Ee650 comm plan_report_schwappach

CTU: EE650: CTU Communication Link with Manaus, Brazil

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Colorado Technical University

EE650 Space Communications

CTU Communication Link with Manaus, Brazil

December 2011

Loren K. Schwappach, Author

ABSTRACT: This lab involves the communication planning for a theoretical link between CTU at Colorado Springs, Colorado and

a research facility in Manaus, Brazil. The report walks through the site and equipment selection process, frequency planning stage,

rain / frequency considerations, and the calculation of several link characteristics.

I. INTRODUCTION

OLARADO Technical University would like to establish

a communication link via satellite with a new research

facility that just started in Manaus, Brazil. CTU has asked for

a plan outlining a possible communication path to include two

earth stations and a commercial satellite. CTU is planning on

using 100 kHz of bandwidth between the two sites and has

request that the proposed link maintain a minimum of total

carrier power to noise power spectral density (C/No)T of 70

dBHz. Finally the communication plan should take into

account rain attenuation (p=0.01%) as the research facility is

in a high rain area.

II. OBJECTIVES & CONSTRAINTS

Completion of this communication plan must include:

Uplink and downlink frequencies

ES Antenna diameter

Antenna efficiency

Required transmit power

Antenna polarization

Feeder requirements

Multiplexing/Modulation method

Any assumed parameters

.

In order to ensure the communication plan is successful it

will be split into 5 sections. Section 1 introduced the project.

Section 2 gave additional requirements for the plan. Section 3

covers the site and equipment (ground station and satellite)

concerns and recommends a specific system. Section 4 covers

the link configuration and thus rain attenuation at the two

locations. Section 5 involves the calculations for satellite

distance, azimuth and elevation pointing angles, EIRP

calculations, path loss calculations, receiving gain

calculations, power received calculations, G/T, and (C/No)

results for uplink and downlink.

III. SELECTIONS

A. Site selection

Identifying/analyzing communication sites should always

be conducted prior to any other communication planning. The

sites must have adequate power, environmental conditions,

grounding, and unobstructed view in order to communicate

with their respective satellites. Therefore site identification

and selection must be completed before satellite and earth

station selections are considered.

CTU has requested a communication link between the CTU

campus in Colorado Springs, Colorado and Manaus, Brazil.

Using Google Earth the latitudes (lat), longitudes (lon) and

height above sea level (hs) were obtained for the two locations

as shown by Fig. 1, and Fig. 2.

Fig. 1. Site 1: Colorado Technical University (latitude 38.9 degrees, longitude -104.84 degrees, elevation (hs=1903m).

C


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Fig. 2. Site 2: Manaus, Brazil (latitude -3.1 degrees, longitude -60.02 degrees,

elevation (hs=30m).

Location Latitude Longitude Height above Sea

Level (Hs)

Site 1: CTU 38.9º -104.8º

(255.2º E)

1903m

Site 2: Manaus Brazil -3.1º -60º (300º E) 30m

Table I: Site Location Data (lat, lon, elevation).

Site selection also involves collection of environmental data

such as weather statistics. Rain attenuation can play a

significant factor at higher frequencies. Thus a look at the rain

intensity exceeded for more than 0.01% of the average year

was completed for both sites. The results are shown by Fig. 3

and Fig. 4.

Fig. 3. Site 1: R0.01 = 35 mm/h. Rain intensity exceeded for more than 0.01%

of the average year. Image/data retrieved from [1].

Fig. 4. Site 2: R0.01 = 100 mm/h. Rain intensity exceeded for more than

0.01% of the average year. Image/data retrieved from [1].

Location R0.01

Site 1: CTU 35 mm/h

Site 2: Manaus Brazil 100 mm/h

Table 2: Rain intensity exceeded for more than 0.01% of the average year

(R0.01) [1].

