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ALFA Surveys Workshop: 10-11 december 2009
CIMA STATUSRfi update
2009 ALFA Surveys Workshop
Phil Perillat
ALFA Surveys Workshop: 10-11 december 2009
Talk Outline
• CIMA status– CIMA versions– Position errs alfa outer beams in mock data.
• RFI:– Radars, Satellites, intermods.– Monitoring available at AO.
Online: http://www.naic.edu/~phil/talks/talks.html alfaSurveys09
ALFA Surveys Workshop: 10-11 december 2009
CIMA Versions
•Moving to mock single pixel V3.2
• includes functionality of previous versions.
•Lets you specify projid for commensal observer’s files.
•Requires update of config files for mock parameters.
Name Highlights
Mock 3.2 Mock single Pixel rcvrs.Users:none
Untested
b.b
Pulsar cals
Users: p2030 pulsar search
Smart
3.1
Smart basket weaving
Users:alfalfa,ages,auds,galfacts, igalfa,
ALFA Surveys Workshop: 10-11 december 2009
CIMA: Running wapps&mock
• Scan mode (start,stop many times):– Mocks start 3 secs after wapps and finish 3 secs after
wapps. Scan takes 6 secs longer• Continuous mode (start once, leave running)
– alfalfa/p2030– Wapps run scan mode, mocks started once and left
running. No impact on wapp running.• Single pixel:
– Wapp IF=250/275, Mock IF=325 so can’t be run together (Not so nice for pulsar verification). Will fix this in the future.
ALFA Surveys Workshop: 10-11 december 2009
ALFA outer beam position errors in Mock fits files
• Problem only in mock fits files: cima and psrfits.• azPos= azCenter + azBmOffGc/sin(za)
– azBmOffGc= -azLen0*cos(th)– Th=(beamNum-5)*60 - rotationAngle
• Error was:– azPos= azCenter + azBmOffGc*sin(za)– Th=(beamNum-5)*60 + rotationAngle– All positions then back computed from az,za
• When problem was fixed: – 1/sinza: 17nov09 cimaV2.01,psrfVer:3.41– Rotation Error: 01dec09. cimaV2.02, psrfVer:3.42– See http://www.naic.edu/~phil/modhistory.html -->30nov09 – Will write program to correct positions in files.
ALFA Surveys Workshop: 10-11 december 2009
Rfi Known culprits
• Radars: (http://www.naic.edu/~phil/rfi/rfi.html)– 1330/1350 faa radar– (1261/1246),(1256,1242) Aerostat balloon– (1270),(1290) remy radar (1 or the other)– (1232,1274,1241,1256) punta salinas modeA
ALFA Surveys Workshop: 10-11 december 2009
Global Navigation SatellitesSatellite Carrier NotesGPS
L2
1227.6 Pcode:10.23 Mhz
L2C: 1Mhz
Glonass
L2
1246+k*Fs
k=-7,13
Fs=437.5 Khz
Std: .511 Mhz
hiAccuracy:5.11 Mhz
Compass2 1268.52 BPSK: 10.23 Mhz
•Galileo:(E6 1260-1300) commercial service coded.
•Giove-B launched 27apr08 uses E6.(5.115 Mhz) till 18mar09.
ALFA Surveys Workshop: 10-11 december 2009
• GPS L2 @ 1227.6 Mhz
• Glonass L2 and compass.
Examples of rfi with alfa/mocks
ALFA Surveys Workshop: 10-11 december 2009
•Compute intermods first alfa mixer to 10th order
•Use 1375 Mhz cfr – galfacts,auds,ages,p2030.
•Use 1385 Mhz cfr – alfalfa, p2030 commensal
•Examples of intermods:
•Auds:1375,1402,1425,1475,1480 birdies.
•Complete table of 1st mixer mocks/wapps, 2nd mixer mocks
•http://www.naic.edu/~phil/mbeam/problems/rdr_intermods_pdev.html
Mock/Wapp 1st Mixer Radar Intermods
Rdr
Freq:
1233
Ps
1242
PS
Aero
1248
PS
1257
PS
Aero
1246
Aero
1261
Aero
1270
Rmy
1290
Rmy
1330
FAA
1350
FAA
Mock
1375
1288
1343
1514
1333
1425
1441
1363
1394
1478
1510
1321
1408
1473
1356
1405
1466
1515
1237
1285
1431
1455
1325
1420
1475
1240
1340
1390
1525
1325
1475
1480
1325
1375
Wapp
1385
1258
1283
1303
1365
1511
1333
1418
1464
1378
1391
1500
1513
1326
1406
1475
1355
1401
1495
1255
1285
1445
1460
1380
1455
1470
1415
1440
1525
1275
1425
ALFA Surveys Workshop: 10-11 december 2009
Alfa long recovery times
• Alfa amps were taking > 30 secs to recover from radar saturation.
• sep09 bias adjusted, recovery < 1sec
• Oct09 alfa brought to labs, leds installed in amps. In lab this fixed the problem.
• Verification of recovery times waiting for final led bias adjustments.
ALFA Surveys Workshop: 10-11 december 2009
Rfi Monitoring at AO
• location= http://www.naic.edu/~phil– Rfi: fractional occurrence by month (wapp,icorr data)
• Using telescope data, compute the fraction of time the rms noise in a channel is 3 sigma > than expected.
• Display is a histogram of fractional occurrence vs frequency
– Rfi: hilltop monitoring. Plots of previous day.• Uses spectrum analyzer and an omni directional antenna. Tsys
is about 1000K, Channel width=3 Mhz, 60 sec peak holds.• /pkg/aosoft/common/bin/imgui to display individual spectra
(on AO computers) of any date.• Screen shot of program with data from a2133 data 18apr09
ALFA Surveys Workshop: 10-11 december 2009
Summary• CIMA
• Write programs to correct alfa outer beam positions for mock fits files (cimafits and psrfits).,
• Commensal observering using 2 mock spectrometers might want to migrate to Version mocksp so they can specify the 2nd project id filename(may not be worth it).
• Running mocks and wapps together, mocks start, finish 3 seconds after wapps.
• Rfi• GNS satellites at 1220-1270 cause rfi
• IDL routines to measure distance from beam. Probably can go a few days into the future and still have reasonable error.
• Radar intermods occuring in 1st/2nd mixing stages.• Questions?