Servo-Performance Parameters of the NASA Deep Space Network Antennas

The performance of an antenna control system is evaluated using performance parameters such as settling time, bandwidth, steady-state error in rate offsets, and antenna root-mean-square servo error while tracking in wind gusts. The performance parameters are measured in the field, or obtained through analysis and simulations. Limited access time to antennas, incomplete test equipment, limited test/analysis time, and partial models do not allow determination of all the parameters. However, field practice and analytical results indicate correlations among them; hence, even incomplete knowledge of the performance parameters would allow for estimation of the missing parameters. This paper investigates the relationships of the antenna performance parameters as a function of controller gains. It also establishes the interrelationships among the parameters. It does this for an idealized (or rigid) antenna, and extends the relationships to the NASA Deep Space Network antennas (flexible structures with dish sizes of 34 or 70 meters). The results obtained should simplify antenna testing, and allow for better performance evaluation from limited data.