The results of Table 2 taken from Fig. 1 and Fig. 2 show

that the rain intensity at Site 2, Manaus Brazil is

approximately three times that of Site 1, CTU. Therefore rain

attenuation may play a significant factor in Site 2’s

calculations especially at higher frequencies. While higher

frequencies allow the use of smaller dish sizes lower

frequencies are less susceptible to rain attenuation.

Another consideration that needs considered during site

analysis is the yearly average 0º C isotherm height above

mean sea level (h0). The results for the two sites are shown by

Fig. 5 and Fig. 6.


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Fig. 5. Site 1: h0 = 3 km. Yearly average 0º C isotherm height above mean sea level. Image/data retrieved from [1].

Fig. 6. Site 2: h0 = 4.5 km. Yearly average 0º C isotherm height above mean sea level. Image/data retrieved from [1].

Location H0

Site 1: CTU 3km

Site 2: Manaus Brazil 4.5km

Table 3: h0, Yearly average 0º C isotherm height above mean sea level [1].

The results from Table 3 show that Site 2’s yearly average

0º C isotherm height above mean sea level will play a more

significant role towards rain attenuation than site 1.

Furthermore, since site 1 is at a much higher elevation (hs is

approximately 1870m higher) than site 2, site 2 will have a

much larger slant length result than site 1.

B. Satellite Selection

With some basic knowledge about site locations and

weather conditions satellites can now be considered. Since

Satellite bandwidth time can become quite costly it is often

better to consider the satellite before considering the ground

station antenna package (earth station).

For simplifying the link analysis as well as providing

simplified satellite tracking at the sites a geosynchronous

(GEO) satellite is required. Since GEO satellites have a 0º

inclination and orbit the earth at approximately 35,786 km

(altitude ra = 35,786 km) their beams/coverage areas remain

apparently fixed at the same location. This will be necessary

for the communication link. A useful chart of GEO satellites

can be found at http://www.satsig.net/sslist.htm [4] there are

over 440 GEO satellites listed on the website. Combining this

data with general site locations can help in narrowing down a

search for satellites with coverage areas.

The satellite selected would also have to be a commercially

available satellite as CTU is a for profit school and there

would be issues obtaining satellite usage on US or foreign

government satellites. Intelsat owns the world’s largest fleet

of commercial satellites [1] so http://intelsat.com [5] was a

great place to start looking for satellite options. Using

Intelsat’s Interactive Satellite Coverage Map [5] the satellite

search was narrowed down to the region covering both North

America and South America. IS-14 quickly looked to be the

optimal choice for the communication link. IS-14 had a single

C-band beam coverage of both sites (allowing both sites to

utilize the same satellite beam). IS-14 also has a large C-band

EIRP over the two locations [5]. C-band frequencies range

from 4 to 8 GHz [1]. The C-band frequency range is less

susceptible to rain attenuation than the higher frequency Ku-

band and Ka-band frequencies making it better suited in high

rain fall areas like Brazil. Fig. 14 and Fig. 15 show some

features of the IS-14 satellite. Fig 16 lists some additional

information.

Fig. 7. IS-14 at -45º (315ºE) C-Band Beam Coverage Map. Image/data retrieved from [5].

http://www.satsig.net/sslist.htm

http://intelsat.com/


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Fig. 8. IS-14 at -45º (315ºE) C-Band Beam Coverage Map (Key Parameters).

Image/data retrieved from [5].

Fig. 9. Wolframalpha.com info on IS-14 at -45º (315ºE) [6].

IS-14 Chosen C-band Parameters Value

Amplifier type TWTA 50 W EIRP (Site 1) 39.5 dBW

EIRP (Site 2) 41.5 dBW

Antenna efficiency .75

1º

Number of C-Band Linear

Transponders

20 x 36 MHz

Polarization Linear – Horizontal or Vertical

Downlink Frequency 3700 to 4200 MHz

Uplink Frequency 5925 to 6425 MHz Orbital Altitude 22239 miles (35,790.2 km)

Inclination 0.0053

Table 4: IS-14 Chosen C-band Parameters [5] [6].

