View/Open - Calhoun: The NPS
Contents
1. Figure 10 Block Diagram 1T1 Initialization of Tektronix RTD720A 38 Figure 11 Block Diagram Initialization Bypass 39 Figure 12 Block Diagram 2 Wait Time of 0 5 Seconds 40 COLLECT M Diagram ic Edit 2n Functions Windows Text set o automatica preposiion or a fxed 4 inch by 4 inch collection plane The Code Interface N fles located in c watcom bin caled prepos c prepos h preposvm addon to these Labview and tcom make addtional lor inking and comp ng The code resource to load is prepos lb ode interface Node Figure 13 Block Diagram 30 repositioning of Receiver 41 Diagram izes fies located in c walcom bin called prepos c prepos h addiion to these Labview and fare To aulomateaby preposiion wed 4 inch by 4 inch colection plane Code Interface N alcom make addtional or inking and coming The code resource to load is repos kb Figure 14 Block Diagram 31 Bypass Prepositioning 42 Oto ructure dota Le arm 72 such iat wil incoming pulse r isa crirecoxd 0 sends al recorde cuve requests 720 to Figure 152. EM c Figure 22 Block Diagram 47 0 Close Current File 50 COLLECT Diagram Edi mm Functions Windows Text LE E Mee Figure 23 Block Diagram 47T1 Move Receiver Down 51 II 2 Figure 24 Block Diagram 47 2 Wait Time of 0 5 Seconds 52 COLLECT VI Diagram Windows Text Chamber Loop boo siructue Ole ecion fo sows Figure 25 Block Diagram 4713 Move Receiver Left 53 Cranba Loog 9 E Curent Colecton Point ma rection 1 2 ui Figure 26 Block Diagram 47T4 Wait Time of 0 5 Seconds 54 COLLECT MI Diagram El File Edit Functions Windows Text bop structure To move Uis deer Figure 27 Block Diagram 47F Move Receiver Right 55 COLLECT Mt Diagrau Eolecton Chamber 00 RT Current
3. 5 Prepositioning of Receiver 20 6 Data Collection Loop 21 IV SYSTEM OPERATION 24 GENERAL PROCEDURES 24 1 Hardware Configuration 24 2 LabVIEW Front Panel and Diagrai 25 3 Waveform Data and Format 26 SUMMARY 29 APPENDIX A SOURCE CODE FOR PREPOS C AND 30 APPENDIX COLLECT VI GRAPHICAL 32 LIST OF REFERENCES 57 INITIAL DISTRIBUTION LIST 59 1 INTRODUCTION The angular spectrum approach is widely used tool to explore the propagation characteristics of continuous ultrasonic sources 1 Associated mathematics for this technique are well understood and are useful in analyzing and predicting acoustic diffraction patterns emitted by ultrasonic and optical sources Ref 2 Many practical applications use pulsed sound instead of continuous sound for acoustic imaging tissue characterization and other specialized functions such as mine detection Computer programs have been developed for prediction of the diffraction patterns from pulsed sources allowing time efficient reconstruction and simulation of patterns 3 However this simulated data must be verified with experimental data The purpose of this thesis was to construct and synthesize a pulsed ultrasonic collection facility using readily available components which could collect these waveform diffraction patterns Using the measure
4. diagram form LabVIEW is a general purpose programming system with extensive libraries of functions and subroutines which are identical in operation to those in conventional language programs The programs developed in LabVIEW are called virtual instruments VIs because their appearance and operation imitate actual instruments VIs have an interactive user interface called a front panel and a source code equivalent called a block diagram The front panel simulates the panel of a physical instrument which contain controls and indicators Data input is accomplished by using a mouse and keyboard Instructions are received from the block diagram which is actually a pictorial solution to the programming problem Ref 14 The program designed for the data collection system is called COLLECT VI Upon aligning the receiver with the centerline axis of the transmitter face using MD 2MOVE running COLLECT V1 is all that is needed for data collection Any changes made to the receiver collection plane dimensions or instrumentation setup are performed within COLLECT VI 2 Data Collection Program Algorithm Figure 2 shows the general processes that COLLECT VI steps through The user sets the program variables in the case selection block The variables are determined by the choice of receiving plane size made on the front panel of the program Features such as options to Initialize Wavetek 270 Tektronix RTD 720A and Prepositioning of Receiver were also
5. stops and data collection is complete An i located on the lower left corner of each loop records the number of times the loop has executed starting with the numeral 0 The outer loop keeps track of the receiver row position and makes the determination of opening a new file A new file is opened for each row Outer loop functions are shown to the right of the inner loop in Figures 15 through 28 Every time the outer loop executes a new file is opened The previously opened file is closed by the 21 inner loop enumerate each row correctly i 1 is calculated and appended to the file data txt e g datal txt data2 txt data3 txt etc Thus new file name is created for each row This new file name is then appended to a path containing the desired directory for data file storage COLLECT VI will store all files in the directory name dat32a on the external Bernoulli drive d The new file is then opened for writing Inner loop structures which contain inner frames 0 through 8 common to Figures 15 through 28 compromise the program core Prior to digitizing the Tektronix 720 is armed just before firing the pulse generator Figures 15 16 and 17 Arming commands are sent to Tektronix 720A located at GPIB address 20 Figure 15 a wait time is inserted for synchronization Figure 16 and fire commands are sent to Wavetek 270 located at GPIB address 4 Figure 17 After firing the waveform is transmitted through t
