NASA/TM--2002-212006

Airborne

at NASA

Satcom Terminal

Glenn

Research

Doug Hoder and Robert Zakrajsek

Glenn Research Center, Cleveland, Ohio

December 2002
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NASA/TM--2002-212006

Airborne

at NASA

Satcom Terminal

Glenn

Research

Doug Hoder and Robert Zakrajsek

Glenn Research Center, Cleveland, Ohio

National Aeronautics and

Space Administration

Glenn Research Center

December 2002
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Available electronically at http://gltrs.grc.nasa.gov
Airborne Satcom Terminal Research at NASA Glenn

Doug Hoder and Robert Zakrajsek

National Aeronautics and Space Administration

Glenn Research Center

Cleveland, Ohio

Abstract:

NASA Glenn has constructed an airborne Ku-band satellite terminal, which provides

wideband full-duplex ground-aircraft communications. The terminal makes use of

novel electronically-steered phased array antennas and provides IP connectivity to and

from the ground.

The satcom terminal communications equipment may be easily changed whenever a

new configuration is required, enhancing the terminal's versatility.

I. Background:

NASA's Aviation Safety, and Aviation Capacity Programs are federally-funded initiatives

designed to utilize technology to improve the nation's air transportation system.

It is well accepted that air travel is one of the safest modes of transportation. The

aviation community has enjoyed one of the best safety records of any form of

transportation. Although the aviation accident rate is extremely low, the projected

growth in air travel through the early part of this century poses a serious safety

challenge to the aviation community. The challenge is that the number of aviation

accidents will significantly increase if the accident rate does not decline. On February

12, 1997 President Clinton called for an 80% reduction in the rate of fatal accidents

within 10yearsand a 90% reduction within 20 years. In response, NASA has initiated

the Aviation Safety Program (AvSP) in partnership with industry and other government

agencies to address the President's National Aviation Safety Goal. The Aviation Safety

Program is a Level I program of NASA's Office of Aerospace Technology (OAT).

In 1997, shortly after the President announced the National Aviation Safety Goal, the

Aeronautics Safety Investment Strategy Team (ASIST) defined many of the technical

objectives of what was to become the AvSP. The team recognized that weather was a

major contributing factor in aviation incidents and accidents. A key recommendation of

the ASIST activity was for a significant effort in weather accident prevention. As a

result, weather accident prevention (WxAP) has been incorporated as a Level II project

of theAvSP. Furthermore, the ASIST weather team producedaprioritized list of

investment areas under weather accident prevention. Weather data dissemination was

considered to be the most critical and highest ranked priority on the list. As a result,

the AvSP, under the WxAP project, created the aviation Weather Information

Communications (WlNCOMM) and the Aviation Weather Information (AWlN) Level III

elements. The combined objective of the WlNCOMM and AWlN elements are to develop

technologies that will provide accurate, timely and intuitive information to pilots,

NASA/T_2002-212006 1
dispatchers, and air traffic controllers to enable the detection and avoidance of

atmospheric hazards. The WINCOMM element in particular addresses the

communications specific issues associated with the dissemination of weather data. The

AWIN element specifically addresses operator support and enhanced weather product

research issues. The WINCOMM and AWIN elements are highly integrated due their

inherent synergy.

NASA Glenn's involvement in the WINCOMM and AWIN programs is primarily in the area

of communications. Glenn has a history of research and development in the area of

satellite communications. They have been responsible for several major innovative

satellite programs, including CTS (Communications Technology Satellite) and ACTS

(Advanced Communications Technology Satellite).

NASA Glenn has constructed a satcom terminal (known as the Aero-Mobile satcom

terminal) to serve as a test bed for investigating and demonstrating new aviation

communications technology--primarily satellite communications. The premise is that

more reliable, wider bandwidth communications can improve both airspace capacity

and safety through increased awareness of position, obstacles, weather, etc. The

terminal's electronics can be easily changed whenever a new communications

configuration is required. A description of the terminal is included the sections ahead.

