extremely high speed avenues for space communications
TRANSCRIPT
Extremely High Speed Avenues for Space Communications: Optical & W-band Waves
8th ASMS/14th SPSC Palma de Mallorca, Spain Sep 5th, 2016
Dr. Ricardo Barrios
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 1
The current telecommunications marketplace is experiencing an ever increasing demand for high-speed services, and the traffic demand for satellite broadband is expected to grow six-fold by 2020. As part of the continuous migration towards higher frequency bands, Optical & W-band waves offer the promise of unprecedented bandwidth compared to current commercial solutions, leveraging enough bandwidth capable to cope with mid and long-term requirements. Together they can realize extremely high speed avenues for space communications in inter-satellite and feeder link applications. This tutorial focuses on giving a thorough overview of the different aspects and challenges to be taken into account when implementing GEO feeder links in the optical domain and W-band waves, including physical layer, channel model, modem, satellite payload and system level aspects. Particular attention is given to the feeder uplink scenario, which—as part of the forward link—presents itself as critical for the successful implementation of future extremely high throughput satellite systems. The tutorial will attempt to stress the practical challenges of these high frequency RF and optical technologies, proposing also ways forward in terms of necessary space and ground technology development, as well as open research directions.
Abstract
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 2
Extremely High Speed Avenues for Space Communications: Optical & W-band Waves
Dr. Ricardo Barrios & Dr. Pantelis-Daniel Arapoglou, 8th ASMS/14th SPSC, 5 Sep 2016
Introduction to Lasercom for Space
Technologies and Modulation Formats
Atmospheric Effects
Atmospheric-induced Fading Mitigation Techniques
Optical GEO Feeder Links
Summary
Outline
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 3
Timeline of Lasercom Space Missions Selection
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 4
2016
•EDRS-C
2013
•α-Sat •LLCD
2005
•OICETS
2007
•LCTSX •NFIRE -LCTs
1998
•SPOT-4
2001
•Artemis SILEX •GEOLITE
•ETS-VI
1994 2015
•EDRS-A •OSIRIS
2014
•Sentinel-1A •SOTA •OPALS
2017
•LCRD
Pictures: ESA, JAXA, NICT, NASA, MIT, DLR
Lasercom Scenarios
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 5
GEO Orbit 36000 km
LEO Orbit 300-500 km
ISL
ISL
LEO Downlink
RF User Link
Feeder Link
Optical Ground Station
RF User Terminal
Introduction to Lasercom for Space
Technologies and Modulation Formats
Atmospheric Effects
Atmospheric-induced Fading Mitigation Techniques
Optical GEO Feeder Links
Summary
Outline
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 6
Components of full-duplex Space Laser Terminals
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 7
Tx-Data
Rx-Data
𝝀𝝀Rx
𝝀𝝀Tx
Coarse Pointing Assembly Examples
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 8
Azimuth-Elevation Gimbal (OICETS)
One-Mirror Periscope (Alphasat)
Optical Ground Stations
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 9
20cm-MOGS
1m Class 60cm Class
40cm Class Rx 15cm Class Tx
Pictures: ESA, ViaLight, NASA, DLR.
Modulation Formats
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 10
• high sensitivity (in Phot./bit) • high data-rates • requires plane Rx-wave • atmosphere is a challenge long range space links (GEO)
• sensitivity limit (photon counting) • high implementation effort • limited data-rate long-range medium-rate (Exploration)
Optical Intensity Detection (incoherent)
Direct Detection (IM/DD) with On-Off Keying (OOK)
PPM (Pulse Position Modulation)
with local oscillator: hom./heterodyne-BPSK, QAM
Self-homodyne-DPSK with PreAmp
Complex Field Detection (coherent)
• Low-to-medium sensitivity. • High data-rates. • Low implementation effort. short range with atmosph. (LEO)
Introduction to Lasercom for Space
Technologies and Modulation Formats
Atmospheric Effects
Atmospheric-induced Fading Mitigation Techniques
Optical GEO Feeder Links
Summary
Outline
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 11
Atmospheric attenuation. Large time scales. Considered constant. Related with visibility. Dominated by fog, clouds, rain, snow, dust. The attenuation coefficient is made up of four parts:
𝜎𝜎 = 𝛼𝛼𝑚𝑚 + 𝛼𝛼𝑎𝑎 + 𝛽𝛽𝑚𝑚 + 𝛽𝛽𝑎𝑎
Background noise Direct Sun or moonlight (also planets) in
the receiver FoV may cause link outages. Sky radiance.
