1. RF Presentation

2. Satellite Communications
Higher Application layer
Data link layer
Physical layer (RF Comm.)

3. Terminology
1.Satellite : Satellite is a repeater in a space which reflects radio signal transmitted towards it after boosting it..
2.Transponder: A Trasnspoder is a hardware component onboard the satellite which is tuned to process some part of spectrum (Bandwidth).A Transpoder is usually 36 Mhz in Bandwidth
3.Polarization:Polariztion is actually physical orientation of RF waves in space.Today in all satellite dual polarization in used e.g Horizontal and vertical polarization.If Transmit is vertical then receive is Horizontal.Dual Polarization doubles the Bandwidth capacity of satellite.

4. In Ku band there are three Bands for Downlinking
Ku Bands
In Ku band there are three Bands for Downlinking
Satellite GE-1A
Ghz
Ghz
Ghz
Uplink
Downlink
Ghz
Vsat
NOC
Vertex (9.3 Meter)

5. Tx Rx HPA U/C D/C 10.95-12.75 Ghz Wide Band Amplifier LNA IF Section
Tx Feeder cable
Wide Band Amplifier
Ghz
LNA
HPA
Ghz
Ghz
U/C
D/C
52-88 Mhz
52-88 Mhz
IF Section
IF Section

6. a) RF section b) Tracking section
RF section receives signal from satellite and converts it into IF signal and provides feed to IF section and it receives IF signal for transmitting from the IF section;upconvertes ,amplifies it and Transmit to the satellite.
RF section also contains the components for Tracking of the satellite.(There is small drift in satellite path).
RF section has rackmounted monitoring for section components and varions signal parameters e.g Spectrum analyzer and Health Monitor PC.
a) RF section b) Tracking section

7. HPA A HPA B HPA Bk U/C switch (MITEQ) Horizo Pol.
Vertical Pol. Coaxial feeder cables
30 dB atte.
Input Ghz output 70 Mhz
Waveguide switch
Bk UP U/C
HPA switch
U/C switch
(MITEQ)
Vertical Pol Tx
U/C A
HPA A
(CPI 25 dB atte.
700 W 75dB)
U/C B
Vertical Tx
U/C C
U/C D
Horizo Pol. Tx
HPA B
Horizo Pol. Tx
Comb.
Comb.
HPA Bk
Fixed Metal cabling

8. D/C switch MITEQ Horizo Rx (DC supply 26 V and control) Bk UP D/C
LNA B
LNA A
Bk UP D/C
D/C switch
MITEQ
D/C A
Horizo Rx
D/C B
D/C C
D/C D
Vertical Rx
LNA Switch
Logic Controller
Split.
Split.

9. Device Operation Each and every component contains front panel for
configuration and control.
There are two modes of Operation Local/Remote.
In local mode control is local and in remote mode component is controlled remotely by switch.Backup components must be in Remote mode.
Protection Switches are used to Switch in the Backup components if some Online components goes down.Switchs keep on polling Online components for health like power supply and alarms.
All switches work in either Auto or Manual mode.In Auto mode in case of failure switch would do switching automatically so switches must be in Auto mode(use front panel for setting it)

10. UPC Uplink power control ACU
There is rain absorption in Ku Band. Uplink power control is used in Ku Band to compensate for rain absorption.
BDC
L band input
U/C
Tracking receiver
ACU
To U/C
Channel(1-10)
(There can be 10 channels and UPC can provide 20 dB Clear Sky Atte.)
Splitter
Receiver A
UPC
(Failsafe By pass)
(Input 0-10 VDC)
10dB fixed atte.
IF Section

11. 2) Closed loop Operation
Uplink power control
Open loop Operation
Rain
Beacon from satellite
2) Closed loop Operation
CW signal is sent by
earth Station itself
Signal generator
Uplink to satellite
UPC

12. Tracking ACU Drive cabinet Interface From BDC Tracking receiver
POL EL
(Control cables to Drive cabinet Resolvers) AZ
ACU
From BDC
Tracking receiver
(Tracking receive process the Beacon
and provides input to UPC and Tracking
receiver.)

13. Tracking
1) Step Tracking:In step tracking ACU tracks the satellite in steps in each direction step tracking is algorithm embedded in ACU as software.ACU tracks the satellite periodically.Time period can be set on the basis of satellite drift and beam width of antenna.
2) Program Tracking: In Program Tracking ACU can be pre-tuned for various satellites.
Antenna can be manually tracked if required in situations like moving to new satellite and when antenna gets trapped in side lobe.
If there is no Beacon visible like in rains or source failure ACU stops tracking.For normal operations ACU should be in Auto Tracking.

14. FEP Remote Monitoring WINNT 4.0 Workstation Running PCANYWHERE
And Compass runtime.
Serial cables
Remote interfaces
LAN connectivity
FEP
WINNT 4.0 Workstation running Compass runtime software for control and monitoring

15. Signal Monitoring Spectrum Analyzer Horizotal Rx (Signal in IF)
LNA B
LNA A
D/C A
Horizotal Rx
D/C B
D/C C
(Signal in IF)
D/C D
Vertical Rx
Spectrum Analyzer
9Khz to 22Ghz
Split.
Split.
(Signal in RF)

16. There is difference between Uplink and Downlink
Some calculations
There is difference between Uplink and Downlink
Frequency that is called Delta of satellite
For GE-1A Delta is 1748 Mhz
Uplink Frequency: Ghz
Downlink Frequency : Ghz
Relation between RF and IF
Frequency in RF=(Center Frequency of U/C)-70+(IF Frequency)

17. Thank You!!
Queries????