NAIC AUSAC Committee Meeting · March Telescope Performance and Datataking 2009 AUSAC Committee Meeting Phil Perillat

NAIC AUSAC Committee Meeting · March Talk Outline Telescope performance –Pointing –Gain/Sefd/Tsys Datataking (mock pdev spectrometer) –Current status and Usage. –What we’ve learned. –Yet to be done. Online:

NAIC AUSAC Committee Meeting · March Pointing Date Az Err (arcsec) Za Err (arcsec) Total Err (arcsec) 1998 mod mod mod mod mod mod Jul08-feb Pointing model made dec07/jan08 after painting shutdown.

NAIC AUSAC Committee Meeting · March Pointing errors vs Za Pointing errors vs Azimuth. –Error vs az looks like a platform tilt toward td12. This gives a 1 azimuth dependence of the the error. –1 platform inch rotation at 192 ft (tdCables) is is 12.5 (za=2) to 18. (za=20) asecs. RmsError (za,az)=(4.6,6.8) asecs. Total=8.2 asecs. –Fine for alfa/lband. Not so great for 28 asec beam of 10Ghz. Pointing: data taken jul08-feb09

NAIC AUSAC Committee Meeting · March Gain,SEFD,Tsys:lband,cband Data jul08 thru feb Mhz 5000 Mhz Gain Tsys Sefd Beam width Lband 1400 Cband 5000 Gain11K/Jy8K/Jy Tsys28 K27 K SEFD2.6 Jy3.3 Jy bmWidth204”55”

NAIC AUSAC Committee Meeting · March Surface error Ruze curve shows gain loss vs surface error. –Gain=G0*exp(-(4*pi*delta/lamda)^2 –Need to pick G0.. Used K/Jy Other factors (besides reflector error) can decrease gain: Under illuminating tertiary (cbh) Bad cals Most source extended for cbh,xband.

NAIC AUSAC Committee Meeting · March Alfa Tsys Alfa tsys measured during survey runs: –1671 measurements dec08 thru feb09. –Each color is a different project: Black:A2010 (alfalfa), Red:A2048(ages), Green:A2133(auds), Blue:(A2432) –PolA on left, polB on right. –Beams 0-3 –Beams 4-6 –Beams 3,4 at highest Za for a2010.

NAIC AUSAC Committee Meeting · March Mock pdev spectrometer: Status 1 box can process: –2*172=342 Mhz, in each of 4 pols (A,B,U,V), and 8192 channels/172Mhz spectrum. We have 14 boxes installed in system: –7 boxes:1/beam for primary observer –7 boxes: 1/beam for commensal observer We own 24 boxes. 1 Fileserver/box (14 fileservers). Each fileserver has 4 Tbytes of disc (14*4 = 56 Tbyes total).

NAIC AUSAC Committee Meeting · March Current pdev projects: G-Alfa continuum Transit survey: 33 sessions –Full stokes, 4096 channels/pol, 1 millisecond sampling with winking cal. –65 Mb/sec per box * 7 boxes = 450 Mb/sec. A 6 hour run generates 10 Tbytes. –After each run: Winking cal separated into calOn, calOff buffers. –Yet another fits file format (calOn,calOff buffers) 1 file has decimated in time (.2 secs) full freq range 2 nd file has decimated in freq (1.3Mhz) End up with 826 Gb per 6 hour run.

NAIC AUSAC Committee Meeting · March Current pdev projects Alfa Ultra deep survey: 50 sessions –8192 channels, polA,B and.1 second sampling Pulsar search: 0 sessions: –512 chan/172 Mhz, 65 Usec sampling, add pols. –32 Mb/sec per box. 220 Mb/sec for 7 beams. –3 hour session= 2.4 Tbyes/3hr session. With observing efficiency of 80% this is about 2 Tbytes.

NAIC AUSAC Committee Meeting · March Current pdev projects Pulsar search cont.. –Psrfits file format implemented –Conversion to sigproc file format done. –Runs ok by itself. Bug when running with zoa commensal observing… Need to figure it out.

