Real-time position readout and fault message
Multiple control modes
Step Track control mode
Memory Track control mode
Practical, user friendly edit mode
Encoding system resolution & repeatability of 0.01°
Battery-backed nonvolatile RAM
Remote control and data entry via RS-232 or RS-422
serial communication ports.
SATCOM Technologies (GDST) Model 7134 Antenna Control System
The General Dynamics SATCOM Technologies (GDST) Model 7134
Antenna Control System is a microprocessor-based system incorporating
digital technology for accurate antenna positioning with high reliability,
maximum flexibility, and a straightforward and practical user interface.
This control system is ideally suited for small to medium aperture antenna
applications requiring capabilities for automatic multiple satellite access,
program track, remote control via an RS-232 or RS-422 communications
link, and optionally automatic step track operation and memory track.
The standard product provides 2-speed axis control for AZ and EL with
a high/low speed ratio of up to 15:1. This is accomplished by application
of user-settable high and low-speed control signals to variable speed
AC drives, which in turn control standard 3-phase induction motors. For
3-axis systems, circuitry is provided for the control of an AC synchronous
stepping polarization motor. The AZ and EL motor controllers employ
integral electronic protection. The drive cabinet includes NEMA-rated
circuit protection devices for each motor/motor controller, which are sized
appropriately for each application.
The rear panel of the 7134
accommodates all I/O for the unit
including drive interface, serial
communications, axis interfaces and
communications with other tracking
7134 Standard Components
The standard product is provided as a 2-speed system for AZ and EL. This
is accomplished by application of user-settable high and low speed control
signals to variable speed AC drives (housed in the 7150 Antenna Drive Unit),
which in turn control standard 3-phase induction motors. For 3-axis systems,
circuitry is provided for the control of a variety of polarization motors. The
AZ and EL motor controllers employ integral electronic protection, and
the drive cabinet includes NEMA-rated circuit protection devices for each
motor/motor controller, sized appropriately for each application. The drive
cabinet housing is foot-mounted and comes standard as a NEMA 4X-rated
enclosure for outstanding corrosion protection.
Adaptive Step Track (AST)
The GDST Adaptive Step Track (AST) algorithm performs the function
of conventional step track peak signal level optimization but without the
random “guessing” errors associated with predetermined fixed scan
patterns. AST employs alternate AZ and EL peaking operations based upon
a mathematical relationship relating the change in received signal level to
a given change in angular position. For each axis, an initial fixed size step
is taken, and signal strength levels before and after the step are used to
determine the magnitude and direction of the corrective (peaking) step
The 7134 system offers standard single
speed brushless size-11 resolvers for
position encoding accuracy.
Once the peak position is determined, flags are set, indicating the direction
of travel of the spacecraft so that the initial step for the next peaking
operation will tend to move the antenna along the satellite ephemeris. This
feature greatly reduces the errors introduced by the “wrong” guess made
during significant portions of the daily satellite drift by algorithms which
consistently make initial steps in a given direction.
Enhanced Memory Track (EMT)
The GDST Enhanced Memory Track algorithm allows the controller to
predict the position of a spacecraft based upon its previous motion.
AST data is stored in an orbit table (residing in non-volatile RAM), and is
available for download over the serial ports. The satellite is tracked from
memory only when the signal power level drops below a user determined
The Intelsat 11-Element (IESS412) Tracking Mode uses ephemeris data to
predict the location of a spacecraft. The antenna is positioned at these
predicted locations and is regularly repositioned to maintain accuracy
within the current deadband. Intelsat sets can be uploaded and viewed
over the serial ports.
Antenna Drive Unit (ADU)
The drive cabinet housing is foot-mounted and comes standard as a NEMA
4X-rated aluminum enclosure for outstanding corrosion protection even in
the harshest of environments.
The 7150 Antenna Drive Unit allows complete manual control of each
antenna axis from the drive cabinet via the Portable Maintenance Control
Unit (PMCU). The PMCU also includes a 50-foot extension cord for
complete control during maintenance operations on or near the antenna
Jog positioning controls for each axis, including
2-speed AZ and EL control, provides fast
and accurate “on-the-fly” positioning. Manual
track “jump” mode allows rapid positioning to
a set of direct-entry coordinates.
Automatic positioning via manual command, to
any of 50 pre-programmed look-angle sets.
Automatic sequential positioning to as many
as 99 time-tagged pre-programmed look-angle
sets over a one week period
Adaptive Step Track
Automatic positioning based on optimization
of a proportional tracking voltage input. Adaptive
nature of Step Track algorithm provides
improved performance with inclined orbit
Enhanced Memory Track
Automatic positioning based on a twentyfour
hour orbit table built with data from Step
Track. This provides the ability to track satellites
when the beacon signal is unavailable.
Automatic tracking to AZ and EL coordinate
sets calculated internally from Intelsat 11
parameter coefficients and site latitude and
Better than 10% of receive beamwidth, RMS, for beamwidths ≥ 0.3° and in
applications with orbit inclinations of up to 5° (orbit inclination ≤ 9 x 3 dB
Absolute, single-speed brushless (size-11) resolvers and LSI resolver-todigital
conversion IC’s (4 volt, 2500 Hz reference signal).
16-bit (.0055°) internal resolution
0.01° front panel display resolution for AZ and EL angles
Absolute Position Encoding Accuracy
0.05° RMS (Standard)
Position Encoding Repeatability
Input Power Requirements
Drive Cabinet: 208-240 or 380-415 VAC, 3-phase, 50-60 Hz, 5-wire WYE.
Current requirements determined by motor horsepower.
ACU: 100-240 VAC, 50-60 Hz, auto-sensing
* Other line voltage interfaces available per specification.
1/2 to 10 HP (Others available per special order).
Dual 0-10 VDC analog inputs, slope 1.0 V/dB to 0.1 V/dB
Contact closure outputs for selecting up to 4 tracking signals.
Remote Communications Interface
RS-232 or RS-422 serial communications for remote monitor and control.
Summary Alarm Output
Normally closed dry contacts, rated 24 VDC at 1 amp.
Required System Interconnect Cabling
(May be provided
by GDST or CFE)
- ACU/Drive cabinet Interface (1) 25/C, #22 AWG
- Resolver/ACU (2) 3-shielded pair, #22 AWG (2-axis systems)
- (3) 3-shielded pair, #22 AWG (3-axis systems)
* System includes 100 feet of interconnect cabling
* Additional cabling available up to a max. length of 500 ft.
Physical Dimensions (Standard Configuration)
5.25H 19W 19D (3 EIA Rack Units)
7150 Drive Cabinet
36H 30W 10D (54H total with legs)
Varies, 100-150 lbs avg.
0 to 50˚ C
-40 to 50˚ C
(Low temp. package necessary below -10˚C)