6. 2move program this done choose yes lo automatically position the receiver for collection ieee 3 Lorie The receiving plane is a feed four inch by four inch quote However the number Qi colecton ports can e aduniad to 432 64 or 129 per side This means 4 rows by 4 columns 32 rows by 32 columns etc essentialy carving the receiving plane into a matrix Higher numbers wil yield more collection points thus an Terese v colection pon densi nthe theron mutipled by the coben length How ROI RBLIJ K nent Fieceiver Postion Figure 3 Front Panel 32 COLLECT Diagram B Colechon densi of recenng plane The receiving plane is faed by four However the number of collection points can be adiusted to 4 3254 or 128 per This means amp rows by columns 32 rows by 22 columns estentaly carving receiving plane into a mati Higher numbers more collection ponis thus an increase p collection pont deny Figure 4 Block Diagram 00 4x4 Collection Density Setup 33 Colleckon densi ol iscesng plane The plane by four quare However the number of colection points can adusted to 4 32 64 or 128 per lide Ths means 4 rows by 4 columns 32 rows by 32 columns ec essential
7. Block Diagram 40 Arming of the Tektronix RTD720A 43 NES file Edit Operate Functions Windows Text 2727 I fae Figure 16 Block Diagram 41 Wait Time of 1 0 Seconds 44 anew erum Figure 17 Block Diagram 42 Wavetek 270 Pulse Firing 45 Figure 18 Block Diagram 43 Wait Time of 3 0 Seconds 46 ion Chamber Colechon Pont To move Dia Toop siue 28 econ 1 or columns 0 1 number of data lo receive Figure 19 Block Diagram 44 Waveform Reception from Digitizer 47 COLLECT VI Diagram file Edit ay Functions Windows Text sue Figure 20 Block Diagram 45 Write to Data File 48 Figure 21 Block Diagram 46 Wait Time of 1 0 Seconds 49 COLLECT M Diagran File Edit Operate Functions Windows Text
8. Figures 9 and 10 Shown under settings within the border are the preset values transmitted The operating tool is used to change these values if needed The LabVIEW icon labeled SEND transmits data bytes preset values to the corresponding instrument indicated by GPIB address Mode indicates that a End Or Identity message will be sent at the termination of the data bytes If is chosen on the front panel all initialization is bypassed and no operations will be carried out as shown in the FALSE case structure of Figure 11 At this point manual entries would have to be made to the Wavetek 270 and Tektronix RTD 720A prior to running the data collection program 4 Wait Time As shown in Figure 12 and as interspersed throughout the program various structures contain wait functions These functions whose icon looks like a timer will cause the program to wait a specified number of seconds or fraction thereof prior to moving on to the next structure Thus COLLECT VI will remain idle upon executing this frame The purpose is to allow completion of previous program tasks and synchronization of operations 5 Prepositioning of Receiver The operator has the discretion to preposition the receiver from the front panel Figure 13 executes if yes is selected on the front panel Shown within case 0 of Figure 13 are Steps for Prepositioning and Code Interface Node Steps for prepositioning is the number of steps sent to PREPOS C via the Code Interf
9. S AND ADDRESS ES 8 PERFORMING ORGANIZATION Naval Postgraduate School REPORT NUMBER Monterey CA 93943 5000 SPONSORING MONITORING AGENCY NAME S AND ADDRESS ES 10 SPONSORING MONITORING AGENCY REPORT NUMBER 11 SUPPLEMENTARY NOTES The views expressed in this thesis are those of the author and do not reflect the official policy or position of the Department of Defense or the U S Government 12 DISTRIBUTION AVAILABILITY STATEMENT Approved for public release 125 DISTRIBUTION CODE iistribution unlimited 13 ABSTRACT maximum 200 words The work reported in this thesis used readily available components to implement data acquisition system for a pulsed ultrasonic data collection facility Use of hardware with controlling software is necessary to collect waveforms of acoustic potential at a given distance from the transmitting source Precise movement and positioning of an acoustic receiver in the collection plane is accomplished by use of an xy coordinate motor driven slide assembly A signal generator and transient digitizer transmit and digitize the signal respectively These components are brought together synchronously using LabVIEW instrumentation software This work provides an efficient means to collect waveform data which can be used to verify computer code written previously for the purpose of modeling pulsed ultrasonic acoustic diffraction patterns 14 SUBJECT TERMS LabVIEW diffraction ultraso
10. acoustic transmitter This slide was positioned between the box rails and permitted arbitrary positioning of the transmitter within the water tank itself Separate plexiglass mounts were fabricated and used to position both the acoustic transmitter and receiver in the water The acoustic transmitter mount was attached to the hand adjustable slide and the receiver mount was attached to the vertical motor driven slide 2 Stepper Motors Motor Driven Slide and Motor Driver Two stepper motors in conjunction with motor driven slides xy coordinate motor driven slides move the acoustic receiver along vertical and horizontal axes For this application the motors use a single step mode which means that for each programmed step the shaft will turn 1 8 degrees As a reference 5100 steps will move a slide 2 5 centimeters 1 inch Ref 5 The xy coordinate motor driven slide incrementally positions the acoustic receiver during data acquisition Each motor drives a screw upon which a slide is attached The screws are approximately 53 centimeters in length and contain eleven threads per centimeter One screw moves the acoustic receiver along the vertical direction y axis while the other moves the vertical slide acoustic receiver along the horizontal direction x axis Thus precise positioning of the acoustic receiver is accomplished by stepping incremental rotation of the shaft the motors Ref 5 6 Current and voltage supplied to the
