an overview of the telecom system for the mars exploration ......telecom level 3 link requirements:...

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


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


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


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.


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


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


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


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


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


What have we built?MER-2 Ch.32 Xband Radio Frequency System in ATLO 10/01/02

SSPA Integration Flight ConfigurationCourtesy: Adolfo Valerin


What have we built? UHF Transceiver S/N 002 Before and After Taping

SSPA Integration Flight Configuration


MER SC-1 Telecom Support Test Equipment: X band and UHF

SSPA Integration Flight Configuration


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


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


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.


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


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


UHF Rover Antenna Patterns Measured on Rover Mockup


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.


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.


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


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.


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


Landing Ellipse SizeLanding Ellipse Size

From Rob ManningFrom Rob Manning


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


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.


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)


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)


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.


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


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


Downlink channel (BVR & TLP)

BlockVRcvr

IF Switch34-mDownlink channel (BVR & TLP)

34-mRadio science receiver


34-mRadio science receiver

Notation:BVR – Block V receiverTLP – Telemetry processor

New

Modified for MER EDL

Carrier Freq,Tones


EDA Displays Seen at MER MSA:Freq and Freq. Acceleration (from Test Run)

From Tim Pham / Dave Fort


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)


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


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


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


Backups


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


Test Article:PLGA under Airbags


Interaction of Airbags and PLGA Performance

• PLGA pattern with inflated airbags• PLGA pattern with deflated airbags


Measured Pattern/Gain Data Inflated Airbag

Azimuth – degrees from boresight

Gain Requirement

Coverage Requirement


Deflated Airbag Over Antenna

2 Folds 4 Folds

5+ Folds Packed w/ MLI Cover


Measured Pattern/Gain DataDeflated Airbag

Azimuth – degrees from boresight

Coverage Requirement

Gain Requirement


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