Atmospheric turbulence Small time scale. Random in nature. Caused by wind and temperature
gradients.
Atmospheric effects
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 12
Atmospheric Attenuation
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 13
0
5
10
15
20
25
30
35
40
Hei
ght o
ver s
ea le
vel [
km]
10 -510 -410 -310 -210 -1
Total absorption coefficient at 1550nm [km-1
]
BackgroundModerate
High
Extreme
Atmospheric Transmission
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 14
600 800 1000 1200 1400 1600 1800 2000
Wavelength [nm]
10 -4
10 -3
10 -2
10 -1
10 0
10 1
10 2
10 3
Tota
l atm
. abs
orpt
ion
coef
ficie
nt [k
m-1
]
Mean sea level
3km altitude
10km altitude
850 1064 1550
What happens when an optical beam passes through turbulent air?
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 15
Far-field intensity-speckles
collimated laser beam at Tx
turbulent volume with IRT-strength
Wavefront distortion → Interference
Cn2 profile Defines IRT strength
Turbulence screen example
Turbulence Characterization KIODO 2009
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 16
Intensity
Focus spot
Reconstr. phase
Shack Hartmann
Introduction to Lasercom for Space
Technologies and Modulation Formats
Atmospheric Effects
Atmospheric-induced Fading Mitigation Techniques
Optical GEO Feeder Links
Summary
Outline
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 17
Downlink Mitigation Strategies
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 18
OFF ON
Aperture Averaging Larger Rx aperture reduces variance
of Rx power in magnitude and spectrum. Rx aperture is larger than the average
structure size of the Rx field.
Adaptive Optics Enables SMF coupling, or
Heterodyning with LO. Requires real time correction of
atmospheric phase distortions.
Histogram
Signal
Uplink Mitigation Strategies
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 19
Transmitter diversity Multiple separated Tx lasers undergo
different atmospheric paths. Non-coherent detection averages out
atmospheric effects. Separation defined by Fried
parameter.
Pre-distortion Adaptive Optics
t1
Atmosphere 20-25 km
t0
𝜽𝜽IPA
IRT Cells 𝜽𝜽AoA
𝜽𝜽IPA> 𝜽𝜽PAA
Error Correction Codes Downlink and uplink
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 20
Robust Data-Recovery and Bit-Level FEC
Interleaved Packet-Layer FEC (Burst Errors from IRT-Fading,
1..10ms)
Low-overhead ARQ for lossy return channel
Delay-Tolerant Transmission Management (only non-
realtime scenarios) Gb-Ethernet
FPGA-Implementation of Laser-Ethernet-Transceiver (LET)
Introduction to Lasercom for Space
Technologies and Modulation Formats
Atmospheric Effects
Atmospheric-induced fading Mitigation Techniques
Optical GEO Feeder Links
Summary
Outline
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 21
Terabit-per-second SatComm is required in future (EU Digital Agenda by 2020)
Every EU-citizen at least 30Mbps
50% with 100Mbps or more.
Number of required RF ground stations grows linear with throughput
Optical Feeder Links provide >1Tbps over one optical ground station
Number of OGSs in the network is driven by robustness against cloud blockage
At least one OGS must be available
Motivation for Optical GEO Feeder Links in Future Satellite Com. Systems
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 22
[*] RF feeder link assumes all spectrum usage in Ka band (blue line), Ka+Q/V band (red line) and Q/V+W band (yellow line). OGEOFL (green line) can provide Terabit capacity with only one OGS.