11. number of inches Fixed 4 inch by 4 inch receiving plane 4 inches o Data Collection Points 4 rows by 4 columns 4 inches Distance between data collection points steps to send C code Figure 8 4x4 Collection Density Plane TABLE 4x4 COLLECTION PLANE DENSITY CALCULATIONS Collection Density Steps to Send 4 4 20400 3 6800 32 32 20400 31 658 64 64 20400 63 324 128 128 20400 127 160 per side for fixed 4 inch 4 inch receiving plane is four the total number of steps side is 4 5100 20400 Each side contains N 4 32 64 or 128 collection points per side Thus the number of steps between each collection point is 20400 N 1 which is the value of steps to send as shown in Figures 4 5 6 and 7 For prepositioning the transmitting and receiving axes are collinear and centered within the receiving plane Thus the number of steps necessary to start data collection with the receiver positioned at the top left corner is steps for prepositioning 1 2 20400 10200 see Figure 13 Note that all numbers in Table II are rounded to an even integer This is because MOVE C and PREPOS C will only accept even valued integers 3 _ Initialization of Equipment If the operator chooses yes on the front panel for Initialize Instruments then preset values will be transmitted to Wavetek 270 and Tektronix RTD 720A as shown in the TRUE case structure of
12. program to allow automatic function generator initialization The pulse generator was connected directly to the PC using GPIB cable and to the transmitter using coaxial cable An additional coaxial cable was connected from the synchronous output of the pulse generator to the external trigger in of the digitizer This trigger was used to initiate the data acquisition process of the digitizer Ref 7 5 Transient Digitizer Upon reception the received waveform was digitized and transferred to a file This was done using Tektronix RTD720A Transient Digitizer The RTD720A is a high bandwidth fast sample rate long record length digitizer designed to accurately capture fast transient events A display provides viewing of each received waveform burst Sampling of each waveform burst is accomplished well above the required Nyquist frequency and is digitized to a record length of 512 bytes This digitized record of the waveform is what is actually transferred to a file on the computer Coaxial cable was used to make a connection between 50 ohm channel input of the digitizer and from the rear channel 1 output of the oscilloscope An additional connection was made for the trigger as mentioned previously The digitizer is automatically initialized using GPIB procedures within the LabVIEW program such that the received waveform is captured with all necessary details Refs 8 and 9 6 Oscilloscope As can be seen from Figure 1 a 100 MHz oscillosco
13. to be calculated within this frame structure Wait time is again employed at the end of this operation Figure 26 Figure 27 shows a FALSE case structure which is executed when the conditions for a TRUE case structure of Figure 22 are not met i e the receiver is not positioned at the end of the present row In this case the code interface node activates the horizontal stepper motor via MOVE C and the receiver is moved to the next data collection point of that row COLLECT VI is idle for two seconds Figure 28 at the completion of receiver movement to allow for any vibrational movements of the receiver plexiglass structure to cease 23 SYSTEM OPERATION GENERAL PROCEDURE Steps have been developed to prepare the data collection system for use These steps are general guidelines which have evolved from use of the system 1 Hardware Configuration After the scanning tank has been filled and sited under the frame both transmitter and receiver can be immersed and positioned relative to each other It is necessary that the transmitter be firmly mounted onto the plexiglass fixture using the rubber gasket such that a watertight seal is made between the transmitter itself and coaxial cable The movable slide upon which the plexiglass and transmitter are attached is then positioned at the desired distance from the receiver This distance is from the face of the transmitter to the face of the receiver Both transmitting and receiving s
14. Cotecton Port To move 10 a Figure 28 Block Diagram 48 Wait Time of 2 0 Seconds 56 LIST REFERENCES Sondhi M M Reconstruction of Objects from their Sound Diffraction Patterns The Journal of the Acoustical Society of America Vol 46 Number 5 Part 2 pp 1158 1164 1969 Goodman J W Introduction to Fourier Optics 48 54 McGraw Hill Inc 1968 Reid W H Microcomputer Simulation of a Fourier Approach to Ultrasonic Wave Propagation Master s Thesis Naval Postgraduate School Monterey California December 1992 Ziskin and Lewin P A Ultrasonic Exposimetry CRC Press Inc 1993 ARRICK Robotics MD 2 Dual Stepper Motor System User s Guide Revision B Hurst Texas 1991 Velmex Inc Unislide Motor Driven Assemblies Bloomfield New York Catalog M 73 Wavetek San Diego Inc Preliminary Instruction Manual Model 270 12 MHz Programmable Function Generator 1982 Strum R D and Kirk D E First Principles of Discrete Systems and Digital Signal Processing pp 54 56 Addison Wesley Publishing Company 1989 Tektronix Inc RTD720A Transient Digitizer User Manual 1992 Kikusui International Contract No F41608 82 D 0337 Oscilloscope 100 MHz Technical Manual MFG P N COS6100M July 1985 Iomega Corportion The Bernoulli Box Removable Cartridge Drive User s Manual and Reference Guide 1989 N
15. M Code modifications were made to MD 2SUBC C saved to a different name PREPOS C or MOVE C and compiled linked in the C2WATCOMSBBIN subdirectory using the commands as shown C gt WATCOM BIN WMAKE F PREPOS LVM or C gt WATCOM BIN WMAKE F MOVE LVM The files PREPOS LVM and MOVE LVM link PREPOS C and MOVE C into the LabVIEW operating environment All modification and debugging of PREPOS C and MOVE C was accomplished C gt WATCOMI BIN subdirectory Appendix A shows the actual code modifications Each corresponding block of code was merged into MD 2SUBC C and saved under the appropriate file name 5 and 13 The hardware and peripheral software are essential components in the data collection system However for full data collection it is necessary for all components to operate synchronously LabVIEW provides the platform from which this can be achieved HI LABVIEW INSTRUMENTATION SOFTWARE A OVERVIEW In this chapter all hardware and peripheral software are tied together using LabVIEW graphical programming techniques An introduction to LabVIEW is followed with program sections as they occur the graphical code COLLECT VI that controls the data acquisition facility 1 Introduction Much like C or BASIC LabVIEW is a program development application However these other programming systems use text based languages to create lines of code while LabVIEW uses a graphical programming language to create programs in block