Intelsat 14 was launched in November 2009 and has an

expected design life of 15 years [6] and was selected as the

ideal satellite for this activity due to its beam coverage and

high EIRP at the site locations.

C. Earth station system selection

After selecting the satellite it was necessary to determine an

adequate and simple to operate C-band capable antenna

system that is easily transportable, and able to provide an

adequate EIRP and gain for transmission and reception. Fly

Away Mobile’s 2.4m C-band system looked like a simple, cost

effective option, providing a quick setup (estimated 20

minutes) portable antenna system featuring a SSPA capable of

200W RF power output, QPSK modulation, Forward Error

Correction (FEC rates of 1/2, 3/4, 5/6, and 7/8), Maximum

data rate of 17.5 Mbps, and capable of taking Analog

Composite or Digital SDI inputs [7]. The system also features

a Midband Gain of 42.6dBi transmit and 38.2dBi receive with

an antenna efficiency of = .76. The system also features a

manual crank for fine tuning azimuth and elevation [7]. Fig.

10 below illustrates some of this information.

Fig. 10. Fly Away Mobile 2.4m C-band Ant Sys Specifications [7].

Fly Away Mobile C-band 2.4m

System Specifications

Value

Amplifier type SSPA 200 W

Antenna diameter 2.4 m

Antenna efficiency .76

1.42º

Transmit Frequency Range 5.7 GHz to 6.725 GHz

Receive Frequency Range 3.4 GHz to 4.2 GHz

Antenna Noise at 30 Elevation 35 K

Midband Gain (Rx/Tx) 38.2dBi / 42.6 dBi Typical G/T (Clear Sky) 19dB/K

Table 5: Fly Away Mobile 2.4m C-band Parameters [7].


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IV. LINK CONFIGURATION

A. Link diagram

Now that both the satellite (IS-14) and earth station (Fly

Away Mobile 2.4m) have been selected the next step would be

to call Intelsat and get a configuration plan for satellite usage.

Intelsat would provide the uplink and downlink frequencies

available for use as well as other settings such as maximum

transmit power allowed. Intelsat 14 has a transponder

translation frequency of 2.2256 GHz which means that the

input (uplink) will be translated to a output (downlink) of

Uplink minus 2.2256 GHz. This exercise will assume Intelsat

14 will allow us to transmit using two separate C-band

transponders for power management and has authorized the

frequencies as shown by Fig. 11. The reason the two uplinks

are separated by 36 MHz is because of the transponders

separation of 36 MHz on the satellite. Often several small

bandwidth users may share a single transponder but have

separate assigned uplink frequencies. However in this

exercise it is assumed that each link (UL-SL-DL) x 2 is using

a separate transponder.

Fig. 11. Simulated Frequency Assignment.

Terminal Value

Site 1 uplink (fu1) 5.961 GHz Site 2 uplink (fu2) 5.997 GHz

Site 1 downlink (fd2) 3.772 GHz Site 2 downlink (fd1) 3.736 GHz

Table 6: Frequency Assignments.

B. Specific rain attenuation at both sites

Before calculating rain attenuation for use in link budget

calculations a knowledge of the specific attenuation caused by

rain for the sites is necessary. Now that frequencies and rain

intensity exceeded for more than 0.01% of the average year

have been identified the specific attenuation caused by rain

can be estimated using a nomogram like the one shown by

Fig. 12 and Fig. 13.

Fig. 12. Specific attenuation caused by rain of Site 1 (Uplink: = 0.18

dB/km, Downlink: = 0.02 dB/km)

Fig. 13. Specific attenuation caused by rain of Site 2 (Uplink: = 0.4 dB/km,

Downlink: = 0.08 dB/km)

It is observed that by choosing to operate in the C-band

frequency range we significantly decreased the attenuation


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effects that would be caused by rain. Since rain attenuation is

no longer a significant factor for the links (<1dB/km) rain

calculations for this assignment will ignore the horizontal and

vertical adjustment factors (which tend to make a minor

reduction in calculation results) and assume the effective

length Le is equal to the slant height Ls when performing rain

attenuation calculations later in this report.

