Post on 23-Jun-2015
description
- An advanced tool for LEOP support -
OPS-G FORUM 20/03/2009
2OPS-G FORUM - 20/03/2009
PART1 - Overview of requirement and Technical implementationPiermario Besso: H/OPS-GSA
– What is XAA?– Why do we need XAA?– Requirements– Alternative solutions?– A challenging trade-off– Design– Factory acceptance tests
PART2 - On-site installation and validationFilippo Concaro: OPS-GSA
– On-site installation– Alignment– Site Acceptance tests– XAA system tests
3OPS-G FORUM - 20/03/2009
•The acquisition and tracking range of a reflector antenna is proportional to its beam size, which is inversely proportional to its diameter and the signal frequency
•The XAA system makes use of a 1.3 m dish to enlarge the acquisition range of ESTRACK 15 m antennas
•The two antennas shares the SERVO system, the switchover from one tracking system to the other is managed at Front End Controller (FEC) level.
4OPS-G FORUM - 20/03/2009
LISA Pathfinder (Rockot launcher) 3σ dispersion from Perth
-1,1
-1,0
-0,9
-0,8
-0,7
-0,6
-0,5
-0,4
-0,3
-0,2
-0,1
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
1,1
-1,1 -1,0 -0,9 -0,8 -0,7 -0,6 -0,5 -0,4 -0,3 -0,2 -0,1 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1,0 1,1
Cross-Elevation Pointing Error
Elev
atio
n po
intin
g Er
ror
Within 15m tracking range (8.1%)
Within XAA Tracking Range (99.8%)
Outside XAA tracking range (0.2%)
•New missions will not use S-band (2 GHz), but X-Band (8 GHz) for LEOP.
•The beam in X-band is 4 times smaller than S-Band
•The tracking range of the ESTRACK 15m antennas is too small to cover the foreseen dispersion area
•The actual 15m antenna search function is too slow to cope with the spacecraft’s speed during LEOP
(In order to cover this latter cases one could use the search function with the XAA antenna)
5OPS-G FORUM - 20/03/2009
• Acquisition beam width: >2°• Minimum Power Flux Density: -148 dBW/m2
• Maximum Modulation Loss: 15 dB• Time to achieve autotrack <10 sec
(switchover to main antenna not included)
6OPS-G FORUM - 20/03/2009
Not compliant in terms of maximum time required to acquire (Worst case: 40 sec)
Fast Search:Improve the already implemented search function of the 15m antennas in order to have the beam scanning a larger area in a shorter time
7OPS-G FORUM - 20/03/2009
• In order to achieve a tracking range sufficiently wide the antenna diameter has to be as small as possible
• In order to get a figure of merit (G/T) sufficient to cope with the other requirements the antenna diameter has to be adequately large
As best trade off a diameter of 1.3 m has been chosen
8OPS-G FORUM - 20/03/2009
• In order to achieve the challenging G/T requirements for such a small antenna state of the art technologies have been selected for the XAA design:
1. Shaped main and sub reflectors2. Optimised Corrugated feed-horn3. Wave guide feeding system4. Very low noise amplifiers5. Compact outdoor down converter6. Temperature controlled outdoor box7. Last generation Tracking Receiver
9OPS-G FORUM - 20/03/2009
10OPS-G FORUM - 20/03/2009
The impact of the gravity deformations have been thoroughly analysed both in terms of:•XAA Pointing error •Impact of XAA Antenna on 15m antenna pointing error
Elevation 0° 30° 60° 90°
AZ error [mdeg] 0 4 7
-16
17
8
EL error [mdeg] 0 -4 -32
TOT error [mdeg] 0 6 33
XAA Pointing errors wrt Antenna Elevation
Elevation 0° 30° 60° 90°
AZ error [mdeg] 0/3 0/1 0/0
14/15
14/15
0/0
EL error [mdeg] 27/30 24/26 0/-3
TOT error [mdeg] 27/30 24/26 0/3
15m Pointing errors wrt Antenna Elevation w/o and with XAA
11OPS-G FORUM - 20/03/2009
Sun-Shield
XAA LNAs Thermal analysis
XAA DC Thermal analysis
Due to the considerable XAA-DC power dissipation the XAA Outdoor box had to be temperature controlled to keep it within the operational temperature range of the LNAs.
