Session
Technical Session VI: Enabling New Technologies and Methods I
Abstract
We will present a model for an earth-to-low-earthorbit optical communications system. The system modeled herein is designed to offer a very lightweight, low power consumption, low data rate communications link from LEO satellites. A novel architecture for a free-space optical communications link is presented and analyzed. For the first time, a method that offers full-duplex communications on a single beam is presented. In addition, a novel data format for free-space optical communications is presented. In this system, both the laser and the downlink receiver are located on the ground. The optical elements located on the spacecraft are a simple uplink receiver and a retromodulator. In fact, the laser transmitter for the system is a semiconductor device. We will present a simple feasibility model for the LOWCAL experiment that provides an estimate of the performance capability and identifies major system tradeoffs. Assuming a laser transmitter power of - 7-dB and a communications data rate of 10-kbps, we expect link margins of 17 dB for the downlink. For the uplink, an SC-FSK format is proposed that is invisible to the downlink and provides a link margin of 20 dB.
Lightweight Optical Wavelength Communications without a Laser in Space
We will present a model for an earth-to-low-earthorbit optical communications system. The system modeled herein is designed to offer a very lightweight, low power consumption, low data rate communications link from LEO satellites. A novel architecture for a free-space optical communications link is presented and analyzed. For the first time, a method that offers full-duplex communications on a single beam is presented. In addition, a novel data format for free-space optical communications is presented. In this system, both the laser and the downlink receiver are located on the ground. The optical elements located on the spacecraft are a simple uplink receiver and a retromodulator. In fact, the laser transmitter for the system is a semiconductor device. We will present a simple feasibility model for the LOWCAL experiment that provides an estimate of the performance capability and identifies major system tradeoffs. Assuming a laser transmitter power of - 7-dB and a communications data rate of 10-kbps, we expect link margins of 17 dB for the downlink. For the uplink, an SC-FSK format is proposed that is invisible to the downlink and provides a link margin of 20 dB.