V. CALCULATIONS

A. Satellite distance calculations

Before performing satellite link budget calculations the

distance between each site and the satellite must be calculated.

The orbital altitude (ra) of IS-14 is 35,790.2 km [6], the

recommended mean equatorial radius of the earth (re) is

6378.14 km [1]. IS-14 is a GEO satellite fixed above the earth

at (lat = 0º, lon = -45º (315º E)). Site 1 is at (lat = 38.9º, lon =

-104.8º (255.2º E)). Site 2 is at (lat = -3.1º, lon = -60º (300º

E)). Using this data and the law of cosines we can find the

distance between the sites (ES1 and ES2) and the satellite (SL).

1) Distance between ES1 and SL

Imagine an imaginary satellite (iSL) forming the triangles

as shown by Fig. 14.

Fig. 14. Diagram used for calculating ES1 to SL distance.

Using the law of cosines:

(1)

Finally we can use ri and riSL-SL to solve for rES1-SL by:

1) Distance between ES2 and SL

Imagine a new imaginary satellite (iSL) forming the

triangles as shown by Fig. 15.

Fig. 15. Diagram used for calculating ES2 to SL distance.

Finally we can use ri and riSL-SL to solve for rES2-SL by:

B. Satellite azimuth and elevation calculations

1) Satellite azimuth calculations

The formula for finding the antenna pointing azimuth for

the two sites where = the absolute value of the difference of

the ES (lon) from the SL (lon) and = the latitude of the ES

is:

(2)

The Azimuth (A) is found by using the chart below:

Fig. 16. Chart for calculating Azimuth [1].

Thus:

AES1 = (A = 180 – a) = 110.08º

AES2 = (A = a) = 78.59º

Values confirmed using Satellite Finder utility [4]


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2) Satellite elevation calculations

The formula for finding the antenna pointing elevation for

the two sites where = the absolute value of the difference of

the ES (lon) from the SL (lon), = the latitude of the ES, and

is:

(3)

Thus:

EES1 = 14.63º

EES2 = 72.01º

Values confirmed using Satellite Finder utility [4]

C. Assumptions required for link analysis

Now that all of the data has been collected / compiled a few

assumptions are provided due to missing/unavailable data.

For this project the following is assumed true:

Horizontal and vertical adjustment factors are

negligible and thus: LE = LS.

There is no loss due to a polarization mismatch

(polarization of Fly Away 2.4m ant is tunable)

Maximum pointing errors and = .05º

LA (Atmospheric attenuation) = 0.3dB (typical

value)

F (SL and ES Receiver Noise Figure) = 1dB

LFRX = 3dBand LFTX = .1dB

TF (Thermodynamic temp, Feeder and SL

connection) = 290 K

TA (SL antenna noise temp) = 290 K

TG (Ground noise temp) = 45 K

TSky (Sky noise temp) = 100 K (based on freq and

Elevation angle (100 K is high estimate)

Table 7: Project assumptions

D. Collected Known Data Values

The data values collected from specification documents,

charts, and assumptions made thus far have provided the

following information:

Earth Station Satellite Link Other

Table 8: Collected Data for Link Calculations Part 1

Earth Station Satellite Link Other

Table 8: Collected Data for Link Calculations Part 2

E. Individual link performance (Site 1 to SL) uplink 1

In this section the uplink performance from Site 1 (CTU,

Colorado Springs, CO) to the SL (IS-14) are calculated in

order to determine the EIRP, path loss, receiving gain, power

received at the satellite, G/T of the satellite and (C/No) of

uplink 1.

