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
- 09jun17: beam 5,6
60 hz problem fixed (15volt supply in bias chassis feeds beams
5,6).
- 17may17: alfa beams
5,6 have strong 60 hz.
- 22jan16: beam6b
jumping around, bias's stage 1 jumping around
- 25sep15: beam 3b goes bad.
- 16may15: calibration
scans to check alfa gain,pointing after installation
- 28apr15: alfa back up to the dome.
- 11apr15: alfa brought down to the lab
- sep15 : beam 6b amp drain current starts to
jump around. beam data not stable.
- 24may14: calibration
scans to update pointing
- 21may14: alfa back to dome. all beams working.
- 28mar14: alfa brought down to lab.
- two beams bad
- lots of diode temp sensors not working
- 20nov13: beam 2A
- mixer card in eddie's box for beam 2a was replaced on
20nov13. After the change, the jumps in beam 2a stopped.
- 20apr12: alfa reinstalled in dome:
- beam1a, beam6b no longer have the cable->fiber switched
upstairs and downstairs. cable 1a->fiber1a ...
->fiber1a=> cable1a. same for 6b.
- 09mar12: alfa brought down to lab.
- 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)
30may16: calibration
scans to check alfa gain,pointing after installation.
16may15: calibration
scans to check alfa gain,pointing after installation
27may14: calibration
scans after alfa reinstalled
05feb14: alfa bandpass (uncalibrated
and in deg K)
03may12: calibration
scans after alfa reinstalled 20apr12.
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..
10oct12:
alfalfa data sep12 shows long recovery time in beam1b. (new amps
installed apr12)
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)
09jun17: 60hz problem in bms
5,6 fixed.
17may17: p2030 pulsar search.
60hz in beams 5 and 6.
30may16: calibration
scans to check alfa gain,pointing after installation.
22jan16: bm6b instabilities
16may15: calibration scans
to check alfa gain,pointing after installation
27may14: calibration scans
after alfa reinstalled
05feb14: alfa bandpass (uncalibrated
and in deg K)
15jan14: alfa winking cal show
total power time variation with calon, caloff.
10oct12: alfalfa
total power data shows long recovery times for beam 1b sep12
14jun12:
20 hz birdies from alfa monitoring come from the bias monitoring.
12jun12: p2030 reported
1.5 hz rfi in data (not present). .838 hz rfi is visible.
02jun12:
glitches in alfa gain caused by alfa dewar monitoring,.
03may12: calibration scans
after alfa reinstalled 20apr12.
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.
csiro final mount position for
alfa (.pdf)
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
