SRT USER'S MANUAL
Contents
1. MSDos prompt or Command prompt to select the desired operating mode of the SRT e howto Contains information about adjusting pointing checking receiver and antenna communication and possible adverse interaction between the SRT program and some screen savers Stow Clicking on the Stow button will return the telescope to the normal stow position in the eastern most low elevation position of the main Az El travel zone The travel zone is established by the AZLIMIT and ELLIMIT commands in the srt cat file Assuming the SRT has been setup with the travel zone centered on 180 azimuth track The track button enables the antenna to slew to the selected source from clicking on the map selecting from the source list or after typing the source information on the command entry text box The track sequence will work automatically when a source is selected from a command cmd file Azel Action on the Azel button allows the user to enter a fixed azimuth elevation position in the command entry text box assuming the entered coordinates are within the Az El limits of travel of the SRT as set in the srt cat file npoint Initiates a 25 point scan map of the source selected The map is 1 2 beamwidth spaced and when finished displays a false color gaussian plot to the left of the accumulated spectrum plot This plot will clear when the clear button is enabled The resulting maximum T ant with associated offset is displayed under scan resu2. L E Moon Center frequency 1 1420 400 MHz E spacing 7 81 kHz l gt a Rosett number bins 64 i tsys not yet calibrated o 58 n Orion J Pye ees Ee eee ees ee eee ey _ 0 20 40 60 80 100 120 140 160 18 200 220 240 260 280 300 320 340 VLSR 36 9 km s azinauth deg Veenter 35 6 km s digital Recvr freq 1420 40 pwr 221 counts temp 221K Status tracking Vpeak 6 0 km s Fpeak 1420 259 MHz m Figure 1 SRT Console 1 3 SRT Control Panel The user interface to the SRT is an interactive JAVA generated window The window consists of a 15 button tool bar a text entry command bar an information side bar listing times coordinates and source information observing frequency and system temperatures and a sky map showing antenna travel limits azimuth and elevation tick marks as well as source plots and galactic coordinates This section will discuss the control window in seven sections to provide the user with details about the display while allowing some easy navigation around the control panel 1 3 1 Command Toolbar The main command input device on the SRT Control Panel is the 15 button command toolbar arrayed across the top of the window Pointing and clicking a mouse on any of these buttons will either initiate an automatic sequence such as Cal calibration or track or wait on further text input from the user freq or offset Figure 2 shows the toolbar as it appears on the SRT console The followi
3. list on file and each source name will display in the message board The message board will also display the current active line command from a command file and the line number This text will appear green in the form filename cmd line nn text command To the right of the message board text area is another space used to echo information after a text command is entered Printed in blue it will repeat the issued command or advise the user that the issued command is waiting on some other action of the telescope Receiver output and telescope status can be read in two small text boxes just above the message board and below the map azimuth scale In the left box reading from the left is the current frequency sweep set in freq receiver counts uncorrected power level detected by the receiver the real time system temperature and the attenuation setting In the right box the user can reading the current status of the telescope as a whole Stowed slewing or tracking 1 3 3 Information Sidebar The information sidebar lists nearly all of the pertinent information the user needs to monitor real time observing with the telescope The sidebar is illustrated in Figure 4 and displays from top to bottom Antenna Coordinates Command computer command Azel actual position Total Offsets User input mapping etc Pointing Corrections degrees Axis Corrections mechanical user set Galactic Coordinates RA and DEC Hrs and Deg
