Citation
Abstract
The existing Deep Space Network (DSN) 34-m antenna was retrofitted with a new PC-based industrial controller, upgraded interface hardware, high-frequency feed and receiver, and a tertiary assembly placed at the vertex of the main reflector. The upgraded wideband radio telescope was designed and built for use in the Goldstone Apple Valley Radio Telescope (GAVRT) outreach program. The servo performance due to the wind disturbance and mechanical components desired for the educational outreach program would be poor if a well-balanced rate loop and new linear-quadratic-Gaussian (LQG) controller were not performed and implemented. This article investigates and addresses antenna servo rateloop anomalies and the effect of the LQG controller to meet the pointing requirement. The anomalies under investigation are: • Low-level azimuth oscillations (~1 mdeg rms) • Elevation oscillations at a rate of 0.6 deg/s (1.4 mdeg rms error) • Poor coherence in elevation compared to DSS-27 (similar antenna) Prior to the servo rate-loop measurement, the servo rate-loop alignment (amplifier parameter configuration and percent torque bias) was performed for both azimuth (AZ) and elevation (EL). Due to the lack of servo rate-loop requirements, the results of the DSS-28 servo rate-loop measurements are compared with the measured values from DSS-27 using a step-function waveform to evaluate percent overshoot, settling time, and rise time, and to address AZ and EL oscillations. The results of both measurements are summarized in Table 4 and Table 5. Figures 9 through 13 illustrate different step amplitudes (0.06 deg/s, 0.6 deg/s, and 1 deg/s), which correspond to different rate commands to show these parameters.
Details
- Volume
- 42-195
- Published
- November 15, 2013
- Pages
- 1–106
- File Size
- 5.6 MB