INTERFERENCE IN PALAPA-C SATELLITE SYSTEM

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SATELLITE OPERATION DIVISION

PT. SATELIT PALAPA INDONESIA

PALAPA-C VSAT FORUM

PALAPA-C CHARACTERISTIC

- Satellite : PALAPA-C1 and PALAPA-C2

- Launched : 1996

- Orbital Position : 150.5O East and 113.0o East

- Transponder : 24 C-band (Max EIRP 39 dBW)

4 Ku-band (Max EIRP 53 dBW)

- Polarization : Linear

- Coverage C-band : ASEAN, India, Taiwan, China, Australia,

New Zealand Hong Kong, Bangladesh

and Papua New Gunea

- Coverage ku-band : Japan, South korea, Hongkong,

China, Taiwan, part of ASEAN

- End of life : 2010

PALAPA-C VSAT FORUM

PALAPA-C NEIGHBORS

PALAPA-C 2 (113.0 DEG EAST)

■ TELKOM-1 108.0 DEG

■ ST-1C 110.0 DEG

■ CHINASAT/SINOSAT 110.5 DEG

■ NSAT-110 DEG

■ KOREASAT-1 116.0 DEG

■ PALAPA-B4 118.0 DEG

PALAPA-C VSAT FORUM

TRAFFIC PER 2000

- Earth station :

Fixed 70

Remote VSAT 2000

Tranportable 20

- Carriers :

SCPC 1700

TDMA 50

DAMA 500

Analog TV 9

Digital TV 5

PALAPA-C VSAT FORUM

TYPE OF INTERFERENCE

■ Sun and Moon

■ Tropospheric scintillation

■ Crosspolarization

■ FM Radio rettransmission

■ Multiple round-trip/loop-back

■ Unwanted emission from internal network or

adjacent satellite network

■ Terrestrial link

PALAPA-C VSAT FORUM

SUN AND MOON

■ Down link Interference (E/S received thermal noise from sun

or Moon)

■ Noise temperature equivalent to ~ 15,00 K for 4 Ghz AND

8,000 k FOR 30 ghZ

■ C/N drop by about 40 dB for 4 GHz

■ Twice a year for GEO System

■ The effective noise temperature of Moon is only about 200 K

PALAPA-C VSAT FORUM

TROPOSPHERIC SCINTILLATION

■ Represent the most importan clear air fluctuations of

signal

■ Magnitude of the flictuations increases in some way

with atmospheric water content and frequency

■ Depedence on antenna size, greater fluctuations the

smaller the antenna diameter

■ More information :

www.nwra.com/scintpred/wbmod.html

http://sideshow.jpl.nasa.gov/scint.html

PALAPA-C VSAT FORUM

TROPOSPHERIC

SCINTILLATION

Illustration of the seasonal varition of troposperic

Scintilation (from Howe, Harris and mehler[1992])

14 GHz co-polar, ten minute block

PALAPA-C VSAT FORUM

CROSSPOLARIZATION

– F1 copol signal from tested antena

– f2 cross-pol signal from tested antena

– f11 copol signal from wanted Xpdr

– f12 cross-pol signal from wanted Xpdr

– f21 copol signal from interferred Xpdr

– f22 crodd-pol signal from interfered Xpdr

– CPI = f11 - f 21

– CPI requirement : 30 dB minimun

ff11

f2

f11

f12

f22

f21

Tested

Antena

Ref. Antena

PALAPA-C VSAT FORUM

FM RADIO RETRANMISSION

■ Fm signal, up to 300 KHz bandwith

■ Bad connection and improper grounding or shilding

■ Magnitude of interference dpand on leakage rate and FM

radio station range from E/S

FM station

___________

__________

__________

PALAPA-C VSAT FORUM

FM RADIO Cont,

Identification

■ Demodulation of interfering signal, if posible

■ calculate the IF to find the radio station

■ Coordinate with users, comparing E/s activity

■ Turn off suspected E/S, monitor interference carrier

Inband response of Filter

36 MHz

88 108

140 MHz IF(36/72 MHz BW)

104 176

70 MHz IF(36 MHz BW)

52 88

PALAPA-C VSAT FORUM

FM RADIO SPECTRUM

PALAPA-C VSAT FORUM

MULTIPLE ROUND-TRIP/LOOP BACK

■ The interfering E/S retransmits all carrier within its transponder,

IF or RF equipment

■ Transponder power suddently increase up to 3 dB, depand on

leakage rate

■ the loop-back signal is shifted about 2 KHz (due to accuracy of

oscillatoer on satellite converter)

■ Frequency shifting eventually visible with high resolution

PALAPA-C VSAT FORUM

MULTIPLE ROUND-TRIP Cont.

Identification

■ Transponder power suddently increase up to 3 dB

■ Network Performance decrease, depand on leakage

■ The PA of interfering E/E may overdrive

■ Compare the time of accident with E/S activity

■ Turn off suspected E/S, monitor the loop-back spectrum using

CW carrier

PALAPA-C VSAT FORUM

MULTIPLE ROUND-TRIP SPECTRUM

PALAPA-C VSAT FORUM

UNWANTED EMISSION

■ Coming from internal network, mostly Caused by error in

ground equipment setting (e.g. modem, ODU, HPA, etc)

■ Coming from adjacent network, mostly caused by mispointing or

bad antenna pattern

■ Hard to indentipy and to solve

■ Analyze thr frequency, power and signal form

PALAPA-C VSAT FORUM

UNWANTED EMISSION

PALAPA-C VSAT FORUM

TERRESTRIAL LINK

- Terrestrial link use same frequency as E/S

- Terrestrial signal within E/S antena Sidelobe

- Installed additional Attenuator or faraday cage

PALAPA-C VSAT FORUM

TERRESTRIAL SPECTRUM

PALAPA-C VSAT FORUM

INTERFERENCE IN 1999

PALAPA-C VSAT FORUM

STATISTICS

1997 1998 1999

- Crosspol 29 35 86

- Unwanted 10 27 8

- FM radio 15 45 50

- Loop back 1 2 1

- Terrestrrial 2 6 5

Total number of Interf. 57 115 150 263.2%

PALAPA-C VSAT FORUM

TREND IN SATELLITE COMMUNICATION

■ In line with develoving VSAT technologi, the use of

smaller antenna will increase

■ Increase in human error caused by VSAT network

operators or installer company

■ A lot of adjacent satellites which use same spectrum and

coverage

■ Equipment competition in the market, create chipper

and low performance

PALAPA-C VSAT FORUM

PROGRESS ACTION

Several action has been taken in order to reduce possibility if

producing interference:

■ Socialization of procedure to accses PLAPA-C to customer

■ Conducting training, technical meeting and assisting for

customer and installer company

■ Monitor and control the use of equipment and eliminate low

performance equipment.

■ All VSAT antenna must be verified by satelindo

■ Cooperation among the satellite operator

PALAPA-C VSAT FORUM

CONCLUSION

■ Some interference shall be taken into account in

designing the link budget

■ Number of interference has rapiddly increased

■ Coordination among satellite operators and customers

are required in solving and preventing interference

■ Operators (satellite and network communication) are

encuraged performing standart procedure and

requirement to access the satellite

T H A N K Y O U