# intro

s3043 wants to see if they can see arcing on satellite solar panels using AO and the 327,430  and 47 MHz receivers. Test data was taken on 150921. The actual run on the satellites occurred 18oct15 through 21oct15.

# 150921: fast dump spectra using the 327 receiver.

On 21sep15 i took some fast dump data using the 327 receiver. The setup was:
• 327 MHz receiver., 53 MHz bw centered at 327 MHz.
• The telescope was sitting at az=288.3394, za=9.12 degrees
• mock spectrometer, spectral line mode
• dump spectra at 19.2 usecs , 256 channels
• dump spectra at 9.6 usecs   , 128 channels
• In both cases data was taken for 60 seconds.

Processing the data:

• each record of data contained about 1 second of data.
• for each record compute the rms/mean along each channel for all of the spectra in the record
• for each rms spectra do a robust fit of : linear polynomial and 2nd order harmonic.
• Flags any freq channels that were more than 3 sigma from the fit.
• For each spectra (19.2 or 9.6 usecs) compute the total power for the spectra throwing out the channels that had fit rms's greater than 3 sigma.

the plots show the total power vs time
• total power vs time for 19.2 usec data (.ps) (.pdf)
• top: 4 seconds of total power data
• bottom: blowup around 3.117 seconds
• the spikes lasted from 1 to 5 spectra (19.2 to about 100 usecs)
• there were 1101 points > 1.2 times tsys in the 60 sec dataset
• there were 3145350 points in 60 seconds
• total power vs time for the 9.6 usec data (.ps) (.pdf)
• top: 4 seconds of data
• bottom: blowup around  .930 seconds
• the spike are mainly 1 sample (< 9.6 usecs)
• there were 3986 points > 1.3 times Tsys in 60 seconds
• there were a total of 6275365 samples in 60 seconds.

### Summary

• we see very narrow spikes at both 19.2 and 9.6 usecs integrations
• This data was taken 17:19 ast. Late at night there  may be fewer narrow spikes.
processing: x101/150921/327arc.pro

# 18oct15 - 21oct15: satellite data

yymmdd  (AST = UTC - 4)
151018
151019
151020
151021

## Setups used:

• gregorian dome tracks object, ch used for rfi monitoring
• All data taken with topocentric frequencies, no doppler correction done.
• gregorian dome
• 53.3 Mhz bw, 128 frequency channels
• 9.6 usecond spectral averages
• center frequency: 327 Mhz.
• 26.6667 Mhz bw, 64 frequency channels
• 9.6 usecond spectral averages
• center frequency 432 Mhz.
• 80 Mhz bw, 4096 channels
• 999.9872 ms spectral averages
• center frequency 1590 Mhz.
• carriage house receiver (for rfi monitoring)
• 2 Mhz bw, .5 usecs complex sampling of voltage data
• center frequency 46.8 Mhz
• 430 Mhz carriage housee receiver
• 2 Mhz bw , .5 usec complex sampling of voltage data
• center frequency 430 Mhz.
• The carriage house remained at the stow position (8.834 deg) while the gregorian dome tracked the satellite (or pulsar).

## Description of daily observations

• 151019(UTC) (151018 AST): lbw, 327 , 47 Mhz
•  start time hh:mm:ss utc object mock fnum mock rcvr ri File nums ri rcvr notes 00:51:12 gps prn 22 000 lbw - - wait for satellite to enter beam 01:39:02 gps prn 22 100 lbw - - tracking satellite.. front end saturated.. ignore data. 02:46:52 gps prn 22 200- 208 327 000-001 47 ri file 0 rec 28749 bad hdr. lost 311 records don't process ri file. 03:04:49 J0006+1834 300- 315 327 - - 03:27:27 J0030+0451 400- 402 327 - - millisec psr. dm smearing 50ms, period:4ms probably junk data..
•
• 151020 (UTC) (151019 AST): 327 with dome, 430 with carriage house
•    start time hh:mm:ss utc object mock fnum mock rcvr ri File nums ri rcvr notes 01:48:52 gps prn 22 000- 025 327 .002-.005 430ch ri ok 227742 recs 02:21:02 prn22 +.75deg offset 100- 108 327 .006-.007 430ch 3 bm offset ri  rec 19022 bad hdr ,skip 02:31:52 gps prn 22 200- 217 327 .008-010 430ch ri ok 157461 recs 02:58:09 B2315+21 300- 313 327 - - tracked pulsar

