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An Overview of the Telecom System for the Mars Exploration Rovers:
Design Challenges and Performance Highlights
High GainAntenna(HGA)
Pancam Calibration
Target
Low GainAntenna(LGA)Navcam (pair)
Pancam (pair)
Pancam MastAssembly (PMA)
InstrumentDeploymentDevice (IDD)
FrontHazcam
(pair)
Rocker-BogieMobility System
In-situ Instruments (APXS, MB, MI, RAT)
WarmElectronicsBox (WEB)
SolarArrays
RoverEquipmentDeck (RED)
UHFAntenna
Capture/Filter Magnets
DESCANSO Seminar by Polly Estabrook
2/21/03
PE - 2DESCANSO Talk: MER Telecom
Project Timeline
Phase Definition MER-A Open
Phase Start MER-B Open Phase Start
Launch Launch to thermally stable, positive energy balance state, launch telemetry played back
May 30,2003 June 25,2003
Cruise End of Launch phase to Entry-45 days
May 31,2003 June 26,2003
Approach Entry-45 days to Entry November 20, 2003
December 11, 2003
EDL Entry to end of critical deployments on Sol 1
January 4, 2004 January 25, 2004
Post-Landing Through Egress
End of EDL to receipt of DTE following successful placement of rover wheels on the Martian surface
January 4, 2004 January 25, 2004
Surface Operations
End of Egress to EOM January 8, 2004 January 28,2004
End of Mission (EOM)
Successful receipt of last scheduled UHF data return the night of Sol 91
April 6, 2004 April 27, 2004
PE - 3DESCANSO Talk: MER Telecom
Where are the Rovers going?
0¼
30¼
60¼
-30¼
-60¼
-8 -4 4 8 12km
0
Elysium (approx)
Prime Sites for MER-A: Hematite, Isidis, GusevPrime Sites for MER-B: Hematite, Isidis, Elysium
PE - 4DESCANSO Talk: MER Telecom
Why Go?
Search for and characterize a diversity of rocks and soils that hold clues to past water activity (water-bearing minerals and minerals deposited by precipitation, evaporation, sedimentary cementation, or hydrothermal activity)Investigate landing sites, selected on the basis of orbital remote sensing, which have a high probability of containing physical and/or chemical evidence of the action of liquid waterDetermine the spatial distribution and composition of minerals, rocks, and soils surrounding the landing sitesDetermine the nature of local surface geologic processes from surface morphology and chemistryCalibrate and validate orbital remote sensing data and assess the amount and scale of heterogeneity at each landing siteFor iron-containing minerals, identify and quantify relative amounts of specific mineral types that contain H2O or OH, or are indicators of formation by an aqueous process, such as iron-bearing carbonatesCharacterize the mineral assemblages and textures of different types of rocks and soils and put them in geologic contextExtract clues from the geologic investigation, related to the environmental conditions when liquid water was present and assess whether those environments were conducive for life
PE - 5DESCANSO Talk: MER Telecom
Telecom’s Mission(AKA Level 1 Requirements)
• Mission Success Criteria:– The spacecraft shall approach Mars on a posigrade trajectory designed to
support direct communications with Earth during EDL through roll stop. The spacecraft shall provide direct communications of data during EDL through roll stop at a rate and volume sufficient to provide support for fault reconstruction
– The MER-2003 rovers shall be designed to utilize direct-to-Earth X-band communications for surface operations
– The MER-2003 Project shall be designed to utilze two-way UHF communications through the MER-2001 Orbiter as an operational capability
• Science Requirements– Drive the rovers to at least 8 separate locations and use the instrument suite to
investigate the context and diversity of the Mars geologic environment. • Technology and Program Feed-Forward Requirements
– To validate the NASA-compatible international telecommunications infrastructure, the MER-2003 Project shall demonstrate telecommunications capabilities through the Mars Express orbiter.
