Monday, 15 July, 2002

The Antenna Tracking and Control System TS3010 is designed for the positional control of satellite communication Earth Station antennae. Highly accurate control, tracking and prediction facilities make the TS3010 ideal for use with large, very narrow beam antennae.

16 Meter C-Band Antenna with TS3010 Control System, able to operate in adverse weather conditions.

TS3010 includes provision for the monitoring of and interlocking with, antenna status indicators - motion limit switches, emergency stop push-buttons, waveguide air pressure and humidity monitors, etc.

Remote and/or local control can be provided, and TS3010 can be interfaced to an existing or new drive system, antenna angle monitors (encoders, synchros or resolvers), and beacon receivers and down converters.

Facilities provided for interaction with the operator include:

• ORBIT TRACK - combines step-track operation with motion prediction.
• PROGRAM TRACK - passive tracking of satellites from notified parameters.
• POSITION CONTROL - operator control of antenna axis  positions.
• RATE CONTROL - operator control of azimuth and elevation speed.
• POLARISER CONTROL - operator control of polariser mode and/or angle.
• STOW CONTROLS - operator control of stow pins, and fully automatic stowing on demand, from any operational state.
• CALIBRATION - facilities for antenna pointing correction development and application: Includes STAR TRACK.
• STATUS-AT-A-GLANCE - one page visual indication of antenna system state.
• TRENDING - continuous recording and display of tracking parameters.
• ALARM LOG - permanent record of all alarms and warnings, complete with time, date, acknowledgment and clearance.
• SYNCHRONISED TIME - the system will accept and slave to an external time code, or run on its own clock.

The ATCU contains all tracking and control software. A sophisticated position control algorithm operates in closed loop with the antenna motors and drive system, and antenna position monitoring system to produce antenna positioning with a control loop error typically less than 0.002 degrees. The ATCU is an industrial-grade x86 class compatible computer, intended to be located in the antenna building close to the motor Drives. It operates under remote control from the CMU, and does not require a display or keyboard for normal use.

16 Meter C-Band Antenna with TS3010 Control System, able to operate in adverse weather conditions.

The PLC or using Input / outout cards in the ATCU monitors the condition of antenna limit switches, safety and equipment protection interlocks. Under CMU control, it provides stow pin commands to the stow pin drives. The PLC is an industrial-grade unit of standard modular construction, which is usually located close to the ATCU.

The CMU is the operator's interface with TS3010. It provides a user-friendly Human Machine Interface for monitoring and control. A Remote CMU (RCMU) is supplied as standard, usually located in the Satellite Communications Control Room. An optional second CMU can be provided, for local control at the ATCU site. This Local CMU (LCMU) is similar to the normally supplied Remote RCMU - with full or restricted control and monitoring capabilities, as required by the client.

The CMU is a standard x86 class compatible computer which may be a commercial style, suitable for desktop use, or a rack-mounted unit.

A standard 19 inch equipment rack can be provided to house the ATCU and the PLC.  A Terminal Panel specifically designed for easy connection of antenna condition-monitoring circuits and safety interlocks to the TS3010, is also mounted in this rack.

A pair of dedicated four-core signal cables connect the ATCU and PLC to each CMU.

Pointing Accuracy

The TS3010 will control antenna position such that the error between demanded position and the position indicated by the angle monitoring system in use will typically be, (when tracking or holding position, with wind less than 50 km/h):
Less than 0.005 degrees rms.

Note that elements outside the TS3000 can have a detrimental effect on pointing accuracy. The error limit stated herein is readily achievable with an antenna drive similar to the BALDOR system, with motors, gearboxes, antenna structure and angle monitoring system in good condition.

Error limits stated apply over any 1 minute interval, and in the elevation and cross-elevation axes only.

The error correction model is capable of correcting for pointing angle errors in the range 10 degrees to 0.001 degrees.

Tracking Perturbation

During Orbit Track operation, the antenna is stepped off the optimum pointing angle periodically, to enable the Orbit Track system to determine where the optimum pointing angle is, and thus to build a model of satellite motion. This model is used to drive the antenna to follow the satellite, should the beacon signal fall below a preset limit. It can also be used to assist in locating the satellite after driving the antenna off the satellite.

The stepping operation inherently causes a small drop in signal strength during each step.   However the sophisticated self-optimising, predictive filtering used in Orbit Track enables the process to take place using steps as small as 5% of beamwidth.   The resulting  perturbation of signal strength  is  thus  less than 0.03 dB.