NAIC AUSAC Committee Meeting · March Current pdev projects Aeronomy: –32 Mhz time domain sampling. –Tamara hall had been working on fpga code (but left) –Student at penn state now working on this Sband radar –32 Mhz time domain sampling –Do doppler correction in fpga. –Tamara hall had been working on this but left. Luis Quintero is the new digital engineer.

NAIC AUSAC Committee Meeting · March FGPA dynamic range and radars 18 bit fixed point arithmetic in fpga. Fft butterfly stages have mult and add. –Noise increases as sqrt(Number adds). Every 2 nd butterfly we downshift. –Coherent signals (radars) increase as N. Every butterfly we need to downshift. Send A/D 12 bits to upper 18 bits of register (leaves 6 bits free below). Downshift on 1 st 6+3 stages then alternate every stage. This keeps the noise from growing. If a radar is strong enough then it can still overflow the butterflies. First 9 stages are down shifts  fft<=512 can’t overflow length fft is difficult –1024*5ns/pnt=5 usecs = pulse width of faa radar. –Every sample in fft will have the radar pulse.

NAIC AUSAC Committee Meeting · March A/D blanking Clipping noise is ok, clipping a radar is like clipping a sine wave, is sends power all over the spectra. Solution: –If a time sample hits the A/D limit, flag it as bad. –Any fft with a bad sample is not included in the accumulation. This resolution is 40 usecs for an 8k fft. This helps the butterfly overflow problem since overflows in the butterfly usually happen with A/D signals that hit the limits. So far everyone has decided to use this mode. This was an option that jeff mock threw in because he thought it was cool.

NAIC AUSAC Committee Meeting · March Complex vs real sampling Pdev uses complex sampling The mixer image rejection works if the I,Q amplitudes are equal and the 90 degree phase shift is met. The radars push the mixers into saturation causing an image to appear on the other side. Real sampling would put mixer harmonics at a higher freq. They could then be removed with a baseband filter. –Example later..

NAIC AUSAC Committee Meeting · March File formats:.pdev for time domain data (Jeff mocks origin) cimaFits for “standard” spectral line data. Galfacts fits for calon, caloff buffer storage. Psrfits for the pulsar community. Used for archiving the data. Sigproc format for the pulsar community. This is what their programs want as input. If this continues, next year I’ll use a smaller font.

NAIC AUSAC Committee Meeting · March band: dynamic spectra.2 sec avg Mhz.2 sec avg. –No aeroStat –With Aerostat –Notes: 1330,1350 FAA radar 1270,1270 REMY radar 1242,1256 aerostat 1232/1248, 1242/1256 Punta salinas mode A Images of radar about 1300 (complex sampling) Radars don’t spread very far Pdev: A look at some data.

NAIC AUSAC Committee Meeting · March To do.. Fix bug so pulsar search runs with ZOA Get single Pixel working: –1 Ghz spectra using 7*150 Mhz bands Partly in cima –Get Aeronomy working: Penn state fpga code and program being tested. –Get sband running: Needs fgpa programming (or use regular baseband sampling with pdev).

NAIC AUSAC Committee Meeting · March To do.. single pixel Baseband sampling: –Need to add functionality to cima –Work on pdev headers. –Bandwidth/box: –7 or 14 boxes.. Bits1pol Mhz 2pol Mhz

NAIC AUSAC Committee Meeting · March Summary Pointing –Current rmsError: za: 4.6, az:6.8, tot:8.2 asecs Ok for alfa, needs az model work for high freq. How important is making the pointing better (with limited people) Gain,Tsys,sefd,Tsys –Sefd: lbw: 2.6Jy, Cband : 3.2Jy –Surface error doesn’t look terrible.. But need to work on the curve.. –Tsys alfa K –Alfa amps need leds installed for stability during radar pulses...(ganesh). Pdev –Galfacts, Auds running. –Pulsar search, ZOA start soon. –Alfalfa.. Stick with wapps. Ages ?? –Get single pixel working –Get aeronomy and sband working Replace Mikael lerner….