PE - 6DESCANSO Talk: MER Telecom
Telecom Level 3 X band Link Requirements (non-EDL)
• Support DOR tone transmission for Delta-VLBI for all Mission Phases (used only in Cruise)
• Near-Earth (Launch to L+14 days):– Nominal: 250 bps Command, 300 bps Telemetry, Ranging (2m for 1 sigma, 600 sec)
into a 34 m DSN, 60 deg off CLGA boresight – Safing: 7.8 bps CMD, 10 bps TLM, no ranging into a 70m DSN, 60 deg off CLGA
boresight• Cruise and Approach:
– Nominal: 125 bps CMD into 34m DSN (10 deg elev, 90% weather), 5 deg off CMGA boresight, max. range (1.33 AU)
– Nominal: Ranging (4m, 600 sec) into 34m DSN, with CMD off, 40 bps TLM into 34m DSN, 5 deg off CMGA boresight, max. range (1.33 AU)
– Safing: 7.8 bps CMD, 10 bps TLM, no ranging, into a 70m DSN, 55 deg off CLGA boresight for CMD, 20 deg off CLGA boresight for TLM, max. range (1.33 AU)
• Surface:– Nominal into a 34m DSN: 125 bps CMD, 400 bps TLM– Nominal into a 70m DSN: 250 bps CMD, 1850 bps TLM– Safing: 7.8 bps CMD, 10 bps TLM, no ranging, into a 70m DSN, 70 deg off RLGA
boresight for CMD, 30 deg off RLGA boresight for TLM, max. range (2.14 AU)
Details: DSN Passes assumed at 10 deg elev during cruise, 20 deg elev during surface, 90% weather for all non-EDL links ,(7, ½) code for a ll safing and cruise ops, (15,1/6) code for HGA links on surface only
PE - 7DESCANSO Talk: MER Telecom
Telecom Level 3 Link Requirements: EDL and UHF
• EDL – X band :– Turn to Entry to CSS separation: 10 bps TLM, max off point CLGA 46
deg, into a 70m DSN, 20 deg elev, 90% weather– From CSS to Lander Separation: Transmit 10 sec tones, with 90%
probability of correct receipt, max off point angle 70 deg, 30 deg DSN elev, 95% weather
– Bridle deployment to Rollstop: Transmit 10 sec tones, best effort basis– At Rollstop: Transmit 20 sec tones with a 40% prob. Of correct receipt,
max offpoint angle 70 deg, 30 deg DSN elev, 95 % weather• EDL – UHF:
– From Lander Separation to Airbag inflation: Transmit one way 8 Kbps link to MGS - best effort basis
• Surface – UHF:– Transmit 100 Mbits on average over 2 sols to MSP’01 Orbiter– Receive 2 Mbits on average over 2 sols to MSP’01 Orbiter
PE - 8DESCANSO Talk: MER Telecom
MER Telecom Block Diagram
Cruise MGA(LCP)
Cruise LGA (RCP)
-
CRUISE STAGE
LANDER
BACKSHELL
Rover UHF
AntennaROVER
RAS
AvionicsPower
Power
Rover LGA (RCP)
Backshell LGA (RCP)
CXS 2
HGA(RCP)
WTS
P1
P2
P3P4
CXS 1
Pos1
LH PortRH Port
Pos2
LH Port
RH Port
SDST
Ch 29 MER1Ch 32 MER2;
Diplexer
Base PetalLGA
(RCP)
Power
UHFTransceiver
UHF DIP
CXS U
DescentUHF
Antenna
SSPA -B3dB cou-pler
SSPA ACXS 0
Pos1Pos2
Pos1Pos1
Pos1 Pos2
Pos2Pos2
Field joint
Field jointHGA Assembly
Avionics
RAAT
RAAR
Power
Avionics
Power Avionics
Avionics
P1-P4, PolarizerCoax cable Waveguide to Coax Adapter Short
PE - 9DESCANSO Talk: MER Telecom
MER Rover Operations -Telecom Overview
MSP’01Orbiter
MER
X-Band 40-110 kbps
1,2
-X
-Ban
d D
TEPRIMARY (P) BACK-UP (B)
1. DSN-ROVER FORWARD LINK 7.8 bps-2 kbps 7140 MHz (P)2. ROVER-DSN RETURN LINK 10 bps-2 kbps 8440 MHz (P)3. ROVER-M’01 RETURN LINK 8, 32, 128, 256 kbps 401.585625 MHz (P)4. M’01-ROVER FORWARD LINK 8 kbps 437.1 MHz (B)5. ROVER-MARS EXPRESS FORWARD 8 kbps 437.1 MHz (B)6. ROVER-MARS EXPRESS RETURN 8, 32, 128 kbps 401.585625 MHz (B)7. ROVER-MGS RETURN 8, 128 kbps 401.528711 MHz (B)
4 - UHF
X-Band
MGS
5,6 - UHF
7 - UHF
X-Band
3 - UHF
MarsExpress
PE - 10DESCANSO Talk: MER Telecom
MER-A Entry, Descent, Landing -Telecom Overview
• Lander Separa tion: E + 277 s
• Heatshield Separation: E + 257 s
• Parachute Deployment: E + 237 s , 10.8 km, 449 m/s wrt atmos.