Ka Ka+Q/V
Q/V+W
Cloud-Blockage Mitigation OGS-Network Availability
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 23
Pcloud < 40%
11 European stations
Availability = 99.67 %
10 Mediterr. stations
Availability = 99.89 %
8 stations Inter-Continental Availability = 99.971 %
Data-basis: Satellite images and simultaneous ground observations (from 1990 to 2006)
1450 1500 1550 1600 1650
Wavelength [nm]
0
20
40
60
80
100
Tota
l Atm
osph
eric
Tra
nsm
ittan
ce [%
]
19km altitude
10km altitude
3km altitude
Mean sea level
800 1000 1200 1400 1600 1800 2000
Wavelength [nm]
0
20
40
60
80
100
Tota
l Atm
osph
eric
Tra
nsm
ittan
ce [%
]
19km altitude
10km altitude
3km altitude
Mean sea level
DWDM-System for Optical GEO Feeder-Links
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 24
HPOAMux Nx1
M Channels
HPOAMux Nx1
HPOAMux Nx1
High
Pow
er M
ux N
x1HP
Mux
N
x1HP
Mux
N
x1
High
Pow
er M
ux N
X1
TelescopeTelescope
MainMainLASER MZM
Tx CHN
DWDM Transmitter
LNOARFE
Demux 1x2
LNOA
LNOA
Demux 1xN
Demux 1xN
M Channels
Telescope
MainRx CHN
WavefrontCorrectionEDFA
EDFA
EDFA Only at OGS
DWDM Receiver
~𝟏𝟏𝟏𝟏THz Bandwidth 1529 1568 1610 | C Band | L Band |
Atmosphere 20-25 km
GEO Orbit 36000 km
IRT Cells
Ground-GEO Optical Channel
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 25
𝜽𝜽PAA ~ 𝟏𝟏𝟏𝟏µrad ~253ms (700m) t1 t0
Histogram
Signal
Signal Histogram
Strong Fading due to beam wander
𝜽𝜽AoA
𝜽𝜽AoA: Angle-of-Arrival 𝜽𝜽PAA: Point-Ahead Angle 𝜽𝜽BW : Beam Wander 𝜽𝜽IPA: Isoplanatic Angle
GEO Orbit t1 𝜽𝜽PAA ~ 𝟏𝟏𝟏𝟏µrad
Atmosphere 20-25 km
Uplink Transmission Approaches Pointing by tracking
Downlink reference can be used to point the uplink.
Beam wander can be compensated.
Smaller uplink divergence is possible Larger Tx Gain
Correlation between down- and up-link paths is not perfect.
Residual beam wander.
Correlation coefficient follows
𝛾𝛾 ∝ exp −𝜃𝜃PAA𝜃𝜃IPA
5/3
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 26 𝜽𝜽AoA: Angle-of-Arrival 𝜽𝜽PAA: Point-Ahead Angle 𝜽𝜽BW : Beam Wander 𝜽𝜽IPA: Isoplanatic Angle 𝜽𝜽B: Beam divergence
t0
𝜽𝜽IPA
IRT Cells 𝜽𝜽AoA
𝜽𝜽IPA> 𝜽𝜽PAA
Atmosphere 20-25 km
Uplink Transmission Approaches Open loop pointing
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 27
GEO Orbit
𝜽𝜽AoA: Angle-of-Arrival 𝜽𝜽PAA: Point-Ahead Angle 𝜽𝜽BW : Beam Wander 𝜽𝜽IPA: Isoplanatic Angle 𝜽𝜽B: Beam divergence
𝜽𝜽PAA ~ 𝟏𝟏𝟏𝟏µrad t1 t0
IRT Cells 𝜽𝜽AoA
Optimum Tx size depends on location and atm. conditions
Transmitter gain
Free-space Loss
Receiver gain
Beam Wander Loss Atm.
Attenuation
R T T T ATM FS SR BW R RP LP G L L Gη τ η=
( )2BW T BWexpL G θ= −
( )2T T /DG π λ=
( )( ) 6/55/3SR 10 T 010log 1 /L D r
−= +
Strehl ratio Loss
DIVT
2 2D
θ λπ
=
𝜽𝜽IPA< 𝜽𝜽PAA
Measured Uplink Received Power at GEO
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 28
Mata-Calvo et al. “Transmitter diversity verification on ARTEMIS geostationary satellite,” Proc. SPIE 8971, pp. 897104, 2014.
Rx-Power with only one
Tx-Beam
Rx-Power with second
Tx-Beam
average
-3dB fade threshold
Alternative Solution: Probing with Laser Guide Star
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 29
Pre-distortion AO system
Deformable mirror
Downlink reference
Uplink
Wave-Front Sensor
Laser
Beam splitter
Wave-Front Processor
Laser Guide Star (LGS)
Round-trip ~0.6ms. Tilt time ~100 ms. For Tx/Rx shared aperture up- and downlink sees same tilt. Classic LGS cannot measure tilt.
LGS
Telescope Aperture
Frozen Turbulence
LGS Tilt correction Bistatic approach breaks up-
and downlink correlation. Min. 2 Rx to retrieve tilt info.