II. Terminal

The Aero-Mobile satcom terminal was designed to be installed in either an aircraft or a

ground vehicle (in this case a large van). The ground vehicle provides an opportunity to

test the system without the expense or logistical burden of flight testing.

A great deal of the integration and initial testing did not require the terminal to be in

flight, so the van proved to be a cost-effective alternative. The van is equipped with a

laser ring-gyro and a Global Positioning Satellite (GPS) receiver which, when integrated

with a computer, provides the required navigational data in the same format as the

aircraft data system.

The terminal uses commercial Ku-band satellites and provides full duplex connectivity

to a fixed station (located at NASA Glenn). The airborne (or mobile) hosts (computers)

are connected into the Glenn network, and appear as local machines.

The terminal design is based around earlier fixed and shipboard reflector antenna

terminals built at NASA Glenn, but incorporates a set of electronically-steered phasedarray antennas (receive and transmit). These were purchased from the Boeing

Company.

The phased-array antennas are configured for frequency, polarization and longitude of

the satellite to be used. The antenna control system takes the position data and

platform attitude data and calculates the correct pointing angle for both the transmit

and receive arrays. The platform position and attitude data are derived from an ARINC

NASA/T_2002-212006 2
429 interface to the laser gyro/GPS system on the van, or directly into the aircraft INS

(inertial navigation system) system (on a ARINC 429-equipped aircraft).

The received downlink RF signal is downconverted and directed to a commercial

satellite mode for demodulation. The demodulated data stream is then routed to a

Cisco router, which serves as a gateway for hosts connected to the terminal.

An earlier version of the terminal used a Sun workstation as a gateway. Although the

Sun workstation provided a much more flexible interface, the Cisco router is a simpler

and more easily-configurable solution, and can also operate at higher data rates.

Similarly, the uplink data stream from airborne hosts is routed through the Cisco router

to a semi-custom spread spectrum modem, into an upconverter and then through the

transmit array.

The spread spectrum modulation is used on the airborne uplink to mitigate adjacent

satellite interference due to the wide beamwidth of the transmit array.

Figure 1: Aero-Mobile van and NASA Glenn fixed station

NASA/T_2002-212006 3
Figure 2: Phased-Array antennas mounted on Aero-Mobile Van

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757 3-phase

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W301 ARINC429 ,., -""': P2

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Figure 3: Block diagram of airborne terminal

NASA/T_2002-212006 4
II1. General Performance Parameters

The general performance parameters of the terminal are:

Ku-band uplink

frequency: 14.0- 14.5GHz

number of elements in the Tx array: 254

EIRP: 36 dBW

modulation: QPSKwith direct-sequence spread spectrum, up to 512 kb/s

error-correcting coding: 1/2 rate convolutional

spreading: to 10 MHz

Ku-band downlink

frequency: 11.75- 12.25GHz

number of elements in the Rx array: 1536

G/T: 34 dB/K

modulation: QPSK, up to 4 Mb/s

error-correcting coding: 1/2 rateconvolutional, rate 235/255 Reed-Solomon

Figure 4: Photo of terminal equipment installed in Aero-Mobile van

NASA/T_2002-212006 5
IV. Data and networking

The terminal sends and receives internet protocol (IP) data, providing an extension of

the NASA Glenn local network.

The gateway device (the Cisco router) is connected through the satellite link and to a

complimentary device at the fixed station. The gateway at the fixed station is

connected to the Glenn local network. This places the airborne gateway and any

airborne hosts directly on the NASA Glenn network. Each host has a unique lP address.

communications

satellite

ethernet

RF & modems

gateway

airborne hosts

airborne terminal

I RF &modems

I

I

I gateway .... I

I I

fixed terminal

J

NASA GRC LAN

firewall

Figure 5: Network diagram

V. Boeing Antennas

The receive antenna was initially developed by Boeing for satellite TV reception in

business jets, from previous Government and internal research. The transmit antenna

was jointly developed between Boeing and NASA Glenn (formerly NASA Lewis). These

antennas are ideal for aircraft use, with very low profile and very fast pointing response.