• Peak Hea ting / Dece le ra tion: 34 W/cm2, 6.5 earth g
• Cruise S tage Separa tion: E - 0:30:00
• Defla tion / Pe ta l La tch Firing: Landing + 90 min
• Radar Ground Acquis ition: L - 34 s, 2.4 km above ground
• Airbag Infla tion: ~450 m, L - 10 s
• Bridle Cut: L - 3 s, 16 m
• Rocke t Firing: L - 6 s, 125 m, 76 m/s
• Landing: E + 359 s
• Roll to a Stop: Base Pe ta l Down, Landing + 2 min
• Entry Turn & HRS Freon Venting: E - 1:30:00
• Entry: E - 0 s, 129 km, 5.4 km/s wrt atmos., γ = -11.5° ine rtia l, -12° re la tive
• Bridle Deployed: E + 287 s
• Bounces : >15, Rolls Up to 1 km
Launch = 6/3/03Arrival = 1/4/04Landing at 5N Nominal Times
and States
Project PDR baseline
• Earth se t: Landing + 69 min
BLGA
RLGA
Petal Ant. / RLGA
Telecom Antennas
PE - 11DESCANSO Talk: MER Telecom
What have we built?MER-2 Ch.32 Xband Radio Frequency System in ATLO 10/01/02
SSPA Integration Flight ConfigurationCourtesy: Adolfo Valerin
PE - 12DESCANSO Talk: MER Telecom
What have we built? UHF Transceiver S/N 002 Before and After Taping
SSPA Integration Flight Configuration
PE - 13DESCANSO Talk: MER Telecom
MER SC-1 Telecom Support Test Equipment: X band and UHF
SSPA Integration Flight Configuration
PE - 14DESCANSO Talk: MER Telecom
MER Antennas !!(see cover page for view on Rover)
HGA: Printed dipole antenna (made by Ball Aerospace), similar to MPF
DUHF: Pop-up Monopole using MPF
actuator on lander mockup
DUHF
PLGA: Petal Low Gain AntennaPeak Gain Free space = 7 dBi
PE - 15DESCANSO Talk: MER Telecom
CLGA, BLGA, RLGA and MGA Hardware Exploded View
Polarizer P3
CLGA Assembly
CLGA
WG-to-Coax Adapters
Polarizer P2 Dual E-BendPolarizer AdapterWG Slip Fit interface
(significantly longer thanshown in this picture)
BLGA
MGA Horn RLGA (base section and sprung section, held together by spring retainer)
WG-to-coax Adapter
Dual E-BendPolarizer Adapter
MGARLGA
Assembly Spring Retainer
Polarizer P4 Polarizer P1
WG-SMA Polarizer Adapter
Antenna Bracket
From MER Antenna Subsystem Peer Review, 5/3/01
Mars Exploration Rover
Depiction of Cable Routing for MER Antennas
CMGA
PLGA
RUHF
RLGA
BLGA
CLGA
HGA
Antenna StackBLGA - Back Shell LGAUsed during Mars entry after cruise stage ejectRLGA - Rover LGA Used during parachute descent & ground opsP1 - Polarizer with WG-SMA Adapter
HGA Rotary Joints
P1
P2P3
P4
Cruise Stage AntennasCMGA - Cruise Stage MGAUsed during Cruise CLGA - Cruise Stage LGAUsed during early & late cruiseP2-P4- Polarizer with dual E-Bend Adapter
a Link Antennas– Rover UHF LGA
Used during ground ops for link with orbiterHGA - High Gain AntennaUsed during ground ops as prime data link
RH LH
RH
LH
LHRH
RAS Antennas RAAT - TransmitRAAR - ReceiveUsed during final descent
RAS A & B
RAAT-A & BRAAR-A & B
Bulkhead test port
test port
DUHF
Descent & Landing Antennas Ground Ops Prime DatRUHF