4. mouse button A sample is seen here B accumulated spectrum Oy x 70 60 50 40 30 VLSR ans 1420 6 1420 5 1420 4 1420 3 1420 2 frequency MHI av spectnmn integ 11 16 mm 2002 137 21 01 29 25 Point Map Display The third window in the plot area far left square field is the output display for 25 point spectral and continuum maps When a 25 point scan is complete a false color image of the map area will automatically display Continuum Display Figure 7 shows the spectral display boxes as they appear during a continuum scan The left side box now reports information showing the number of observation cycles in this example an off on off beamswitch observation and the total integration time above the graphical output Below the graph the average temperature the RMS and vertical scale are reported av 0 04 0 05 scale 1 3 max min 6 8K freq gt Figure 7 Continuum Output 1 3 6 Total Power Chart Recorder Ppveewe cing seer aee vrtina power vs time scale Oto 400K 219K f max min 5 0K slope 0 1K max min 12 9K freq gt pae aah ao AAPA a we l A ate Figure 8 Total Power Chart Recorder The area of the SRT control console above the Sky Map is a continuously running chart recorder showing relative power of the signal received vs time The plot will continually overwrite as it paints from left to right and will reset to the bottom of the chart when the plot value reaches the 4
5. 00K vertical scale maximum To minimize confusion when the scale resets 400K steps the plot is color coded note the color dot icon to the right of the temperature indicator black 0 400 blue 400 800 green 800 1200 red 1200 1600 11 1 3 7 Antenna Drive Motion Status Display This box at the upper left of the control fey sit console display Figure 9 shows the ae atten source Stow station name latitude and longitude as read Pasaak dts ie from the srt cat file The second line lists yack ekta Sn i antenna drive status the current antenna drive status such as moving simulate stopped power vs time 400 fullscale Figure 9 Motion Status Display 1 4 Manual Command Entry Most users will start SRT observations by entering text commands into the text box at the bottom of the control console As explained in Section 1 3 most of the button actions can be duplicated with command lines or must be supplemented with manual command entries Example The user may want to conduct a simple test observation of hydrogen along the galactic equator The required steps are 1 Move the SRT to the intended source 2 Calibrate The calibration can be done with the hydrogen frequency off source preferred or a non hydrogen frequency on source 3 Set the observing frequency and scan width or observing mode for digital 4 Decide on a suitable integration time Manual commands slow method Digital Comm
6. APT ati CS SEES CE2 ESE CEE SEEE CEEE EESE SNA B DOSA OS DOS OONO OPNS IOSA DONORS IONS BASN OOSA DENS DOOS O DN OA B E EEE EEE CEN EEE E EEE E EN 20 40 60 80 100 120 140 160 180 200 220 240 60 280 300 320 340 azimuth deg Figure 5 Sky Map Plotted automatically and labeled are the sources listed in the srt cat file Geo synchronous communications satellites in the catalog are indicated by blue dots The galactic equator is plotted The north galactic pole and the 0 90 180 and 270 galactic longitude quadrants are also plotted since they have been placed in the catalog The user can move the pointer to any plotted source and click on that source to select it from the source list When the source is selected the source plot label and the telescope crosshairs will be colored red Selecting a source in this manner does not initiate telescope motion to the source however only an additional action such as clicking the track button will engage the telescope controls While the SRT is slewing the right side information box below the map will carry the message Status slewing The sky map will show the telescope crosshairs superimposed on the selected source and illuminated until the SRT arrives at the source The SRT travel limits are also plotted as square boxes on the screen The azimuth travel limits are set in the srt cat file In the above illustration the limits are approximately 91 to 269 degrees Coverage of the 271 to 89
7. SRT USER S MANUAL How to use the SRT software and perform experiments Taken from Haystack Labs MIT 1 1 Overview of Capabilities The SRT is capable of spectral line 1420 MHz hydrogen and continuum observations using source tracking 25 point maps and drift scans Aperture 2 1 Meters LO Frequency Range 1370 1800 MHz LO Tuning Step 40 kHz Preamp Frequency Range 1400 1440 MHz System Temperature 150 K Pointing Accuracy 1 Degree Travel Limits degrees 91 269 Azimuth 0 179 Elevation See added capabilities of the digital receiver at http web haystack mit edu SRT receiver_1 html 1 2 Getting Started The SRT control software is a JAVA based program designed to be portable to most computer operating system platforms The main telescope control interface is an active window with which the user can enable the telescope functions either by a simple mouse click or by a combination of mouse clicks and text entry Users can also construct command files form filename cmd which will take data and calibrate the SRT automatically The control window can be seen in Figure 1 For the purposes of this tutorial the explanation of the control screen will be covered in seven separate sections in section 1 3 The Java software consists of fourteen java files geom java plots java time java velspec java srt java disp java sport java hdisp java global java cat java map java Added with the 3 2002 checkey java procs java outfile ja
