averaging to smoothen the signals and remove as much random noise as possible 3 3 4 Signal Reference Reference Sign al Reference Reference l l Add Constant signal Reference 1 i Figure 3 3 Observation Block These blocks actually perform the mathematical operation described above They are implemented with the following simplification Signal Reference Signal Reference Reference Reference Reference Signal Reference Sig
40. lt Ez salsa banade files Places Name v Size Modified g Search nabeel txt 17 bytes Yesterday at 15 53 Recently Used mss E3 salsa umair txt 18 bytes Yesterday at 16 05 E Desktop E File System E Documents 3 Music E3 Pictures 3 Videos 3 Downloads Text Files Cancel Open Figure 5 8 GUI When Loading Coordinates From a txt File 95 3 PROGRAM S MAIN PARTS 5 3 1 Interfacing With RIO Rio uses Ethernet 100Base T to interface with a PC The manufacturer provides the libraries to use Rio with languages like C CH VB etc Galil h is used to interface and interrogate RIO in Linux environment This library function provides simple functions to perform complicated tasks Like a simple command g command SB4 is used to set high the digital output 4 A simple command like Galil g ip address is used to perform a very complicated part of connecting the PC with Rio This command takes care of all the overhead information used to connect the PC Ethernet port to the RIO The user does not have to take care of these overhead and flag information This library function eases the programming of RIO 5 3 2 Detecting feedback Pulses The main problem in the project is to detect feedback pulses as the frequency of the feedback pulses is not constant It varies from 8 to 12Hz and it depends upon the motor speed which can vary due to wind speed and direction The solution to this problem is
41. ly parabolic reflector the incoming signal is amplified by a high gain Low Noise Amplifier LNA which is down converted to Intermediate Frequency IF using mixers in order to facilitate further processing Then the Analog to Digital conversion takes place so that the signal can be digitally processed in modern receivers A Digital Down converter down converts the IF signals into baseband for processing by dedicated or general purpose PC processors The output can be in the form of display showing some spectra and or data files 1 3 OBSERVING TECHNIQUES There are different observation techniques to observe weak signals from the sky These are defined below e Frequency Switching in which the spectrum at exactly the frequency of interest is observed calculated first for a certain period of time and stored Then the local oscillator frequency of the mixer is changed to a few MHz away from frequency of interest and then the spectrum is calculated at that frequency The spectrum at exact frequency of interest is termed Signal and the spectrum at some offset frequency is termed Reference e Position Switching in which first for a few moments the spectrum at exactly the frequency of interest and exactly at the right position on the sky is observed calculated and stored Then the direction of the antenna is changed only to some other position from where there is no emission at the frequency of interest and then the spectrum is calculated at the same f
42. m this standard fits format is not implemented yet Second the interface between the software receiver developed in GNU radio and the antenna motion controller software could be improved even though it is functional as it is Third a tracking part could be included in the software which can lock an object and then track it automatically Last there is a possibility of creating interferometer with two antennas 36 REFERENCES 1 http en wikipedia org wiki 2 Bhushan Billade Design of Dual Polarization Sideband Separation Mixer for ALMA Band 5 Department of Radio and Space Science Chalmers University of Technology Sweden 2009 3 Courtesy of Onsala Space Observatory 4 Per Simon Kildal Foundations of Antennas Spring 2009 5 Naveen Manicka GNU RADIO TESTBED University of Delaware 6 Marcus Leech VE3MDL GnuRadio and USRP Solderless Breadboarding for the 21st Century 7 http sine ni com nips cds view p lang en nid 207050 8 http www vanu com technology sdr html 9 www pentek com 10 www gnuradio org 11 Private Communication with Cathy Horellou Onsala Space Observatory 12 http www rabbit com products op7200 13 www triomotion com 15 http www galilmc com products dmc 17x0 ph 16 User manual for 74xxx series 17 http www alfaradio ca 18 http www oso chalmers se horellou OUTREACH SALSA radiosweden pdf 37 Digital Receiver For SALSA