High implementation complexity.
Piston: Not relevant in FSO communications
Lower modes Relative error
~80%
Higher modes Relative error
~20%
Absolute error still significant
Tip/Tilt: Beam wander
Higher modes produce only scintillation
Phase distortions can be represented by Zernike modes.
Correction of only higher modes might not provide enough improvement. Beam wander correction either by
divergence optimization or pointing by tracking.
Uplink Transmission Approaches Pre-distortion Adaptive Optics
DVB-S2 Signal
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 30
Functional block diagram of the DVB-S2 system
Multiple Inputs
Mode
Adaptation
FEC
Encoder
Mapping
& Framing
BB Filter
& APSK
RF
Receiver
Ka band
converter
Gateway
RF uplink channel
User Terminal RF downlink
channel Satellite
Simplified block diagram including the satellite and user in the chain.
Uplink Transmission Schemes
AT: Analog Transparent DT: Digital Transparent FEC: Forward Error Correction S: Soft F: Full
Transparent Options
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 31
Multiple Inputs
Mode
Adaptation
FEC
Encoder
Mapping
& Framing
BB Filter
& APSK
Rx Telescope
& LNOA
Ka band
converter
Gateway
Optical uplink
channel
User
Terminal RF downlink channel
Satellite
Optical
carrier
O/E
converter AGC
Multiple Inputs
Mode Adap.
FEC encoder
Mapping
& Framing
BB Filter &
APSK
ADC
Sampler
Rx Telescope
& LNOA
Ka band
converter
Gateway
Optical uplink
channel
User
Terminal RF downlink channel Satellite
Optical
carrier
O/E
converter DAC
IRT
FEC
IRT
FEC
Digital transparent transmission scheme for DVB-S2 signals. Dashed blocks are optional.
Analog transparent transmission scheme for DVB-S2 signals
Minimum impact on sat payload. Due to high Tx powers HPOA
nonlinearities can be a problem. No protection against long
fades.
Processing power needed onboard. Specific protection against IRT
fading possible. Considerable bandwidth
expansion.
Digital Regenerative Options
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 32
Digital soft-regenerative transmission scheme for DVB-S2 signals.
Multiple Inputs
Mode Adap.
FEC encoder
Mapping
& Framing
BB Filter &
APSK
Rx Telescope
& LNOA
Ka band
converter
Gateway Optical uplink
channel
User
Terminal RF downlink channel
Satellite
Optical
carrier
O/E
converter
IRT
FEC
IRT
FEC
Fully regenerative: Data a is also transmitted in baseband over the optical carrier, but DVB-S2 modulation and coding blocks are included in the satellite RF chain to achieve most robust system against BER.
Lower bandwidth reqs. compared to DT option. Excellent protection against
fading. Major impact on sat payload. Transparency is almost lost. SWaP penalty due to BB-to-
Ka onboard conversion.
Most robust in terms of BER. Maximum SWaP impact. No standard upgrades after
Sat launch.
Link Budget
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 33
Link Budget Analog Transparent Example
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 34
Parameter Unit Tenerife Tirana Gibraltar Paris Tx antenna gain dB 113.53 108.82 105.87 103.01 Transmitter loss dB -3.01 -3.01 -3.01 -3.01 Tx diversity gain dB 0.00 0.00 0.00 0.00 Free-space loss dB -289.66 -289.75 -289.68 -289.89 Atmospheric attenuation dB -0.14 -0.28 -0.34 -0.49 Cloud margin dB -3.00 -3.00 -3.00 -3.00 Strehl ratio loss dB -1.14 -1.14 -1.11 -1.09 Beam wander loss dB -5.19 -5.19 -5.02 -4.93 Scintillation loss dB -2.19 -3.75 -4.16 -5.76 Tx antenna gain dB 114.10 114.10 114.10 114.10 Receiver loss dB -3.01 -3.01 -3.01 -3.01 Fiber coupling loss dB -1.07 -1.07 -1.07 -1.07 Total link loss dB -80.79 -87.29 -90.44 -95.14 Total OGS Tx power dBm 44.77 44.77 44.77 44.77 Received power dBm -36.02 -42.52 -45.67 -50.37 Carrier-to-noise ratio dB 23.85 16.53 12.45 5.39
OGS Tx optical power per lambda 30W. One lambda per beam. BW 1.45GHz per beam. DWDM Grid: 100-50-25 GHz RFE photodetector at SAT
BW=20GHz SAT: EDRS-A @ 9ºE
-8 -6 -4 -2 0 2 4 6 8
Frequency [GHz]
2 RF subcarriers over DWDM optical channel
1.5GHz RF-subcarrier; 5 % roll-off factor; 150MHz band guard
c =1550.00nm
f c =193.414THz
WDM Bandwidth 100GHz
RFE Bandwidth 20GHz
RF carrier 1 | fc= 4.000GHz
RF carrier 2 | fc= 5.650GHz
Uplink IF in RF C-band 4-8GHz.
