types of commercial satellites

Technical Introduction to Geostationary Satellite Communication Systems Original Prepared by Telesat Canada

Slide Number 1Rev-, July 2001

Vol 2: Communication Satellites

Section 1Types of Commercial

Satellites

Photo Used By PermissionPhoto Used By Permission

Figure 2.1b. Panamsat PAS-7Figure 2.1a. COBE

Photo Used By PermissionPhoto Used By Permission



• Earth Observation• Navigation• Scientific• Technology Development• Communications

2.1: Types of Commercial Satellites

This course will focus on Communication Spacecraft, but a brief overview of other types of spacecraft will be presented in this section.

One possible way of categorizing spacecraft types is as follows:

Introduction

Over 80% of existing satellites fall into the Communications category.




2.1: Types of Commercial SatellitesVol 2: Communication Satellites

.01nm.1nm 1nm 10nm .1 1 10 100 0.1cm 1cm 10cm 1m 10m 100m 1km 10km 100km

RadioInfraredUltra-Violet

X-RaysGammaRays

EHF SHF UHF VHF HF MF LF VLF

Visible

3x1019 3x1018 3x1017 3x1016 3x1015 3x1014 3x1013 3x1012 3x1011 3x1010 3x109 3x108 3x107 3x106 3x105 3x104 3x103

0.4 0.6 0.8 1.0 1.5 2 3 4 6 8 10 15 20 30

Visible Near Infrared

V B G Y O R

MiddleInfrared

Far Infrared(Thermal IR)

ExtremeInfrared

Satcom

Figure 2.1c. The Electromagnetic Spectrum

Courtesy of Telesat CanadaCourtesy of Telesat Canada

Depending upon their intended function, satellites make use of some part of the electromagnetic spectrum.



2.1.1: Earth Observation SatellitesSec 1: Types of Commercial Satellites


Figure 2.1.1a. Visual Image, Montego Bay, Jamaica

Photo Courtesy of Photo Courtesy of Spaceimaging.comSpaceimaging.com

Earth Observation Satellites can be subcategorized by where they operate in the frequency spectrum and the processes employed.

Visual, or Optical, satellites offer the highest resolution with the simplest,

mostly passive technology.

Four Categories•Visual•Infrared•Microwave Radiometric•Radar





Figure 2.1.1b. Jubail, Saudi Arabia

However, optical satellites can only be used in the daytime when there is sufficient light, and not in the presence of obscuring weather formations.

Optical imaging satellites require

precise attitude and position control in

order to realize their high resolution

potential.

Optical satellites are used for numerous imaging applications including carto-

graphy, urban or agricultural planning, and . . .

Photo Used by Photo Used by Permission of the Space Permission of the Space

Research Institute, Research Institute, KACSTKACST



. . . Weather Observation. . . Weather Observation

Photo Courtesy of Photo Courtesy of the NOAA Satellite the NOAA Satellite Active ArchiveActive Archive Figure 2.1.1c. Visual Image





Figure 2.1.1d. Infrared Weather Image From METEOSAT-7

Infrared satellites offer moderate resolution, but operate both day and night.

Infrared satellites can also detect thermal radiation, making them ideal for detecting . . .

The disadvantages of infrared satellites

are their limited coverage and

complicated onboard electronics.

Photo Used By Photo Used By PermissionPermission



Photos Courtesy of Photos Courtesy of the NOAA Satellite the NOAA Satellite Active ArchiveActive Archive



Figure 2.1.1e. Infrared Fire Images, Cuba and Manitoba, Canada (Inset)

Fire!





Figure 2.1.1f. Composite Image of a Hurricane

Earth Observation Satellites usually have numerous sensor packages onboard.

The output of these packages can be combined to form stunning images.

This image was created by combining visible, near-infrared, and infrared imagery. Photo Courtesy of SSEC, UW-MadisonPhoto Courtesy of SSEC, UW-Madison



Figure 2.1.1g. Rain & Fire in Borneo, TRMM Spacecraft

This image was created by a similar combination of sensors, this time including Precipitation Radar (PR)

Images like this led to an understanding of how

smoke suppresses rain formation.



It’s raining on the left, but in the middle the green depicts suspended droplets. Smoke particles cause the droplets to condense before they grow large enough to fall as rain.

