RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
The RFI monitoring systems for the Medicina
and the Sardinia Radio Telescope
R. Ambrosini (IRA), P. Bolli (OAC), C. Bortolotti (IRA),
F. Gaudiomonte (OAC), F. Messina (OAC), M. Roma (IRA)
Osservatorio Astronomico di Cagliari
Istituto di Radioastronomia
Sezione di Medicina
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
Agenda
• The Italian radio telescopes;
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
• Update of the SRT’s construction;
• The RFI monitoring systems of Medicina and
SRT:
• Fixed station;
• Mobile station;
• Recent activity of the RFI group: (i) faraday
room, (ii) wind farm, and (iii) routine
2/26
measurements.
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
Italian network
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
Matera
operato da ASI
3/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
SRT Technical Specifications
• Fully steerable radio telescope for: Radio astronomy , Geodynamical studies, Deep
Space Network, Single dish and VLBI
• 0.3-100 GHz continuous frequency coverage
• 64 m diameter primary mirror; 7.9 m diameter secondary mirror
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
• Gregorian configuration with Shaped Surfaces
• Active Surface: Primary mirror with 1116 actuators
a) Compensate gravitational and thermal deformations
b) Convert Shaped surface of the primary to a Parabolic
surface for primary focus operation
• Six focal positions (up to 20 receivers):
Primary, Gregorian, Four Beam Wave Guide
• Primary surface accuracy:  150 um RMS
• Pointing accuracy (RMS): 2 ÷ 5 arcsec
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P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
RA receivers for the first light
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
Frequency band
Note
305 – 410 MHz
Primary, dual
frequency
1.3 – 1.8 GHz
Primary, dual
frequency
5.7 – 7.7 GHz
BWG, mono-feed
18 – 26 GHz
Gregorian, multi-feed
5/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
RFI campaigns in Sardinia
RFI
Campaign
Goals
October
1992
RFI monitoring across South and
Center Sardinia
May 1996
RFI monitoring in Gerrei area
November
1997
RFI monitoring in Gennargentu
area
October
2002
RFI characterization of the site
chosen to host SRT
June 2004
RFI measurement in the
frequency bands of the first light
receivers
April 2007
Joined campaign with RFI mobile
laboratory and fixed station
installed at the site
6/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
Features of SRT site
The SRT site is located 35 Km North of Cagliari (700 m
asl).
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
Latitude: 39d 29m 50s N
Longitude: 9d 14m 40s E
1. The site is well shielded by mountains
sorrounding the radio telescope.
2. The area is far away from populated centers.
7/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
SRT update
High level meeting between INAF and Communication
Department of the Government are underway.
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
Full support from National Administration.
8/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
RFI monitoring system: goals
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
1. …. monitoring the frequency bands allocated by
ITU to RAS. If man-made signals interfere with the radio
astronomical observations, an official claim must be
reported to the National Administration asking for
protection.
2. …. monitoring also the out-of-RAS bands used by
astronomers to observe the sky. The RFI information
can improve the design of microwave receivers, the
strategies of scientific observation, and the mitigation
9/26
techniques.
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
RFI monitoring system: scheme
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
A fixed station with
antennas placed on a
tower close to the radio
telescope
A mobile laboratory to
move closer to the RFI
transmitter
(i) receive the interference, (ii) collect as many data as possible of the
RFI, (iii) identify the content of the signal, (iv) and detect the exact
position of the transmitter (triangulation).
(i) good sensitivity, (ii) high compression point, (iii) wide frequency
bands, (iv) automatically (24 h / day) and remotely controlled.
10/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
Fixed RFI station: scheme
11/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
Microwave front-end
12/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
Fixed RFI station: comparison
Features
Medicina
SRT (current version)
Tower height
25 m
12 m
>25 m
Max frequency
2.4 GHz
3 GHz
18 GHz
Antennas
2 LPDA (80 – 500 MHz)
2 LPDA (500 – 1000 MHz )
2 dual pol. Yagi (320 – 332 MHz)
2 dual pol. Yagi (400 – 416 MHz )
2 dual pol. Yagi (606 – 612 MHz )
1 reflector 1.2 m pol. 45° (1.3 – 2.4 GHz )
1 LPDA (0.3 – 5 GHz)
1 LPDA (1.2 – 2.5 GHz)
Rotor
1 axis for azimuth direction
2 axis for: azimuth direction and
polarization
Lenght & type
of coaxial cable
35 m LCF ½” Cu2Y CELLFLEX (max 3
GHz)
55 m of FSJ4-50B Andrew (max 10
GHz)
Spectrum
Analyzer
AGILENT 8562EC
HP 8594
Receiver
ICOM R9000
Satellite
monitoring
1 Az-El reflector 1.5 m pol. 45° (1.1 – 12
GHz)
PSA 4446E
ICOM R9500
Optical fiber link
Not yet available
13/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
RFI towers
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