43. n in some file Antenna Motion Controller Software In the existing system the control of antenna is divided into two parts the C program and Q radio microcontroller based hardware With the upgrade the antenna is completely controlled by a single C program This program is flexible enough to easily change the number of pulses per degree position of the closed switches both in azimuth and elevation directions initial position of antenna etc Also if one wants to reconfigure the interface between antenna and the C program for future extensions one would just need to change some parameters in the program clearly commented The antenna motion controller software is flexible enough to be used with different antenna mounts due to the use fast sampling to read feedback pulses from antenna 1 5 THESIS ORGANISATION Digital Receiver For SALSA Chapter 1 Introduction to Radio Astronomy Receivers Umair Naeem The report comprises of two parts Antenna Steering and Control Software and a Software based Digital Receiver These two tasks were completed by Nabeel Ahmed Durrani and Umair Naeem respectively and their reporting is organized as follows Chapter 2 gives an overview of the existing system and currently available Software Defined Radio SDR architectures Chapter 3 covers the design analysis done for the receiver using GNU Radio and future possibilities and extension in the system Chapter 4 covers hardware configuration physical interfaces c
44. nal Reference Reference 15 Digital Receiver For SALSA Chapter 3 Design For The Software Receiver Using GnuRadio Umair Naeem 3 3 5 Conversion to Time Domain and FFT Scope Conversion to Time Domain Complex I Inverse FFT Conjugate Figure 3 4 Conversion to Time Domain Block This block converts the freguency domain signal back into time domain For this it takes the inverse FFT since we need to display the power spectrum of Sig Ref Ref and the FFT scope does this on time domain signal The FFT Scope also provides with additional averaging options to smoothen the signal as much as reguired The complex conjugate block takes the complex conjugate of the incoming time domain signal This is to invert flip the spectra The previous blocks actually process the signals and the resultant signals spectra is flipped to negative side of the frequency scale In order to re flip it to positive side of the frequency scale this block is added here 3 3 6 File Save This sink block is used to store the time domain signal in binary file format This file can be read by a File Source block Following figure shows the software receiver made in a tool named GnuRadio Companion or GRC of GnuRadio which provides graphical user interface to design systems Chapter 3 Design For The Software Receiver Using GnuRadio Umair Naeem Options ID top_block Run True USRP2 Source Interface eth MAC Addr D
45. ne using frequency switching The spectrum at exactly the Hydrogen line 1420MHz is calculated and stored for a certain period of time Then the local oscillator frequency of the mixer IF stage is changed to a few MHz away from Hydrogen line and then spectrum is calculated at that frequency The Spectrum at exact the Hydrogen line is termed Signal and spectrum at some offset frequency from Hydrogen line is termed Reference e A signal processing technique is employed to make the weak Hydrogen line signal further detectable within the noise which in mathematical form is Signal Reference Reference 3 3 IMPLEMENTATION IN GNURADIO AND USRP2 According to the above methodology for the receiver the digital software receiver was implemented in the chosen SDR architecture as follows e The RF signal coming from Antenna amplified through LNA and pre amplified as necessary is fed into USRP2 which has a DBS RX daughter board that contains an IF stage for converting RF into IF and then baseband with a maximum bandwidth of 50 MHz This baseband signal is available through Ethernet interface to GnuRadio running on a PC for further processing GnuRadio makes use of software filters and FFT to calculate and display the power spectrum e There is some limitation in GnuRadio It works well in real time not in store and process method In order to have two slightly different frequency signals Signal and Reference frequency switching is not us
