Effects of polarization rotation in the detection and tracking of orbiting objects using LabVIEW

The detection and tracking of orbiting space debris is vital for spacecraft safety and satellite longevity. The United States Air Force Space Surveillance System (AFSSS) uses a continuous wave (CW), multiplestatic site radar system designed to detect, catalog, & track objects orbiting over the continental United States. Object position data collected by the AFSSS stations is categorized by the operation center and sent to the North American Aerospace Defense Command (NORAD) to issue warnings to the aerospace community. The AFSSS was designed using cost effective linear polarization for their transmitter´s (vertical polarized) and receiver´s antennae (horizontal polarized). When the vertically transmitted polarized radio frequency (RF) fence is crossed by an orbiting object, the object rotates the RF polarization, resulting in a RF horizontally polarized echo. However, charged particles in the ionosphere often randomly rotate the RF polarization as RF travels through the atmosphere. The AFSSS receivers´ antennae lack the equipment to detect vertically polarized RF echoes, which leads to a substantial loss of RF echo signal and degradation in AFSSS performance. A LabVIEW-based Monitor Receiver System (MRS) was designed to receive vertical & horizontal polarized signals of a selected target. By comparing signals received using the MRS vertically & horizontally polarized antennae, we show that there is significant signal power transfer from horizontal polarized to vertical polarized echoes, as a result of signal polarization rotation. In addition, this work: 1) Compares control of antennae direction models using transfer functions (TF), 2) Develops a proportional integral derivative (PID) controller TF for improved antennae positioning, 3) Tracks John Glenn 1998 space shuttle trip. This makes the MRS a viable tool for evaluating AFSSS performance and future modifications to increase detection and tracking of orbiting objects.