Photo Courtesy of Visual Photo Courtesy of Visual Earth, NASAEarth, NASA Image by Greg Image by Greg

Shirah, NASA Goddard Space Flight Shirah, NASA Goddard Space Flight Center Scientific Visualization Center Scientific Visualization

StudioStudio


Slide Number 11Rev-, July 2001 Figure 2.1.1h. Mideast Dust Storms by Microwave Radiometry

Microwave Radiometry is a passive process employing only receivers. These measure the intensity of radiation—or thermal brightness—across a band of interest.

Microwave Radiometry is used

to measure many atmospheric and

surface conditions including rain, dust, soil, ocean and ice.

Dust Storm

Photo Courtesy of Photo Courtesy of the NOAA Satellite the NOAA Satellite Active ArchiveActive Archive



Figure 2.1.1i. The TRMM Spacecraft Instrument Package

Microwave Radiometry can be used day and night, is somewhat immune to weather conditions, has good swath coverage, offers below-surface penetration, and can take advantage of unique target signatures.

On the other hand, Microwave Radiometry

has poor resolution and requires very precise

instrument calibration.



Photo Courtesy of Photo Courtesy of NASA/NASDA/CRLNASA/NASDA/CRL



Figure 2.1.1j. Radarsat 1 Image of Montreal, Canada (Radarsat 2 Inset)

Radar Satellites play a key role in agriculture, cartography, forestry, oceanography, ice studies, coastal monitoring, wind scatterometry, and groundwater studies.

Radar Satellites employ Synthetic Aperture

Radar (SAR), which is a way of producing,

with a small antenna, resolutions that would otherwise be possible

only with extremely large antennas.



Photos Courtesy Canadian Space AgencyPhotos Courtesy Canadian Space Agency© Canadian Space Agency 2001© Canadian Space Agency 2001Website: http://www.space.gc.caWebsite: http://www.space.gc.ca



Figure 2.1.1k. Radarsat Image of an Oil Spill

Radar-equipped satellites have tremendous advantages. They actively provide own illumination, produce images of excellent resolution, operate both night and day, and can operate through weather formations. Radar can penetrate below Earth’s surface, provide a large coverage area, and can even detect motion.



Photo Courtesy Canadian Space AgencyPhoto Courtesy Canadian Space Agency© Canadian Space Agency 2001© Canadian Space Agency 2001Website: http://www.space.gc.caWebsite: http://www.space.gc.ca



Figure 2.1.1m. Radarsat Image of Cape Bretton Island, Canada

Disadvantages certainly include the high power, complexity and cost of the satellite, and the fact that vast amounts of data are generated, which must then be downlinked and processed.



Figure 2.1.1l. Radarsat Imaging Model

Photos Courtesy Canadian Space AgencyPhotos Courtesy Canadian Space Agency© Canadian Space Agency 2001© Canadian Space Agency 2001Website: http://www.space.gc.caWebsite: http://www.space.gc.ca



Sec 1: Types of Commercial Satellites

2.1.2: Navigation Satellites

Vol 2: Communication Satellites Figure 2.1.2a. Global Positioning System

Global Positioning System (GPS)

Courtesy of The AerospaceCorporation

The importance of Satellite Navigation increases each year as airports, land transports and maritime transports need increased location accuracy.

Originally, navigation satellites were used to examine characteristics of the orbit of a satellite, until it became clear that if we could track the position of a satellite, that the satellite signal could be used to track our own position.

The GPS Constellation began in 1995 and consists of 24 satellites worldwide.

GPS provides satellite signals that are processed in a GPS receiver allowing calculation of location, time and velocity. Accuracy of the GPS can be determined up to the centimeter, depending on the receiver.



2.1.2: Global Navigation Satellite SystemsSec 1: Types of Commercial Satellites


GLONASS (Russian Military)

Figure 2.1.2c. GLONASS

European Geostationary Navigation Overlay System (EGNOS)

© Mark Wade

http://www.astronautix.com/

Figure 2.1.2b. EGNOS


Slide Number 18Rev-, July 2001 Vol 2: Communication Satellites

2.1.2: Navigation SatellitesSec 1: Types of Commercial Satellites

Wide Area Augmentation System (WAAS)

Courtesy of Rannoch Corporation

Figure 2.1.2e. Global Features of Earth’s Ionosphere Captured in GIM

Figure 2.1.2d WAAS

Provided through the courtesy of Jet Propulsion Laboratory,

California Institute of Technology, Pasadena, California.