46. nt In order to compensate the behaviour of the windy environment the sampling of the incoming feedback pulses is kept very fast so that even not a single feedback pulse would be missed Every part of the software was thoroughly checked tested and verified in the lab so the software worked perfectly in real conditions ar gt CHAPTER 6 CONCLUSION AND FUTURE WORK A software receiver for SALSA and a new antenna motion controller we designed realised and successfully tested under real operation condition The antenna motion controller is fully functional and flexible the software receiver is performing far better than the existing one with real time signal processing less hardware resources and with the advantage of re configurability All the parts of the project thesis are now to be integrated to have a fully functional operating system with Software Receiver and Antenna Control Software running on a PC and to have a single piece of enclosure for all the necessary hardware This will ensure maximum integrity and minimum parts in the surroundings of the antenna The software receiver shows real time signals Signal and Reference which can also be set by the user Observations can be made using the Signal Reference Reference technique which is shown in separate tab in the software The software receiver is highly flexible in terms of changing frequency gain bandwidth without changing hardware components It is not required to switch the freq
47. nus onscreen keypads data transmission reception over TCP IP and serial connections analog volt meter display and many more 12 The main disadvantage of op 7210 is its number of digital outputs it has only 8 digital outputs This project utilizes 5 digital outputs but such a short number of digital outputs will limit the possibility of future expandability 4 1 2 Trio Motion CAN 16 1 0 The CAN 16 1 0 module from Trio Motion Technologies allows the 24volt digital inputs and outputs of the Motion Coordinator to be extended in blocks of 16 bi directional channels It provides its own made Motion Perfect software for programming and analyzing I O status However this module does not provide the flexibility to be used with most widely used languages like MATLAB C etc It supports G code which is one of the standard languages that is widely used in CNC machines 13 4 1 3 NI compactHIO Series National Instruments provide a series of compactRIO components These series provide the control to a variety of hardware types with the integration of the very popular LabView software The main drawback in NI compactRIO series is that it only supports single axis devices while the antenna mount used in this project utilizes two axes motion Using these compactRIO just increases un necessary components and so the cost will also increase 14 4 1 4 Galil s DMC family Galil s DMC family is also a strong candidate for our application The DMCs are spec
48. onnected to different hardware and characteristics of hardware components used in this project Chapter 5 deals with different aspects of the antenna motion controller software Chapter 6 includes conclusions and suggests future work of this thesis CHAPTER 2 OVERVIEW OF EXISTING SYSTEM AND SOME OF THE SOFTWARE DEFINED RADIO SDR ARCHITECTURES 2 1 OVERVIEW OF THE EXISTING SYSTEM pp eS aS M Iw aS ee A a po O RADIO RECEIVER BOR i Mixer u Zu Filter a Filter CN I LO Antenna _ I zm je pem f F EEE EEE a Linux based software Running on PC Figure 2 1 Block Diagram of the Existing System Figure 2 1 shows the existing system used for the observation of the hydrogen line After the amplification in the LNA the signal is carried by coaxial cable to a preamplifier box where it is further amplified and filtered in a narrow bandwidth filter to remove interference signals around the 1420MHz line The receiver box named Q Radio accommodates the down conversion circuitry the driving IC s for the antenna motors the correlator and a micro controller which controls all functions and communicates with a PC In the receiver box the signal from the preamplifier box is further amplified and then down converted to an Intermediate Frequency IF and a total bandwidth of 2 4 MHz using Side Band Separation technique The microcontroller performs auto correlation of the signal
49. plex processing performed at baseband is handled in the digital software domain 6 Yet such hardware is usually fairly simple comprising of a local oscillator and mixer and a pair of low pass filters 2 3 REVIEW OF AVAILABLE SDR PLATFORMS There are many platforms or architectures available to perform signal processing together with software domain A brief introduction to some of the devices that use SDR is given below 2 3 1 NI PXle 5641R 7 The NI PXle 5641R uses LABView software to develop signal processing algorithms and applications The NI PXle b641R is an intermediate frequency IF transceiver for applications such as radio frequency identification RFID tests spectral monitoring real time spectrum analysis RF dynamic test and software defined radio SDR It features e 100 MS s A D converters with 20 MHz bandwidth digital down converters DDCs e 200 MS s D A converters with 20 MHz bandwidth digital up converters DUCs e Radio frequency RF applications at frequencies up to 2 7 GHz with bandwidths up to 20 MHz 2 3 2 WinRadio 1 WiNRADIO is the name of a manufacturer of radio communication equipment as well as a brand name of applied software radio receivers antennas and accessories Applications of WiNRADIO receivers include general purpose radio radio astronomy or SETI Search for Extraterrestrial Intelligence WinRadio has developed its own receivers G303 etc with software to digitize the signal coming from