The two Boeing antennas were a result of both SBIR and DoD/NASA development

contracts. The Air Force's Rome Laboratories had a development contract with Boeing

NASA/T_2002-212006 6
for large phased array antenna design, with a subarray module as one of the

deliverables. NASA requested that Rome Labs add a task to the original contract to

provide a nominal 16 element receive array for NASA experiments. The receive array

was to be a similar size as an older Texas Instruments transmit antenna--to result in

similar performance. Both NASA and the Air Force supported this effort andasmall

antenna was ordered. While the original antenna design usedawaveguidefeed, to

minimize cost and complexity, this antenna was space fed and had 23 dielectric loaded

elements arranged in five rows. This antenna was one of three antennas that were

flown on NASA Glenn's LearJet supporting the Aero-X experiment with the ACTS

satellite _/

Boeing later redesigned the radiating modules to lower the antenna height. This

antenna became their Ku-band receive antenna which was used as a business-jet

television receive antenna.

NASA Glenn initiated a development contract, with Boeing, for a 254 element Ku-band

transmit antenna through the US Navy'sSPAWAR. The transmit antenna had the same

radiating element design as the current receive antenna.

As the transmit antenna is physically smaller than the receive, an adapter plate was

designed to permit the transmit antenna to be installed in a second receive antenna

mounting frame attached to the aircraft's fuselage.

Since most of the current aircraft band communication links are both narrowband and

utilized to capacity, a test utilizing a wide band satellite link would be performed. The

two Ku-band antennas would allow wide band link testing through a satellite to verify

the system operation. Operational satellites would probably operate at different

frequencies, but the link characteristics and delays would be similar.

NASA/T_2002-212006 7
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Figure 5: Phased-Array antennas mounted on NASA Dryden DC-8

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Figure 6: Front of NASA Dryden DC-8 showing receive antenna

NASA/T_2002-212006 8
Figure 7: Tail of NASA Dryden DC-8 showing transmit antenna

70 MHz Uplink

70 MHz Downfink

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........J _ort] .........._ ] / S_a(_(ATN! _ ............... .........................

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Thunderbolt

antenna

Figure 8: Block diagram of fixed terminal

VI. Experiments

The terminal has been used in the mobile environment since the spring of 2000, and

was flown on the NASA Dryden DC-8 in December of 2000. The terminal was later

NASA/T_2002-212006 9
installed on the NASA Langley 757 "ARIES" (Airborne Research Integrated Experiment

System).

A. IP applications tested

So far, most of the applications tested through the system have used IP: telnet, ftp, ssh,

http, etc. These all function as they would on a terrestrial network (aside from a 1/2

second transit delay). Two ATN (Aeronautical Telecommunication Network)-based

demo applications from Eurocontrol have also been tested.

In order to get terrestrial-like performance out of the satellite link, the bit error rate

must be extremely low, typically less than 10 -_. With error-correcting coding, this

performance is easily achieved

Typical performance is BER <= 10 -a, with an Eb/N o of about 15 dB*Hz, for both uplink

and downlink.

B. Mobile tests

The first tests were performed in AATT Aero-Mobile van. In addition to RF performance

measurements, the standard IP suite of test was performed. The data is included in

Appendix 1.

C. AeroSAPIENT tests

In December of 2000, the terminal was flown on the NASA Dryden DC-8 Airborne

Sciences Laboratory. The system supported a sensor-data experiment, providing

connection to a ground internet.

Dryden also tested a Java-based measurement network and data transport middleware

concept called the Ring Buffered Network Bus, orRBNB. The RBNBprovided

simultaneous onboard data archival and online distribution of multiple flight data

streams over the satellite link to a nationwide network of destinations on the ground.

Some of these data streams were encrypted with public key infrastructure (PKI)

technology.

This experiment successfully demonstrated real-time data link technology to move and

distribute unique and distinct flight data to multiple sites in real time while addressing

multilevel priorities in a secure, high-integrity data-sharing environment.

