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Satellite Downlink Signal Generator

Colmek recently completed work on a custom engineered product for ORBCOMM in Dulles, Virginia. The project consisted of building a Satellite Downlink Signal Generator; the system used an Ettus software radio USB base board and custom transmit module. Colmek wrote a GNU Software Radio application to control the system. Engineers used a SAW filter to achieve the desired specifications. A Mini-ITX (small form factor computer) was selected to run the GNU software radio application. Linux was used as the host operating system. A significant portion of the development effort focused on creating a custom Linux distribution, enabling compact design and rapid start-up. The finished product allowed ORBCOMM to simulate a satellite output using SDPSK modulation, allowing users to accurately test their ground based hardware.