16. NAVAL POSTGRADUATE SCHOOL Monterey California THESIS EXPERIMENTAL HARDWARE DEVELOPMENT FOR A PULSED ULTRASONIC DATA COLLECTION FACILITY by Peter A Gatchell June 1994 Thesis Advisor John P Powers Approved for public release distribution is unlimited Thesis G23585 DUDLEY LIBRARY NAVAL POSTGRADUATE MONTEREY 93943 510 REPORT DOCUMENTATION Form Approved OMB No 0704 Public reporting burden for this collection of information is estimated to average 1 hour per response including the time for reviewing instruction searching existing data sources gathering and maintaining the data needed and completing and reviewing the collection of information Send comments regarding this burden estimate or any other aspect of this collection of information including suggestions for reducing this burden to Washington headquarters Services Directorate for Information Operations and Reports 1215 Jeflerson Davis ighway Suite 1204 Arlington VA 22202 4302 and to the Office of Management and Budget Paperwork Reduction Project 0704 0188 Washington DC 20503 1 AGENCY USE ONLY Leave blank 2 REPORT DATE 3 REPORT TYPE AND DATES COVERED June 1994 Master s Thesis TITLE AND SUBTITLE Experimental Hardware Development for Pulsed Ultrasonic 5 FUNDING NUMBERS Data Collection Facility AUTHOR S GATCHELL Peter A PERFORMING ORGANIZATION NAME
17. a numeral or a True False label at the top while the frame only uses a numeral In addition the case structure uses a different style of border as can be seen in the figure Another example Figure 24 contains layered frame and case structures The outer frame 4 contains two loops The outside loop contains the inside loop which also contains a frame labeled 7 at the top Within this frame there is a case structure labeled True and frame structure labeled 2 The structures sequential such that operations within each structure are not begun until the previous Structure s operations have completed All block diagrams are annotated for easy interpretation and are titled Block Diagram xxxx The xxxx are a combination of numerals and or letters identifying the structure and to connote the point that it occurs in the program sequence Each figure contains numerous labels to help explain block diagram icon operations Further discussion of block diagram icons can be found in the LabVIEW User Manual Ref 14 1 Front Panel Operating controls shown in Figure 3 provide for the initialization of instruments prepositioning of receiver and for adjusting the receiving aperture size The operator has a choice of collection plane densities 32x32 64x64 and 128x128 for actual data collection or a 4x4 for testing purposes Since the receiving aperture is actually fixed at four inches by four inches choosing a different density
18. ace Node to activate the stepper motors and position the receiver As mentioned previously in Chapter II under WATCOM 32 Compiler PREPOS C and MOVE C are linked into the LabVIEW environment The Code Interface Node is the tool by which LabVIEW VI s are 20 able to link with external source code written in conventional programming languages The Code Interface Node of Figure 13 is a block diagram node associated with the C programming source code PREPOS C Other nodes used in COLLECT VI Figures 23 25 and 27 are associated with MOVE C Each of the nodes used in COLLECT VI send information to the external code for processing If no is selected case 1 of Figure 14 will execute At this point COLLECT VI will remain idle prepositioning will not occur and the program will begin data collection at the current location 6 Data Collection Loop Two loop structures were used to perform the repetitive processes for data collection Outer frame structure 4 as is common to Figures 15 through 28 contain an outer loop and an inner loop Each loop contains a N on the upper left corner This connotes the total number of times the loop will repeat and is always equal to row column length Thus each loop will execute for N 4 32 64 or 128 times The inner loop will complete N cycles for each of the N rows of the outer loop When the outer loop reaches the value of N and the inner loop completes data collection over N columns the program
19. actual ultrasonic diffraction pattern This graph was created by taking the relative amplitude of the 80 point for each of the 4096 individual data collection points of the 64x64 collection density plane The shape of the source transmitter as can be inferred from Figure 30 is circular 26 RECEIVED ACOUSTICE WAVEFORM gt 8 8 0 100 200 300 400 500 600 700 800 900 1000 1100 TIME MICRO SECONDS Figure 29 Waveform Pulse from a 64x64 Collection Density 27 CIRCULAR TRANSMITTER 40mm SEPARATION 64X 64 COLLECTION DENSITY SETUP 180 REL 140 1 n 1 Figure 30 Ultrasonic Diffraction Pattern from a 64x64 Collection Density 28 SUMMARY This thesis presented effective method by which puised ultrasonic waveform collection chamber system could be constructed Most components used were those which were readily available in the laboratory or could be fabricated at minimal cost Initially the primary focus was on identifying candidate hardware and software for the system It was decided that all components would be chosen in view of how they could be implemented with LabVIEW This was done so that data collection would be totally automated requiring no attention from the operator while COLLECT VI was running It has been determined that several modifications to the system could enhance the data collection process One such improvement would be