This mission was a collaborative effort using in-flight network communications

technology, enabling various simultaneous applications to be conducted at bidirectional

rates 1O0 times greater than what is operational in today's National Airspace System.

In addition to constructing a network architecture that included a mobile platform and

simultaneous bidirectional applications, the evaluation of the physical electrical

NASA/T_2002-212006 10
interconnect and the network performance was of particular interest in understanding a

high-integriW communications environment. Because this mission was the first NASA

flight of the prototype Ku-band antenna system, the antennas were characterized in a

variety of flight profiles that included different combinations of roll, pitch, and heading

with regard to the geostationary satellite.

The experimental link performed extremely well, yielding data transfers of

approximately 2.1 Mbits/sec onto the aircraft, and 256 kbits/sec from the aircraft to

the ground network that extended across the Nation. The data rates were limited by

the installed firmware on the various modems used in the network, and could be

increased by upgrading to the latest modem firmware revisions. Extreme flight profiles

(e.g., a 45 ° change in roll coupled with a 50 ° change in heading) were purposely flown

to determine the threshold of sustaining the communication link. This also provided

some insight into the relationship between the antenna system performance and the

network recovery, during a particular flight profile or system event.

A comprehensive report is available in reference (2)

D. NASA Langley 757

In early 2002, the terminal was installed on the NASA Langley 757 "ARIES", in support of

NASA's WinComm project. It was to be used to transfer realtime weather data to and

from the 757.

The satellite link provided realtime weather data from Rockwell Collins. The data was

used by the airborne researchers to guide the aircraft into areas of convective

turbulence, in order to calibrate/quantify/check out an airborne weather radar system.

The system performance was nominal during ground testing and the early flights. The

experimenters on the 757 were satisfied with the data quality. Unfortunately, later in

the flight campaign, the data quality degraded to the point of being unusable. The

problem was traced to a malfunctioning Low Noise Block downconverter (LNB). The LNB

was eventually replaced after the flight campaign was concluded.

NASA/T_2002-212006 11
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Figure 9:

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NASA LaRC "ARIES" 757 with antennas installed along top of fuselage

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Figure 1O: Terminal equipment rack inside NASA LaRC 757

NASA/T_2002-212006 12
VII. Conclusions and Observations:

1) In the mobile environment, and with a good INS system (like our laser gyro) we can

make the Boeing antennas work pretty well--both at rest and in motion. Since they

don't do any real tracking for pointing, the occasional bridge doesn't present much of a

problem to recovery of the antenna pointing.

That is not the case however for polarization. Polarization tracking is accomplished

with a servo loop, so the fades from obstructions have been known to cause 180

degree flips in the antenna polarization--requiring manual intervention. The loop

seems to be slow enough however, that brief fades do not seem to be a problem.

2) With the 8 m antenna of the fixed station, we were able to transmit 2.048 Mb/s from

the fixed station to the mobile (forward link) with zero errors. We had almost 6 dB of

margin. In the initial system, we were constrained by modem interface cards to about2

Mb/s. Later, these were replaced with higher-speed interfaces which allowed us to

transmit up to 4 Mb/s--although we typically held this to 2 Mb/s in order to maintain

some link margin.

On the reverse link (mobile-to-fixed) we were able to transmit 256 kb/s with no errors.

Again, we had about 6 dB of margin. We initially had trouble with the L3 modem at this

rate, but this was later corrected and we were able to transmit data at 512 kb/s. Again,

we sometimes backed this down to a lower rate (typically 256 kb/s) in order to have

some link margin.

The satellite we used (AMC-2--formerly GE-2) has both high EIRP and G/T, giving very

good performance with a small-aperture satellite terminal. The performance would not

necessarily be as good with an older satellite. A typical estimated link budget is

included in Appendix 5.

3) We were able to establish IP connectivity between any host in the van and any host

in the GRC network. We were able to run the usual IP applications (http, ftp, telnet,

ssh) with no problems related to routing.

The only minor problem was the non-optimum performance of the ftp. This is due to

the large bandwidth-delay product of the 2 Mb/s link and the 500 ms GEO delay,and

non-optimized window sizes in the ftp application.

