We are participating in a series of observations with the RadioAstron spacecraft where it's downlink signal is recorded by the 12m antenna while the Yarragadee SLR also tracks the spacecraft. The data are only useful if both the SLR and 12m successfully track.
On the 12m, we use the Field System to record the data to the Mark5 and the HMI antenna interface (on the timeyg VNC server) to control the antenna. The RadioAsdtron group provide a file for HMI as well as a VEX file.
The receiver cross-over switches have been re-wired to allow additional attenuation in the signal path and/or a reduced supply voltage to the X-band RCP LNA. This is to reduce the signal strength entering the DBBC and hopefully improve phase stability. The S-band cross-over with enables a variable power supply for the LNA when crossed and the X-band cross-over switch will put a (manually configurable) variable attenuator into the X-band RCP signal path after the LNA. The Field System commands to set the 4 possible modes are:
"x-band rcp lna 20V, atten in rfpic=cross,direct,* " "x-band rcp lna 20V, no atten rfpic=direct,direct,* " "x-band rcp lna variable voltage, atten in rfpic=cross,cross,* " "x-band rcp lna variable voltage, no atten rfpic=direct,cross,*
The tracking file is provided by the RadioAstron group. It must be transferred to the timeyg PC. FTP is probably the easiest method, so place the file somewhere (e.g. fourier) and give it a name with a .txt extension. Open the file with emacs and check that it's in DOS ASCII format. e.g. on Fourier:
emacs -nw <filename.txt>
You should see
(DOS) in the lower left corner. If you do, all is well. If not, convert to DOS format in emacs by typing:
C-x RET f undecided-dos
where “C-x” = [Ctrl]-x, RET = the Return/enter key.
On timeyg, open a Command Prompt and type:
cd "C:\Documents and Settings\Astro\RadioAstron" ftp fourier.phys.utas.edu.au (log in) bin get <filename.txt> quit
Note the file should be transferred in binary (bin) mode.
cd /usr2/sched drudg <filename>.vex Yg 3 12 0 mv <filename>yg.prc /usr2/proc emacs -nw <filename>yg.snp (comment out the source command(s), then exit emacs) cd /usr2/proc emacs <filename>yg.prc
We usually modify this to record both polarisations instead of one as there is some leakage into LCP and the signal may be more stable than the very strong RCP tone. Changes need to be made to the following procedures:
setup01change the recording mode to
"X-band RCP LNA on, atten in rfpic=cross,direct,* "Take out attenuation in X-band, IF rack ifpic=*,*,15,15,0,0
define dbbc014 16273135148x bbc01=798.75,a,4.00 bbc02=798.50,a,4.00 bbc03=798.25,a,4.00 bbc04=798.00,a,4.00 bbc05=798.75,b,4.00 bbc06=798.50,b,4.00 bbc07=798.25,b,4.00 bbc08=798.00,b,4.00 enddef
define ifd01 16273135148x ifa=1,agc,1,25000 ifb=1,agc,1,29000 lo= lo=loa,7600.00,usb,rcp,off lo=lob,7600.00,usb,rcp,off enddef
define checkmk5 16273141501x scan_check !+1s mk5=get_stats? mk5=get_stats? mk5=get_stats? mk5=get_stats? mk5=get_stats? mk5=get_stats? mk5=get_stats? mk5=get_stats? mk5=status? enddef
specyg) set the centre frequency to 800 MHz and the span to 2 MHz.
vncserverinto the terminal. Now, open the vnc session to the pcfsyg and start the schedule
ERROR st -28 UT1TimeOffset non-zero, see value above.
. Silence them with the command
Watch out for the spacecraft signal in the spectrum analyser, check both polarisations using
ifpic=xl (LCP). Make notes in the log on signal strength etc.
The attenuator values can be changed using the “rfpic=<xband>,<sband>”, replace xband and sband with either “direct” (no attentuation) or “cross” for variable attenuation (Check with yg staff regarding the voltage of the variable attenuation). (Arwin)