Table of Contents

• Overview
• Pictures
• Specifications
• Tracking Software

Overview

• The satellite communication ground station or base station uses two tracking antennas to communicate at 150 and 440 MHz. It will be part of a world-wide network. Tracking maps and current uplink and downlink signals will be available in real-time online. The antennas are located on the roof of Weniger Hall and the transceivers, computers and support equipment are situated in room 635B.
• The ground station consists of a pair of high gain Yagi Uda antennas from M2, a Yeasu G-5500 rotator set, a Kenwood TS-2000X. For software the ground station uses GPredict and FLDigi. The antennas are designed for amateur radio satellite operations. One made of 42 elements circularly polarized, operates from 430 to 438 MHz covering the satellite portion of the amateur 70cm band. It has a 18.9dBic gain and a 21 degree beam width. The other is a 22 element antenna covering the 2m band, 144 to 148MHz, with 14.39dBic gain and 38 degree beam width. The G-5500 provides 360 degrees of azimuthal motion and 180 degrees of elevation, covering all of the visible sky. The motors have an effective pointing accuracy of about 1 degree. The TS-2000X is capable of operating both the 2m and 70cm bands as well as the 1.2GHz bands, the ability to work 2.4GHz can be added with a simple transverter. The radio is used to handle the RF modulation and demodulation. The software FLDigi is used to deal with the encoding and decoding of digital signals into and from audio signals. GPredict uses tracking information from NORAD to track the positions of multiple satellites and provide calculations of the Doppler shift to facilitate communication with the satellites. It also controls the radios and motors. With the current hardware the system can track about 20 satellites at any time and maintain the antennas within about 5 degrees of the target.

Pictures

• Dual Yagi antennas, circularly polarized for 150 and 440 MHz operation, are oriented toward the western horizon.
• Informative display showing passing satellites, antenna orientation and a signal from the transceiver and the USB sound card.
• Motor controllers are interfaced to the computer through the RS-232 protocol.

Specifications

• Ground station specification sheet.

Tracking Software

• Gpredict is the software package used, the manual for which is here.