8. TPUT file would automatically be written and labeled 0207414 rad Where the file label is yydddhh rad Information about the output data file can be found in section 1 6 1 6 Output Data Files The output data file yydddhh rad is an ASCII text file Data reduction on the raw output can be done with a spreadsheet program like MS Excel with some effort The development of spreadsheet MACROS to reduce the data are desirable for large files and long integrations Future releases or updates of the SRT software could also output certain observations in formats for other data reduction methods Comment lines Start with an asterisk and list the STATION LAT and LONG E W on the first line STATION LAT 42 50 DEG LONGW 71 50 When the output data is the result of an input command file the next comment line could be the listing of the first command line in the input file filename cmd line 1 command Calibration results will also follow an asterisk tsys 215 calcons 0 98 trecvr 195 tload 300 tspill 20 Data lines Start with a time mark yyyy ddd hh mm ss then list azimuth elevation offsets center frequency and data points 2002 074 14 32 44 104 5 16 0 0 0 0 0 1419 60 110 111 111 Data points listed in the rad file are multiplied by the calibration constant produced prior to the data taking The command file test emd starts a short calibration and hydrogen spectral line run on the CasA The input file listing and out
9. Time Universal Time UT Local Sidereal Time LST Source Source Name RA and DEC Azimuth and Elevation Center Frequency Input Frequency MHz spacing Bin spacing MHz number of bins From input Integer tsys degrees K calcons trec degrees K Scan Results Max K offset Az El Widths VLSR Velocity Local Standard of Rest Vcenter Center velocity of the current observation Vpeak Velocity of peak signal Fpeak Frequency bin of peak signal td Remdfl Cal Antenna coordinates cmd 214 8 72 7 deg azel 214 8 72 7 deg total offsets 0 0 0 0 pointing corr 0 0 0 0 axis corr 0 0 0 0 Galactic 1 141 b 89 radec 12 8hrs 27 7 deg Time UT 1999 194 22 55 04 LST 13 6 hrs source GNpole 12 48 00 28 00 00 1950 azel 214 8 72 7 deg Center frequency 1420 40 MHz spacing 0 04 MHz number bins 41 tsys 273K VLSR 16 1 km s Veenter 14 8 km s Figure 4 Information Sidebar 1 3 4 Sky Map The most obvious feature of the SRT control panel window is the sky map Figure 5 The map shows full sky coverage in azimuth and elevation with 10 degree tick marks in both axes The azimuth axis is labeled every 20 degrees the elevation every 10 degrees The elevation scale is exaggerated 33 from the azimuth scale lt _ lt yu P2 48 G180 i E Crab j i 70 e i Moon f 6 H Rosett a i Hsp i 88 B Orion i 440 n i ii Androm Cass 3 L i 42 GNpole i i i ii j coo 1 H south H y
10. ands in Blue 1 Click on the desired source 2 1419 1 1419 0 non hydrogen frequency for cal 3 Cal or Vane begins noise vane calibration 5 1420 4 35 1420 4 4 set observing frequency Since the hydrogen line will be about 500K Hz wide 35 bins times the 40 KHz default bin size should be enough to display the spectra correctly Alternately the 3 x SOOMHz digital mode 4 is needed to display the hydrogen line with the digital receiver Combination Manual and Button commands preferred 1 Move the mouse to the source on the map and left click 2 Move the mouse pointer to the track button and click 3 Click on the freq button then type 1419 0 1 in the command text box 4 Click on the Cal button 5 Click on the freq button then type 1420 4 35 in the command text box 6 Observe the accumulated spectrum While use of the mouse and the text box can quickly start observations or change observer settings it can get cumbersome if the user wants to do many observations or long integration or other long term measurements Section 1 5 discusses the construction of automatic input command files and the recording of SRT data 1 5 Input Command Files The use of input command files filename cmd will speed the entry of SRT commands as well as reduce command entry mistakes A list of the command file syntax can be found by moving the mouse pointer to the Remdfl button The first part of the list will appear in the message board ab
