ALFA (lband multi-beam system).
june,2002
The Arecibo Lband Feed Array (alfa) consists
of
7 feeds. 6 hexagonal feeds with 1 in the center.
Sections
History
- 16apr08: alfa 0b still misbehaving. increased gain by 3db at
downstairs if amplifier so wapps get get enough power.
- dec07 alfa back to telescope.
- apr07: alfa down to lab for maintenance
- 07mar07 - beam6b had instabilities in total power. Started
sometime in
feb07. Fixed 07mar07. Problem was
a bad cable in wapp4 brd1 polB that went from digitizer to filter
chassis.
Jumps could be up to 5% of Tsys
- 08nov06 - amp1b died. recovered 22nov06 after warmup,cooldown.
- 23jan06 - pixel 6a amp failure on alfa monitor.
- xxdec06 - installed 1440 filter bank. amps downstairs
installed
for
this (xx gt 16)
- 18nov04 - sband transmitter run while alfa uncovered.
- 21apr04 - alfa installed in dome
Calibration measurements (top)
(see also sysperf
alfa)
09may05:comparing the system performance of alfa and lbw at OH
frequencies (with10db amps in)
01apr05:comparing the system performance of alfa and lbw at OH
frequencies (no 10db amps in)
16jan05: beammaps on 3C138 using calibration scan data.
29nov04: calibration scans on B1756+134. Beammaps and Measurement of
the zero offset in the rotation
angle.
16aug04:
system performance (spider scans) at 1665 Mhz
29jul04:
measuring the cal values at 1665 Mhz using sky and absorber.
22apr04:
alfaTsys/Tcal using the old if/lo system.
apr04:
Alfa cal values measured in the lab.
Tsys (top)
Monitoring alfa performance
- System
performance:
gain,Tsys,sefd,beamwidth,sidelobes from calibration scan data.
- Tsys
by month
- Alfalfa
drift search. Gain variations with time, source deflections,rfi,
compression.
- Alfalfa
drift search. images of TsysPolA/TsysPolB showing any jumps in power.
- Ages
drift
search. Gain variations with time, source deflections, rfi, compression.
Jumps in Tsys caused by radars. (top)
04apr08: pulsed noise source into
alfa mixer to create long recovery times.
25mar08:
za location for power jumps along the meridian (using pdev)
25mar08:
faa radar causes
jumps and slow recovery. measured with pdev spectrometer.
A2010
total power strips show jumps: see 11jan07,13jan07,08mar06, 28apr06..
etc
06mar08: radar compression causes
jumps and slow recovery. measured with pdev spectrometer.
- Alfa had been worked on during the telescope. After reinstalling
it, this data shows that the problem is still present.
01aug05:
compression, baseline variation with long recovery time in p2030 data
(from
faa radar)
- Sampled with 64Usec resolution. shows the initial increase in
power and then the long recovery time. Also shows that the
compression
periods are those of the FAA radar.
28feb,03mar05:
faa radar causes increase in power with slow recovery time.
- Problem occurs before downstairs fiber optice receiver output.
28sep04:
compression of alfa receiver from faa radar. Az dependence
(64Usecsampling)
- Shows rapid compresssion, and azimuth where compression max (for
za=18). Does not show slow recovery times.
24sep04:
radar causes power jumps in some alfa beams.
06sep04:
jumps in the total power while doing drift scans (A1946 precursor).
Measurements by
date (top)
04apr08: pulsed noise source into
alfa mixer to create long recovery times.
25mar08: za location
for
power jumps along the meridian (using pdev)
25mar08: faa radar causes
jumps and slow recovery. measured with pdev spectrometer.
09may05:comparing
the system performance of alfa and lbw at OH
frequencies (with10db amps in)
03apr07:
radar comb seen in 28mar07 data using serendip 5 and alfa.
12nov06:
alfa beam1a is noisier than the other beams. Probaby coming from the
fiber
transmitter.
18apr06:
one of alfa's refrigerators fails.
01apr05:comparing
the system performance of alfa and lbw at OH frequencies (no 10db amps
in)
24feb06:
Harmonics created in the alfa/wapp configuration with cfr=1385Mhz.
21feb06:
measure the channel number of the center of the wapp/alfa spectra.
17oct05:
location of 1350 faa radar aliases in alfa.
15sep05:
Measurements show that the cal deflection is not a function of the
rotation
angle.
27aug05:
the alfa motor controller was creating the 16Khz comb in the 327 Mhz
rcvr.
22aug05:
looking at TsysA-TsysB vs azimuth and feed rotation angle.
01aug05:
compression, baseline variation with long recovery time in p2030 data
(from
faa radar)
19jul05:
galfa pixel4a,6a were switched (11jul05 to 19jul05).
13jul05:
power levels in galfa pixel 2b changing.
01jun05:
the 174 khz ripple in pixel 4A of alfa.
12jun05:
1428 Mhz biridie in alfa 18may05 thru 23may05
31may05:
galfa pixel4a,6a were switched (before 02may05 until 31may05).
21may05:
pixel 4a still has a173Khz ripple (amplitude of .09K).
08may05:
p2030 data feb05 thru apr05 shows aerostat compression with filterbank
amps.
11apr05:
p2030 pulsar data show compression with new rf amps and wapps are not
starting
together.
08apr05:
totpwr images a2010 drift scans (apr05) show when faa 1350 radar
problem
occured.
27mar05:
1350 faa radar appears at 1370 to 1390 Mhz.
24mar05:
1430 Mhz birdie in pixel0b of alfa.
28feb,03mar05:
faa radar causes increase in power with slow recovery time.
16jan05:
beammaps on 3C138 using calibration scan data.
29nov04:
calibration scans on B1756+134. Beammaps and Measurement of the zero
offset in the rotation
angle.
06oct04:
faa, punta salinas, and aerostat radars pwr vs time using alfa.
28sep04:
a1956 test data. Start of scan ra,dec hdr positions off.
28sep04:
compression of alfa receiver from faa radar. Az dependence
(64Usecsampling)
24sep04:
radar causes power jumps in some alfa beams.
08sep04:
1380 birdie in pixel0b of alfa.
08sep04:
174 khz ripple in pixel4a alfa data.
06sep04:
jumps in the total power while doing drift scans.
01aug04:
compression from the faa radar.
22apr04:
resonance in alfa receiver at 1537.7 Mhz.
22apr04:
alfaTsys/Tcal using the old if/lo system.
apr04:
Alfa cal values measured in the lab.
HIPASS paper:
The HI Parkes all sky survey: southern observations, calibration and
robust
imaging (pdf file)
Pre Installation (till
21apr04) (top)
12apr04:
computing
the wedge position on the floor.
04mar04:
testing the alfa rf/if processor with noise sources in the receiver
room.
15may03:
looking at the alfa IF using lbw horn.
03oct02: Some
notes on the upstairs IF power levels that will be needed.
jun02:
Field of view measurements using turret offsets and lbn feed.
Do we
have
to rotate the feed array.
Horn
spacing, rotation angle for drift scans, and sampling on the sky.
maximum
beam separation for multi beam nyquist sampling with ...german cortes..
MOTOR INFO: (top)
Setup
and
Reference Guide ServorStar CD (we're using a CE06)
ServoStart
S and ServoStar CD installation manual
ServoStar
S andCD series Sine encoder feedback
Application
note: S/CD Series Serial communications protocol
Application
note: Servostar S/CD position control
Kolmorgon
documentation ServoStartCD controller.
home_~phil