•
• 151020/21  (UTC) (151020 AST) 430 with dome, 430 with carriage house (afternoon)
•  start time hh:mm:ss utc object mock fnum mock rcvr ri File nums ri rcvr notes mock beam 0 17:44:24 rbspb 000- 018 430 .011-.015 430ch did not hit new file for ridata between this scan and the next. So ri file .015 has end of 1st, start of 2nd file. ri started 2 minutes after mock.. 18:29:13 rbspb 1bm offset 100- 104 .015-.016 ri file started middle of file .015 merged ri file ok 18:39:43 rbspb 200- 204 .017-.018 ri file rec 12283 file 17 bad hdr.. lost 311 ri recs.. 18:49:41 rbspb 1 bm offset 300- 304 .019-.020 ri 68803 recs ok 18:59:41 rbspb 400- 404 .021-.022 ri 68999 recs ok 19:09:35 rbspb 1 bm offset 500- 504 .023-.024 ri 68666 recs ok 19:19:35 rbspb 600- 604 .025-.026 ri 68875 recs ok 19:29:38 rbspb 1 bm offset 700- 704 .027-.028 ri 68703 recs ok 19:39:40 rbspb 800- 805 .029-.030 remained on satellite till it set. 19:53:26 1 bm offset 900- 901 .031 offset at least 1 bm. increased as satellite continued out of the beam. 151021 UTC - mock beam 4 01:42:27 gps prn 22 100- 104 430 .032-.033 430ch raw data written to mock b4s1g0 (/share/pdata5/pdev) 01:52:35 1 bm offset 200- 204 .034-.035 02:02:37 on sat 300- 304 .036-.037 02:12:36 1 bm offset 400- 404 .038-.039 02:22:35 on sat 500- 504 .040-.041 02:32:32 1 bm offset 600- 604 .042-.043 02:42:35 on sat 700- 702 .044 02:52:46 off 800-803 .000 .045 raw file .000, after processing filenum is .045 offset by at least 1 bm as went out of the beam.

•
• 151022 UTC (151021 AST)  mock bm 4
•  start time hh:mm:ss utc object mock fnum mock rcvr ri File nums ri rcvr notes 01:38:42 gps prn 22 000-012 327 001-002 430 on satellite.. too much rfi, switch to 430 on next scan ri ok. 109874 recs 01:56:00 off sat 100-117 430 003-007 430 sitting at az,za the entire time. entire scans is an off ri ok   nrec 289950 02:40:10 on sat 200-202 008 on satellite ri ok. nrecs=37541 02:51:59 B2351+21 300-302 - track pulsar B2351+21 till set

# Acquiring the data:

Two sets of simultaneous data were taken:
• satellite beam:
• this used the gregorian dome. The receivers used were 430, 327, or lband.
• The satellite position was tracked or a position 1 beam offset from the satellite.
•  The two receivers used were:
• 430 receiver: 26.6667 Mhz bandwidth (160Mhz/6) 64 frequency channels
• 327 receiver: 53.3333 Mhz bandwidth (160Mhz/3.) 128 frequency channels.
• 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).
• each file contained:
• 139 rows, 104165 spectra each with 64 freq channels.. (about 1 second of data) per row.
• 97 rows, 79435 spectra each with 128 freq channels..(about .8 seconds of data) per row.
• rfi beam:
• This used the carriage house receivers:
• the postion 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 two receivers used were:
• 430 Mhz line feed
• 47 Mhz line feed (reciever bandwidth is less then 2Mhz).

# Processing the data:

From the radiometer equation we have that:
• 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).