PLGA - Petal LGAUsed just after rollstopDUHF – UHF Descent AntennaUsed during parachute descent
PE - 17DESCANSO Talk: MER Telecom
Design Challenges:X band Cable Routing and Associated Cable Losses
PDR Peer Review Present12/18/00 5/23/01 7/22/02
AntennaTransmit Loss (dB)
Transmit Loss (dB)
Transmit Loss (dB)
CLGA 1.75 2.53 2.31BLGA 1.39 1.64 1.30RLGA 1.38 1.62 1.30CMGA 4.29 4.53 3.44HGA 4.22 4.28 2.79
PLGA 4.28 5.01 2.71
Cable Losses reflect use of 4 PLGAAnd associated switches
PDR Peer Review Present12/18/00 5/23/01 7/22/02
AntennaReceive Loss (dB)
Receive Loss (dB)
Receive Loss (dB)
CLGA 2.20 2.72 1.71BLGA -- 1.82 1.04RLGA 1.80 1.81 1.04CMGA 4.60 4.72 3.07HGA 4.30 4.47 2.52
PLGA -- -- --
Concern over X-band cable routing and Level 3 specification to support ranging,command, and telemetry at Mars Approach led to change in CMGA from Mars Pathfinder baseline to higher gain horn prior to PDR.
PE - 18DESCANSO Talk: MER Telecom
Design Challenges: Spacecraft Pointing
• Trade studies on solar array vs. CMGA pointing performed to balance power vs. telecom needs and to establish CLGA pointing during safing
• Maximum CMGA offpoint is 8 degrees (2.2 dB down from max. gain)• Maximum CLGA offpoint is 55 degrees post near-Earth (6 dB down from
max. gain)
Sun and Earth Offpoint AnglesMER-B Close
0102030405060708090
1 16 31 46 61 76 91 106
121
136
151
166
181
196
Days Since Injection
Offp
oint
Ang
le Sun Earth
Worst Case Safing Angles (1/02)
0
10
20
30
40
50
60
70
80
90
100
110
120
6/14/2003 7/12/2003 8/9/2003 9/6/2003 10/4/2003 11/1/2003 11/29/2003 12/27/2003 1/24/2004
Date
-Z to
Ear
th A
ngle
(deg
rees
)
MER-B-Open MER-B-Close
Max Angle = 55.5 deg (Close) on 12/15/03
PE - 19DESCANSO Talk: MER Telecom
UHF Rover Antenna: Design and Location
• Post PDR, UHF Baseline Antenna, a monopole located on Rover Solar Panel, was measured on a rover mockup and found to have very asymmetric pattern– Resulted in widely varying Data Return vs. Rover Orientation and ODY
pass geometry• Breadboard models of 5 other antennas were made, tested on the
Rover mockup, some found to possess more azimuthally symmetric patterns but were deemed too difficult to implement given tight MER timeline
• Baseline antenna was kept– Level 3 Requirements can be met (on average can achieve 100 Mbits/2 sols,
but minimum may be 60 Mbits/2 sols!); – MGS support is planned to achieve additional data return;– Data return for a given day cannot be predicted
PE - 20DESCANSO Talk: MER Telecom
UHF Rover Antenna Patterns Measured on Rover Mockup
PE - 21DESCANSO Talk: MER Telecom
UHF Surface Performance: Telemetry Link(MER2 to ODY at Hematite)
0
10
20
30
40
50
60
70
80
90
100
110
120
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 31 32 33 34 35
Sol
M b
its
Min Avg Max
Data Return Bars show minimum, average, and maximum data return per sol for ‘worst’, average, and ‘best’ rover orientation.