4) The IP phones worked very well, providing there is enough bandwidth available.

NASA/T_2002-212006 13
References:

(1) Zakrajsek, Robert J., Advanced Antenna Technology for Aeronatuical

Communications--Space Communication Technology Link vol 2, no., April 1999 (NASA

Glenn Research Center, Cleveland Ohio).

(2)) Brooks, David E., Romaniak, Gregory W., Frantz, Brian D., AeroSAPIENT Final

Report: DC-8 Flight Experiment: November through December 2000 for RSIS Task A6. 1

Task Requirement--July 11, 2001 (NASA Glenn Research Center, Cleveland Ohio).

NASA/T_2002-212006 14
Appendix I: Test Descriptions

1) C/N o

This measurement gives a qualitative assessment of the RF performance, without

considering the subsequent stages.

A pure carrier (at the same power output as the modulated signal) is transmitted from

each station to the receiving end. The carrier power is measured at the first IF (L-band)

using a spectrum analyzer with it's resolution bandwidth set fairly wide (about 3 MHz).

This value is recorded as "C", in dBm.

While the carrier is still present, the spectrum analyzers noise measurement function

("noise marker") is activated. This provides an approximate measurement of noise

spectral density. The marker is moved around the carrier in about a 5 MHz span, and

an average is taken of several values. This averaged value is recorded as "No", in

dBm/Hz.

The carrier-to-noise density ratio (C/N o) is simply the difference, expressed in dB*Hz.

2) Eb/N o

The energy per bit-to-noise density ratio Eb/N o provides a measurement of signal

quality as seen by the demodulators.

The Comstream CM-701 modems (used in the fixed-to-mobile link) provide a direct

display of Eb/N o. The L3 EB200 modems (used in the mobile-to-fixed link), provide no

such measurement, so the Eb/N o is calculated by subtracting lO*log of the data rate.

For example, with a C/N o of 70 dB*Hz and a data rate of 256 kb/s, the Eb/N o will be 70

- lO*log (256,000) = 70 - 54 = 16 dB.

The calculated number for the other modem is usually very close to that displayed.

3) network tests

The network tests verify connectivity and IP services between hosts. The tests were

performed both between the mobile and fixed gateway hosts and between hosts

connected to the gateway machines.

The following hosts combinations were tested:

mobile gateway to fixed gateway

fixed gateway to mobile gateway

NASA/T_2002-212006 15
host attached to the fixed gateway to the mobile gateway

host attached to the mobile gateway to the fixed gateway

host attached to the fixed gateway to host attached to the mobile gateway

host attached to the mobile gateway to host attached to the fixed gateway

3.1) ping

An IP"ping" was performed between hosts and the success and round trip time were

observed and recorded.

Typical ping times were about 520 msec. This is pretty standard for a geosynchronous

satellite link, where the length of each path is approximately 125 msec. The complete

ping path requires four hops (to the satellite, down to the first ground station, back to

the satellite and back to the other station).

All pings were successful.

3.2) ssh

Secure-Shell (SSH) Iogins were performed in the same combinations. These were all

successful.

3.3) ttcp

ttcpisaperformance measurement tool for TCP links. It provides an accurate

measurement of real data throughput rate--which can be highly dependent upon the

delay*bandwidth product. With the long geosynchronous satellite delay, this becomes

an issue.

With the van fixed, typical throughput rates were 1980 kb/s from the fixed to the

mobile, and 240 kb/s from the mobile to the fixed. Compare this to the modem rates

of 2048 and 256 kb/s respectively.

Results for the mobile experiment were slightly less--due to outages caused by

underpasses. These rates were recorded from 660 to 1320 kb/s for the fixed-tomobile link and 210 kb/s for the mobile-to-fixed link.

3.4) ftp

File transfer were performed using standard ftp. This was done simply to verify

functionality, as the ftp parameters were not tuned to compensate for the large

bandwidth*delay product. Although the file transfer were successful, the speed was not

impressive. Also, the ftp application does not correctly report the true transfer rate.