This has been achieved by means of a protective sun-shield and two Peltier elements
12OPS-G FORUM - 20/03/2009
XAA FAT has taken place at Eads ASTRIUM Compact Range facilities in Ottobrunn (D)
During the FAT Compliance with respect to the specification for all RF components has been proven
XAA Tracking patterns for all operation frequencies
13OPS-G FORUM - 20/03/2009
14OPS-G FORUM - 20/03/2009
Supporting structure Antenna
Outdoor Equipment box Counterweights
15OPS-G FORUM - 20/03/2009
Correct XAA-15m antennas alignment is crucial
1. Mechanical alignment2. RF alignment
(Calibration tower)3. RF alignment verification
on spacecraft
Specified alignment accuracy is 30 mdeg
Alignment procedure consists of 3 steps:
16OPS-G FORUM - 20/03/2009
Rough alignment at 90° Elevation
Fine alignment at 0° Elevation
17OPS-G FORUM - 20/03/2009
D = 4400 m
θ = 0.110°
θ = atan(L/D)
-30,0
-20,0
-10,0
0,0
10,0
20,0
30,0
40,0
50,0
60,0
70,0
-0,400 -0,300 -0,200 -0,100 0,000 0,100 0,200 0,300 0,400
Offset from Boresight direction (deg)
Ant
enna
Gai
n (d
Bi)
XAA SUM XAA DELTA 15m DELTA 15m SUM
The distance between the XAA and the 15m antenna electrical centres (L) is not negligible with respect to the antenna – Calibration tower distance (D), this results in an angular offset (θ), which has to be taken into account for the RF alignment and the acceptance tests
θ
L = 8.5 m
Alignment goal:0.110°±0.03° offset in Azimuth0 ° ±0.03° offset in Elevation
18OPS-G FORUM - 20/03/2009
• Measurement on calibration tower are affected by several factors:
1. Deformation of antenna mechanical structure due to gravity
2. Multipath and fading effects due to ground reflections
15 meter antenna null position on Calibration Tower “moves” with frequency and polarisation
PER1 15m antenna - X-Band Tracking Null Positions on Calibration Tower
0,7400,7500,7600,7700,7800,7900,8000,8100,8200,8300,8400,8500,8600,8700,8800,890
202,860202,870202,880202,890202,900202,910202,920202,930202,940202,950202,960202,970202,980202,990203,000203,010203,020203,030203,040203,050203,060203,070203,080
Azimuth (deg)
Elev
atio
n (d
eg)
RHC LHC
Plank Herschel
Lisa PF RHC Lisa PF LHC
(Measurement accuracy ~10 mdeg)
XAA-15m RF alignment on Calibration Tower is frequency dependant
19OPS-G FORUM - 20/03/2009
RF Alignment on Calibration Tower is optimised for Lisa Pathfinder (8495 MHz) frequency RHC polarisation
20OPS-G FORUM - 20/03/2009
Perth X-Band 15m and XAA Tracking (Delta) Null and Sum pattern Peak positions
0,7000,7100,7200,7300,7400,7500,7600,7700,7800,7900,8000,8100,8200,8300,8400,8500,8600,8700,8800,8900,9000,9100,920
202,85202,86202,87202,88202,89202,90202,91202,92202,93202,94202,95202,96202,97202,98202,99203,00203,01203,02203,03203,04203,05203,06203,07203,08203,09203,10
Azimuth (deg)
Elev
atio
n (d
eg)
15m SUM RHC
15m DELTA RHC
15m SUM LHC
15m DELTA LHC
XAA SUM RHC NF
XAA DELTA RHC NF
XAA SUM LHC NF
XAA DELTA LHC NF
XAA SUM RHC FF
XAA DELTA RHC FF
XAA SUM LHC FF
XAA DELTA LHC FF
15m antenna tracking range
The enlarged points are the ones for 8495 MHz (Lisa Pathfinder) RHC
RF RF Alignment on Calibration Tower for LPF frequency, RHCAlignment on Calibration Tower for LPF frequency, RHC
Measurement Accuracy is:±5 mdeg for 15m delta null and sum peak±15 mdeg for XAA delta null±30 mdeg for XAA sum peak
21OPS-G FORUM - 20/03/2009
Perth X-Band 15m and XAA Tracking (Delta) Null and Sum pattern Peak positions
0,7000,7100,7200,7300,7400,7500,7600,7700,7800,7900,8000,8100,8200,8300,8400,8500,8600,8700,8800,8900,9000,9100,920
202,85202,86202,87202,88202,89202,90202,91202,92202,93202,94202,95202,96202,97202,98202,99203,00203,01203,02203,03203,04203,05203,06203,07203,08203,09203,10
Azimuth (deg)
Elev
atio
n (d
eg)
15m SUM RHC
15m DELTA RHC
15m SUM LHC
15m DELTA LHC
XAA SUM RHC NF
XAA DELTA RHC NF
XAA SUM LHC NFXAA DELTA LHC NF
XAA SUM RHC FF
XAA DELTA RHC FF
XAA SUM LHC FF
XAA DELTA LHC FF
15m antenna tracking range
The enlarged points are the ones for 8495 MHz (Lisa Pathfinder) LHC
Even if affected by the mentioned disturbance factors, the graph shows that also for LHC polarisation the XAA tracking null position corrected by the Far Field (FF) –Near Field (NF) offset falls within the 15m antenna tracking range.