PE - 22DESCANSO Talk: MER Telecom
UHF Surface Performance: Command Link(ODY to MER2 at Hematite)
0
1
2
3
4
5
6
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 31 32 33 34 35
Sol
M b
its
Min Avg Max
Data Return Bars show minimum, average, and maximum data return per sol for ‘worst’, average, and ‘best’ rover orientation.
PE - 23DESCANSO Talk: MER Telecom
UHF Data Volume per Pass: Ops Point of View
MER2-ODYMonopole FM1, Max Elevation per Pass vs Data Volume, 128 kbps, 2dB Fixed Margin
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
20.00 25.00 30.00 35.00 40.00 45.00 50.00 55.00 60.00 65.00 70.00 75.00 80.00 85.00 90.00
Max Elevation per Pass (deg)
Dat
a Vo
lum
e (M
bits
)
IdealRot 0Rot 45Rot 90Rot 135Rot 180Rot 225Rot 270Rot 315
PE - 24DESCANSO Talk: MER Telecom
Results of EMC Tests on MER2 Rover
-133
-131
-129
-127
-125
-123
-121
-119
-117
-115
-113
-111
18:11 18:21 18:31 18:41 18:51 19:01 19:11 19:21 19:31 19:41
time
Pwr (
dBm
)
PMACAPTURE_IMAGE
LNAV,RNAV19:07:10
PMACAPTURE_IMAGE
LNAV,RNAV19:13:19
MICRO-IMAGERCAPTURE_IMAGE
MI19:24:54
MTES_IMAGE18:33:16?
3 Others same commands donot show effect in AGC
UHF_OSC_T=30°Cal Poly change UHF_OSC_T=38.7°
PMACAPTURE_IMAGE
LPAN,RPAN19:32:45
Certain science instruments (PMA, and Micro Imager) have been found to create EMC which degrades UHF transceiver’s receiver threshold. Flight Rules have been made so that these instruments will NOT operate during a UHF pass.
PE - 25DESCANSO Talk: MER Telecom
X-band EDL Design Issues
• Signal Structure• Expected Pt/No at 70m DSN• Residual Doppler (and Doppler Acceleration)• Dynamics• Plasma• EDL Data Analysis (EDA) System
PE - 26DESCANSO Talk: MER Telecom
Landing Ellipse SizeLanding Ellipse Size
From Rob ManningFrom Rob Manning
PE - 27DESCANSO Talk: MER Telecom
EDL Signal Structure and EDA Performance
• Spacecraft telecom system transmits carrier and MFSK signals (RCP) using– Backshell LGA (BLGA) used from entry to lander separation– Rover LGA (RLGA) used from lander separation to landing
– MFSK Signal Format– Desired carrier suppression 3 dB ONLY (desired modulation index of 45deg for all subcarrier
frequencies) during entry and descent; 3.5 dB for post-rollstop tones– MFSK alphabet is 256 (each MFSK signal denotes particular state or event on spacecraft)
– Small Deep Space Transponder (SDST) can generate subcarriers in steps of 0.7 Hz– MFSK Duration:
• Every 10 sec from Entry to Bridle Deploy– Specific events trigger immediate generation of MFSK signal, e.g. parachute deploy – These signals override currently transmitted tone
• Every 20 sec post roll-stop• DSN configured with Radio Science Receivers to digitize received signal for subsequent
post processing to determine carrier and identify transmitted MFSK tone• EDL Data Analysis (EDA) System has been developed to recover carrier and tones from
digitized data using FFT-based analysis techniques. • EDA Algorithm performance depends on the following signal characteristics:
• Pc/No and Pd/No, residual Doppler acceleration, tone duration
PE - 28DESCANSO Talk: MER Telecom
MER B Received Power to Noise Ratio at 70m DSN
MERB EDL Received Signal-to-Noise Ratio
0
5
10
15
20
25
30
35
400 20 40 60 80 100
120
140
160
180
200
220
240
260
280
300
320
340
Time from Entry (sec)
Nominal Pt/NoMax Pt/No
(due to dynamics)
Min Pt/No(due to dynamics)
Thresholds for MFSK Detection Based on Presumed Signal Freq. Widening, Uncompensated Doppler
Acceleration, and need for Acq or Track mode
246 secParachute
Deploy
276 secLander
Separa-tion
286 secBridle FullyExtended
Fluctuation in Pt/No arise due to change in BLGA and RLGA antenna off-boresight Angle during EDL;Variations in Required Threshold due to changes in EDA algorithm (FFT BW, coherent vs. non-coherent Integration time) during the phases of EDL.