50. requency of interest The spectrum at exact frequency of interest observed from the exact position of interest is termed Signal and the spectrum observed from offset position is termed Reference e A signal processing technique is employed to make the weak signal at frequency of interest further detectable within the noise which in mathematical form is Signal Reference Reference 1 4 THESIS MOTIVATION The usual approach hardware based to detect signals has some limitations like to adapt to new services and standards Each element in the receiver usually works for a particular specification and needs to be changed or re designed or re purchased if there is some change in the receivers pecifications Frequency Gain Bandwidth Weight etc This increases the hardware cost and is time consuming design purchase and installation Software Defined Radio SDR as described later can do almost all of the said processing using software running on PCs with a general purpose single piece device Re designing the software is time and cost effective Considering figure 1 2 the section in dotted lines a digital acquisition device is usually integrated into a single device USRP2 in our case with configurable parameters and all the remaining signal processing is done in software which gives more flexibility over the entire hardware based approach The second part of the project deals with steering of the antenna saving and loading antenna positio
51. s buffer 50 in fgets buffer2 50 in display what we ve just read printf first line of fred txt s n buffer printf first line of fred txt Ssin buffer2 double f atof buffer double f2 atof buffer2 cout lt lt f lt lt endl cout lt lt f2 lt lt endl putting values in form ul gt azimuth gt setValue f ui elevation setValue f2 close the stream fclose in 45 Digital Receiver For SALSA Appendix A d 4 o oo o ooo ELECTRICAL DIAGRAM OF AMPLIFIER BOX APPENDIX B 0POB 9 0P0A iod i Ah we 5 7 tt Zy E n A n HH ww jJ A OS Ot x Aa 1 MEM 7 NW AW t eiie OS OV OV A OEZ AS C 1TH 9 NOHWO VSV OQAZEL 0Z0Z 1040 Alddns Jamog 47 48 n APPENDIX C INSTALLATION OF SOFTWARES GnuRadio was installed on Linux Fedora Core operating system Following links were used to install and configure GnuRadio and GRC e http gnuradio org redmine wiki gnuradio e ftp ftp gnu org gnu gnuradio gnuradio 3 2 2 tar gz e http gnuradio org redmine wiki 1 GNURadioCompanion Once everything is installed the file receiver grc can be open in GRC and can be run from there Alternatively the python code that is also generated can be run directly from terminal by typing in the directory RA Receiver e python top_block py Following are the instructions to install Antenna Motion Controller software on computer e Pre requisite is a personal computer on
52. s designed in such a way that it does not miss even a single feedback pulse there are 4 feedback pulses in one degree The accuracy factor of software is 0 25 degrees The old receiver was hardware based thus every new configuration required new hardware However in our case the software receiver is highly flexible in which a wide range of configuration is possible without changing or upgrading existing hardware The new receiver also works in real time mode real time signal processing while the old one used to do store and process This upgrade reduces the user interaction to continuously obtain signal spectra and also minimizes the hardware needs ACKNOWLEDGEMENTS First of all we would like to thank Almighty ALLAH the most merciful and beneficent who always shows us path of success and helps us in every moment of life and to whom we have to return one day We would also like to honor our parents who always pray for us and give us courage to work hard in every step of studies Special thanks to our supervisor Miroslav Pantaleev and our examiner Vincent Desmaris for supervising us in every single stage of work and managing their time from their tight schedule Many Thanks to Lars Peterson and Michael Olberg in OSO for providing a great software support and to Magne in OSO who not only helped us in initial antenna controller design but also gave us time to troubleshoot during the final testing stages Thanks to Cathy Horellou in OSO Run