We know this because the application reported rates HIGHER than the data rate for

mobile-to-fixed transfers.

NASA/T_2002-212006 16
3.5) IPPhones

A set of E-tel IP phones was used with the system to demonstrate voice-over-IP. The

quality in all cases was okay to good. These phones use an adaptive codec, so

generally, the sound quality is better when there is more bandwidth available. With

other traffic on both links, the higher-speed fixed-to-mobile link sounds better than

the mobile-to-fixed. With both links clear, the sound quality is comparable on both

ends.

NASA/T_2002-212006 17

Appendix 2: Aero-mobile Van Test Results

The concise results follow below. More detailed logs and tcp dumps available.

Stationary Test:

Wednesday, February 21, 2001

12:55 PM

Fixed test at GRC, bldg 311

weather: CLEAR

satellite: GE-2 85 ° W

mobile-to-fixed link

xpndr K16H

uplink14320 MHz

downlink 12020 MHz H

fixed-to-mobile link

xpndr K14H

uplink14280 MHz

downlink 11980 MHz H

f-to-m

uplink pwr: 10 W (at the fixed station)

tx pol offset: 125 ° (on the van)

rate: 2048 kb/s

(measured at the van)

C: -50.2

No: -1 30

C/N o = 79.8

BER: 0

Eb/No: 15.7

m-to-f

uplink pwr: 1.24 (in the van)

rate: 256 kb/s

(measured at the fixed station)

C: -30.0

No: -100

C/N o = 70

BER: 0

Eb/No: 16 (calculated)

NASA/T_2002-212006 19
1:14 PM

4.1 m-to-f gateway

("fixed-gw" is main host and gateway at the fixed station,

"mobile-gw" is the gateway on the van)

ping fixed-gw: 520 ms

ssh fixed-gw YES

ttcp f-m: 1980 kb/s avg rate

ttcp m-f: 240 kb/s avg rate

ftp from fixed-gw/home/aatt/ntp.tar

4030464 bytes 83sec47.50kB/s = 380 kb/s

(we know that is slow compared to the link data rate, but we

used standard ftp, without the TCP parameters optimized)

ftp from mobile-gw/home/aatt/ntp.tar

4030464 bytes 110 sec 36.2 kB/s = 289.5 kb/s

(we know this is somewhat high, but that is what ftp reported)

IP phones: quality okay/good

4.2 m-to-f network (portal)

("portal" is a remote host on the GRC network)

ping portal: 525 ms

ssh portal: YES

ttcp f-m: 1810 kb/s avg rate

ttcp m-f: 240 kb/s avg rate

4.3 network to network

("mobile_pc" is a remote host in the van, connected to the

gateway via ethernet)

ping portal to mobile_pc 522 ms

ping mobile_pc to portal 510 ms

mobile_pc connected to van hub (1 39.88.12.31)

3:04 PM

mobile uplink pwr: 1.24 (readjusted)

(we have noticed that the van uplink power drifts as much as 2 or 3 dB throughout the day--we

think it's thermal)

Mobile Test:

(same comments on each item apply AND we had to travel under bridges occasionally)

Thursday, February 22, 2001

NASA/T_2002-212006 20
8:56 AM

Mobile test

weather: OVERCAST

GE-2 85 ° W

mobile-to-fixed

K16H

uplink14320 MHz

downlink 12020 MHz H

fixed-to-mobile

K14H

uplink14280 MHz

downlink 11980 MHz H

f-to-m

uplink pwr: 9 W

tx pol offset: 125 °

rate: 2048 kb/s

C: -42.0

No: -129.5

C/N o = 87.5

BER: 0

Eb/No: 15.7

m-to-f

uplink pwr: 1.24

rate: 256 kb/s

C: -28.5

No: -99.0

C/N o = 70.5

BER: 0

Eb/No: 16.5(calculated)