RF RF Alignment on Calibration Tower for LPF frequency, LHCAlignment on Calibration Tower for LPF frequency, LHC
Measurement Accuracy is:±5 mdeg for 15m delta null and sum peak±15 mdeg for XAA delta null±30 mdeg for XAA sum peak
22OPS-G FORUM - 20/03/2009
-30,0
-20,0
-10,0
0,0
10,0
20,0
30,0
40,0
50,0
60,0
70,0
-0,400 -0,300 -0,200 -0,100 0,000 0,100 0,200 0,300 0,400
Offset from Boresight direction (deg)
Ant
enna
Gai
n (d
Bi)
XAA SUM XAA DELTA 15m DELTA 15m SUM
D >> L
θ = 0°
In the case of a spacecraft, the distance between the XAA and the 15m antenna electrical centres (L) is negligible with respect to the Ground Station – Spacecraft distance (D), this results in a negligible angular offset (θ), and thus in a perfect alignment between the two antennas
23OPS-G FORUM - 20/03/2009
Spacecraft GEOTAIL ERS2 ENVISAT
Agency JAXA ESA
8040/1840
Cross Correlation
Fast
Flux at antenna(including Modulation Loss) <-163 dBW/m2 >-133 dBW/m2 >-131 dBW/m2
1 or 2 times/day
ESA
Frequency [MHz] 8474.66 8200/8300
Tracking Mode PLL Cross Correlation
Spacecraft Speed Slow Fast
Availability 1 day/week at perigee 1 or 2 times/day
24OPS-G FORUM - 20/03/2009
GEOTAIL Autotrack XAA-15m comparison for a 40° Elevation Pass & 120.000 km range
-0,200
-0,150
-0,100
-0,050
0,000
0,050
0,100
0,150
0,200
-0,200 -0,150 -0,100 -0,050 0,000 0,050 0,100 0,150 0,200
Cross-elevation Pointing Error (deg)
Elev
atio
n Po
intin
g Er
ror (
deg)
XAA Average Null (with STDEV)15m Average Null (with STDEV)15m NULLXAA NULL
High dispersion due to very low signal
Offset magnitude is consistent with what observed on the Calibration Tower
25OPS-G FORUM - 20/03/2009
XAA-DC
XAA-TRR
XAASUM & DELTA
Channel Selection
TRR
LDCSUM & DELTA
Channel Selection FEC
ELXEL
ELXEL
EL
ELEL
ELXEL
XELXEL
XEL
AGC
AGC
SwitchM&C
Switch M&C
Test Signal
AZEL
XAAAntenna
PER1Antenna
Spacecraft
Frequency
EL, XEL, AGC, Lock, PLL BW, TR Mode
EL, XEL, AGC, Lock, PLL BW, TR ModeFrequency
Switch M&C
Switch M&CAZ, EL
PLOTTERor
DATALOGGER
XDCMIXER
TEST SYNTHESIZER
Frequency
SMC
XAA-SMC
AGC
AGC
ACU
Both ERS2 and Envisat are using X-band to dump data at high data rate.