11. degrees azimuth is achieved by moving the elevation axis through the zenith to the desired elevation and thus a plus 180 azimuth position A total elevation travel of up to 179 degrees is possible by setting the ELLIMIT command in srt cat allowing full sky coverage Example AZLIMIT 91 269 ELLIMIT 0 179 1 3 5 Spectral line and Continuum Display Figure 6 displays the spectral line plotting area of the SRT control panel There are two spectral windows max min 5 0K slope 0 1K max min 12 9K freq gt Figure 6 Spectral Display Discrete Spectrum The right side black is the plot of each individual spectrum as it finishes the user input span in MHz see freq in section 1 3 1 The top of the display lists the input center frequency and the frequency step The bottom line lists the difference of the maximum and minimum values measured during the frequency scan There is also an arrow indicator showing the direction of increasing frequency Accumulated Spectrum The left side red spectral line plot shows the accumulated spectra since the selected observation began Listed at the top of this window is the title av Spectrum as well as the total integration time The bottom script shows the same max min difference and increasing frequency direction A snapshot of the accumulated spectrum can be seen in a pull down window by moving the mouse pointer to the accumulated spectrum window and clicking the left
12. dth with a 7 81 kHz spacing offset Enables the user to enter any az el offset pair desired Left click the offset button and enter the offsets in the command entry box Usage Azimuth offset Elevation offset default sign is positive Drift A left mouse click on Drift will offset the SRT in Right Ascension and Declination to allow the selected source to drift through the 7 degree beam of the telescope record Toggles output file recording on and off Output data files are labeled in the form yydddhh rad Record also allows the user to enter a filename Remdfl Initiates reading of the default command file srt emd and begins data recording The current line number and text being read is echoed on the message board above the text entry box To start automatic recording and reading of a file other than the default srt cmd enter the desired command file name with the emd suffix in the command text entry box Cal Starts an automatic calibration sequence during which a noise source located at the apex of the antenna surface is enabled for 1 second The system then takes a data sample without the noise source enabled The resulting system noise temperature is reported in the information side bar as Tsys Vane Starts an automatic calibration sequence during which the receiver is blocked by an ambient temperature vane calibrator motion 20 seconds The system then compares data with the vane in place to data with the va
13. ion of the galactic equator The user must start data recording unstow the telescope calibrate the receiver set the observing frequency center and frequency scan and then repeat the spectral line observations for ten points along the equator Note Allow a space between the colon and the command record rotation rad Start data recording of file rotation rad galactic 206 20 unstow and move to calibration position freq 1419 1 Off hydrogen calibration frequency calibrate freq 1420 4 51 0 04 Set center frequency with 51 40K Hz bins galactic 205 0 Move to first data point galactic 210 0 Next point galactic 215 0 galactic 220 0 galactic 225 0 freq 1419 1 Off hydrogen calibration frequency galactic 225 20 Calibration point calibrate freq 1420 4 51 0 04 Set center frequency with 51 40KHz bins galactic 230 0 Move to sixth data point galactic 235 0 Next point galactic 240 0 galactic 245 0 galactic 250 0 roff End data recording See Control Panel Help menu for digital receiver commands If this input command file were named galactic emd the user could initiate this observation by clicking in the command text box galactic cmd The SRT will read each line in turn and report the current line read as green text in the message board area If for example the start time was 1400 Universal Time on March 15 2002 and no output file name was entered the default OU
