Transcript Alcatel Company Presentation

Page 1
BepiColombo: Ka-band Translator
R. Giordani, L. Simone
February 27, 2007
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Outline
Page 2
 AAS-I Heritage: Cassini KaT Equipment
 Main Performance
 Architecture & Frequency Plan
 Allan Deviation Test Result
 Anomaly during Mission
 Goals of MORE/KaT Phase A/B1
 Architectural Issues & Trade-Offs
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CASSINI KaT Performance
Page 3
• Coherent frequency Translator which converts the received signal (34
GHz) with a ratio of 294/315 (32 GHz) for Doppler testing purposes.
• Satisfy stringent requirements in terms of phase noise and Allan
deviation.
• C/No > 32 dBHz
• Acquisition Probability > 99%
• Acquisition Time: less than 10 min
• Doppler Range:  350 KHz
• Doppler Rate  320 Hz/sec
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CASSINI KaT Block Diagram
Page 4
 Fully analogue architecture
315 Fo
21 Fo
LNA
Fo
2 GHz IF
X
X
294 Fo
108 MHz IF
20 Fo
HPLL
MULTIPL
(X5)
(X3)
X
Fo
Fo
X
MULTIPL
(X2)
SPLL
2 Fo
(X49)
LOOP
FILTER
LOCK
DETECTOR
MULTIPL
(X2)
SPE
BUFFER
Fo
90°
0°
LOCK STATUS
VCXO
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CASSINI KaT Allan Deviation
Page 5
 Allan Deviation requirement fully met
1,00E-13
1,00E-14

1,00E-15
SPECIFICATION
MEASURED
1,00E-16
VALUE
1,00E-17
1
10
100
1000
sec
Integration
time: sec
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CASSINI KaT
Page 6
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CASSINI KaT Anomaly
Page 7
• During the cruise (in Jupiter gravitational field), an anomaly occurred at
KaT level: the Unit rest frequency shifted about 13 MHz from the
nominal value.
• The explanation is based on the assumption that the varactor
(hyperabruct type) used in the 109 MHz VCXO modified its
voltage/capacitance characteristic by the effect of low dose
radiations/static charges.
• The varactor operates by the charges stored at the reverse biased
junction. A modification of this environment may change the intrinsic
capacitance characteristic.
• The effects of the varactor degradation have been proven on a VCXO
breadboard, experiencing the same behavior of the flying circuit.
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MORE KaT Requirements
Page 8
EID-B KaT Requirements
Uplink frequencies
Downlink frequencies
Translation ratio (Fr/Ft)
Uplink RF level
Noise figure
RF output level
Up-link Tracking Range
Allan Deviation
WBRS Ranging Channel
Tone frequency
34.31 GHz (TBC)
32.02 GHz (TBC)
15/14
-105 dBm (nominal)
<5 dB (nominal)
1 dBm (nominal)
1 MHz
 1015 (=1000 sec)
Delay accuracy
(calibrated)
Output spurious
DC power consumption:
Mass
<0.5 nsec
20 MHz
- 50 dBc
16 W
3.25 Kg (max)
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MORE/KaT: Phase A/B1 Overview
Page 9
 MORE/KaT Phase A/B1 Schedule:
 Start Event (To): Kick-Off (15/01/2007)
 End Event (To + 16): KaT detailed specification (15/05/2008)
 MORE/KaT Phase A/B1 Main Goals:
 Scientific Requirements Analyses
 KaT Architectural Design
 KaT Requirement Specification
 KaT B/B of Critical Components (Allan Variance Test)
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KaT Digital approach example
Page 10
Digital Module
Receiver Analogue Module
218F1+Fd
1st IF
Section (11F1)
2nd IF
Section (5F1)
ADC
x2
DAC
6F1+Fd
S-Band
Section (218F1)
207F1
2932F1
Frx=3150F1+Fd
A
5F1
11F1+Fd
Frequency Generation & WBRS Module
A
DS16
3F1+Fd/2
TCXO
x4
4F1
4F1
733F1
FPGA
WBRS
Channel
Frequency Generation
based on Integer-N PLL
675F1
Ftx=315F
Ftx=294F
F1=F/10
Phase
Mod.
240F1+KFd
32F1
x4
207F1
Ftx=2940F1+KFd
2700F1
Ka-Band Transmitter Module
MLC
DAC
SAW
F1+KFd
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BepiColombo Radio-Frequency Subsystem
Page 11
 Preliminary configuration based on single
Ka-Band amplifier (i.e. TWTA) serving
both the DST and KaT down-links.
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Scientific Requirements for RadioScience Experiment (1/2)
Page 12
 The main requirements concerning the BepiColombo radio-science experiment are
summarized hereafter:


range accuracy: 15 cm (on-board contribution only)
range-rate accuracy (integration time 1000 – 10000 s): 1.510-4 cm/s (overall link)
 Multi-frequency link equations have to be taken into account when apportioning the
top-level requirement over X/X, X/Ka and Ka/Ka links.
On-Board
Radio-Frequency Subsystem
(DST + KaT)
X-Band
Antenna
   KK
Ka-Band
Antenna
X-Band
Antenna
Ka-Band
Antenna