20. arl int32 var2 int32 var3 int32 var4 if var2 dir3 if var2 direction for motor 3 forward f is up reverse r is down if var4 dir if var4 direction for motor 4 forward f is left reverse r is right motor 34 initialize ports for motors 3 amp 4 md2_init move action s speed 3 14000 steps to move 3 varl direction 3 dir3 md2 move speed 4 14000 steps to move 4 var3 direction 4 dir4 md2 move md2 reset return noErr CIN MgErr CINInit void return noErr CIN MgEr CINDispose void return noEr CIN MgErr CINAbort void return noErr CIN MgErr CINLoad RsrcFile rf return CIN MgErr CINUnload void return noErr CIN MgErr CINSave RsrcFile rf return noErr 31 APPENDIX COLLECT VI GRAPHICAL CODE This appendix contains all graphical code for COLLECT VI Each block diagram executes in the order shown exactly as it occurs in the program COLLECT File Operate Controls Windows Text _ 2151908 2874 Initialization You can choose to iie Wavetek 270 and Tektrorix 7204 with data colection l you choose not o manual anties wil have to to iiia no for manual erties using the hand symbol 2 posiioning of ieceiver by the receiver and tiansmitet onthe same Ais This can be done manualy js using the md
21. ational Instruments 7 488 2 Software Reference Manual for MS DOS March 1992 Edition 57 13 WATCOM International Corporation WATCOM C C 32 User s Guide st Edition 1993 14 National Instruments LabVIEW for Windows Austin Texas August 1993 Edition 58 INITIAL DISTRIBUTION LIST No Copies Defense Technical Information Center 2 Cameron Station Alexandria Virginia 22304 6145 Library Code 52 2 Naval Postgraduate School Monterey California 93943 5002 Chairman Code EC 1 Department of Electrical and Computer Engineering Naval Posteraduate School Monterey California 93943 5002 Professor John P Powers Code EC Po 4 Department of Electrical and Computer Engineering Naval Postgraduate School Monterey California 93943 5002 Professor Ron J Pieper Code EC Pr 1 Department of Electrical and Computer Engineering Naval Postgraduate School Monterey California 93943 5002 Lt Peter A Gatchell USNR 1 2 University Circle Naval Postgraduate School Box 2112 Monterey California 93943 59 Te _3 2768 00019610 9
22. built in for adjusting the setup The core of the program called the Collection Chamber Loop accomplishes the data collection This loop runs continuously until completion of data collection at which time the program stops DATA COLLECTION PROGRAM COLLECT VI The figures in Appendix B Figures 3 7 and 9 28 are LabVIEW graphical code block diagrams Each block diagram depicts operations which are performed at that point in the program In every block diagram of Figures 3 7 and 9 28 note that operations are encompassed by a frame or case structure and that every frame or case structure contains either a numeral or a True or False label at the top Some structures contain other structures such that all inner structures will complete first prior to execution of the outer structure For example Figure 7 contains frame structure with the numeral 0 at Case Selection Adjust collection density of receiving plane Initialize Wavetek 270 and RTD 720A Initialize n Yes n No Collection Chamber Loop 1 Open file if needed 2 Fire generator 3 Digitize received waveform 4 Write to open file 5 Move receiver 6 Close file if needed Figure 2 COLLECT VI Block Diagram Algorithm the top and case structure located within that frame with numeral 3 at the top Note that the frame structure has a border that replicates photographic film thus the name frame The case structure can have
23. d waveform from the collection facility diffraction patterns can be reconstructed and compared with those simulated on computer The collection facility is needed in order to confirm that previously written computer code is valid and reasonable and that the simulated diffraction patterns are accurate The collection facility described here enables numerous sets of waveform data to be collected using various combinations of transmitters and receivers Operator controls are at a minimum so data collection can be implemented in a short period of time The receiving plane utilized in the program can also be resized to accommodate user defined requirements Chapter II of this thesis consists of a problem description including both hardware and peripheral software components used to implement the system Chapter III provides program explanations of COLLECT VI code and how it was used to implement the collection facility system System operation is described in Chapter IV and ends with a brief discussion on waveform data format Following the summary of Chapter V Appendix A gives the C programming language source code used to drive the stepper motors Appendix B provides the LabVIEW graphical source code for the collection facility program COLLECT VI II PROBLEM DESCRIPTION A general ultrasonic data collection facility consists of a water tank scanning device pulse generator waveform digitizer and for a central point of control for all these de
24. he water and received by the Tektronix RTD720A Additional time is inserted to allow for digitization of the waveform Figure 18 In Figure 19 the RECEIVE icon reads up to 2000 waveform data bytes from GPIB address 20 Next COLLECT VI writes this information to the open file Figure 20 Wait time of one second was programmed in after this operation Figure 21 To determine the current receiver position in the collection plane the inner loop uses row column length and the i counter from the outer loop These two values are multiplied together added to i 1 form the inner loop and compared to the computation of i 1 from the outer loop times row column length If the comparison is equal the TRUE case structure Figure 22 within frame 7 of the inner loop structure will 22 execute COLLECT VI has determined that the receiver just collected data from the last column of the present row and the current file is closed The next frame within this case structure Figure 23 contains a code interface node to activate the vertical stepper motor The proper number of steps to move and direction for each stepper motor is sent to MOVE C such that the receiver is moved down to the next row After a one half second wait Figure 24 the receiver is moved back to the beginning of the row Figure 25 This is accomplished using an additional code interface node for MOVE C Note that the correct number of steps to move the horizontal stepper motor has
