intro

• 06apr17:  AM.pulsars were tracked.  The feed was then offset to see the sidelobe pattern of the 327 receiver.
  
• 06apr17: PM  satellites were tracked.
  
• dome 327 receiver -> mock spectrometer
• ch 430 receiver -> ri baseband sampling
• on,offs were done
  
• 08apr17:satellites were tracked.
  
• Dome 327 receiver -> mock spectrometer
• ch 430 receiver -> ri baseband sampling.
• on,offs were done.

Acquiring the data:

• satellite
  
• this used the gregorian dome. The 327  receiver was used.
  
• The satellite position was tracked or a position 3 beams offset ( great circle azimuth) from the satellite.
  
• The receiver, backend setup:
  
• 327 receiver: 53.3333 Mhz bandwidth (160Mhz/3.) 128 frequency channels, sum polA, polB. Centered at 327 Mhz.
  
• the data was piped to the mock spectrometer where the spectral density function was computed  and integrated for 9.6 micro seconds
• the spectra were output to fits files:
• A continuous (in time) data set (called a scan)  consisted of multiple fits files (each about 2.2 gbytes).
• rfi beam:
• This used the carriage house receiver:
• the position was 180 Degrees from the satellite. The za was fixed at the stow position (8.8343 deg).
• The data was piped to the ri a/d converters.
• complex voltage samples were taken at a .5 usec sampling rate (giving a 2 Mhz bw), 8 bit samples, and then written to disc.
• The 430 Mhz receiver was used (centered at 430 Mhz)

Unlike previous experiments, we used a command file to control the data acquistion. A cycle was:

• load ephemeris
• track ephemeris
• adjust power.
• window pops up waiting for user entry
• user hits return when they want to start.
  
• ri gets started
• mock gets started (takes about 10 secs..)
• mock finishes after 10 minutes
• stop ri
• move to offset position (3 beams).
• start ri
• start mock
• wait till end of 600 sec mocks.
• stop ri
• move to next on position.
• this cycle would then repeat (on the same satellite, or move to a new satellite)
• see /share/obs4/usr/a3164/06apr17_arcing.cmd, 08apr17_arcing.cmd
• Note -->
•  the ristartnow from the command file did not end up defining the full hdr.
• riraw should have done this.. maybe i forgot to do it after moving the datataking window to the control room
• if we use this again, check that this gets done

06apr16 (UTC/AST): tracking satellites

Observation sequence.

• 170406(UTC) (170406 AST): dome: 327 rcv, ch : 430 monitoring.

• start time hh:mm:ss utc	on/off	object	mock fnum	mock rcvr	ri File nums	ri rcvr	notes
  20:15:02 to 20:25:02	on	tdrs	000 - 008	327	000	430 ch	ri started 5 minutes late (around 20:20:xx)
  20:25:41 to 20:35:41	off		100 - 108		001-002		tieposoff 2 td 12  .. no tension i td 12. pulled down 1 inches.
  							switch mock setup noise shift-> radar shift..
  20:40:36 to 20:50:36	on	optus	200- 208		003-004
  20:51:11 to 21:01:11	off		300- 308		005-006
  21:02:28 to 21:12:28	on	brazil	400- 408		007-008
  21:13:03 to 21:23:03	off		500- 508		009-010
  21:24:10 to 21:34:10	on	expressam1	600- 608		011-012
  21:34:44 to 21:44:44	off		700- 708		013-014		21:35 getting dark clouds off to south..may have some lightning tieposoff -2 td 12. back to normal position. dist 3 still out. ridata has only about the first 300 secs of the 600 secs. There was then a missingbad block sent across the net.
  21:47:01 to 21:57:01	on	galaxy5	800- 808		015-016
  21:57:37 to 22:07:37	off		900- 908		017-018		22:01 got dist 3 back. tietrk.

08apr17 (UTC/AST): Tracking satellites.

• 170408(UTC) (170408 AST): dome 327 rcvr, ch: 430 monitoring.
• these satellites were looked at in the  far sidelobes (all below our dec range).
• For 08apr17 no offs were done.
• We sat for about 1800 seconds on each satellite.
  

• start time hh:mm:ss utc	on/off	object	mock fnum	mock rcvr	ri File nums	ri rcvr	notes
  20:03:44 to 20:24:xx	on	gps	000- 009	327	no data	430	stopped before 30 minutes were up.
  20:24:28 to 20:52:xx	on	echostar18	100- 121		000-002		ri started about 7 minutes late clouds delta za = 2.5 deg
  20:52:45 to 21:22:45	on	amc-4	200- 224		003-006		more black clouds. delta za = 1.9 deg
  21:23:50 to 21:53:50	on	amc-3	300- 324		007-010		delta za 2.837 deg
  21:55:09 to 22:25:09	on	staronec1	400- 424		011-014		delta za = 1.96 deg
  22:25:56 to 22:55:56	on	telstar 14r	500- 524		015-018		delta za=2.22 deg

  
  

Processing the data:

• deltaTsys/Tsys = 1/sqrt(channelBandwidth*time)
• (Since we've added polarizations, the channel bandwidth has been doubled..)
• So computing the rms by channel and then normalizing to the average channel value will give sigma values that should be determined by the bandwidth and integration time.. if the signal is noise like.. Any intermittent rfi (narrow channel frequeny broadcasts) will increase the rms values in these channels..
  