14. lts in the information sidebar The color plot will NOT refresh if the SRT window is reduced then refreshed bmsw Initiates a continuous off on off beamswitched comparison observation of the selected source at the frequency settings entered with freq The off on off measurements are a set and are complimentary meaning that the two off source positions switch sign within each set The off source measurements are spaced at 1 beamwidth in azimuth offset beamwidth cos EL BEAMWIDTH is set in the srt cat file A left mouse click on the bmsw button after the scan has started will abort the beamswitch operation Results of the bmsw observation appear in the left red spectral plot window freq Sets the center frequency number of frequency steps and the step width in MHz Clicking on the freq button prompts the user to enter the desired settings in the command entry window Example for the analog receiver To observe the hydrogen line at 1420 4 MHz move the mouse pointer to the freq button Left click the button then move the cursor to the lower text input section and enter 1420 4 25 0 04 0 04 MHz is the default where 1420 4 is the center frequency of an observation that is 25 times 0 04 MHz wide or spanning from 1419 9 to 1420 9 MHz Example for the digital receiver 1420 4 4 where 1420 4 is the center frequency of an observation and 4 is the digital observing mode In this case mode 4 3 x 500 MHz bandwi
15. ne retracted The resulting system noise temperature is reported in the information side bar as Tsys The actions initiated by the command tool buttons can also be listed in a command file and run automatically See section 1 5 for information about building command files Note All input actions are delayed until the completion of any in progress frequency scan A message to this effect is shaded blue and is displayed in the upper right of the message board area see figure 3 1 3 2 Message Board and Text Input Sey Vcenter 14 5 KMYS Recvr freq 1419 72 pwr 282 counts temp 267K atten 0dB Status tracking click on text area to enter center frequency num of freqs spacing default 0 04 MHz entered freq 1420 40 nfreg 41 SHS Figure 3 Message Board and Text Input The command text input box and the system message board are located at the bottom of the SRT control panel window figure 3 Many of the actions initiated by clicking the command toolbar are implemented by entry of parameter settings in the text box Information regarding the correct entry is printed in a message board above the text entry area when the mouse pointer is moved over the desired command button Some of the buttons source and Remdfl will display more than one set of instructions if the pointer is moved away then returned to the button area In the case of the source button continuous clicking of the left mouse button will scroll through the source
16. ng is a listing of the button functions reading left to right on the toolbar Est ioix clear atten Help Stow track Azel npoint bmsw freq offset Drift record Remadfl Cal Vane Figure 2 Command Toolbar clear As the label implies the clear button will clear the control console display of accumulated spectral line data 25 point scan data This function is useful if the user is accumulating multiple spectra from different sources or galactic coordinates The system will treat new source spectra as additions to the accumulated spectrum atten Enabling the atten attenuation button adds or removes a 10dB attenuation to the receiver with successive left button mouse clicks The atten will illuminate red while the 10dB attenuation is active The attenuation value can also be read just above the center of the message board area to the right of the power temperature information Help Clicking Help opens a window titled srthelp that contains a 6 button taskbar e srt cat Contains a list of keywords available to the SRT user that can be set in the srt cat file A brief explanation of the keyword use is included e srt cmd Lists the general rules and usage of command file entries with a few examples e plots A Brief explanation of all the plot windows seen on the SRT console e outputfile Contains a key to reading the ASCII output of a recorded data file e cmdline This button will show a brief list of commands used at the
17. ove the text entry box Moving the pointer off the button then back on will show the rest of the syntax list The command file is ASCII and can accept instruction lines those that are read and take some action blank lines they are ignored and comment lines also ignored by the system Comments Start with an asterisk and can be any text the user wishes The following are examples of command file entries 2002 074 00 00 00 Cas x Instruction The line must start with a time mark either UT or LST or a colon 2002 074 00 00 00 radec 23 00 00 06 50 00 yyyy ddd hh mm ss UT LST 06 00 00 LST hh mm ss 120 azel 120 30 sss azel position Rules cmd execute the command and proceed to the next line 120 cmd execute the command and wait 120 seconds taking data before proceeding to the next line in the schedule 120 wait 120 seconds taking data before proceeding to the next line This is a convenient way of increasing the radiometer integration to more than one scan Note There is NO space allowed between the colon and a time wait command 13 LST 06 00 00 wait until LST 06 00 00 taking data before proceeding to the next line 2002 074 00 00 00 wait until UT yyyy ddd hh mm ss before proceeding to the next line Example Set Instructions can be set in order to perform an observation The following set of instructions will command the SRT to take 1420 4 MHz hydrogen spectra in 5 degree spacing along a sect