25. ly carving the receiving plane into matix Higher numbers wil yield more collection ports thus an jncrease n collection pont density Figure 5 Block Diagram 01 32x32 Collection Density Setup 34 Diagram p LCCC Calecion dansiy of receveng plane The receiving plane i a ed foz reh by four However the number of colection points can be dusted to 4 3254 or 128 per lide The means 4 rows by 4 columns 32 rows by 32 columns elc exsentaly carang receiving plane into Higher numbers yiekd more collection points thus an increase in collection density Figure 6 Block Diagram 02 64x64 Collection Density Setup 35 COLLECT VI Wi However the number of colection points can be adkusted to 4 3264 or 128 per This 4 rows by 4 columns 32 tows by 32 columns elc carving plane into matin Higher numbers wil yield more collection thus an Ease Selector lection densty of receiving plane The receiving plane is a ed sah by four density Figure 7 Block Diagram 03 128x128 Collection Density Setup 36 COLLECT M Diagram Edit si Functions Windows Text Figure 9 Block Diagram ITO Initialization of Wavetek 270 37 or off Ql time for acquisiton
26. motion control program MD 2MOVE displays all motion control functions in a simplified environment Initial positioning of the acoustic receiver was done by using this program with motion control function settings as shown in Table 1 Once the motors were moved to their initial position this program was exited back to the DOS environment The robotics software package also included a library of subroutines written in C programming language called MD 2SUBC C These subroutines contained a collection of motor control functions which were slightly modified for use in the LabVIEW data collection program Several lines of code were written and merged with these subroutines to allow control of motor parameters and functions See Appendix A for the revised code The code was compiled and linked to LabVIEW using WATCOM C C Motor control could then be performed within the LabVIEW environment Ref 5 3 WATCOM C C 32 Bit Compiler To use the MD 2SUBC C subroutines it was necessary to compile them first using WATCOM This brand of 32 bit C compiler is the only type supported by TABLE I MOTION CONTROL FUNCTION SETTINGS Motor 3 4 Move Control F5 F6 F7 F8 Single 0 Step Backlash Step Increment 5100 Speed Switch Status Current Position 14 LabVIEW The compiler was loaded on the PC s internal hard drive in the DOS environment under the directory WATCO
27. motors comes from a dual stepper motor driver This motor driver is controlled via programming language C code during data collection or by a separate Disk Operating System DOS program for manual operation The motor driver is basically a computer controlled power supply and is connected to the PC using a standard parallel printer cable Ref 6 3 Acoustic Transmitter and Receiver Two acoustic transmitters operating at 2 25 MHz were used and could be interchanged The first one contained a rectangular shaped active transmitting area that measured 5 1 by 0 65 centimeters while the second contained a circular active transmitting area with a diameter of 2 55 centimeters Both transmitters used interchangeably were connected directly to the pulse generator using coaxial cable and pulsed with one cycle of 10 volt amplitude sine wave A piezoelectric acoustic receiver with an active receiving diameter of 0 2 centimeters across was used to detect the pressure wave in the water Coaxial cable connected the receiver directly to an oscilloscope 4 Pulse Generator A Wavetek Model 270 12 MHz Programmable Function Generator provided the pulsed sine wave to be transmitted Appropriate values for frequency 2 25 MHz amplitude 10 volts signal offset 0 signal mode burst function type sine wave and burst mode one cycle were programmed using GPIB procedures Although manual entries could be made the values were incorporated into the LabVIEW
28. nic propagation 15 NUMBER OF PAGES 66 16 PRICE CODE 17 SECURITY 18 SECURITY 19 SECURITY 20 LIMITATION OF CLASSIFICATION OF REPORT CLASSIFICATION OF THIS CLASSIFICATION OF ABSTRACT PAGE ABSTRACT UL Unclassified Unclassified Unclassified NSN 7540 01 280 5500 Standard Form 298 Rev 2 89 Prescribed by ANSI Std 239 18 for public release distribution is unlimited EXPERIMENTAL HARDWARE DEVELOPMENT FOR PULSED ULTRASONIC DATA COLLECTION FACILITY by Peter A Gatchell Lieutenant United States Naval Reserve B S Texas A amp M University 1985 Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN ELECTRICAL ENGINEERING from the NAVAL POSTGRADUATE SCHOOL June 1994 Author Peter A Gatchell Approved by hn Powers Thesis Advisor 5 Second Reader R Department of Electrical and Computer Engineering ABSTRACT work reported in this thesis used readily available components to implement a data acquisition system for a pulsed ultrasonic data collection facility Use of hardware with controlling software is necessary to collect waveforms of acoustic potential at a given distance from the transmitting source Precise movement and positioning of an acoustic receiver in the collection plane is accomplished by use of an xy coordinate motor driven slide assembly A signal gene