The frequency used are:8040 and 8140 MHz for ERS28200 and 8300 MHz for ENVISAT
While XAA Downconverter covers the band between 8025 to 8500 MHz, the 15m antenna Downconverters covers only the Space Research band (8400-8500 MHz)
an additional converter (mixer) had to be used to translate the frequency in the required range
TEST SETUP
26OPS-G FORUM - 20/03/2009
ENVISAT Autotrack XAA-15m comparison for a 55° MAX Elevation Pass
-0,200
-0,150
-0,100
-0,050
0,000
0,050
0,100
0,150
0,200
-0,200 -0,150 -0,100 -0,050 0,000 0,050 0,100 0,150 0,200Cross-elevation Pointing Error (deg)
Elev
atio
n Po
intin
g Er
ror (
deg)
XAA Average Null (with STDEV)15m Average Null (with STDEV)15m NULLXAA NULLProgram Track
Smaller dispersion due to much higher signal (like expected in a LEOP scenario)
Offset magnitude is consistent with what observed on GEOTAIL and on the Calibration Tower
27OPS-G FORUM - 20/03/2009
• G/T• Tracking range & tracking slope• Acquisition range
28OPS-G FORUM - 20/03/2009
XAA G/T at 5 and 30 deg Elevation
10,0
11,0
12,0
13,0
14,0
15,0
16,0
17,0
18,0
19,0
20,0
8000 8100 8200 8300 8400 8500
Frequency [MHz]
dB/K
RHC - LNA1 - 5 deg LHC - LNA2 - 5 degRHC - LNA1 - 30 deg LHC - LNA2 - 30 deg
Specification
29OPS-G FORUM - 20/03/2009
XAA Tracking Sensitivity8495 MHz LHC (Lisa Pathfinder)
-10,00
-9,00
-8,00
-7,00
-6,00
-5,00
-4,00
-3,00
-2,00
-1,00
0,00
1,00
2,00
3,00
4,00
5,00
6,00
7,00
8,00
9,00
10,00
-1,50 -1,00 -0,50 0,00 0,50 1,00 1,50
Boresight Azimuth offset (°)
Trac
king
Err
or V
olta
ges
(V)
DELTA X DELTA Y
•The graphs shows the linearity of the tracking errors wrt angular offset at 8495 MHz.
•Due to the fact that the antenna beam gets narrower as the frequency increases, it can be considered as a worst case scenario.
•In the specified range of ±1°the red curve is pretty much linear and the cross talk (blue curve) negligible
•The tracking range extends up to roughly ±1.2°
30OPS-G FORUM - 20/03/2009
XAA Tracking Sensitivity8495 MHz LHC (Lisa Pathfinder)
-10,00
-9,00
-8,00
-7,00
-6,00
-5,00
-4,00
-3,00
-2,00
-1,00
0,00
1,00
2,00
3,00
4,00
5,00
6,00
7,00
8,00
9,00
10,00
-1,50 -1,00 -0,50 0,00 0,50 1,00 1,50
Boresight Azimuth offset (°)
Trac
king
Err
or V
olta
ges
(V)
DELTA X DELTA Y
XAA Tracking Sensitivity8495 MHz RHC (Lisa Pathfinder)
-10,00
-9,00
-8,00
-7,00
-6,00
-5,00
-4,00
-3,00
-2,00
-1,00
0,00
1,00
2,00
3,00
4,00
5,00
6,00
7,00
8,00
9,00
10,00
-1,50 -1,00 -0,50 0,00 0,50 1,00 1,50
Boresight Azimuth offset (°)
Trac
king
Err
or V
olta
ges
(V)
DELTA X DELTA Y
XAA Tracking Sensitivity8495 MHz LHC (Lisa Pathfinder)
-10,00
-9,00
-8,00
-7,00
-6,00
-5,00
-4,00
-3,00
-2,00
-1,00
0,00
1,00
2,00
3,00
4,00
5,00
6,00
7,00
8,00
9,00
10,00
-1,50 -1,00 -0,50 0,00 0,50 1,00 1,50
Boresight Elevation offset (°)
Trac
king
Err
or V
olta
ges
(V)
DELTA X DELTA Y
XAA Tracking Sensitivity8495 MHz RHC (Lisa Pathfinder)
-10,00
-9,00
-8,00
-7,00
-6,00
-5,00
-4,00
-3,00
-2,00
-1,00
0,00
1,00
2,00
3,00
4,00
5,00
6,00
7,00
8,00
9,00
10,00
-1,50 -1,00 -0,50 0,00 0,50 1,00 1,50
Boresight Elevation offset (°)
Trac
king
Err
or V
olta
ges
(V)
DELTA X DELTA Y
The graphs below show the measured tracking slopes for different polarisations and axis
31OPS-G FORUM - 20/03/2009