9:37 AM

4.1 m-to-f gateway

ping fixed-gw: 520 ms

ssh fixed-gw YES

ttcp f-m: 1 320 kb/s

ttcp m-f: 210 kb/s avg

ftp from fixed-gw/home/aatt/ntp.tar

NASA/T_2002-212006 21
4030464 bytes l OOsec 39.3 kB/s = 314.4kb/s

ftp from mobile-gw/home/aatt/ntp.tar

4030464 bytes 110 sec 34.3 kB/s = 274.4 kb/s

IP phones: quality okay/good

4.2 m-to-f network (portal)

ping portal: 520 ms

ssh portal: YES

ttcp f-m: 660 kb/s

ttcp m-f: 210 kb/s

4.3 network to network

ping portal to mobile_pc 524 ms

ping mobile_pc to portal 580 ms

mobile_pc connected to van hub (1 39.88.12.31)

11:01 AM

mobile uplink pwr: 1.40 (readjusted)

11:25 AM

f-to-m

uplink pwr: 9 W

tx pol offset: 125 °

rate: 2048 kb/s

C: -51.0

No: -129.5

C/No = 78.5

BER: 0

Eb/No: 14.8

m-to-f

uplink pwr: 1.24

rate: 256 kb/s

C: -28.6

No: -99.6

C/No = 71.0

BER: 0

Eb/No: 1 7.0 (calculated)

NASA/T_2002-212006 22
Appendix 3: Typical AeroSAPIENT DC-8 Aircraft Test Results

December 11, 2000 location: Tinker AFB (in flight)

ant mode: INS satellite: GE-2

Notes: GE-2 (85 °w) Mobile K16 H, Fixed K14 H

flight test

transmit pol offset angle = 30 °

mobile to fixed time: 12:40 pm

m:f xpndr: K16H UL freq: 14320

user data rate: 256

Viterbi: 0.5 R-S: 0.9 (255/235)

C:-35.4 No: -101.9 C/No: 66.5

Eb/No: 12.5 (calculated) BER: 8 E-3

DL freq: 12020

fixed to mobile

f:m xpndr: K14H

user data rate: 21 80

Viterbi: 0.5

C: -51.2

Eb/No: 14.1

time: 12:50 pm

UL freq: 14280

R-S: 0.9 (255/235)

No: -129.5 C/No: 78.3

BER: 2 E-6

DL freq: 11980

NASA/T_2002-212006 23

Appendix 4: Typical ARIES 757 Aircraft Test Results

April 3, 2002 location:36.566 N -77.319W, SW of Emporia, VA

ant mode: INS satellite: AMC-2

Notes: AMC-2 (85 ° W) Mobile K16 H, Fixed K12 H

pre-takeoff at LaRC

transmit pol offset angle = 103 °

Fixed uplink power = 11 W

pwr meter = 2.0 dBm;

measured M->F frequency: 70.00074 MHz

fixed to mobile

f:m xpndr: K12H

user data rate: 2048

C: -52.2

Eb/No: 14.6

time: 1:06 pm

UL freq: 14240 DL freq: 11940

Viterbi:0.5 R-S:0.9(255/235)

No: -1 30.0 C/No: 77.8

BER: 0

mobile to fixed

m:f xpndr: K16H

user data rate: 256

C: -34.3

Eb/No: 12.7 (calculated)

time: 1:06 pm

UL freq: 14320

Viterbi: 0.5 R-S: none

No: -101.0 C/No: 66.7

BER: 0

DL freq: 12020

NASA/T_2002-212006 25

Appendix 5: Typical Link Budget

Title: GE5 aeronautical experiment (GE-5)