Link Budget Analog Transparent Example
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 35
QPSK r2/9
QPSK r13/4
5
QPSK r9/20
QPSK r11/2
0
8APSK r5
/9-L
8APSK r2
6/45-L
8PSK r2
3/36
8PSK r2
5/36
8PSK r1
3/18
16APSK r1
/2-L
16APSK r8
/15-L
16APSK r5
/9-L
16APSK r2
6/45
16APSK r3
/5
16APSK r3
/5-L
16APSK r2
8/45
16APSK r2
3/36
16APSK r2
/3-L
16APSK r2
5/36
16APSK r1
3/18
16APSK r7
/9
16APSK r7
7/90
32APSK r2
/3-L
32APSK r3
2/45
32APSK r1
1/15
32APSK r7
/9
64APSK r3
2/45-L
64APSK r1
1/15
64APSK r7
/9
64APSK r4
/5
64APSK r5
/6
128A
PSK r3/4
128A
PSK r7/9
256A
PSK r29/4
5-L
256A
PSK r2/3-
L
256A
PSK r31/4
5-L
256A
PSK r32/4
5
256A
PSK r11/1
5-L
256A
PSK r3/4
0
5
10
15
20
25
Car
rier-t
o-no
ise
ratio
C/N
[dB
]
DVB-S2X C/N performance at QEF operation FER=10-5
C/N=23.85 dB Tenerife
C/N=16.53 dB Tirana
C/N=12.45 dB Gibraltar
C/N=5.39 dB Paris
Target C/N (AWGN channel)
DVB implementation guidelines; part 2 - S2 Extension (DVB-S2X). Doc. A171-2, 2015.
R. Mata-Calvo, P. Becker, D. Giggenbach, F. Moll, M. Schwarzer, M. Hinz, and Z. Sodnik, “Transmitter diversity verification on Artemis geostationary satellite,” in Free-Space Laser Communication and Atmospheric Propagation XXVI, 2014, vol. 8971, p. 897104.
S. Dimitrov, B. Matuz, G. Liva, R. Barrios, R. Mata-Calvo, and D. Giggenbach, “Digital Modulation and Coding for Satellite Optical Feeder Links,” in 7th Advanced Satellite Multimedia Systems Conference (ASMS), 2014.
D. Giggenbach, “Optical Satellite Feeder Links for Terabps Throughput.” DLR Institute of Communications and Navigation, Presentation, on elib.dlr.de
Sylvain Poulenard, Michael Crosnier, and Angélique Rissons, “Ground Segment Design for Broadband Geostationary Satellite With Optical Feeder Link,” J. OPT. COMMUN. NETW. 7(4), pp. 325-336, 2015.
N. Perlot, T. Dreischer, C. M. Weinter, and J. Perdigues, “Optical GEO Feeder Link Design,” in Future Network & MobileSummit 2012 Conference Proceedings, 2012.
D. Giggenbach, P. Becker, R. Mata-Calvo, C. Fuchs, Z. Sodnik, and I. Zayer, “Lunar Optical Communications Link (LOCL): Measurements of Received Power Fluctuations and Wavefront Quality,” in Proc. International Conference on Space Optical Systems and Applications (ICSOS), 2014.
D. Giggenbach, R. Barrios, F. Moll, R. Mata-Calvo, S. Bobrovskyi, F. Huber, N. Johnson-Amin, F. Heine, and M. Gregory, “EFAL: EDRS Feeder Link from Antarctic Latitudes - Preliminary Results of Site Investigations, Availability, and System Requirements,” in International Conference on Space Optical Systems and Applications (ICSOS), 2014.
Selected References
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 36
Preguntas?
> R. Barrios > Extremely High Speed Avenues for Spacecom: Optical & W-band Waves > 05.09.2016 DLR.de/kn • Slide 37