The X-band Acquisition Aid (AAP) software is a low-cost acquisition aid for the Deep Space Network (DSN) antennas, and is used while acquiring a spacecraft shortly after it has launched. When enabled, the acquisition aid provides corrections to the antenna-predicted trajectory of the spacecraft to compensate for the variations that occur during the actual launch. The AAP software also provides the corrections to the antenna-predicted trajectory to the navigation team that uses the corrections to refine their model of the spacecraft in order to produce improved antenna-predicted trajectories for each spacecraft that passes over each complex.
The software provides an automated Acquisition Aid receiver calibration, and provides graphical displays to the operator and remote viewers via an Ethernet connection. It has a Web server, and the remote workstations use the Firefox browser to view the displays. At any given time, only one operator can control any particular display in order to avoid conflicting commands from more than one control point. The configuration and control is accomplished solely via the graphical displays. The operator does not have to remember any commands. Only a few configuration parameters need to be changed, and can be saved to the appropriate spacecraft-dependent configuration file on the AAP’s hard disk.
AAP automates the calibration sequence by first commanding the antenna to the correct position, starting the receiver calibration sequence, and then providing the operator with the option of accepting or rejecting the new calibration parameters. If accepted, the new parameters are stored in the appropriate spacecraft-dependent configuration file. The calibration can be performed on the Sun, greatly expanding the window of opportunity for calibration. The spacecraft traditionally used for calibration is in view typically twice per day, and only for about ten minutes each pass.
This work was done by Michael J. Britcliffe and Martha M. Strain of Caltech and Michael Wert of ITT for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com /tsp under the Software category.
The software used in this innovation is available for commercial licensing. Please contact Daniel Broderick of the California Institute of Technology at
This Brief includes a Technical Support Package (TSP).
X-Band Acquisition Aid Software
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Overview
The document outlines the X-Band Acquisition Aid (AAP) software and hardware developed by NASA's Jet Propulsion Laboratory (JPL) to enhance the capabilities of the Deep Space Network (DSN) antennas during the critical phase of acquiring spacecraft shortly after launch. The DSN consists of three complexes located in Goldstone, California; Madrid, Spain; and Canberra, Australia, each equipped with multiple antennas.
The AAP is designed to address the inherent uncertainties associated with spacecraft launches, including variations in launch timing and trajectory. The software utilizes a spacecraft-dependent configuration file to automate the configuration of Acquisition Aid equipment, relieving operators of manual tasks. Once a spacecraft is launched and within view, the antenna equipped with the Acquisition Aid follows a predicted trajectory, which is subject to significant uncertainty.
The Acquisition Aid Processor Software plays a crucial role by polling the Acquisition Aid receiver for the spacecraft's signal level and calculating receiver errors—discrepancies between the receiver's pointing direction and the spacecraft's actual location. It then transforms these errors into corrections for the antenna's predicted trajectory, which are displayed graphically for the operator. When the Acquisition Aid is enabled, the software sends these trajectory corrections to the antenna, improving its alignment with the spacecraft and enhancing the received signal level.
This iterative process continues, leading to increasingly accurate antenna positioning and stronger signal reception. If the spacecraft's signal level drops below a predefined threshold, indicating it may be moving out of the antenna's range, the software automatically disables the Acquisition Aid process.
Additionally, the Acquisition Aid Processor Software provides automated calibration of the Acquisition Aid equipment. It commands the antenna to the correct position for measurements, initiates the calibration sequence, and presents the results to the operator for approval. Accepted calibration values are stored in the configuration file for future use.
Overall, the X-Band Acquisition Aid system significantly improves the efficiency and effectiveness of spacecraft tracking during the critical post-launch phase, ensuring better communication and data acquisition for missions managed by the DSN. The technology not only aids in immediate tracking but also contributes to refining models for future spacecraft passes, enhancing overall mission success.