29. pe was used between the acoustic receiver and transient digitizer The oscilloscope was used in part as a tool for manual waveform analysis An additional feature was that it provided a 50 ohm impedance output to match the digitizer input impedance Coaxial connections were made directly from the acoustic receiver to the front panel channel 1 input of the oscilloscope and from the rear channel 1 output to the 50 ohm channel input of the transient digitizer Ref 10 7 Personal Computer PC Bernoulli Drive An IBM compatible PC with an Intel 486DX 33 MHz processor and 8 megabytes MB of random access memory RAM provided a suitable platform from which all software applications could be run The fast processor speed makes for easy system programming debugging All applicable software for the collection facility was loaded onto the internal 105 MB hard drive For waveform data storage an Iomega Bernoulli Box II 20 MB 5 25 inch removable dual external drive was used A single 5 25 inch drive was sufficient since it satisfied the requirement of ample storage space and removability Data could then be removed and transferred to another PC for processing Writing to a file on the Bernoulli drive is simply a matter of specifying the correct path An adapter board and cable were provided with the Bernoulli Box II for integration into the PC system Ref 11 8 National Instruments General Purpose Interface Bus GPIB The GPIB is an interface s
30. rator and transient digitizer transmit and digitize the signal respectively These components are brought together synchronously using LabVIEW instrumentation software This work provides an efficient means to collect waveform data which can be used to verify computer code written previously for the purpose of modeling pulsed ultrasonic acoustic diffraction patterns TABLE CONTENTS I INTRODUCTION PROBLEM DESCRIPTION 3 A IMPLEMENTATION OF HARDWARE 5 1 Scanning Tank and Frame 5 2 Stepper Motors Motor Driven Slide and Motor Driver 6 3 Acoustic Transmitter and Receiver 7 4 Pulse Generator 7 5 Transient Digitizer 8 6 Oscilloscope 8 7 Personal Computer PC Bernoulli Driv 9 8 National Instruments General Purpose Interface Bus 9 B IMPLEMENTATION OF PERIPHERAL SOFTWARE 9 1 National Instruments NI 488 2 Software Package 9 22 ARRICK Robotics Software Package 10 3 WATCOM 32 bit Compiler LABVIEW INSTRUMENTATION SOFTWARE 13 A OVERVIEW DUDLEY LIBRARY NAVAL POSTGRADUATE SCH MONTEREY CA 93943 5101 s 1 Introduction 13 2 Data Collection Program Algorithm 14 B DATA COLLECTION PROGRAM COLLECT VI 14 1 Front 16 2 Case Selection 17 3 Initialization of Equipmen 19 4 Wait Time 20
31. the ability to control the stepper motors manually while in the LabVIEW environment instead of from the DOS environment using 2 These improvements would ease positioning the receiver Other modifications could have been made to COLLECT VI in regards to directory file manipulation such as enabling changes to be made from the front panel The end goal of this thesis effort was to build a system which would be simple and effective These objectives have been accomplished using available materials as outlined 29 APPENDIX SOURCE CODE FOR PREPOS C AND MOVE C The following source code is that which was used to modify MD 2SUBC C This code was inserted within the body of MD 2SUBC C and saved under PREPOS C or MOVE C PREPOS C CIN MgErr CINRun int32 var1 34 initialize ports for motors 3 amp 4 md_2init move action s steps_to_move 3 1 Steps_to_move 4 0 speed 3 14000 direction 3 md2_move steps_to_move 3 0 steps_to_move 4 var1 speed 4 14000 direction 4 md2 move md 2reset return noErr CIN MgErr CINInit void return noErr MgErr CINDispose void return noErr CIN MgErr CINAbort void return noErr CIN MgErr CINLoad RsrcFile rf return noErr CIN MgErr CINUnload void return noErr CIN MgErr CINSave RsrcFile rf return noErr 30 MOVE C char dir3 char dir4 CIN MgErr CINRun int32 v
32. urfaces must be parallel to each other It is best to manually operate the Wavetek 270 pulse generator and Tektronix RTD720A at this point By manually pulsing the generator captured waveform bursts can be observed on the Tektronix RTD720A and any necessary adjustments recorded for later incorporation into COLLECT VI As a final check insure that all cables are connected to the various instruments and that there are no obstructions impeding the movement of vertical and horizontal slides 24 2 LabVIEW Front Panel and Diagram Choose the desired options on the front panel If it is necessary to change the settings of Wavetek 270 and Tektronix RTD720A Figures 9 and 10 go into the block diagram and use the LabVIEW operating tool to enter new values Note that all changes will be effected using the LabVIEW operating tool Other changes which might be necessary are steps to send C code Figures 4 5 6 and 7 and Steps for Prepositioning Figure 13 If the receiving plane is changed from a 4 inch by 4 inch plane to a 3 inch by 3 inch plane then steps to send C code and Steps for Prepositioning will have to be recalculated following the same guidelines as shown in Figure 8 The directory and file name to which the data is written can be changed too This is done in Figure 15 To the far right of the outer loop structure contained within frame 4 are the file directory and name As programmed COLLECT VI writes to drive d into directory dat32a as sho
33. ven Driver Scan Assemblies 2 2 Acoustic gt Receiver PC amp Controlling Software Bernoulli Drive Transient Digitizer Trigger Line Figure 1 Overall Experimental Arrangement and motor drivers The following two sections outline implementation of both hardware and peripheral software in the collection facility design A description of each component is given along with how it is used A IMPLEMENTATION OF HARDWARE 1 Scanning Tank and Frame A scanning tank with outside dimensions 76 4 by 33 6 by 34 5 centimeters was used to contain the water Constructed of aluminum sheet metal and wood it was sealed with silicon rubber and lined on the inside with styrofoam The styrofoam served to attenuate acoustic echoes The tank was filled with tap water which had been filtered using an ion exchanger This was done to remove impurities and provide for a homogeneous medium through which the acoustic waveform could travel The tank was placed on a cart that could be wheeled in and out of the tank frame in addition to allowing insertion and removal of water The tank frame was constructed of welded 0 6 centimeter aluminum bar stock in a horizontal rectangular box frame design so that it could be mounted upon and between two laboratory tables XY motor driven slides for vertical and horizontal positioning of the acoustic receiver were mounted at one end of the frame A movable slide was also constructed for attachment of the
