Intro  (top)

    The glonass satellites are the Russian global navigation satellites.

Orbit:  3 planes of 8 satellites each

• inclination: 64.8deg
• each orbit spaced by 120 degrees in longitude (see  RA ascending node in tle).
• 19100 km altitude.
  

Aug14: Monitoring the glonass signal for 3 days

    During tropical storm Bertha (01-03Aug14) the telescope was locked in position. lband wide data was taken to monitor the band during this time.

the setup and observation

• Telescope:
• az: 257.5330 (encoder value)
• za dome: 8.4773
• ch         : 8.8347
• Rcvr:
• lbw , linear polarization, full band (1150 to 1736 MHz0
• Acquisition time:
• Start:: 01Aug14: 21:11:42 (utc)
• end :   03Aug14: 11:25:00 (utc)
• Pattern:
• 3570 seconds data
• 10 sec cal on
• 10 sec cal off
• (note some patterns were terminated prematurely because of power dips).
  
• backend
• mock spectrometer. 4 boards
• 8192 channels, 172.032 MHz bandwidth, polA, polB per board
  
• board cfr's = 1200,1350, 1500, 1650 MHz
  
• 1 second dumps
• Datafiles:
• aofits file format
  
• /share/pdataN/pdev/x101.2014080D.bMs1g0.xxxxx.fits
• N=1..4 for the 4 boards
• D=01.. 03 for the 3 days
• M=0..3  the 4 boards
• xxxxx     file numbers..
  
• each file starts on a multiple of 100,
  

Dynamic images covering glonass band

    dynamic spectra from each pattern (typically 3570  seconds)  were made covering  1550 to 1620 MHz

• This includes gps L1 (1575), glonass, and the start of the iridium band (1618).

• A bandpass correction for each image was made by:
• compute the median bandpass for the pattern
• do a robust fit (throwing out outliers)  to 1550 to 1620 MHz
• use a 2nd order polynomial and 5th order harmonic.
• Scale the flatten image to -3 + 6 sigma (full scale lut).

• The vertical scale is in 1 second steps
• the dashed vertical lines are the centers of glonass channels (L1)
  
• horizontal lines that cover the image are probably continuum source drifting through the beam
• when a satellite gets close to the beam, the power spreads in freq (we see more sidelobes).

Processing the data

•  idl routines in x101/lbwmon
• 13oct14: split each dataset into separate subdir:
• 140801 - bertha
• 141013 - gonzalo
• ./pro      - holds generic .pro files
• doit.pro - copy in each subdir (140801,141013). Defines parameters for each data set. These are used by the generic .pro routines to get/save the data.
  
• for 01 - 03aug14 data (taken during storm)
• did 1 hour scan followed by 10 sec calOn, calOff.
  
• 460 files, 4files/scan (since 4 boards) --> 125 scans, data/calOn,calOff per pattern so about 40 patterns
  
• procdat.pro - get info on all files, hdrs, patterns taken. store in idl save file for later use.
  
• fnmIAll[Nfiles]: fname list of all files taken
• sumI[Nfiles]: summary header from each file
  
• PatI[npat]: hold info on each pattern taken (pattern is data scan and then cal)
  
• patId: scan number
• hasCal: 0/1
• nrowsD: number rows of data
• brdAr[4} info on each board
• cfr:  Mhz of board
• Idat: index into fnmIAll[] for data file
• iCon: index into fnmIAll[] for cal on
• iCoff: indesc into fnmIAll[] for cal off 
• fnmIAll, patI,fnmIall,sumI  saved to patI.sav (idl save file)
• to process data just  restore patI.sav and go from there.
• procglonass.pro - create idl save file for each pattern. Contains total power for each sec for each glonass channel. also contains header summary,date timestamp
  
• for each pattern, select the 4th board (1650 band)
• keep 1570-1620 mhz
• make a dynamic spectra (optionally write to disc)
• compute the total power for each 1 second integration for each glonass frequency channel
• remove 2nd order baseline using data outside the glonass band (1593-1597) and (1608-1615)
• save the tpAr,sumI1,ldate to an idl save 
• stored in mocksave/20140801_211142.sav (yyyymmdd_hhmmss.sav) time stamp is start of pattern.
• inpsav.pro - Load save files (generated by procglonass) into  glar[]. one entry for each second of data taken
  
• jd time stamp for this second
• tpch[18]:  total power for each satellite for this second (from save files generated by procglonass)
• az[18]:  az position of sat for this second (to be computed)
  
• za[18]:  za position of sat for this position. (tobe computed)
• cmpsatpos.pro - using time stamps from glar[] compute constellation sat position for each second
• glAr[] from inpsav.pro has the timestamp
• calls satpass routine to compute constellation position at 1 sec intervals for 12 hour blocks.
• generates satAzAr[npntsTot,nsat], satZaAr[npntsTot,nsat] . save to satazza.sav file
• npntsTot same as glar[npntsTot] so indices should be the same
• plotsatpwr.pro - plot sat positions vs az,za.. make image of power in glonass freq chn vs az,za position on satellite..
• currenly only have 6 satellites mapped to freq channel. need to find the rest.
• doit.pro : after above run, doit.pro will inpsav,,restore satazza.sav and then run plotsatpwr..
  
• Processing sequence:
• procdat.pro. generates file list -> patI.sav
  
• procglonass. compute power in glonass channels --> mocksave/yymmdd_hhmmss.sav . 1 for each 1 hour pattern
• inpsav.pro : input save file sfrom procglonass.pro.create glAr[npntsTot] .. to hold total power , time ,satpositio
• cmpsatpos: using timestamps from glAr. compute sat pos for each sec, sat. Save to satazza.sav . (should put it in glar.azpos,glar.zapos but  don't)
• plotsapwr: plot sat pos vs az,za, make image of sat chan power.

• red triangle - the platform triangle
• red bar: the azimuth arm
• green dot. position of the dome
• dotted circles. every 4 or 10 degrees in za.
• Positions: different colors are different satellites
• I've only mapped 6 satellites to frequency channels.. so that's all that i've plotted.
• za Range. with a 3 arcminute beam, it is difficult to see the satellite pass thru the sidelobes when the entire image cover +/- 90 deg. The smaller za ranges let you start to see the on/off of the signal as it passes through the sidelobes (although we may have been sampling too slowly at once per second).
• Probably need to work on increasing the dynamic range of the power image.