18. put file 0207414 rad examples are listed below INPUT test cmd record azel 125 45 freq 1419 1 0 calibrate Cas freq 1420 4 41 20 roff 15 OUTPUT 0207414 rad STATION LAT 42 50 DEG LONGW 71 50 test cmd line 1 record 2002 074 14 32 44 104 5 16 0 0 0 test cmd line 2 azel 125 45 2002 074 14 32 49 125 0 45 0 0 0 test cmd line 3 freq 1419 10 2002 074 14 32 50 125 0 45 0 0 0 test cmd line 4 calibrate 2002 074 14 32 50 125 0 45 0 0 0 2002 074 14 32 50 125 0 45 0 0 0 tsys 215 calcons 0 98 trecvr 195 tload 2002 074 14 32 51 125 0 45 0 0 0 test cmd line 5 Cas 2002 074 14 32 51 171 2 52 1 0 0 2002 074 14 32 52 171 2 52 1 0 0 test cmd line 6 freq 1420 4 41 2002 074 14 32 56 171 2 52 1 0 0 test cmd line 7 20 2002 074 14 33 01 171 3 52 1 0 0 2002 074 14 33 06 171 3 52 2 0 0 2002 074 14 33 10 171 3 52 2 0 0 2002 074 14 33 15 171 3 52 2 0 0 2002 074 14 33 19 171 3 52 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1419 60 110 111 111 1419 60 111 110 111 1419 00 109 1419 00 252 1419 00 109 300 tspill 20 1419 00 213 1419 00 213 1419 00 213 1419 60 227 221 Plus 1419 60 223 215 39 1419 60 212 220 more 1419 60 215 219 columns 1419 60 215 221 here 1419 60 211 218
19. units of K BEAMWIDTH 5 0 3 dB antenna beamwidth in degrees NOISECAL 1000 1000 for temp value of noise source MANCAL 0 0 or absence indicates automated cal vane DIGITAL Flag for digital receiver TOLERANCE 5 Optional max error in counts COUNTPERSTEP 50 Optional stepped antenna motion RECORDFORM TAB VLSR_ Optional tabs between fields and VLSR in output ELBACKLASH 3 0 Optional correction for elevation backlash When you have compiled the code there are six run modes available to run the SRT software Run the SRT java srt 0 Simulate SRT java srt 11 Simulate Antenna java srt 0 1 Simulate Radio java srt 1 Simulate speed time x 10 java srt 1 10 Simulate with 1 hour advance java srt 1 1 The SRT window will open ready for command input Go to section 1 3 for the operational details of the command console Est iol clear atten Help Stow track Azel npoint bmsw freq offset Drift record Remadfl Cal Vane Haystack lat 42 5 lonw 71 5 av spectrum integ 0 09 min 1420 40 span 0 50 MHz cmd isd 085 ae antenna drive simulated azel 155 3 68 4 deg trans move 1705 total offsets 0 0 0 0 pointing corr 0 0 0 0 generating random data i min 6 6K slope 27K max min 222 2K_ freq gt ae coe power vs time scale Oto 400K 182K eR Bs Be oe q Galactic 1 201 b 30 radec 8 4 hrs 22 5 deg Time UTdate May 17 UT 2002 137 20 49 54 peli LST 7 8 hrs Source Moon T azel 155 4 68 5 deg
20. va SRT software release Also needed are dynamically linked library files dII which are imported when the java files are complied The user will need to import a Java Standard Edition SDK as well as the javacomm20 win 32 zip windows OS for the serial port communication API Note Previous editions were titled Java Development Kit JDK In the user s autoexec bat file include the line j2sdk1 x x rc bin in your PATH Or ad lib for your version of SDK and add CLASSPATH c j2dk1 x x re lib comm jar Or ad lib for your version of SDK The syntax for compiling the SRT JAVA code is javac java J SRT users need to construct an ASCII file label srt cat This file contains the user source list the telescope station latitude and longitude telescope azimuth and elevation limits in addition to other optional information if defaults are not acceptable An example file is listed here A line which starts with is a comment first word is key word line starting STATION latitude longitude west in degrees SSAT synchronous orbit satellite ID then longitude west SOU source ra dec name STATION 42 5 71 5 Haystack AZEL 170 50 P1 GALACTIC 180 10 P2 source coords epoch 1950 unless specified SOU 05 31 30 21 58 00 Crab SOU 05 32 48 5 27 00 Orion SOU 05 42 00 1 00 00 S8 AZLIMITS 90 0 269 0 mid az range is south ELLIMITS 0 179 0 COMM 1 COM1 CALCONS 0 5 initial gain correction constant puts power in
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