PE - 29DESCANSO Talk: MER Telecom
Doppler Residuals Expected during EDL
Difference in Doppler Rate MER A P redicts
-1200
-800
-400
0
400
800
1200
0 100 200 300 400 500
Time (s ec)
Diff
. in
Dop
pler
Rat
e(H
z/se
c)
Difference in Doppler between Nominal and S teep (Hz)Difference in Doppler between S teep and Shallow (Hz)
Difference in Doppler MER A Predicts
-20000
-10000
0
10000
20000
30000
40000
0 100 200 300 400 500
Time (sec)
Diff.
in D
opp
ler (H
z)
Difference in Doppler between Nominal and Steep (Hz)Difference in Doppler between Steep and Shallow (Hz)
Difference in Doppler Accel MER A P redicts
-100-80-60-40-20
020406080
100
0 100 200 300 400 500
Time (s ec)
Diff
. in
Dop
pler
Acc
el(H
z/se
c^2)
Difference in Doppler between Nominal and S teep (Hz)Difference in Doppler between S teep and Shallow (Hz)
PE - 30DESCANSO Talk: MER Telecom
Plasma: Is it an Issue?Mars Pathfinder Comm. during EDL
Pathfinder Electron Density Profile
1.0E-07
1.0E-04
1.0E-01
1.0E+02
1.0E+05
1.0E+08
1.0E+11
1.0E+14
0 20 40 60 80 100 120 140 160 180 200
Time From Entry (s)
Elec
tron
Den
sity
(cm
^-3)
Wake Electron Density (Old Atmosphere Model)X-band Critical Plasma DensityStagnation Electron Density (Old Atmosphere Model)Stagnation Electron Density (New Atmosphere Model)Wake Electron Density (New Atmsophere Model)
CommunicationsBlackout Period
Max heating rate
Max dynamic pressure
Critical Electron Density to cause comm outage at X-band = 8.8 *1011
Conclusion: Comm blackout more or less aligned with time period when electron density in wake region (where BLGA is located) greater than critical density. (Courtesy D. Morabito)
PE - 31DESCANSO Talk: MER Telecom
Mars Pathfinder Electron Density Prediction from LAURA program at Langley (P. Gnoffo)
Critical Electron Density to cause comm outage at X-band = 8.8 *1011
MPF S/C CrossSection
MPF BLGA
Location
Electron Density around MPF Entry Vehicle at Entry + 60 sec
MPF Heatshield
Conclusion: For MPF, comm signal path from BLGA to Earth would passthrough regions of plasma containing an electron density greater than critical density.
PE - 32DESCANSO Talk: MER Telecom
MER B Electron Density Prediction at S/C -z axis Wake and Stagnation Region Points
MER-B Electron Density
1.E+00
1.E+02
1.E+04
1.E+06
1.E+08
1.E+10
1.E+12
0 50 100 150 200 250 300
Time (sec)
Elec
tron
Dens
ity (c
m^-
3)
StagnationWakeCritical
Velocity and altitude profile provided by P. Desai (8/13/2001)
Conclusion: It is unlikely that there will be a communications blackout due to ionized charged particles for MER-B.
From D. Morabito
PE - 33DESCANSO Talk: MER Telecom
DSN Configuration during MER EDL (Draft)
70-m
Downlink channel (BVR & TLP) MER
MER Level 2 Reqs.: 70m at one DSN station with a goal of arraying all available antennas; rx andprocess data tx via UHF to MGS during EDL
EDA System
IFDistribution
RF/IF Downconv Downlink channel (BVR & TLP) MGS
IFDistribution
IFDistribution
IFDistribution
RF/IF Downconv
RF/IF Downconv
RF/IF Downconv
Radio science receiver
FSPIF Switch
Radio science receiver
Downlink channel (BVR & TLP)
BlockVRcvr
IF Switch34-mDownlink channel (BVR & TLP)
34-mRadio science receiver
Radio science receiver
34-mRadio science receiver
Notation:BVR – Block V receiverTLP – Telemetry processor
New
Modified for MER EDL
Carrier Freq,Tones
PE - 34DESCANSO Talk: MER Telecom
EDA Displays Seen at MER MSA:Freq and Freq. Acceleration (from Test Run)
From Tim Pham / Dave Fort
PE - 35DESCANSO Talk: MER Telecom
Tone Detection Screen (based on Test Data)
Freq
uenc
y
From Tim Pham / Dave Fort
Each rectangle represents freq estimateproduced by processing 1 sec of processed received signal (I.e with Dynamics removed). Color of rectangle indicates signal strength.