• broad band bursts from the satellite that lasts for 10's of usecs will not affect this  (since they are too short in time).
• PolA and polB were added together in the mock spectrometer, before outputting the spectra.
  

Satellite beam:

• each row of data (.76 sec 327) was processed separately:
• dome 327: 79435 9.6 usec spectra /rec
• compute rms/mean for each channel (over the 79435  spectra in  a record)
• do a linear fit to the rms over the 128   freq channels (excluding the edge channels where the analog/digital filter) response fell off.
• Create a freq channel mask that includes all freq channels whose value is within 3 sigma of the fit.
  
• This mask will be used to compute the total power for each 9.6 usec spectra .. for this .76  sec of data.
• for each of the 9.6 usec spectra in the row () compute the total power using the above row
• output the data, and record which frequency channels were used for this row.
• repeat the above for each file of the scan
• and continue for each scan of the day.
• There will be 1 output file of floating point total power data (sampled at 9.6 usecs) for each 2.2 gbyte file of each scan.
• repeat the above for each day of data taking.

RFI BEAM:

• this was 2 Mhz of complex voltage samples, centered at 430 Mhz.
•  8bit complex voltages was sampled with the a/d's.
• there is 1 output file for each mock scan.
  
• the mean was subtracted from the i, q channels (to get rid of DC offsets)
• the power was then computed for each .5 usec sample , and then averaged to 10 usecs.
• the mean and rms was then computed for the entire data set.
• the output values were the tpOut[i]= (tpAvg[i] - mean)/rms
• Comparing the two beams.
• If we find a large sigma in the on source beam, we should check the same time (and maybe 10 usecs on each side) to see if there is a corresponding large sigma in the rfi beam..
  
• If this is true, then the sigma in the on source beam is probably not from the satellite.
• Passing this test does not guarantee that the on source large sigma is from the satellite..
  
• the rfi beam is at 430 mhz, while the sat. beam was at 327 Mhz.
  
• the rfi bandwidth is only 2 Mhz.. there could be some frequency channels outside this 2 mhz that has terrestrial rfi.
• broad band interference (say lightning)  may appear in both the satellite beam (at 327 Mhz) and the rfi beam at 430 Mhz.
  

Decide which broad band spikes to keep.

• The satellite beam total power array was converted to sigmas.
• sigSat[i]=(tpSat[i]- mean(tpSat))/rms(tpSat)
• The rfi beam was already in sigmas
  
• to be a valid  broad band spike, the point had to meet:
• the sigSat[i]  had to be larger than the sigma threshold (say 5 sigma)
• the sigRfi[j]  had to be less then the sigma threshold
  
• For every sigSat[i] point, 3 points were checked in the sigRfi[j] array (the one closest, 1 above, and 1below in time)
• If any of the 3 points in the sigRfi array were > than the sigma threshold, then the sigSat[i] point was ignored.
• The satellite spikes should be narrow in time .. say up to 100 usecs..??
  

Exporting files:

• A scan is a contiguous set of data.
• For each scan:
• there is are two data sets:
  
• there is a data set from the gregorian dome, mock spectrometer
• this is the beam that pointed at or close to the satellite
• the files start with mtp_ (mock Total Power)
• There is a data set from the carriage house, ri a/d interface
• This is the beam that pointed 180 degrees from the satellite (rfi beam)
  
• the files start with rtp_ 
• Each data set has:
• file of total power data (4 byte floating point, little endian)
• Equally spaced in time
• ends with .dat
• an ascii  header file that has some info on the scan
  
• Filenames:
• mtp_yyyymmdd_hhmmss.dat / .hdr
  
• The date, time is the utc start time for the data in the file
  
• rtp_yyyymmdd_hhmmss.dat/hdr
• The date, time is the utc start time for the data in the file
• Note: the mtp and rtp files do  not necessarily start at the same second
• one of the rtp files is was not acquired..
  
• Headers:
• mtp_20170406_202541.hdr
  
• start1970 :                         1491510341    start time secs 1970
  timeStep  :                        0.000009600    time step seconds
  nsamples  :                           62500000    number of samples in file
  cfr       :                        327.0000000    center freq Mhz
  bandwid   :                         53.3333333    bandwidth Mhz before bad channels
  mockNmSt  :   a3164.20170406.b0s1g0.00100.fits    fname for first mock raw file
  nmockFiles:                                  9    number of mock raw files this scan
  rifname   :                rtp_20170406_202540    basename (or none) for ri tp (rfi beam) file
• rifname is the rfi file (ri data) that corresponds to this file
  
  
  
• rtp_20170406_202540.hdr
  
• start1970 :                         1491510340    start time secs 1970
  timeStep  :                        0.000010000    time step seconds
  nsamples  :                           60130099    number of samples in file
  cfr       :                        430.0000000    center freq Mhz
  bandwid   :                          2.0000000    bandwidth Mhz
  riNmSt    :                 a3164.20170406.001    fname for first ri raw file
  mfname    :                mtp_20170406_202541    basename for mock tp (on beam) file
  
  
• mfname is the mock file that goes with this ri file.
  

• gpuserv0:/media/DATA0/phildat/a3164/export