### Satellite beam:

• each row of data (1 sec 430, .8 sec 327) was processed separately:
• compute rms/mean for each channel (over the 104165 or 79435 spectra)
• do a linear fit to the rms over the 64 (or 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 fit 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 1 sec of data.
• for each of the 9.6 usec spectra in the row (104165 or 79435 specra) 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 scan.
• repeat the above for each day of data taking.

### RFI BEAM:

• this was 2 Mhz of complex voltage samples, centered at 430, 327, or 46.8 Mhz.
• an entire file (2 Gbytes of 8bit complex voltages was read in.
• 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 an rms was then computed for the entire data set.
• the output values were the tpOut[i]= (tpAvg[i] - mean)/rms
• Comparing the two beams.
• This is use when the on source an rfi beams are both 430 Mhz...
• 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 not from the satellite.
• Passing this test does not guarantee that the on source large sigma is from the satellite..
• the rfi bandwidth is only 2 Mhz.. there could be some frequency channels outside this 2 mhz that has terrestrial rfi.

### 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.. about 1 time sample (9.6 usecs).
• i tried excluding all > 5sigma spikes that lasted for more than 3 consecutive time samples.. this reduced the number of spikes by about 10% (this last one has not yet been implemented..)

## Looking at the data

• Does it make a difference how many spectra we used when computing the rms?
• by default, 1 row of data was used to compute the rms by channel (about 1 second)
• for 430 Mhz this was
• for 430 Mhz that was 104165
• I looked at a file with lots of spikes to see if the rfi rejection changed with the # spectra used for rms computation:
• 14,467,824 spectra in the file
• date:20151020 scan start: 17:44:24 (utc), file number 00005 has lots of spikes
• the table below shows the number of 5 sigma spikes i got while varying the number spectra per rms
•  # of spectra per rms TmDuration for rms (secs) # spikes>5sigma 104165 .999984 6315 10416 .1 6291 1041 .01 6283

• So the number of spikes decreased a little, but no appreciably.  So i stayed with 1 sec of data for the rms by chan computation

# Exporting files:

Each days data are stored under a separate subdirectory (the directory names are the AST dates when data was taken):
20151018,20151019,20151020,20151021.
• 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
• 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)
• 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 did not start at the same second
• mtp_20151020_174424.hdr
• start1970 :                         1445363064    start time secs 1970
timeStep  :                        0.000009600    time step seconds
nsamples  :                          265099925    number of samples in file
cfr       :                        432.0000000    center freq Mhz
bandwid   :                         26.6666667    bandwidth Mhz before bad channels
mockNmSt  :   s3043.20151020.b0s1g0.00000.fits    fname for first mock raw file
nmockFiles:                                 19    number of mock raw files this scan
rifname   :                rtp_20151020_174620    basename (or none) for ri tp (rfi beam) file

• rifname specified the ri  file that corresponds to the  mock total power file
• rtp_20151020_174620.hdr
• start1970 :                         1445363180    start time secs 1970
timeStep  :                        0.000010000    time step seconds
nsamples  :                          243258982    number of samples in file
cfr       :                        430.0000000    center freq Mhz
bandwid   :                          2.0000000    bandwidth Mhz
riNmSt    :                 s3043.20151020.011    fname for first ri raw file
mfname    :                mtp_20151020_174424    basename for mock tp (on beam) file
• mfname is the mock file that goes with this ri file.

processing:usr/s3043/*.pro   (lots of programs)
data: sitting on gpuser0: /export/phildat/s3043/

# 03mar17 looking at objects in 327 sidelobes

Most geostationary satellites are below our minimum dec range (0deg).
One idea to look farther south, is to put the object in a sidelobe of a the receiver.

The plots shows the sidelobe gain loss (relative to main beam) vs angular separation from main beam (.ps) (.pdf)
• The plots used:
• 14 Amin for the FWHM of the 327 receiver
• (sin(X)/X)^2 for the sidelobe rolloff (the actual sidelobes may fall off faster).
• To look 2.5 Degrees away from the main beam, the signal will be 30db down from the main beam.
processing: x101/170303/satArc_sdlb.pro

home_~phil