53. t of profile frequency shape bandwidth etc of the incoming signal 1 2 RADIO ASTRONOMY RECEIVERS Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies The initial detection of radio waves from an astronomical object was made in the 1930s when Karl Jansky observed radiation coming from the Milky Way Subsequent observations have identified a number of different sources of radio emission These include stars and galaxies as well as entirely new classes of objects such as radio galaxies quasars pulsars and masers The discovery of the cosmic microwave background radiation which provided compelling evidence for the Big Bang was made through radio astronomy 1 Radio astronomy is conducted using large radio antennae referred to as radio telescopes 1 that detect weak signals from the sky There are two types of receivers direct detectors and heterodyne detectors In heterodyne detectors one or more mixer stages are involved to down convert the incoming RF signal to reduce processing overheads After detecting a signal its power spectrum is calculated using correlators or FPGA based Fourier Transform receivers and is used to further process the signal in order to read and get information about source of emission These types of receivers are usually termed as spectrometers Figure 1 1 and 1 2 show typical and simplified low frequency lower than 100 GHz Radio Astronomy Receiver RAR or Spectrometer
54. t on tuning in 1Hz steps Accurate signal strength indicator Very low phase noise DRM decoder option Continuously variable IF bandwidth 1Hz 15kHz User adjustable filter selectivity Built in test and measurement instrumentatio n Interactive block diagrams Frequency 850 MHz 1800 MHz 1900 MHz Output Power 20W per carrier Backhaul IP over Ethernet or E1 T1 Interfaces Antenna ports 50 ohm N female GSM BTS to BSC GSM A bis over IP CDMA BTS to BSC CDMA A bis over IP Supported Standards GSM GPRS Edge CDMA2 000 1xRTT Sensitivity GSM 112 dBm CDMA 126 dBm Capacity GSM upto 48 carriers CDMA upto 24 carriers Pentek Model 7142 428 Full scale input 10 dBm into 50 ohms 3 dB passband 250 kHz to 300 MHz ADC Sampling rate 1 MHz to 125 MHz Resolution 14 bits Decimation 1 to 4096 Input B W 40 MHz Upconverte Sample Rate 500 MHz max and resolution 16 bits Interface PCI Bus 64 bit 66 MHz DMA 9 channel demand mode and chaining controller USRP2 and GNURadio Gigabit Ethernet interface 25 MHz of RF bandwidth Xilinx Spartan 3 2000 FPGA Dual 100 MHz 14 bit ADCs Dual 400 MHz 16 bit DACs 1 MByte of high speed SRAM Locking to an external 10 MHz reference 1 PPS input Configuration stored on standard SD cards The ability to lock multiple systems together for MIMO 2 4 CHOICE OF SDR PLATFORM Comparing the different SDR platforms
55. uency from Signal to Reference because both are shown simultaneously in real time In the antenna motion control software the user enters azimuth and elevation to direct the antenna in the proper direction towards Hydrogen line source The software controls completely the steering of the antenna initializing the antenna position controlling of noise diode and saving and loading antenna position in some file In the previous system the control of antenna is divided in two parts the C program and Q radio a microcontroller based hardware But now the antenna is completely controlled by a single C program This program is flexible enough that most of the things like number of pulses per degree position of the closed switches both in azimuth and elevation directions initial position of antenna etc can be easily changed Further if one wants to reconfigure RIO for future extensions one would just need to change some numbers in program clearly commented Antenna motion controller software is also sufficiently flexible to be used with different antenna mounts because sampling which is used to read feedback pulses is fast enough to accommodate high frequency feedback pulses as well The current receiver system has an option to save the spectrum in a binary format There are a few extensions that could also be made to make it a little more versatile Currently the GnuRadio itself is in development stage and the save data procedure could be optimized k
56. vation so when performing the reset function software moves the antenna 5 degrees from its close switch to get the actual zenith position The flow graph of reset function is presented below Establishing connection with RIO Command Rio to move antenna in right direction Analyzing feedback pulses Continuous stream of 1s close switch continuous stream O Os or continuous stream of 1s comes Continuous stream of Os close switch Reset done Reset done Reset Rio to get Reset Rio to get azimuth and azimuth and elevation values elevation values Figure 5 2 Flow Graph of Resetting Antenna 5 2 3 Noise Diode A noise diode is a device used to simulate the atmospheric noise It is turned on for calibration and simulation purposes The control signal of the noise diode is connected to one of the outputs of the Rio board and it can be turned on or off just by sending O or 1 at this output A Boolean variable is declared for the noise diode whenever the GUI sends this Boolean variable as true a 1 is sent to the output of the RIO and the noise diode is turned on and when it is false a O is sent to the output of RIO and noise diode is turned off Digital Receiver For SALSA Chapter 5 Antenna Motion Controller Software Nabeel Ahmed Durrani Establish connection with RIO Analyzing check box condition If unchecked turn off noise diode If checked turn on noise diode Figure 5
