2.1    SATELLITE INTERFACES

Kodiak Tracking Station is required to operate with satellites that may differ from each other in their space paths, and in the frequency, type of telemetry, and power requirements of their electronic equipment. The top level system block diagram for KTS shown in Figure 2-1 illustrates the overall configuration required to interface with satellite systems.

In order to interface with the Satellite systems supported by the SCF, the station must have the capability to support the satellite trajectories and frequencies described in the following paragraphs.

2.1.1    Satellite Trajectories

The requirement for acquisition, tracking, telemetry and command coverage applies to satellite tractories (including near-circular, transfer, and maneuvering orbits) having the following characteristics:


Altitude  Range(nmi)       Inclination
Low       100 - 500        Polar and near-polar        
Medium    500 - 20,000     Polar and near-polar
Reentry   4000 - horizon   Polar and near-polar
2.1.2    Frequency Bands

Satellite acquisition, tracking, telemetry and command transmission support shall be provided within the following frequency bands:


Signal        Frequency      Receive
Receive      225 - 260 MHz   VHF
             2.2 - 2.3 GHz   SGLS/
                             Non-SGLS 

Auto Track   225 - 260 MHz   VHF SGLS
             2.2 - 2.3 GHz   SGLS/
                             Non-SGLS
                                                   
Transmit     370 -  470 MHz  UHF
            1.75 - 1.85 MHz  S-band
2.2    MISSION SUPPORT FUNCTIONAL REQUIREMENTS

In the top level functional flow diagram of Figure 2-2 the blocks depict basic requirements applicable to the development and operation of the station. Only those requirements pertaining to mission support are addressed herein.

Lower-level block diagrams of the mission support function -- generally independent of program or station configuration peculiarities -- identify essential support functions and provide a logical framework for hardware, software and procedural development. Mission support (function 1.0 ) includes the pass operations functions (acquisition, tracking, telemetry readout, and commanding), and is illustrated in the first level functional flow diagram, Figure 2-3. Pass operations (function 1.4) are further illustrated in the second-level functional diagram, Figure 2-4. Each of the pass operations functions is discussed individually in the following paragraphs.

2.2.1    Acquisition

The tracking, telemetry, and command (TT&C) antenna subsystem shall be capable of acquiring satellites on the main antenna beam at 3 deg above the horizon and with a 99.9 probability of success (for spatial intercept), under the following conditions:

  1. Satellite rise azimuth uncertainties do not exceed + or - 30 deg.

  2. The signal from the satellite transmitter (including doppler) falls within the frequency tracking range of the ground receiver.

  3. The received signal exceeds the ground receiver acquisition threshold level.

  4. Orbital altitudes are 100 nmi or greater.

For near-zenith passes where the satellite is lost because tracking rates are exceeded, the antenna shall reacquire by moving at maximum angular rates to the predicted reacquisition point using acquisition data on the station slave bus. Functions which must be accomplished to reacquire the satellite as depicted in the third level functional flow diagram of Figure 2-5

2.2.2    Tracking

The first function, illustrated in the block diagram of Figure 2-6, shall provide for positioning of all antennas and for track data generation by the 14-ft TT&C and the 200 MHz Autotracker antenna subsystem as described below:

  1. Antenna Positioning. The direction of the RF axis of the TT&C and the 200 MHz Autotracker antennas shall be controlled in each axis and

 

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