1
1

 XX 
 XK
13
35
KK rms of the observable relevant to Ka/Ka link
XX rms of the observable relevant to X/X link
XK rms of the observable relevant to X/Ka link
On-Ground Segment
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Scientific Requirements for RadioScience Experiment (2/2)
Page 13
 Preliminary budget for Range Measurement (only on-board, including aging):
Ka/Ka
X/X
X/Ka
Overall
Range Measurement
Group Delay Variation (ns-pk-pk)
1
2.5
2.5
1.26
Range Error (cm-rms)
9.5
KaT
 Preliminary budget for Range-Rate Measurement (overall):
Ka/Ka
X/X
X/Ka
Overall
Range Rate Measurement
Allan Deviation
8.00E-15
5.00E-14
1.00E-13
1.5E-14
Range Rate Error (cm/s-rms)
2.2E-04
 In order to meet the required range rate accuracy, the following preliminary requirement can be considered
for 1000 s of integration time:
 y  10-15 for the Ka/Ka section
 y  610-15 for the X/X section
 y  110-14 for the X/Ka section
January 2007
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Architectural Issues (1/3)
Page 14
 Selection of the Ka/Ka turn-around ratio (up-link over down-link
frequency ratio):
 Cassini figure: 315/294
 ECSS current figures: 3599/3344, 3599/3360, 3599/3328
 NASA proposal in the frame of CCSDS SLS-RFM meeting (07-03-2007):
3611/3360
– “Proposed Additional Ka/Ka Transponder Turnaround Ratios for the 31.8-32.3 GHz
and 34.2-34.7 GHz Band, Category-B”, S. Kayalar, C. C.Wang, JPL
 Selection of the equipment frequency plan:
 Inclusion of digital capabilities allows to easily demodulate the up-link ranging
channel.
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Architectural Issues (2/3)
Page 15
 Carrier recovery scheme
 Phase detector and digital loop filter implemented in the digital domain (no quartz
filter is needed).
Effect of Phase & Frequency Quantization on the Down-Link Allan Deviation
-10
10
10
-12
10
Allan Deviation (rms)
 EM DST uses 40 bit DDS.
Relevant simulation results
show good Allan deviation
performance that will be
verified by test within April.
Simulation Results
ESA Mask
-11
-13
10
-14
10
-15
10
-16
10
-17
10
-18
10
-1
10
0
1
10
10
2
10
Integration Time (sec)
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Architectural Issues (3/3)
Page 16
 Selection of Ranging scheme and relevant clock frequency (4 ÷ 8 MHz)
 Best candidate is the PN Ranging with flexible majority voting (Tausworthe
approach) already implemented on the X/X/Ka DST.
 On-board calibration based on phase measurement (digital PLL
approach)
 This capabilities appears fundamental to ensure the required group delay stability
(1 ns-pk-pk) and to overcome potential drift due to the aging.
 This approach is also pursued in the X/X/Ka DST equipment for testing purpose.
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Architectural Issues (3/3)
Page 17
 Use of dedicated SSPA to avoid intermodulation effects in Ka-Band
(see next slides) due to the simultaneous amplification of both the DST
and KaT down-link carriers.
 The RF output power level (2.5 W) can be obtained putting in parallel two power
MMICs from TRIQUINT
 This configuration has η = 20% excluding DC/DC converter efficiency
+ 20 dBm
TGA4514
+ 5 dBm
+ 35.5 dBm
TGA4209
TGA4514
+ 20 dBm
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Intermodulation Effects on Ka-Band
Down-Link (1/3)
Page 18
F1 @ 44 dBm
18 dB
2F1-F2 @ 26 dBm
F2 @ 34 dBm
33.1 dB
18.9 dB
2F2-F1 @ 15.1 dBm
3F1-2F2 @ 10.9 dBm
-1.5 dBm (max output power
for in-band interference)
•F1 = DST Frequency (31.9925 GHz)
•F2 = KaT Frequency (32.180 GHz)
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Intermodulation Effects on Ka-Band
Down-Link (2/3)
Page 19
DST
KaT
Compare with previous slide to identify the spurious signals order
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Intermodulation Effects on Ka-Band
Down-Link (3/3)
Page 20
DST
KaT
(modulated)
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