57. veloped for graphics in C language 5 2 PROGRAM FLOW 5 2 1 Steering of Antenna The antenna motion controller software enables the user to steer antenna in both azimuth and elevation directions from GUI The user can give azimuth values form 0 360 degrees and elevation values from 0 90 degree in double spin box created using Qt library The flow graph of the program to steer the antenna in desired directions is presented below Establish connection with RIO Obtaining values from Ul ompare curren position value with previous positio If greater mowe If lesser move right Left Calculating number of pulses from number of degrees Same processes as moving left Comparing calculated number of pulses with feedback pulses Reset Rio to get another input Put value in Gul Figure 5 1 Flow Graph of Antenna Steering 29 Digital Receiver For SALSA Chapter 5 Antenna Motion Controller Software Nabeel Ahmed Durrani 30 5 2 2 Initialization of Antenna Position The software enables the user to the reset antenna to the north direction in azimuth i e O degree and to the zenith in elevation i e 90 degree The antenna has its close switches both in horizontal and vertical directions The antenna is mounted so that it has its horizontal close switch at North and vertical close switch at zenith direction Indeed the vertical close switch is not exactly at 90 degree it is around at 95 degree ele
58. ware Nabeel Ahmed Durrani Antenna Motion Controller Azimuth Elevation 24 00 4 Actual Azimuth o 49 00 s Actual Elevation 0 1 Reset C Noise Diode Save Figure 5 6 The Main GUI of Antenna Motion Controller Software When the user clicks on the save button a windows method is invoked which shows a dialog window whose parameters are set so that the file is saved to the specified folder Antenna Motion Controller Elevation 87 50 3i Actual Elevation Azimuth 2 50 Actual Azimuth Reset Load C Noise Diode Y Browse for other folders e salsa banade files Create Folder v Size Modified 17 bytes Yesterday at 15 53 18 bytes Yesterday at 16 05 Name 2 nabeel txt 12 umair txt Places d Search Recently Used P3 salsa T8 Desktop E File System E Documents 3 Music Pictures BS videos Downloads Text Files lt gt Cancel Save Figure 5 7 GUI When Saving Coordinates to a txt File 32 DS Digital Receiver For SALSA Chapter 5 Antenna Motion Controller Software Nabeel Ahmed Durrani The following window is shown when user clicks load button Again a windows method is invoked whose parameters are set to show only txt files Antenna Motion Controller Azimuth Elevation 2 50 2 87 50 E OK Actual Azimuth Actual Elevation Reset Noise Diode D
59. with a resolution of 12 5 kHz and also gives the possibility to integrate over a certain period of time This pattern is sent to the PC via serial port A Linux based software calculates the frequency spectrum and logs the data The user enters the azimuth and elevation coordinates for the observation in the software and then the computer communicates with the microprocessor which commands the mount motors and reads its current position Figure 2 2 shows the detailed block diagram of the existing receiver in Onsala Space Observatory developed by Rune Bystr m Are Elektronik It can be seen that the RF signal is split in two branches and are mixed with a sinusoidal signal Digital Receiver For SALSA Chapter 2 Overview Of Existing System And Some of the SDR Architectures Umair Naeem from a local oscillator with a frequency of about 1418 MHz which are phase shifted with 90 degrees After mixing both signals are digitized and then added together after introducing additional 90 degrees phase shift in the corresponding channel to cancel the unwanted side band B n OPTOLTHE OPTOLLHE EL DRIVE MIRO ES 232 CONTROLLER AZ DRIVE DIGITAL E E Figure 2 2 Existing SALSA Receiver Q Radio Block Diagram 3 Digital Receiver For SALSA Chapter 2 Overview Of Existing System And Some of the SDR Architectures Umair Naeem One of the main objectives for this thesis is to replace the correlator with a general purpose digital front end device
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