34. vices a computer See Figure 1 The water tank is the facility which confines the acoustic medium The motor driven scanning device transmitter receiver and associated mounting hardware are used for acoustic wave collection within the facility A pulse generator is needed to drive the transmitter and a digitizer is used for analog to digital conversion of the data The digitizer puts the signal in a format which can be easily recorded to disk on a Bernoulli drive A computer enables synchronization of all these components For assembly necessary components had to be identified The water tank xy coordinate motor driven slides and acoustic receiver were available components around which the system was built Other components such as the scanning tank frame and plexiglass pieces were fabricated to nominal system specifications These specifications were inferred from other scanning tank designs and integrated with facilities available in the laboratory Ref 4 Other equipment such as pulse generator and transient digitizer were recognized as essential pieces because their use could be controlled via a General Purpose Interface Bus GPIB A personnel computer PC using an Intel 486DX 33 MHz processor served as the central point of control for all other hardware LabVIEW graphical program for instrumentation control linked the different instrumentation Pulse Generator Water Tank Acoustic Transmitter Motor Motor Dri
35. will change the number of collection points within the aperture Indicators are shown at the bottom right to keep track of receiver position 2 Case Selection Selection of program variables are shown in Figures 4 5 6 and 7 The operator chooses a receiving plane density and from that choice the program variables total points row column length and steps to send are set Figures 4 5 6 and 7 perform the same functions in regards to calculation and storage of values For example if the operator chooses a 32x32 receiving plane density the program will execute case 1 see Figure 5 Total points is the total number of data collection points in the receiving plane and is computed by multiplying 32 by 32 as shown This value is displayed on the front panel Row column length is used in the loop structures of Figures 15 through 28 for keeping track of receiver position For a 32x32 collection density row column length is 32 Steps to send are precalculated numbers used in MOVE C These values are the number of steps between each data collection point Shown in Figure 8 is an example of the 4x4 collection density plane This model was extended to a 32x32 64x64 and 128x128 collection density plane for proof of concept and calculation purposes Calculations for a 4x4 32x32 64x64 and 128x128 collection density planes and the number of steps needed for MOVE C are shown in Table The number of steps per inch was determined to be 5100 Since the
36. wn by d dat32a Yt is necessary that this directory be created prior to running COLLECT VI COLLECT VI will create all necessary files into which data is stored but it will not automatically create the directory to which the files are written The name of the file is shown data d txt The name data and the three letter extension xt can be changed but the characters must be left unaltered in the corresponding position as shown The characters 4 are used by LabVIEW to insert an integer which corresponds to the current row of the collection plane 25 3 Waveform Data and Format After COLLECT VI is run the waveform data can be viewed upon exiting LabVIEW and going into the file itself Each individual digitized waveform is preceded by the word curve as seen in the file Actual waveform data is written in binary format All recorded data is ready for immediate processing after the program is finished An acoustic waveform collected from the system is shown in Figure 29 Similar to what is seen on the Tektronix RTD 720A the waveform is plotted in relative amplitude vs time This waveform was taken on row 32 column 32 of a 64x64 collection density setup using a circular acoustic transmitter When the Tektronix 720A digitizes this waveform it breaks the time axis into 1024 points Note that the Tektronix RTD720A as described in this thesis was programmed for 512 points as shown by acquisition length in Figure 10 Figure 30 is the
37. ystem through which interconnected electronic devices communicate In this case an IEEE 488 2 industry standard AT GPIB board controlled the pulse generator and transient digitizer Incorporation of this device involved installing the AT GPIB board onto the PC motherboard and connecting the cables to the pulse generator and transient digitizer Commands embedded in the LabVIEW program activated these devices synchronously for system operation Ref 12 IMPLEMENTATION OF PERIPHERAL SOFTWARE 1 National Instruments NI 488 2 Software Package The NI 488 2 software was installed on the PC s internal hard drive under the directory AT GPIB The CONFIG SYS file was modified so that the AT GPIB driver was loaded each time the PC was started Hardware diagnostic utilities included with the software were run to insure correct AT GPIB board installation No other files included with this software package were used All necessary peripheral information was entered into a similar program contained within the LabVIEW environment Ref 12 2 Robotics Software Package Two programs within this software package were used to drive the stepper motors All programs were installed on the PC s internal hard drive under the directory 2 Manual operation of the motors was effected in the DOS environment using keyboard commands Once in the MD 2 directory the command MD 2MOVE typed at the DOS prompt provided manual operation An interactive
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