PLL bandwidth (Hz) 3000 1000 300 100
Acquisition range (°) >±0.5 >±1 >±1.25 >±1.4
Cross correlation bandwidth (kHz) 5000 500
Acquisition range (°) >±0.750 >±1
Type of offset combined along and cross track 1° offset along or cross track 1° offset
Tests on GEOTAIL•Marginal Power Flux Density•Offsets wrt nominal trajectory obtained applying time offset to the program track
Tests on ERS2/ENVISAT•Suppressed carrier mode•Offsets wrt nominal trajectory obtained using ad-hoc modified STDMs
32OPS-G FORUM - 20/03/2009
• Various tests performed both on Spacecrafts and Calibration Tower
• Time to get lock on XAA antenna (depends on tracking BW selected and entity of the offset): <4 sec
• Time to get stable XAA autotrack and lock on 15m antenna after XAA autotrack has been commanded: <4 secTime to achieve autotrack on a signal being within the acquisition area: <8 sec ([URD-PE-006]: 10 sec)
• Time to switch from XAA to 15m autotrack: <5 sec + decision time
• Overall acquisition process has been achieved in less than 10 sec on GEOTAIL (time from closing the PLL loop at 1° offset wrt program track to achieve 15m autotrack)
33OPS-G FORUM - 20/03/2009
-10-9-8-7-6-5-4-3-2-10123456789
10
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Time (sec)
Trac
king
Err
ors
(V)
15m Delta X 15m Delta Y
-2,50-2,25-2,00-1,75-1,50-1,25-1,00-0,75-0,50-0,250,000,250,500,751,001,251,501,752,002,252,50
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Time (sec)
Poin
ting
Erro
r (°)
Azimuth Pointing Error Elevation Pointing Error Overall Pointing Error
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Time (sec)
Sign
al L
evel
at T
rack
ing
rece
iver
Inpu
t (dB
m)
XAA AGC 15m AGC
-10-9-8-7-6-5-4-3-2-10123456789
10
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Time (sec)
Trac
king
Err
ors
(V)
XAA Delta X XAA Delta Y
Start of XAA AutotrackOffset
PT
3sec
XAA Autotrack
Start of 15m Autotrack
3sec
15m Autotrack
34OPS-G FORUM - 20/03/2009
-10-9-8-7-6-5-4-3-2-10123456789
10
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Time (sec)
Trac
king
Err
ors
(V)
15m Delta X 15m Delta Y
-10-9-8-7-6-5-4-3-2-10123456789
10
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Time (sec)
Trac
king
Err
ors
(V)
XAA Delta X XAA Delta Y
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Time (sec)
Sign
al le
vel a
t Tra
ckin
g re
ceiv
er in
put (
dBm
)
XAA AGC 15m AGC
-2,50-2,25-2,00-1,75-1,50-1,25-1,00-0,75-0,50-0,250,000,250,500,751,001,251,501,752,002,252,50
-5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Time (sec)
Poin
ring
Erro
r (°)
Azimuth Pointing Error Elevation Pointing Error Overall Pointing Error
Start of XAA AutotrackOffset
PT
3sec
XAA Autotrack
Start of 15m Autotrack
2sec
15m Autotrack
35OPS-G FORUM - 20/03/2009
• Herschel Plank LEOP support (April 2009)• Factory Acceptance test of 2nd and 3rd XAA (June 2009)• Installation and Site Acceptance in KRU (December 2009)• Installation and Site Acceptance in MSP (June 2010)• Lisa pathfinder LEOP support (March 2011)
36OPS-G FORUM - 20/03/2009
• M. Arza & Perth M&O team (ONN)• M. Lanucara, P. Droll, X. Enrich, A.Scior (GS)• W. Hell (ONV)• ERS2 & ENVISAT Flight Control Team• M.A. Martin-Serrano & Flight Dynamic team• K. Someya (JAXA)