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
- 20oct11: afternoon switched fibers used
- beam1a upstairs cable 1a-> fiber 6b downstairs fiber rcvr
output 6b -> cable 1a
- beam6b upstairs cable 6b -> fiber 1a, downstairs fiber
rcvroutput 1a -> cable 6b
- After doing this beam1 caldeflections a2130
show +/- 2% amplitude change with za.
- 19oct11:
- 11oct11: beam4a changed 12db amp after filter bank to 16db amp
before filterbank.
- 06oct11: beam4a decreased drain current to 11 milliamps, added
12db amp after filterbank.
- 02oct11: beam 6b power drops out, becomes erratic.
- 06sep11: alfa reinstalled in dome
- 26jul11: alfa brought down to lab to work on it.
- 23may11: bias voltages for beam 1 were
adjusted on 16feb11 when an open loop bias card was installed for
testing. This card was in use for a only a few days. When a closed loop
card was put back in, the bias voltages were never put back to the old
values. The lower bias voltages set for the open loop card made the amp
leds more sensitive to power supply voltage changes. This probably
caused the jumps
seen
by a2130.
- 9dec10: beam 5 2.5 Mhz oscillation found and quenched in bias
card.
- 19oct10: alfa motor replaced.
- 28dec09: bias voltages adjusted
- 17oct09: leds turned on
- 30oct09:alfa reinstalled
- leds installed on amps (but not turned on yet) to improve slow
recovery from radars.
- in line capacitors for bias lines inside dewar removed.
- had to be replaced on cables outside dewar to stop bias line
oscillations.
- 15sep09: alfa brought down to the lab
- 16jan09. beam1 has been jumping around. 17:00 swapped bias cards
bm1, bm2 to see if the problem jumps.
- 19sep08: Finished modifying alfa's bias voltages for stage 3
ampsfor long recovery times (see below for when each beam done)
- 16aug08: beam 6b dies.
- 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)
sep_oct11: calibration scans
after alfa reinstalled.
02nov09: calibration scans
after alfa re installed, alfa rotation angle offset check.
29jun09: calOn,calOf:
averaging over the band vs linear fits.
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)
Note: the 26aug08 measurements show
that the long recovery time caused when the radars hit alfa are a gain
change in the dewar..
19nov09: alfa recovery
with
the leds installed
24sep08
alfa long recovery times vs alfa rotation angle
23sep08 alfa long
recovery times after bias changes (on sky).
18sep08:remove zener
bias circuit 3a amp3, modify Vd,I for 3a and 3b.
16sep08:remove zener
bias circuit 3b amp3, modify Vd,I.
11sep08: pulsed noise
into alfa horn, modifying the bias currents.
26aug08:Pulsed
noise
into
alfa horn shows long recovery is in dewar
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).
Bandpass ripples caused by the fiber.
18oct11:
174khz ripple in bandpass from alfa fiber (data taken 14oct11)
23apr11: ripples
in bandpass caused by fiber.
01jun05:
the
174
khz ripple in pixel 4A of alfa.
21may05:
pixel
4a
still has a173Khz ripple (amplitude of .09K).
08sep04:
174
khz
ripple in pixel4a alfa data.
Measurements by
date (top)
07dec11: run switching
test on alfa filter bank.
28nov11: beam2a shows some
jumps in ages data.
27oct11:
fit C0,1az,3az terms to alfa pointing errors.
sep_oct11:
calibration scans
after alfa reinstalled.
19oct11: cleaning alfa fibers
caused beam1A tsys to jump to 150K.
18oct11: 174khz
ripple in bandpass from alfa fiber (data taken 14oct11)
10oct11: tsys beam4a while
dana uses the spectrum analyzer.
07oct11:a2010 total
power for 06-07oct11 showing bm4awith low drainI and bm6b failures.
03oct11: beam6b power
drops out , becomes erratic.
27sep11: beam5a dropout
seen by alfalfa.
26jun11:
a2130
adc,pfb overflows vs za for jun11.
20may11:a2130
caldeflection
beam 1b jumps occurs with 20k diode temp jump.
04may11:
a2130(galfacts)
bm4B caldeflection has za dependence
02may11: a2130
(galfacts)
cal deflection show gain stability.
26apr11:
instabilities in beam 1b.
23apr11: ripples
in bandpass caused by fiber.
28mar11: radar
intermods in galfa spectrometer.
16mar11: plots
of alfa temps during
cooldown sequence (.ps) (.pdf)
08mar11- alfa motor controller,
dome cameras rfi at 750 Mhz.
02mar11: 327 rfi caused by alfa
motor controller.
15feb11: 5.2 sec oscillation
in beam 2 from the dewar bias monitoring.
30nov09: Alfa outer beam
position errors in mock fits files.
19nov09: 2.5 Mhz oscillations
from bias box
19nov09: look at total power
stability with leds on.
19nov09:
alfa
recovery
with the leds installed
02nov09: calibration scans
beam 0 after alfa re installed.
11sep09: 1390 rdr appears in
alfalfa data.
29jun09:
calOn,calOf:
averaging
over
the band vs linear fits.
14may09: Intermods
seen in alfa/pdev
14may09: table of intermods
created in 1st and 2nd mixers of alfa/pdev.
26apr09: radar
looking rfi in alfa data at 1403,1424, 1475 Mhz.
11apr09:
gps
L3
in a2010 data jan09-mar09.
19mar09: GPS L2,
GLONASS L2, and COMPASS E6 rfi 1200-1300 MHz
24sep08 alfa
long recovery times vs alfa rotation angle
23sep08 alfa long recovery
times after bias changes (on sky).
21sep08:check alfa stability after bias
voltages changed.
18sep08:remove zener
bias circuit 3a amp3, modify Vd,I for 3a and 3b.
16sep08:remove
zener
bias
circuit 3b amp3, modify Vd,I.
11sep08: pulsed noise
into alfa horn, modifying the bias currents.
04sep08: gps satellite flies
thru a2010 observation causing birdies at 1346.7
26aug08:Pulsed noise into alfa
horn shows long recovery is in dewar
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..
home_~phil