Fri Mar i0 09:21:29 2000

mobile to satellite

mobile uplink frequency:

mobile uplink EIRP:

mobile-to-sat range:

atmospheric attenuation:

pointing loss:

satellite GT:

mobile-to-sat uplink C/No:

satellite to fixed

14.50 GHz

36.00 dBW

40000 km

0.30 dB

0.30 dB

4.00 dB/K

60.29 dB*Hz

flux density at satellite: -127.63 dBW/m2

flux density for saturation: -88.00 dBW/m2

difference: 39.63 dB

saturated satellite EIRP: 46.00 dBW

sat-to-fixed frequency: 12.20 GHz

sat-to-fixed range: 40000 km

atmospheric attenuation: 0.30 dB

pointing loss: 0.30 dB

fixed station GT: 34.00 dB/K

flux density at fixed station:

base sat-to-fixed downlink C/No:

adjusted sat-to-fixed downlink C/No:

composite

composite C/No:

data rate:

convolutional code rate:

block code rate:

modem bit rate:

composite Eb/No:

required Eb/No:

downlink margin:

uplink margin:

-117.63 dBW/m2

101.79 dB*Hz

62.16 dB*Hz

58.11 dB*Hz

64.00 kb/s

0.50

0.90

142.22 kb/s

6.58 dB

5.50 dB

1.08 dB

3.26 dB

NASA/T_2002-212006 27
fixed to satellite

fixed uplink frequency:

fixed uplink EIRP:

fixed-to-sat range:

atmospheric attenuation:

pointing loss:

satellite GT:

fixed-to-sat uplink C/No:

satellite to mobile

14.50 GHz

80.00 dBW

40000 km

0.30 dB

0.30 dB

2.00 dB/K

102.29 dB*Hz

flux density at satellite: -83.63 dBW/m2

flux density for saturation: -88.00 dBW/m2

difference: -4.37 dB

saturated satellite EIRP: 46.00 dBW

sat-to-mobile frequency: 12.20 GHz

sat-to-mobile range: 40000 km

atmospheric attenuation: 0.30 dB

pointing loss: 0.30 dB

mobile station GT: 12.00 dB/K

flux density at mobile station: -117.63 dBW/m2

base mobile-to-sat downlink C/No: 79.79 dB*Hz

adjusted sat-to-fixed downlink C/No:

composite

composite C/No:

data rate:

convolutional code rate:

block code rate:

modem bit rate:

composite Eb/No:

required Eb/No:

downlink margin:

uplink margin:

79.79 dB*Hz

79.77 dB*Hz

1544.00 kb/s

0.50

0.90

3431.11 kb/s

14.41 dB

6.50 dB

7.91 dB

30.44 dB

NASA/T_2002-212006 28

Form Approved REPORT DOCUMENTATION PAGE

OMB No. 0704-0188

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources,

gathering and maintainingthe data needed, and completing and reviewingthe collection of information. Send comments regarding this burden estimate or any other aspect of this

collection of information, including suggestions for reducing this burden,to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson

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1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

December 2002 Technical Memorandum

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

Airborne Satcom Terminal Research at NASA Glenn

6. AUTHOR(S)

Doug Hoder and Robert Zakrajsek

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

John H. Glenn Research Center at Lewis Field

Cleveland, Ohio 44135-3191

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

WB S-22-727-01-04

8. PERFORMING ORGANIZATION

REPORT NUMBER

E- 13693

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

NASA TM--2002-212006

11. SUPPLEMENTARY NOTES

Responsible person, Doug Hoder, organization code 5640, 216433-3438.

12a. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified - Unlimited

Subject Category: 04 Distribution: Nonstandard

Available electronically at bttp://gltrs.arcmasa.gov

This publication is available from the NASA Center for AeroSpace Information, 301-621-0390.

12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

NASA Glenn has constructed an airborne Ku-band satellite terminal, which provides wideband full-duplex groundaircraft communications. The terminal makes use of novel electronically-steered phased array antennas and provides

IP connectivity to and from the ground. The satcom terminal communications equipment may be easily changed

whenever a new configuration is required, enhancing the terminal's versatility.

14. SUBJECT TERMS

Satellite communication; Aircraft communication

17. SECURITY CLASSIFICATION

OF REPORT

Unclassified

NSN 7540-01-280-5500

15. NUMBER OF PAGES

31

16. PRICE CODE

18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT

OF THIS PAGE OF ABSTRACT

Unclassified Unclassified

Standard Form 298 (Rev. 2-89)

Prescribed by ANSI Std. Z39-18

298-102