1) EIRP

(4)

(5)

(6)


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2) Calculate Path Loss

(7)

(8)

(9)

(10)

= 207.8 dB

3) Calculate Receiving Gain

(11)

(12)

4) Calculate Power Received

(13)

W (1uW)

5) Calculate figure of merit G/T of the satellite

(14)

(15)

(16)

6) Calculate Carrier Power to Noise Power Spectral

Density for the Uplink

(17)

F. Individual link performance (SL to Site 2) downlink 1

In this section the uplink performance from Site 1 (CTU,

Colorado Springs, CO) to the SL (IS-14) are calculated in

order to determine the EIRP, path loss, receiving gain, power

received at the earth station, G/T of the earth station and

(C/No) of downlink 1.

1) EIRP

2) Calculate Path Loss

= 196.7 dB

3) Calculate Receiving Gain

(18)

(18)

4) Calculate Power Received

(19)

W (2pW)

5) Calculate figure of merit G/T of the Earth Station

(20)


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6) Calculate Carrier Power to Noise Power Spectral

Density for the Uplink

(17)

G. (C/No)T Verification

The project specified a restriction to ensure a minimum

Total Carrier Power to Noise Power Spectral Density (C/No)T

of 70 dBHz. The formula for determining (C/No)T is:

Thus

This is above the minimum of 70

dBHz and fulfills the requirements for the link. This report

excludes calculations for uplink 2 and downlink 2 (Manaus,

Brazil to SL and then from SL to CTU) since the two sites are

using identical ground stations, similar frequencies, minor

losses due to attenuation and sharing IS-14 and thus would

produce similar +/-5% results (still within the

requirement .

VI. CONCLUSIONS

This assignment proved to be an excellent example of the

thought, research, planning, and formula’s that go into

planning a satellite link. In a real world scenario the satellite

coordinators would utilize planning software to assist the user

in planning such a link. As this report showed the power,

frequency, gain, modulation and low noise features of the

earth station can make or break the success of a

communication planning. Choosing a satellite with a large

coverage area and high BW and EIRP can drastically improve

the SNR of equipment and simplify communication planning.

IS-14 launched in late 2009 is a great example of an excellent

commercial satellite and Fly Away Mobile’s 2.4m C-band

antenna is an effective, portable, and easy to setup antenna

with a high enough SSPA (200W) and antenna gain to ensure

connectivity.

REFERENCES

[1] Maral, G. & Bousquet, M. (2009). Satellite Communications Systems 5th

ed. United Kingdom: Wiley

[2] Google Earth Image

[3] Google Earth Image

[4] List of Satellites in Geostationary Orbit. (2011). Retrieved from Satellite Signals Website on December 14, 2011, from

http://www.satsig.net/

[5] Intelsat Coverage Map. (2011). Retrieved from Intelsat Website on December 14, 2011, from http://www.intelsat.com/flash/coverage-

maps/index.html

[6] Flyaway Mobile-Uplink Systems (2.4m C-Band) Brochure. (2011). Retrieved from ATCI Website on December 14, 2011, from

http://www.atci.com/datasheets/Flyaways/Flyaway_Uplink2.4mCband.p

df [7] n2yo.com. Real Time Satellite Tracking INTELSAT 14. Retrieved from

http://www.n2yo.com/satellite/?s=36097

[8] Jamalipour, A. (1998). Low Earth Orbital Satellites for Personal Communication Networks. Boston, MA: Artech House Publishers.

[9] ITU-R (2008). Radiowave propagation information for designing

terrestrial point-to-points links, L. A. R. da Silva Mello & T. Tjelta,

(Ed.), pp. 8-10, ITU, ISBN 92-61-12771-1, Geneva

[10] Kvicera V.; Grabner M. & Fiser O. (2009). Frequency and path length

scaling of rain attenuation from 38 GHz, 58 GHz and 93 GHz data obtained on terrestrial paths, Proceedings of European Conference on

Antennas and Propagation (EuCAP), [CD-ROM], ISBN 978-3- 8007-

3152-7, Berlin, Germany, March 2009, VDE VERLAG GMBH, Berlin


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