SRT
MEDICINA
14/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
SRT
RFI laboratories
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
MEDICINA
15/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
Fixed RFI station: performance
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
Band
M
E
D
I
C
I
N
A
S
R
T
Frequency band
Antenna
gain
Chain
gain
Noise figure
320 – 332 MHz
14 dBi
37 dB
3 dB (300 K)
400 – 416 MHz
15 dBi
36 dB
3 dB
606 – 612 MHz
16 dBi
32 dB
3 dB
L
1.29 – 1.73 GHz
20 dBi
34 dB
3.5 dB
S
2.20 – 2.34 GHz
23 dBi
33 dB
3.5 dB
Satellite 1.1 – 12 GHz (AZmonitor EL)
19 dBi
12 dB
12 dB @ 10 GHz
Band
Frequency band
Antenna
gain
Chain
gain
Noise figure
P
295 – 428.5 MHz
6 dBi
28 dB
10.5 dB (3000K)
L
1.18 – 1.80 GHz
12.5 dBi
22.3 dB
10.0 dB
S
2.07 – 3.39 GHz
5.5 dBi
15.7 dB
13.0 dB
P
16/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
Mobile RFI stations
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
SRT
MEDICINA
17/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
SRT Mobile RFI station
18/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
Mobile RFI station: comparison
Features
Medicina
SRT
Van
Fiat Ducato
Mercedes Sprinter 315 CDI
Maximum seats
3
2
Max frequency
18 GHz (Normal operation)
40 GHz
18 GHz (Normal operation)
40 GHz
Antennas
1 LPDA (0.31 – 0.62 GHz)
1 LPDA (0.1 – 1.3 GHz)
1 LPDA (1.2 – 2.4 MHz)
1 dual ridge horn (1 – 18 GHz)
1 horn (18 – 26.5 GHz)
1 horn (26.5 – 40 GHz)
1 LPDA (0.3 – 0.6 GHz)
1 LPDA (0.1 – 1.3 GHz)
1 dual ridge horn (1 – 18 GHz)
1 dual ridge horn (18 – 40 GHz)
Telescope pole
height
11 m
11 m
Telescope
movement
Up/down  servo
Azimuth  manual
Polarization  manual (standard 45°)
Up/down  servo
Azimuth  servo or manual
Polarization  servo
Equipped SA
SA HP 8562A (up to 26.5 GHz)
PSA 4446 E (up to 44 GHz)
Other characteristics
Laboratory + storehouse; anti-shock rack; self powered (auxiliary batteries / AC
220 V); GPS
19/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
Mobile RFI station: performance
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
Band
M
E
D
I
C
I
N
A
S
R
T
Frequency band
Antenna gain
Chain gain
Noise figure
300 – 434 MHz
5.5 dBi
32 dB
6 dB
604 – 611 MHz
5.5 dBi
29 dB
9.5 dB
L/S
1.22 – 2.45 GHz
4 or 9 dBi
32 dB
4.5 dB
S
2.45 – 4 GHz
4.5 dBi
26dB
5 dB
C
4 – 8 GHz
5 dBi
28 dB
4.5 dB
X
8 – 12 GHz
6 dBi
49 dB
5 dB
Ku
12 – 18 GHz
8 dBi
37 dB
8.5 dB
K
18 - 26.5 GHz
21 dBi
56 dB
3.1 dB
Ka
26.5 – 40 GHz
21 dBi
50.5 dB
4 dB
Band
Frequency band
Antenna gain
Chain gain
Noise figure
P
290 – 428 MHz
9 dBi
36.2 dB
3.8 dB
L
1.17 – 1.84 GHz
7 dBi
29.8 dB
4 dB
S
1.99 – 3.37 GHz
7.8 dBi
25 dB
5.3 dB
S/C
2.98 – 5.81 GHz
12 dBi
25 dB
5.5 dB
C/X
5.22 – 9.25 GHz
11.5 dBi
TBD
TBD
X / Ku
7.76 – 18 GHz
12.5 dBi
TBD
TBD
K / Ka
18 – 40 GHz
TBD
TBD
TBD
P
20/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
Faraday room at SRT site
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
RFI measurements were conducted to evaluate
the emission of a super-computing facility (80
nodes with dual CPU dual core each) to be
placed at SRT.
Goal of the measurement was to evaluate if the
auto-interference are compatible with Rec. 769.
If not, to identify the shielding level of a Faraday
room to be installed at SRT station.
21/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
Faraday room at SRT site
The figures we got (especially at frequencies lower than 1
GHz) exceed by about 60 dB, the detrimental values
suggested by ITU-R RA.769-2 as the ones representative for
continuum and spectral line radio astronomy observations.
22/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
RFI campaign at a wind farm
Wind farm
Monte Guzzini (CA)
Number of turbins
26
Electrical power
(maximum)
22 Mwatt (850 Kwatt
each)
Modell of turbine
VESTAS V-52
Dimension of each
turbine
Height of the mast 55
m, 3 blades with radius
26 m
Type of
measurement
Primary emission
(no reflection
contribution)
23/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
RFI campaign at a wind farm
-85 dBW (0 dBi)
Very strong wide band impulsive signal mainly in P (350
MHz) and L (1.5 GHz) bands associated electrical
discharges in the power station of the wind farm.
24/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
Routine RFI measurements
Workshop
Mitigation
RFI2010 Power
- RFI [dBm]
with respect
to 0 dBi (RBW=100 KHz)
29 - 31 March, 2010, Groningen (NL)
Routine RFI measurements are conducted every week to monitor the
band of interest for the first light of SRT.
External CW at
426 MHz
The P frequency band of
the dual frequency
receiver was reduced from
305-425 MHz to 305-410
MHz.
Two identical HTS
microwave band-pass
filters are underway in
collaboration with Prof.
Lancaster and Dr. Huang
(Univ. of Birmingham)
Frequency [MHz]
25/26
P. Bolli, The RFI monitoring systems for the Medicina and the Sardinia Radio Telescope
Conclusions
• SRT is very close to its inauguration;
RFI2010 - RFI Mitigation Workshop
29 - 31 March, 2010, Groningen (NL)
• A team of local technicians has been trained to take
care of the RFI problems;
• SRT is in progress to be equipped with state-of-the-art
RF instrumentation for monitoring the RFI, following
the thirty-year experience gathered at Medicina;
• The RFI activity consists both: (i) in routine
measurements at the site, and (ii) in ad hoc campaign
addressed to specific questions.
26/26