GNSS - 2: Global Positioning and Navigation Satellite System. It will be

associated with the civilian controlled European satellite constellation GALILEO.MSAS: Multi-Satellite Augmentation System.

MSAS is Japan’s Multi-Functional Transport Satellite (MTSAT) based Satellite System. It is equivalent to the United States’ WAAS, or Wide Area Augmentation System.

2.1.

2



Most early satellites carried a scientific payload.

Today they are mostly looking at space environment, and used for space exploration.

Generally they work over a wide range of energy spectrums:

• Gamma Rays

• X-Rays, UV to Infrared

Photo Used By Permission ofhttp://www.jpl.nasa.gov/galileo/

Figure 2.1.2f Galileo: Space Probe

Most using passive devices to collect

energy.

Trend is toward heavy scientific

payloads.

2.1.3



Figure 2.1.3b Tsinghua-1 and SNAP-1 spacecraft in a launch site clean room. Photo: SSTL

Figure 2.1.3a Engineers look over the SNAP-1 spacecraft in a clean room prior to launch. Photo: SSTL

Photos used bypermission of Surrey Satellite

Technology Ltd


2.1.3: Scientific SatellitesSec 1: Types of Commercial Satellites



4 Main Types of Service• Broadcast Satellite Services (BSS) or DBS

• Fixed Satellite Services (FSS)

• Mobile Satellite Services (MSS)

• Multimedia Services

2.1.4: Communication SatellitesSec 1: Types of Commercial Satellites


Image Courtesy of Telesat Canada

Figure 2.1.4 Satellite Communications System for Telesat Canada



2.1.4.1: BSS/DBS Communication SatellitesPart 4: Communication Satellites

Vol 2: Communication Satellites, Sec 1: Types of Commercial Satellites

Broadcast a signal from selected ground stations to a widely distributed audience (point to multipoint.)

One-way high data rate operation, Forward Link Only. No limitation on the transmit station.

For DBS, user terminal should be as small as

possible since service is directed to private home.

Large spectrum available.

BSS/DBS Requirements

Figure 2.1.4.1 Broadcast System for Arabsat

Image Courtesy of Arabsat



FSS Communication SatellitesFSS Communication Satellites were the first services provided by satellite.

They use mainly C- and Ku-Band.

Requirements:

• Adapt to low and high data rate, mainly in Star Network

• Adapt to numerous types of modulation and access schemes

• Service directed to Business and Government, terminal cost not as critical as BSS, larger antennas acceptable

• Fairly large spectrum available at Ku-Band, crowded at C-Band

2.1.4.2: FSS Communication SatellitesPart 4: Communication Satellites




MSS Communication SatellitesFirst Generation of Geo-Mobile Satellites had a very limited capacity, using large beams and low power transponders.

User terminals were huge Shipborne (INMARSAT-B) using high power and large antennas.

There was no capability of frequency re-use.

Transponders were bent-pipe.

2.1.4.3: MSS Communication SatellitesPart 4: Communication Satellites


Photos Used By Permission of

Quest Telecom International

Figure 2.1.4.3 Inmarsat-B



2.1.4.3: MSS Communication SatellitesPart 4: Communication Satellites


MSS Communication SatellitesMSS Communication Satellites are mobile communications from anywhere in the world. Today it is a critical part of global data, broadband and voice communication.

By 2004 it is expected that over 1,000 Mobile Satellite Service Satellites will provide satellite telephone coverage. Members of this constellation include Aces, Agrani, EAST, Globalstar, ICO, Odyssey, Teledesic and Thuyra.

Today MSS is being used for:• Public Uses • Private Uses

• Land Mobile Telephone • Federal Uses

• Cellular Telephone • Radio Paging



Requirements • Asymmetric traffic with high data rate from user to the

gateway and ideally unlimited rate from the gateway to the user.

• Similar to MSS, for financial success, the user terminal must be inexpensive, with antenna sizes less than 1m and power in the area of 1 to 2 Watts maximum.

• Even with 1 GHz of bandwidth available at Ka-Band, the total data rate throughput requires a high frequency re-use factor.

2.1.4.4: Multi-Media Satellite ServicePart 4: Communication Satellites


types of commercial satellites

Engineering