TIME (sec)
PE - 36DESCANSO Talk: MER Telecom
MER on MARS
High GainAntenna(HGA)
Pancam Calibration
TargetLow GainAntenna(LGA)
Navcam (pair)
Pancam (pair)
Pancam MastAssembly (PMA)
InstrumentDeploymentDevice (IDD)
FrontHazcam
(pair)
Rocker-BogieMobility System
In-situ Instruments (APXS, MB, MI, RAT)
WarmElectronicsBox (WEB)
SolarArrays
RoverEquipmentDeck (RED)
UHFAntenna
Capture/Filter Magnets
PE - 37DESCANSO Talk: MER Telecom
For More Information: Documents
• MER Telecommunications System Handbook– Covers X-band telecom system, performance, test results, ideosyncrasies
• MER UHF Telecom Handbook– Covers UHF telecom system, performance, compatibility with MGS, ODY,
and Mars Express, idiosyncrasies• MER Mission Plan
– Description of MER Mission Plan by Mission Phase• MER Entry Descent and Landing Performance Assessment Report
– EDL geometry for DTE and UHF link, S/C to Earth range rates, • MER Interplanetary Trajectory Characteristics Document
– Range, pointing angles, DSN station elevation, • MER Detailed Mission Requirements
– Covers DSMS support agreements• Many test results on MER Docushare
PE - 38DESCANSO Talk: MER Telecom
For More Information: Telecom Team
• Telecom System and Project Interaction: Jeff Hilland• X band System Engineering Issues: Andre Makovsky• UHF System Engineering Issues: Andrea Barbieri• MER Antennas: Joe Vacchione• X band Radio Frequency System: Brian Cook• UHF Telecom System: Peter Ilott• X band Integration and Test: Ernie Stone, Adolfo Valerin, Tuan Tran• Radar Altimeter System: Scott Shaffer
PE - 39DESCANSO Talk: MER Telecom
Backups
PE - 40DESCANSO Talk: MER Telecom
CLGA Pattern on Cruise Mockup
CLGA Pattern on Cruise Mockup
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
5.00
10.00
0.0 20.0 40.0 60.0 80.0 100.0 120.0
Angle of Boresight (deg)
Gai
n (d
Bi)
Transmit Gain Receive Gain
On-Boresight Gain:Receive Gain = 7.7 dBiTransmit Gain = 7.2 dBi
PE - 41DESCANSO Talk: MER Telecom
Test Article:PLGA under Airbags
PE - 42DESCANSO Talk: MER Telecom
Interaction of Airbags and PLGA Performance
• PLGA pattern with inflated airbags• PLGA pattern with deflated airbags
PE - 43DESCANSO Talk: MER Telecom
Measured Pattern/Gain Data Inflated Airbag
Azimuth – degrees from boresight
Gain Requirement
Coverage Requirement
PE - 44DESCANSO Talk: MER Telecom
Deflated Airbag Over Antenna
2 Folds 4 Folds
5+ Folds Packed w/ MLI Cover
PE - 45DESCANSO Talk: MER Telecom
Measured Pattern/Gain DataDeflated Airbag
Azimuth – degrees from boresight
Coverage Requirement
Gain Requirement
PE - 46DESCANSO Talk: MER Telecom
Other Telecom System Engineering Trade Studies and Test Issues
• Frequency interference issues with Deep Impact• Telecom H/W interaction with FSW
– Telecom Support Board Issues· Clock rate· Uplink FPGA
• UHF EMC performance in Screen Room• Communication Behavior Manager• EDL Comm. Manager
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